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153 results on '"N. D. R. Bhat"'

1. Comparing Recent Pulsar Timing Array Results on the Nanohertz Stochastic Gravitational-wave Background

Author: G. Agazie, J. Antoniadis, A. Anumarlapudi, A. M. Archibald, P. Arumugam, S. Arumugam, Z. Arzoumanian, J. Askew, S. Babak, M. Bagchi, M. Bailes, A.-S. Bak Nielsen, P. T. Baker, C. G. Bassa, A. Bathula, B. Bécsy, A. Berthereau, N. D. R. Bhat, L. Blecha, M. Bonetti, E. Bortolas, A. Brazier, P. R. Brook, M. Burgay, S. Burke-Spolaor, R. Burnette, R. N. Caballero, A. Cameron, R. Case, A. Chalumeau, D. J. Champion, S. Chanlaridis, M. Charisi, S. Chatterjee, K. Chatziioannou, B. D. Cheeseboro, S. Chen, Z.-C. Chen, I. Cognard, T. Cohen, W. A. Coles, J. M. Cordes, N. J. Cornish, F. Crawford, H. T. Cromartie, K. Crowter, M. Curyło, C. J. Cutler, S. Dai, S. Dandapat, D. Deb, M. E. DeCesar, D. DeGan, P. B. Demorest, H. Deng, S. Desai, G. Desvignes, L. Dey, N. Dhanda-Batra, V. Di Marco, T. Dolch, B. Drachler, C. Dwivedi, J. A. Ellis, M. Falxa, Y. Feng, R. D. Ferdman, E. C. Ferrara, W. Fiore, E. Fonseca, A. Franchini, G. E. Freedman, J. R. Gair, N. Garver-Daniels, P. A. Gentile, K. A. Gersbach, J. Glaser, D. C. Good, B. Goncharov, A. Gopakumar, E. Graikou, J.-M. Griessmeier, L. Guillemot, K. Gültekin, Y. J. Guo, Y. Gupta, K. Grunthal, J. S. Hazboun, S. Hisano, G. B. Hobbs, S. Hourihane, H. Hu, F. Iraci, K. Islo, D. Izquierdo-Villalba, J. Jang, J. Jawor, G. H. Janssen, R. J. Jennings, A. Jessner, A. D. Johnson, M. L. Jones, B. C. Joshi, A. R. Kaiser, D. L. Kaplan, A. Kapur, F. Kareem, R. Karuppusamy, E. F. Keane, M. J. Keith, L. Z. Kelley, M. Kerr, J. S. Key, D. Kharbanda, T. Kikunaga, T. C. Klein, N. Kolhe, M. Kramer, M. A. Krishnakumar, A. Kulkarni, N. Laal, K. Lackeos, M. T. Lam, W. G. Lamb, B. B. Larsen, T. J. W. Lazio, K. J. Lee, Y. Levin, N. Lewandowska, T. B. Littenberg, K. Liu, T. Liu, Y. Liu, A. Lommen, D. R. Lorimer, M. E. Lower, J. Luo, R. Luo, R. S. Lynch, A. G. Lyne, C.-P. Ma, Y. Maan, D. R. Madison, R. A. Main, R. N. Manchester, R. Mandow, M. A. Mattson, A. McEwen, J. W. McKee, M. A. McLaughlin, N. McMann, B. W. Meyers, P. M. Meyers, M. B. Mickaliger, M. Miles, C. M. F. Mingarelli, A. Mitridate, P. Natarajan, R. S. Nathan, C. Ng, D. J. Nice, I. C. Niţu, K. Nobleson, S. K. Ocker, K. D. Olum, S. Osłowski, A. K. Paladi, A. Parthasarathy, T. T. Pennucci, B. B. P. Perera, D. Perrodin, A. Petiteau, P. Petrov, N. S. Pol, N. K. Porayko, A. Possenti, T. Prabu, H. Quelquejay Leclere, H. A. Radovan, P. Rana, S. M. Ransom, P. S. Ray, D. J. Reardon, A. F. Rogers, J. D. Romano, C. J. Russell, A. Samajdar, S. A. Sanidas, S. C. Sardesai, A. Schmiedekamp, C. Schmiedekamp, K. Schmitz, L. Schult, A. Sesana, G. Shaifullah, R. M. Shannon, B. J. Shapiro-Albert, X. Siemens, J. Simon, J. Singha, M. S. Siwek, L. Speri, R. Spiewak, A. Srivastava, I. H. Stairs, B. W. Stappers, D. R. Stinebring, K. Stovall, J. P. Sun, M. Surnis, S. C. Susarla, A. Susobhanan, J. K. Swiggum, K. Takahashi, P. Tarafdar, J. Taylor, S. R. Taylor, G. Theureau, E. Thrane, N. Thyagarajan, C. Tiburzi, L. Toomey, J. E. Turner, C. Unal, M. Vallisneri, E. van der Wateren, R. van Haasteren, A. Vecchio, V. Venkatraman Krishnan, J. P. W. Verbiest, S. J. Vigeland, H. M. Wahl, S. Wang, Q. Wang, C. A. Witt, J. Wang, L. Wang, K. E. Wayt, Z. Wu, O. Young, L. Zhang, S. Zhang, X.-J. Zhu, A. Zic, and The International Pulsar Timing Array Collaboration
Subjects: Gravitational waves, Pulsars, Astrophysics, QB460-466
Abstract: The Australian, Chinese, European, Indian, and North American pulsar timing array (PTA) collaborations recently reported, at varying levels, evidence for the presence of a nanohertz gravitational-wave background (GWB). Given that each PTA made different choices in modeling their data, we perform a comparison of the GWB and individual pulsar noise parameters across the results reported from the PTAs that constitute the International Pulsar Timing Array (IPTA). We show that despite making different modeling choices, there is no significant difference in the GWB parameters that are measured by the different PTAs, agreeing within 1 σ . The pulsar noise parameters are also consistent between different PTAs for the majority of the pulsars included in these analyses. We bridge the differences in modeling choices by adopting a standardized noise model for all pulsars and PTAs, finding that under this model there is a reduction in the tension in the pulsar noise parameters. As part of this reanalysis, we “extended” each PTA’s data set by adding extra pulsars that were not timed by that PTA. Under these extensions, we find better constraints on the GWB amplitude and a higher signal-to-noise ratio for the Hellings–Downs correlations. These extensions serve as a prelude to the benefits offered by a full combination of data across all pulsars in the IPTA, i.e., the IPTA’s Data Release 3, which will involve not just adding in additional pulsars but also including data from all three PTAs where any given pulsar is timed by more than a single PTA.
Published: 2024
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2. The Parkes pulsar timing array second data release: timing analysis

Author: D J Reardon, R M Shannon, A D Cameron, B Goncharov, G B Hobbs, H Middleton, M Shamohammadi, N Thyagarajan, M Bailes, N D R Bhat, S Dai, M Kerr, R N Manchester, C J Russell, R Spiewak, J B Wang, and X J Zhu
Published: 2021
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3. Commensal discovery of four fast radio bursts during Parkes Pulsar Timing Array observations

Author: S Osłowski, R M Shannon, V Ravi, J F Kaczmarek, S Zhang, G Hobbs, M Bailes, C J Russell, W van Straten, C W James, A Jameson, E K Mahony, P Kumar, I Andreoni, N D R Bhat, S Burke-Spolaor, S Dai, J Dempsey, M Kerr, R N Manchester, A Parthasarathy, D Reardon, J M Sarkissian, R Spiewak, L Toomey, J-B Wang, L Zhang, and X-J Zhu
Published: 2019
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4. Modelling annual and orbital variations in the scintillation of the relativistic binary PSR J1141−6545

Author: D J Reardon, W A Coles, G Hobbs, S Ord, M Kerr, M Bailes, N D R Bhat, and V Venkatraman Krishnan
Published: 2019
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5. A targeted search for repeating fast radio bursts with the MWA

Author: J Tian, G E Anderson, P J Hancock, J C A Miller-Jones, M Sokolowski, C W James, N D R Bhat, N A Swainston, D Ung, and B W Meyers
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE), Space and Planetary Science, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics - High Energy Astrophysical Phenomena
Abstract: We present a targeted search for low-frequency (144--215\,MHz) FRB emission from five repeating FRBs using 23.3\,hr of archival data taken with the Murchison Widefield Array (MWA) Voltage Capture System (VCS) between 2014 September and 2020 May. This is the first time that the MWA VCS has been used to search for FRB signals from known repeaters, which enables much more sensitive FRB searches than previously performed with the standard MWA correlator mode. We performed a standard single pulse search with a temporal and spectral resolution of $400\,μ$s and 10\,kHz, respectively, over a $100\,\text{pc}\,\text{cm}^{-3}$ dispersion measure (DM) range centred at the known DM of each studied repeating FRB. No FRBs exceeding a $6σ$ threshold were detected. The fluence upper limits in the range of 32--1175\,Jy\,ms and 36--488\,Jy\,ms derived from 10 observations of FRB 20190711A and four observations of FRB 20201124A respectively, allow us to constrain the spectral indices of their bursts to $\gtrsim-1$ if these two repeaters were active during the MWA observations. If free-free absorption is responsible for our non-detection, we can constrain the size of the absorbing medium in terms of the electron temperature $T$ to $, Accepted for publication in MNRAS
Published: 2022
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6. Studying the Solar system with the International Pulsar Timing Array

Author: R N Caballero, Y J Guo, K J Lee, P Lazarus, D J Champion, G Desvignes, M Kramer, K Plant, Z Arzoumanian, M Bailes, C G Bassa, N D R Bhat, A Brazier, M Burgay, S Burke-Spolaor, S J Chamberlin, S Chatterjee, I Cognard, J M Cordes, S Dai, P Demorest, T Dolch, R D Ferdman, E Fonseca, J R Gair, N Garver-Daniels, P Gentile, M E Gonzalez, E Graikou, L Guillemot, G Hobbs, G H Janssen, R Karuppusamy, M J Keith, M Kerr, M T Lam, P D Lasky, T J W Lazio, L Levin, K Liu, A N Lommen, D R Lorimer, R S Lynch, D R Madison, R N Manchester, J W McKee, M A McLaughlin, S T McWilliams, C M F Mingarelli, D J Nice, S Osłowski, N T Palliyaguru, T T Pennucci, B B P Perera, D Perrodin, A Possenti, S M Ransom, D J Reardon, S A Sanidas, A Sesana, G Shaifullah, R M Shannon, X Siemens, J Simon, R Spiewak, I Stairs, B Stappers, D R Stinebring, K Stovall, J K Swiggum, S R Taylor, G Theureau, C Tiburzi, L Toomey, R van Haasteren, W van Straten, J P W Verbiest, J B Wang, X J Zhu, and W W Zhu
Published: 2018
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7. Searching for continuous Gravitational Waves in the second data release of the International Pulsar Timing Array

Author: Falxa, M, Babak, S, T Baker, P, Bécsy, B, Chalumeau, A, Chen, S, Chen, Z, J Cornish, N, Guillemot, L, S Hazboun, J, F Mingarelli, C, Parthasarathy, A, Petiteau, A, S Pol, N, Sesana, A, B Spolaor, S, R Taylor, S, Theureau, G, Vallisneri, M, J Vigeland, S, A Witt, C, Zhu, X, Antoniadis, J, Arzoumanian, Z, Bailes, M, R Bhat, N, Blecha, L, Brazier, A, R Brook, P, Caballero, N, D Cameron, A, A Casey-Clyde, J, Champion, D, Charisi, M, Chatterjee, S, Cognard, I, M Cordes, J, Crawford, F, T Cromartie, H, Crowter, K, Dai, S, E DeCesar, M, B Demorest, P, Desvignes, G, Dolch, T, Drachler, B, Feng, Y, C Ferrara, E, Fiore, W, Fonseca, E, Garver-Daniels, N, Glaser, J, Goncharov, B, C Good, D, Griessmeier, J, J Guo, Y, Gültekin, K, Hobbs, G, Hu, H, Islo, K, Jang, J, J Jennings, R, D Johnson, A, L Jones, M, Kaczmarek, J, R Kaiser, A, L Kaplan, D, Keith, M, Z Kelley, L, Kerr, M, S Key, J, Laal, N, T Lam, M, G Lamb, W, W Lazio, T, Liu, K, Liu, T, Luo, J, S Lynch, R, R Madison, D, Main, R, Manchester, R, Mcewen, A, Mckee, J, A McLaughlin, M, Ng, C, J Nice, D, Ocker, S, D Olum, K, Osłowski, S, T Pennucci, T, P Perera, B, Perrodin, D, Porayko, N, Possenti, A, Quelquejay-Leclere, H, M Ransom, S, S Ray, P, J Reardon, D, J Russell, C, Samajdar, A, Sarkissian, J, Schult, L, Shaifullah, G, M Shannon, R, J Shapiro-Albert, B, Siemens, X, J Simon, J, Siwek, M, L Smith, T, Speri, L, Spiewak, R, H Stairs, I, Stappers, B, R Stinebring, D, K Swiggum, J, Tiburzi, C, Turner, J, Vecchio, A, W Verbiest, J, Wahl, H, Q Wang, S, Wang, J, Wu, Z, Zhang, L, Zhang, S, Collaboration, I, M Falxa, S Babak, P T Baker, B Bécsy, A Chalumeau, S Chen, Z Chen, N J Cornish, L Guillemot, J S Hazboun, C M F Mingarelli, A Parthasarathy, A Petiteau, N S Pol, A Sesana, S B Spolaor, S R Taylor, G Theureau, M Vallisneri, S J Vigeland, C A Witt, X Zhu, J Antoniadis, Z Arzoumanian, M Bailes, N D R Bhat, L Blecha, A Brazier, P R Brook, N Caballero, A D Cameron, J A Casey-Clyde, D Champion, M Charisi, S Chatterjee, I Cognard, J M Cordes, F Crawford, H T Cromartie, K Crowter, S Dai, M E DeCesar, P B Demorest, G Desvignes, T Dolch, B Drachler, Y Feng, E C Ferrara, W Fiore, E Fonseca, N Garver-Daniels, J Glaser, B Goncharov, D C Good, J Griessmeier, Y J Guo, K Gültekin, G Hobbs, H Hu, K Islo, J Jang, R J Jennings, A D Johnson, M L Jones, J Kaczmarek, A R Kaiser, D L Kaplan, M Keith, L Z Kelley, M Kerr, J S Key, N Laal, M T Lam, W G Lamb, T J W Lazio, K Liu, T Liu, J Luo, R S Lynch, D R Madison, R Main, R Manchester, A McEwen, J McKee, M A McLaughlin, C Ng, D J Nice, S Ocker, K D Olum, S Osłowski, T T Pennucci, B B P Perera, D Perrodin, N Porayko, A Possenti, H Quelquejay-Leclere, S M Ransom, P S Ray, D J Reardon, C J Russell, A Samajdar, J Sarkissian, L Schult, G Shaifullah, R M Shannon, B J Shapiro-Albert, X Siemens, J J Simon, M Siwek, T L Smith, L Speri, R Spiewak, I H Stairs, B Stappers, D R Stinebring, J K Swiggum, C Tiburzi, J Turner, A Vecchio, J P W Verbiest, H Wahl, S Q Wang, J Wang, Z Wu, L Zhang, S Zhang, IPTA Collaboration, Falxa, M, Babak, S, T Baker, P, Bécsy, B, Chalumeau, A, Chen, S, Chen, Z, J Cornish, N, Guillemot, L, S Hazboun, J, F Mingarelli, C, Parthasarathy, A, Petiteau, A, S Pol, N, Sesana, A, B Spolaor, S, R Taylor, S, Theureau, G, Vallisneri, M, J Vigeland, S, A Witt, C, Zhu, X, Antoniadis, J, Arzoumanian, Z, Bailes, M, R Bhat, N, Blecha, L, Brazier, A, R Brook, P, Caballero, N, D Cameron, A, A Casey-Clyde, J, Champion, D, Charisi, M, Chatterjee, S, Cognard, I, M Cordes, J, Crawford, F, T Cromartie, H, Crowter, K, Dai, S, E DeCesar, M, B Demorest, P, Desvignes, G, Dolch, T, Drachler, B, Feng, Y, C Ferrara, E, Fiore, W, Fonseca, E, Garver-Daniels, N, Glaser, J, Goncharov, B, C Good, D, Griessmeier, J, J Guo, Y, Gültekin, K, Hobbs, G, Hu, H, Islo, K, Jang, J, J Jennings, R, D Johnson, A, L Jones, M, Kaczmarek, J, R Kaiser, A, L Kaplan, D, Keith, M, Z Kelley, L, Kerr, M, S Key, J, Laal, N, T Lam, M, G Lamb, W, W Lazio, T, Liu, K, Liu, T, Luo, J, S Lynch, R, R Madison, D, Main, R, Manchester, R, Mcewen, A, Mckee, J, A McLaughlin, M, Ng, C, J Nice, D, Ocker, S, D Olum, K, Osłowski, S, T Pennucci, T, P Perera, B, Perrodin, D, Porayko, N, Possenti, A, Quelquejay-Leclere, H, M Ransom, S, S Ray, P, J Reardon, D, J Russell, C, Samajdar, A, Sarkissian, J, Schult, L, Shaifullah, G, M Shannon, R, J Shapiro-Albert, B, Siemens, X, J Simon, J, Siwek, M, L Smith, T, Speri, L, Spiewak, R, H Stairs, I, Stappers, B, R Stinebring, D, K Swiggum, J, Tiburzi, C, Turner, J, Vecchio, A, W Verbiest, J, Wahl, H, Q Wang, S, Wang, J, Wu, Z, Zhang, L, Zhang, S, Collaboration, I, M Falxa, S Babak, P T Baker, B Bécsy, A Chalumeau, S Chen, Z Chen, N J Cornish, L Guillemot, J S Hazboun, C M F Mingarelli, A Parthasarathy, A Petiteau, N S Pol, A Sesana, S B Spolaor, S R Taylor, G Theureau, M Vallisneri, S J Vigeland, C A Witt, X Zhu, J Antoniadis, Z Arzoumanian, M Bailes, N D R Bhat, L Blecha, A Brazier, P R Brook, N Caballero, A D Cameron, J A Casey-Clyde, D Champion, M Charisi, S Chatterjee, I Cognard, J M Cordes, F Crawford, H T Cromartie, K Crowter, S Dai, M E DeCesar, P B Demorest, G Desvignes, T Dolch, B Drachler, Y Feng, E C Ferrara, W Fiore, E Fonseca, N Garver-Daniels, J Glaser, B Goncharov, D C Good, J Griessmeier, Y J Guo, K Gültekin, G Hobbs, H Hu, K Islo, J Jang, R J Jennings, A D Johnson, M L Jones, J Kaczmarek, A R Kaiser, D L Kaplan, M Keith, L Z Kelley, M Kerr, J S Key, N Laal, M T Lam, W G Lamb, T J W Lazio, K Liu, T Liu, J Luo, R S Lynch, D R Madison, R Main, R Manchester, A McEwen, J McKee, M A McLaughlin, C Ng, D J Nice, S Ocker, K D Olum, S Osłowski, T T Pennucci, B B P Perera, D Perrodin, N Porayko, A Possenti, H Quelquejay-Leclere, S M Ransom, P S Ray, D J Reardon, C J Russell, A Samajdar, J Sarkissian, L Schult, G Shaifullah, R M Shannon, B J Shapiro-Albert, X Siemens, J J Simon, M Siwek, T L Smith, L Speri, R Spiewak, I H Stairs, B Stappers, D R Stinebring, J K Swiggum, C Tiburzi, J Turner, A Vecchio, J P W Verbiest, H Wahl, S Q Wang, J Wang, Z Wu, L Zhang, S Zhang, and IPTA Collaboration
Abstract: The International Pulsar Timing Array 2nd data release is the combination of data sets from worldwide collaborations. In this study, we search for continuous waves: gravitational wave signals produced by individual supermassive black hole binaries in the local universe. We consider binaries on circular orbits and neglect the evolution of orbital frequency over the observational span. We find no evidence for such signals and set sky averaged 95 per cent upper limits on their amplitude h95. The most sensitive frequency is 10 nHz with h95 = 9.1 × 10-15. We achieved the best upper limit to date at low and high frequencies of the PTA band thanks to improved effective cadence of observations. In our analysis, we have taken into account the recently discovered common red noise process, which has an impact at low frequencies. We also find that the peculiar noise features present in some pulsars data must be taken into account to reduce the false alarm. We show that using custom noise models is essential in searching for continuous gravitational wave signals and setting the upper limit.
Published: 2023

8. The High Time Resolution Universe Pulsar Survey – XVII. PSR J1325−6253, a low eccentricity double neutron star system from an ultra-stripped supernova

Author: R Sengar, V Balakrishnan, S Stevenson, M Bailes, E D Barr, N D R Bhat, M Burgay, M C i Bernadich, A D Cameron, D J Champion, W Chen, C M L Flynn, A Jameson, S Johnston, M J Keith, M Kramer, V Morello, C Ng, A Possenti, B Stappers, R M Shannon, W van Straten, and J Wongphechauxsorn
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE), Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astrophysics::Solar and Stellar Astrophysics, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Astrophysics - High Energy Astrophysical Phenomena, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics
Abstract: The observable population of double neutron star (DNS) systems in the Milky Way allow us to understand the nature of supernovae and binary stellar evolution. Until now, all DNS systems in wide orbits ($ P_{\textrm{orb}}>$ 1~day) have been found to have orbital eccentricities, $e > 0.1$. In this paper, we report the discovery of pulsar PSR J1325$-$6253: a DNS system in a 1.81 day orbit with a surprisingly low eccentricity of just $e = 0.064$. Through 1.4 yr of dedicated timing with the Parkes radio telescope we have been able to measure its rate of advance of periastron, $\dotω=0.138 \pm 0.002$ $\rm deg$ $\rm yr^{-1}$. If this induced $\dotω$ is solely due to general relativity then the total mass of the system is, $M_{\rm sys} = 2.57 \pm 0.06$ M$_{\odot}$. Assuming an edge-on orbit the minimum companion mass is constrained to be $M_\mathrm{c,min}>0.98$ M$_{\odot}$ which implies the pulsar mass is $M_\mathrm{p,max}1.3$ M$_\odot$), then the companion neutron star is probably less than $\sim1.25$ M$_\odot$ and the system is inclined at about $50^{\circ}$-$60^{\circ}$. The low eccentricity along with the wide orbit of the system strongly favours a formation scenario involving an ultra-stripped supernova explosion., 12 pages, 7 figures, 1 table, accepted for publication in MNRAS
Published: 2022
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9. The Southern-sky MWA Rapid Two-metre (SMART) pulsar survey -- II. Survey status, pulsar census, and first pulsar discoveries

Author: N. D. R. Bhat, N. A. Swainston, S. J. McSweeney, M. Xue, B.W. Meyers, S. Kudale, S. Dai, S. E. Tremblay, W. van Straten, R. M. Shannon, K. R. Smith, M. Sokolowski, S. M. Ord, G. Sleap, A. Williams, P. J. Hancock, R. Lange, J. Tocknell, M. Johnston-Hollitt, D. L. Kaplan, S. J. Tingay, and M. Walker
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE), Space and Planetary Science, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Instrumentation and Methods for Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM)
Abstract: In Paper I, we presented an overview of the Southern-sky MWA Rapid Two-metre (SMART) survey, including the survey design and search pipeline. While the combination of MWA's large field-of-view and the voltage capture system brings a survey speed of ~450 square degrees per hour, the survey progression relies on the availability of compact configuration of the Phase II array. Over the past few years, by taking advantage of multiple windows of opportunity when the compact configuration was available, we have advanced the survey to 75% completion. To date, about 10% of the data collected thus far have been processed for a first-pass search, where 10 minutes of observation is processed for dispersion measures out to 250 ${\rm pc\,cm^{-3}}$, to realise a shallow survey for long-period pulsars. The ongoing analysis has led to two new pulsar discoveries, as well as an independent discovery and a rediscovery of a previously incorrectly characterised pulsar, all from ~3% of the data for which candidate scrutiny is completed. Here we describe the strategies for further detailed follow-up including improved sky localisation and convergence to timing solution, and illustrate them using example pulsar discoveries. The processing has also led to re-detection of 120 pulsars in the SMART observing band, bringing the total number of pulsars detected to date with the MWA to 180, and these are used to assess the search sensitivity of current processing pipelines. The planned second-pass (deep survey) processing is expected to yield a three-fold increase in sensitivity for long-period pulsars, and a substantial improvement to millisecond pulsars by adopting optimal de-dispersion plans. The SMART survey will complement the highly successful Parkes High Time Resolution Universe survey at 1.2-1.5 GHz, and inform future large survey efforts such as those planned with the low-frequency Square Kilometre Array., 22 pages, 9 figures, 7 tables, Accepted for publication in PASA
Published: 2023

10. Image-based searches for pulsar candidates using MWA VCS data

Author: S. Sett, N. D. R. Bhat, M. Sokolowski, and E. Lenc
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE), Space and Planetary Science, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Instrumentation and Methods for Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM)
Abstract: Pulsars have proven instrumental in exploring a wide variety of physics. Pulsars at low radio frequencies is crucial to further our understanding of spectral properties and emission mechanisms.The Murchison Widefield Array Voltage Capture System (MWA-VCS) has been routinely used to study and discover pulsars at low frequencies, offering the unique opportunity of recording complex voltages ,which can be off-line beamformed or imaged at millisecond time resolution.Devising imaged-based methods for finding pulsar candidates, which can be verified in beamformed data, can accelerate the complete process and lead to more pulsar detections by reducing the number of tied-array beams required, increasing compute resource efficiency.Despite a factor of ~4 loss in sensitivity, searching for pulsar candidates in images from the MWA-VCS, we can explore a larger parameter space, potentially leading to discoveries of pulsars missed by high-frequency surveys such as pulsars obscured in high-time resolution timeseries data by propagation effects.Image-based searches are also essential to probing parts of parameter space inaccessible to traditional beamformed searches with the MWA.In this paper we describe the innovative approach and capability of dual-processing MWA VCS data, i.e. finding pulsar candidates in these images, and verifying by forming tied-array beam.We developed and tested image-based methods of finding pulsar candidates, based on pulsar properties such as spectral index, polarisation and variability.The efficiency of these methodologies has been verified on known pulsars, and the main limitations explained in terms of sensitivity and low-frequency spectral turnover of some pulsars.No candidates were confirmed to be a new pulsar.This new capability will now be applied to multiple observations to accelerate pulsar discoveries with MWA and speed up future searches with the SKA-Low., 12 pages, 9 figures, accepted for publication in Publications of the Astronomical Society of Australia (PASA)
Published: 2023
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11. The Southern-sky MWA Rapid Two-metre (SMART) pulsar survey—I. Survey design and processing pipeline

Author: N. D. R. Bhat, N. A. Swainston, S. J. McSweeney, M. Xue, B.W. Meyers, S. Kudale, S. Dai, S. E. Tremblay, W. van Straten, R. M. Shannon, K. R. Smith, M. Sokolowski, S. M. Ord, G. Sleap, A. Williams, P. J. Hancock, R. Lange, J. Tocknell, M. Johnston-Hollitt, D. L. Kaplan, S. J. Tingay, and M. Walker
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE), Space and Planetary Science, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Instrumentation and Methods for Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM)
Abstract: We present an overview of the Southern-sky MWA Rapid Two-metre (SMART) pulsar survey that exploits the MWA's large field of view and voltage capture system to survey the sky south of 30 degree in declination for pulsars and fast transients in the 140-170 MHz band. The survey is enabled by the advent of the Phase II MWA's compact configuration, which offers an enormous efficiency in beam-forming and processing costs, thereby making an all-sky survey of this magnitude tractable with the MWA. Even with the long dwell times of the survey (4800 s), data collection can be completed in < 100 hours of telescope time, while still retaining the ability to reach a limiting sensitivity of ~2-3 mJy. Each observation is processed to generate ~5000-8000 tied-array beams that tessellate the full ~610 square degree field of view, which are then processed to search for pulsars. The voltage-capture recording allows a multitude of post hoc processing options including the reprocessing of data for higher time resolution. Due to the substantial computational cost in pulsar searches at low frequencies, processing is undertaken in multiple passes: in the first pass, a shallow survey is performed, where 10 minutes of each observation is processed, reaching about one-third of the full search sensitivity. Here we present the system overview and initial results. Further details including first pulsar discoveries and a census of low-frequency detections are presented in a companion paper. Future plans include deeper searches to reach the full sensitivity and acceleration searches to target binary and millisecond pulsars. Simulation analysis forecasts ~300 new pulsars upon the completion of full processing. The SMART survey will also generate a complete digital record of the low-frequency sky, which will serve as a valuable reference for future pulsar searches planned with the low-frequency Square Kilometre Array., 22 pages, 12 figures, 2 tables, Accepted for publication in PASA
Published: 2023
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12. A Pulsar-Based Time-Scale from the International Pulsar Timing Array

Author: G. Hobbs, L. Guo, R. N. Caballero, W. Coles, K. J. Lee, R. N. Manchester, D. J. Reardon, D. Matsakis, M. L. Tong, Z Arzoumanian, M Bailes, C. G. Bassa, N. D. R. Bhat, A. Brazier, S. Burke-Spolaor, D. J. Champion, S. Chatterjee, I. Cognard, S. Dai, G. Desvignes, T Dolch, R. D. Ferdman, E. Graikou, L Guillemot, G H Janssen, M. J. Keith, M Kerr, M Kramer, M T Lam, K Liu, A Lyne, T J W Lazio, R Lynch, J W McKee, M A McLaughlin, C M F Mingarelli, D J Nice, S Oslowski, T T Pennucci, B B P Perera, D Perrodin, A Possenti, C J Russell, S Sanidas, A Sesana, G Shaifullah, R M Shannon, J Simon, R Spiewak, I H Stairs, B W Stappers, J K Swiggum, S R Taylor, G Theureau, L Toomey, R van Haasteren, J B Wang, Y Wang, and X J Zhu
Subjects: Astronomy
Abstract: We have constructed a new time-scale, TT(IPTA16), based on observations of radio pulsars presented in the first data release from the International Pulsar Timing Array (IPTA). We used two analysis techniques with independent estimates of the noise models for the pulsar observations and different algorithms for obtaining the pulsar time-scale. The two analyses agree within the estimated uncertainties and both agree with TT(BIPM17), a post-corrected time-scale produced by the Bureau International des Poids et Mesures (BIPM). We show that both methods could detect significant errors in TT(BIPM17) if they were present. We estimate the stability of the atomic clocks from which TT(BIPM17) is derived using observations of four rubidium fountain clocks at the US Naval Observatory. Comparing the power spectrum of TT(IPTA16) with that of these fountain clocks suggests that pulsar-based time-scales are unlikely to contribute to the stability of the best time-scales over the next decade, but they will remain a valuable independent check on atomic time-scales. We also find that the stability of the pulsar-based time-scale is likely to be limited by our knowledge of solar-system dynamics, and that errors in TT(BIPM17) will not be a limiting factor for the primary goal of the IPTA, which is to search for the signatures of nano-Hertz gravitational waves.
Published: 2019
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13. Spectral analysis of 22 radio pulsars using SKA-Low precursor stations

Author: C. P. Lee, N. D. R. Bhat, M. Sokolowski, N. A. Swainston, D. Ung, A. Magro, and R. Chiello
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE), Space and Planetary Science, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics - High Energy Astrophysical Phenomena
Abstract: We present the first observational study of pulsars performed with the second-generation precursor stations to the low-frequency component of the Square Kilometre Array (SKA-Low): the Aperture Array Verification System 2 (AAVS2) and the Engineering Development Array 2 (EDA2). Using the SKA-Low stations, we have observed 100 southern-sky pulsars between 70-350 MHz, including follow-up observations at multiple frequencies for a selected sample of bright pulsars. These observations have yielded detections of 22 pulsars, including the lowest-frequency detections ever published for 6 pulsars, despite the modest sensitivity of initial system where the recording bandwidth is limited to ~1 MHz. By comparing simultaneous flux density measurements obtained with the SKA-Low stations and performing rigorous electromagnetic simulations, we verify the accuracy of the SKA-Low sensitivity simulation code presented in Sokolowski et al. (2022). Furthermore, we perform model fits to the radio spectra of the detected pulsars using the method developed by Jankowski et al. (2018), including 9 pulsars which were not fitted in the original work. We robustly classify the spectra into 5 morphological classes and find that all but one pulsar exhibit deviations from simple power-law behaviour. These findings suggest that pulsars with well-determined spectra are more likely to show spectral flattening or turn-over than average. Our work demonstrates how SKA-Low stations can be meaningfully used for scientifically useful measurements and analysis of pulsar radio spectra, which are important inputs for informing pulsar surveys and science planned with the SKA-Low., 16 pages, 6 figures, 4 tables, accepted for publication in PASA
Published: 2022

14. High time resolution search for prompt radio emission from the long GRB 210419A with the Murchison Widefield Array

Author: J Tian, G E Anderson, P J Hancock, J C A Miller-Jones, M Sokolowski, N A Swainston, A Rowlinson, A Williams, D L Kaplan, N Hurley-Walker, J Morgan, N D R Bhat, D Ung, S Tingay, K W Bannister, M E Bell, B W Meyers, M Walker, and High Energy Astrophys. & Astropart. Phys (API, FNWI)
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE), Space and Planetary Science, 0201 Astronomical and Space Sciences, FOS: Physical sciences, Astronomy and Astrophysics, Astronomy & Astrophysics, Astrophysics - High Energy Astrophysical Phenomena
Abstract: We present a low-frequency (170\textendash200\,MHz) search for prompt radio emission associated with the long GRB 210419A using the rapid-response mode of the Murchison Widefield Array (MWA), triggering observations with the Voltage Capture System (VCS) for the first time. The MWA began observing GRB 210419A within 89\,s of its detection by \textit{Swift}, enabling us to capture any dispersion delayed signal emitted by this GRB for a typical range of redshifts. We conducted a standard single pulse search with a temporal and spectral resolution of $100\,\upmu$s and 10\,kHz over a broad range of dispersion measures from 1 to $5000\,\text{pc}\,\text{cm}^{-3}$, but none were detected. However, fluence upper limits of $77\text{--}224$\,Jy\,ms derived over a pulse width of $0.5\text{--}10$\,ms and a redshift of $0.6, Comment: Accepted for publication in MNRAS
Published: 2022

15. Lense–Thirring frame dragging induced by a fast-rotating white dwarf in a binary pulsar system

Author: Andrew Jameson, Thomas M. Tauris, V. Venkatraman Krishnan, Stefan Oslowski, Norbert Wex, Chris Flynn, Evan Keane, Paulo C. C. Freire, Pablo Rosado, Matthew Bailes, N. D. R. Bhat, and W. van Straten
Subjects: General relativity, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, General Relativity and Quantum Cosmology (gr-qc), Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Frame-dragging, 01 natural sciences, General Relativity and Quantum Cosmology, Binary pulsar, Orbital inclination, Pulsar, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), High Energy Astrophysical Phenomena (astro-ph.HE), Physics, Multidisciplinary, 010308 nuclear & particles physics, White dwarf, Orbit, Astrophysics - Solar and Stellar Astrophysics, Physics::Space Physics, Precession, Astrophysics::Earth and Planetary Astrophysics, Astrophysics - High Energy Astrophysical Phenomena
Abstract: Radio pulsars in short-period eccentric binary orbits can be used to study both gravitational dynamics and binary evolution. The binary system containing PSR J1141$-$6545 includes a massive white dwarf (WD) companion that formed before the gravitationally bound young radio pulsar. We observe a temporal evolution of the orbital inclination of this pulsar that we infer is caused by a combination of a Newtonian quadrupole moment and Lense-Thirring precession of the orbit resulting from rapid rotation of the WD. Lense-Thirring precession, an effect of relativistic frame-dragging, is a prediction of general relativity. This detection is consistent with the evolutionary scenario in which the WD accreted matter from the pulsar progenitor, spinning up the WD to a period $< 200$ seconds., Accepted for publication in Science
Published: 2020
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16. pulsar_spectra: A pulsar flux density catalogue and spectrum fitting repository

Author: N. A. Swainston, C. P. Lee, S. J. McSweeney, and N. D. R. Bhat
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE), Space and Planetary Science, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Instrumentation and Methods for Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM)
Abstract: We present the pulsar_spectra software repository, an open-source pulsar flux density catalogue and automated spectral fitting software that finds the best spectral model and produces publication-quality plots. The python-based software includes features that enable users in the astronomical community to add newly published spectral measurements to the catalogue as they become available. The spectral fitting software is an implementation of the method described in Jankowski et al. (2018, MNRAS, 473, 4436) which uses robust statistical methods to decide on the best-fitting model for individual pulsar spectra. pulsar_spectra is motivated by the need for a centralised repository for pulsar flux density measurements to make published measurements more accessible to the astronomical community and provide a suite of tools for measuring spectra.
Published: 2022
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17. MWA tied-array processing IV: A multi-pixel beamformer for pulsar surveys and ionospheric corrected localisation

Author: N. A. Swainston, N. D. R. Bhat, I. S. Morrison, S. J. McSweeney, S. M. Ord, S. E. Tremblay, and M. Sokolowski
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE), Space and Planetary Science, Astrophysics::Instrumentation and Methods for Astrophysics, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - High Energy Astrophysical Phenomena, Instrumentation and Methods for Astrophysics (astro-ph.IM)
Abstract: The Murchison Widefield Array (MWA) is a low-frequency aperture array capable of high-time and frequency resolution astronomy applications such as pulsar studies. The large field-of-view of the MWA (hundreds of square degrees) can also be exploited to attain fast survey speeds for all-sky pulsar search applications, but to maximise sensitivity requires forming thousands of tied-array beams from each voltage-capture observation. The necessity of using calibration solutions that are separated from the target observation both temporally and spatially makes pulsar observations vulnerable to uncorrected, frequency-dependent positional offsets due to the ionosphere. These offsets may be large enough to move the source away from the centre of the tied-array beam, incurring sensitivity drops of $\sim$30-50\% in Phase II extended array configuration. We analyse these offsets in pulsar observations and develop a method for mitigating them, improving both the source position accuracy and the sensitivity. This analysis prompted the development of a multi-pixel beamforming functionality that can generate dozens of tied-array beams simultaneously, which runs a factor of ten times faster compared to the original single-pixel version. This enhancement makes it feasible to observe multiple pulsars within the vast field of view of the MWA and supports the ongoing large-scale pulsar survey efforts with the MWA. We explore the extent to which ionospheric offset correction will be necessary for the MWA Phase III and the low-frequency Square Kilometre Array (SKA-Low)., 10 pages, 5 figures
Published: 2022
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18. The MeerTime Pulsar Timing Array -- A Census of Emission Properties and Timing Potential

Author: R. Spiewak, M. Bailes, M. T. Miles, A. Parthasarathy, D. J. Reardon, M. Shamohammadi, R. M. Shannon, N. D. R. Bhat, S. Buchner, A. D. Cameron, F. Camilo, M. Geyer, S. Johnston, A. Karastergiou, M. Keith, M. Kramer, M. Serylak, W. van Straten, G. Theureau, and V. Venkatraman Krishnan
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE), Space and Planetary Science, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics - High Energy Astrophysical Phenomena
Abstract: MeerTime is a five-year Large Survey Project to time pulsars with MeerKAT, the 64-dish South African precursor to the Square Kilometre Array. The science goals for the programme include timing millisecond pulsars (MSPs) to high precision (< 1 $\mu$s) to study the Galactic MSP population and to contribute to global efforts to detect nanohertz gravitational waves with the International Pulsar Timing Array (IPTA). In order to plan for the remainder of the programme and to use the allocated time most efficiently, we have conducted an initial census with the MeerKAT "L-band" receiver of 189 MSPs visible to MeerKAT and here present their dispersion measures, polarization profiles, polarization fractions, rotation measures, flux density measurements, spectral indices, and timing potential. As all of these observations are taken with the same instrument (which uses coherent dedispersion, interferometric polarization calibration techniques, and a uniform flux scale), they present an excellent resource for population studies. We used wideband pulse portraits as timing standards for each MSP and demonstrated that the MeerTime Pulsar Timing Array (MPTA) can already contribute significantly to the IPTA as it currently achieves better than 1 $\mu$s timing accuracy on 89 MSPs (observed with fortnightly cadence). By the conclusion of the initial five-year MeerTime programme in July 2024, the MPTA will be extremely significant in global efforts to detect the gravitational wave background with a contribution to the detection statistic comparable to other long-standing timing programmes., Comment: Accepted to PASA. 27 figures. Data to be made available under the DOI 10.5281/zenodo.5347875 at the time of publication
Published: 2022
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19. A fast radio burst with a low dispersion measure

Author: Evan Keane, Vikram Ravi, Cherry Ng, Shivani Bhandari, L. C. Oostrum, Simon Johnston, Andrew Jameson, A. D. Cameron, A. Possenti, Lina Levin, Samuel Bates, Michael Kramer, Vincent Morello, D. J. Champion, Michael Keith, Benjamin Stappers, Chris Flynn, M. Burgay, Matthew Bailes, Ralph Eatough, Emily Petroff, Caterina Tiburzi, N. D. R. Bhat, W. van Straten, David J. Thornton, Sarah Burke-Spolaor, Ewan Barr, and High Energy Astrophys. & Astropart. Phys (API, FNWI)
Subjects: Physics, High Energy Astrophysical Phenomena (astro-ph.HE), Millisecond, 010308 nuclear & particles physics, Fast radio burst, media_common.quotation_subject, FOS: Physical sciences, Astronomy and Astrophysics, Time resolution, Astrophysics, 01 natural sciences, Universe, law.invention, Telescope, Beam pattern, Space and Planetary Science, law, Sky, 0103 physical sciences, Dispersion (optics), Astrophysics - High Energy Astrophysical Phenomena, 010303 astronomy & astrophysics, media_common
Abstract: Fast radio bursts (FRBs) are millisecond pulses of radio emission of seemingly extragalactic origin. More than 50 FRBs have now been detected, with only one seen to repeat. Here we present a new FRB discovery, FRB 110214, which was detected in the high latitude portion of the High Time Resolution Universe South survey at the Parkes telescope. FRB 110214 has one of the lowest dispersion measures of any known FRB (DM = 168.9$\pm$0.5 pc cm$^{-3}$), and was detected in two beams of the Parkes multi-beam receiver. A triangulation of the burst origin on the sky identified three possible regions in the beam pattern where it may have originated, all in sidelobes of the primary detection beam. Depending on the true location of the burst the intrinsic fluence is estimated to fall in the range of 50 -- 2000 Jy ms, making FRB 110214 one of the highest-fluence FRBs detected with the Parkes telescope. No repeating pulses were seen in almost 100 hours of follow-up observations with the Parkes telescope down to a limiting fluence of 0.3 Jy ms for a 2-ms pulse. Similar low-DM, ultra-bright FRBs may be detected in telescope sidelobes in the future, making careful modeling of multi-beam instrument beam patterns of utmost importance for upcoming FRB surveys., 8 pages, 3 figures, accepted for publication in MNRAS
Published: 2019
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20. The High Time Resolution Universe survey – XIV. Discovery of 23 pulsars through GPU-accelerated reprocessing

Author: Sarah Burke-Spolaor, Cherry Ng, Caterina Tiburzi, N. D. R. Bhat, Samuel Bates, Lina Levin, Vincent Morello, Emily Petroff, M. Burgay, S. Cooper, Evan Keane, D. J. Champion, Michael Kramer, Matthew Bailes, W. van Straten, Michael Keith, Ewan Barr, Chris Flynn, Simon Johnston, A. Possenti, Andrew Jameson, Ralph Eatough, Benjamin Stappers, A. D. Cameron, and High Energy Astrophys. & Astropart. Phys (API, FNWI)
Subjects: Astrophysics::High Energy Astrophysical Phenomena, Pipeline (computing), media_common.quotation_subject, FOS: Physical sciences, Binary number, general [pulsars], 01 natural sciences, Pulsar, Millisecond pulsar, pulsars: general, 0103 physical sciences, data analysis [methods], Instrumentation and Methods for Astrophysics (astro-ph.IM), 010303 astronomy & astrophysics, media_common, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, 010308 nuclear & particles physics, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy, Astronomy and Astrophysics, Time resolution, methods: data analysis, Universe, Space and Planetary Science, Anomaly detection, Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - High Energy Astrophysical Phenomena
Abstract: We have performed a new search for radio pulsars in archival data of the intermediate and high Galactic latitude parts of the Southern High Time Resolution Universe pulsar survey. This is the first time the entire dataset has been searched for binary pulsars, an achievement enabled by GPU-accelerated dedispersion and periodicity search codes nearly 50 times faster than the previously used pipeline. Candidate selection was handled entirely by a Machine Learning algorithm, allowing for the assessment of 17.6 million candidates in a few person-days. We have also introduced an outlier detection algorithm for efficient radio-frequency interference (RFI) mitigation on folded data, a new approach that enabled the discovery of pulsars previously masked by RFI. We discuss implications for future searches, particularly the importance of expanding work on RFI mitigation to improve survey completeness. In total we discovered 23 previously unknown sources, including 6 millisecond pulsars and at least 4 pulsars in binary systems. We also found an elusive but credible redback candidate that we have yet to confirm., Accepted for publication in MNRAS, 14 pages, 5 figures, 10 tables
Published: 2018
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21. Discovery of a steep-spectrum low-luminosity pulsar with the Murchison Widefield Array

Author: G. Sleap, N. D. R. Bhat, Shi Dai, Andrew Williams, W. van Straten, B. W. Meyers, N. A. Swainston, D. L. Kaplan, Marcin Sokolowski, S. E. Tremblay, Mengyao Xue, I. S. Morrison, S. J. McSweeney, Melanie Johnston-Hollitt, Ryan Shannon, Randall B. Wayth, Sanjay Kudale, Steven Tingay, Stephen M. Ord, and K. R. Smith
Subjects: 010504 meteorology & atmospheric sciences, Astrophysics::High Energy Astrophysical Phenomena, Population, FOS: Physical sciences, Murchison Widefield Array, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Luminosity, Pulsar, 0103 physical sciences, Continuum (set theory), education, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), education.field_of_study, Giant Metrewave Radio Telescope, Spectrum (functional analysis), Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy and Astrophysics, Square kilometre array, Space and Planetary Science, Astrophysics - High Energy Astrophysical Phenomena
Abstract: We report the discovery of the first new pulsar with the Murchison Widefield Array (MWA), PSR J0036$-$1033, a long-period (0.9 s) nonrecycled pulsar with a dispersion measure (DM) of 23.1 ${\rm pc\,cm^{-3}}$. It was found after processing only a small fraction ($\sim$1%) of data from an ongoing all-sky pulsar survey. Follow-up observations have been made with the MWA, the upgraded Giant Metrewave Radio Telescope (uGMRT), and the Parkes 64 m telescopes, spanning a frequency range from $\sim$150 MHz to 4 GHz. The pulsar is faint, with an estimated flux density ($S$) of $\sim$1 mJy at 400 MHz and a spectrum $S(\nu)\,\propto\,\nu^{-2.0 \pm 0.2}$, where $\nu$ is frequency. The DM-derived distance implies that it is also a low-luminosity source ($\sim$ 0.1 ${\rm mJy\,kpc^2}$ at 1400 MHz). The analysis of archival MWA observations reveals that the pulsar's mean flux density varies by up to a factor of $\sim$5-6 on timescales of several weeks to months. By combining MWA and uGMRT data, the pulsar position was determined to arcsecond precision. We also report on polarization properties detected in the MWA and Parkes bands. The pulsar's nondetection in previous pulsar and continuum imaging surveys, the observed high variability, and its detection in a small fraction of the survey data searched to date, all hint at a larger population of pulsars that await discovery in the southern hemisphere, with the MWA and the future low-frequency Square Kilometre Array., Comment: 12 pages, 6 figures, 2 tables, Accepted for publication in The ApJ Letters
Published: 2021
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22. A Southern-Hemisphere all-sky radio transient monitor for SKA-Low prototype stations

Author: A. Mattana, David B. Davidson, Federico Perini, Andrew McPhail, Riccardo Chiello, Alessio Magro, Randall B. Wayth, Gianni Bernardi, G. Sleap, Gianni Comoretto, Marcin Sokolowski, Danny C. Price, Steven Tingay, Andrew Williams, Jader Monari, Daniel C. X. Ung, J. W. Broderick, Giuseppe Pupillo, Brian Crosse, Giulia Macario, D. Minchin, Pietro Bolli, and N. D. R. Bhat
Subjects: Physics, High Energy Astrophysical Phenomena (astro-ph.HE), Scintillation, media_common.quotation_subject, Bandwidth (signal processing), FOS: Physical sciences, 020206 networking & telecommunications, Astronomy and Astrophysics, Ranging, 02 engineering and technology, 01 natural sciences, Pulsar, Interference (communication), Space and Planetary Science, Sky, 0103 physical sciences, 0202 electrical engineering, electronic engineering, information engineering, Transient (oscillation), Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - High Energy Astrophysical Phenomena, 010303 astronomy & astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), Communication channel, media_common, Remote sensing
Abstract: We present the first southern-hemisphere all-sky imager and radio-transient monitoring system implemented on two prototype stations of the low-frequency component of the Square Kilometre Array. Since its deployment the system has been used for real-time monitoring of the recorded commissioning data. Additionally, a transient searching algorithm has been executed on the resulting all-sky images. It uses a difference imaging technique, and has enabled identification of a wide variety of transient classes, ranging from human-made radio-frequency interference to genuine astrophysical events. Observations at the frequency 159.4 MHz and higher in a single coarse channel (0.926 MHz) were made with 2s time resolution, and multiple nights were analysed. Despite having modest sensitivity (~few Jy/beam), using a single coarse channel and 2-s imaging, the system detected bright transients from PSR B0950+08, proving that it can be used to detect bright transients of an astrophysical origin. The unusual, extreme activity of the pulsar PSR B0950+08 (up to ~155 Jy/beam) was initially detected in a "blind" search in the 2020-04-10/11 data and later assigned to this specific pulsar. The limitations of our data, however, prevent use from making firm conclusions of the effect being due to a combination of refractive and diffractive scintillation or intrinsic emission mechanisms. The system can routinely collect data over many days without interruptions; the large amount of recorded data at 159.4 and 229.7 MHz allowed us to determine a preliminary transient surface density upper limit of $1.32 \times 10^{-9} \text{deg}^{-2}$ for a timescale and limiting flux density of 2s and 42 Jy, respectively. We plan to extend the observing bandwidth to tens of MHz and improve time resolution to tens of milliseconds in order to increase the sensitivity and enable detections of Fast Radio Bursts below 300 MHz., Comment: 22 pages, 11 figures, 3 tables, Accepted for publication in PASA
Published: 2021
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23. Identifying and mitigating noise sources in precision pulsar timing data sets

Author: Shi Dai, N. D. R. Bhat, Matthew Bailes, Nithyanandan Thyagarajan, J. B. Wang, Renée Spiewak, Eric Thrane, Ryan Shannon, George Hobbs, Xing-Jiang Zhu, Stefan Oslowski, R. N. Manchester, Daniel J. Reardon, Matthew Kerr, Aditya Parthasarathy, B. Goncharov, and Christopher J. Russell
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE), Physics, 010308 nuclear & particles physics, Gravitational wave, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astronomy and Astrophysics, General Relativity and Quantum Cosmology (gr-qc), 01 natural sciences, General Relativity and Quantum Cosmology, Pulse (physics), Noise, Pulsar timing array, Pulsar, Space and Planetary Science, Millisecond pulsar, 0103 physical sciences, Sensitivity (control systems), Spurious relationship, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Instrumentation and Methods for Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), 010303 astronomy & astrophysics, Algorithm
Abstract: Pulsar timing array projects measure the pulse arrival times of millisecond pulsars for the primary purpose of detecting nanohertz-frequency gravitational waves. The measurements include contributions from a number of astrophysical and instrumental processes, which can either be deterministic or stochastic. It is necessary to develop robust statistical and physical models for these noise processes because incorrect models diminish sensitivity and may cause a spurious gravitational wave detection. Here we characterise noise processes for the 26 pulsars in the second data release of the Parkes Pulsar Timing Array using Bayesian inference. In addition to well-studied noise sources found previously in pulsar timing array data sets such as achromatic timing noise and dispersion measure variations, we identify new noise sources including time-correlated chromatic noise that we attribute to variations in pulse scattering. We also identify "exponential dip" events in four pulsars, which we attribute to magnetospheric effects as evidenced by pulse profile shape changes observed for three of the pulsars. This includes an event in PSR J1713$+$0747, which had previously been attributed to interstellar propagation. We present noise models to be used in searches for gravitational waves. We outline a robust methodology to evaluate the performance of noise models and identify unknown signals in the data. The detection of variations in pulse profiles highlights the need to develop efficient profile domain timing methods., 18 pages, 7 figures, 5 tables
Published: 2020

24. An ultra-wide bandwidth (704 to 4 032 MHz) receiver for the Parkes radio telescope

Author: Andrew Jameson, Santy Castillo, K. Jeganathan, Michael Kramer, Linqing Wen, Richard N. Manchester, Bin Dong, Stacy Mader, Ryan Shannon, Paul Doherty, Vince McIntyre, Vanessa A. Moss, Ettore Carretti, Yoon S. Chung, Andrew Cameron, Malcolm B. Smith, Danny C. Price, Sean Severs, John Sarkissian, Matthew Whiting, Nathan Pope, Nick Carter, Balthasar T. Indermuehle, Lawrence Toomey, Matthew Bailes, Les Reilly, M. Bourne, M. Marquarding, Stephanie Smith, Charlotte Sobey, Ken W. Smart, Nina Wang, Timothy Robishaw, J. A. Green, M. Bowen, Anastasios Tzioumis, Paul Roberts, Xu-Yang Gao, Elaine M. Sadler, M. Leach, Ron Beresford, B. Preisig, Philip G. Edwards, Peter Roush, George Hobbs, Jin-Lin Han, J. Tuthill, Ken Reeves, Willem van Straten, Simon Johnston, Jane F. Kaczmarek, W. Cheng, D. George, Azeem Ahmed, Douglas B. Hayman, N. D. R. Bhat, Shi Dai, Daniel A. Craig, Stefan Oslowski, Tim Ruckley, Douglas C.-J. Bock, Henry Kanoniuk, James Dempsey, Lister Staveley-Smith, Joanne Dawson, A. Dunning, Tuohutinuer Ergesh, Chris Phillips, John Reynolds, R. Chekkala, M. J. Kesteven, and S.W. Amy
Subjects: Physics, Digital signal processor, business.industry, Instrumentation, Pipeline (computing), instrumentation receivers, Electrical engineering, Linearity, FOS: Physical sciences, 020206 networking & telecommunications, Astronomy and Astrophysics, 02 engineering and technology, radio astronomy, 01 natural sciences, Antenna efficiency, Radio telescope, Space and Planetary Science, 0103 physical sciences, 0202 electrical engineering, electronic engineering, information engineering, Calibration, business, Astrophysics - Instrumentation and Methods for Astrophysics, 010303 astronomy & astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), Noise (radio)
Abstract: We describe an ultra-wide-bandwidth, low-frequency receiver ("UWL") recently installed on the Parkes radio telescope. The receiver system provides continuous frequency coverage from 704 to 4032 MHz. For much of the band (~60%) the system temperature is approximately 22K and the receiver system remains in a linear regime even in the presence of strong mobile phone transmissions. We discuss the scientific and technical aspects of the new receiver including its astronomical objectives, as well as the feed, receiver, digitiser and signal-processor design. We describe the pipeline routines that form the archive-ready data products and how those data files can be accessed from the archives. The system performance is quantified including the system noise and linearity, beam shape, antenna efficiency, polarisation calibration and timing stability., submitted to PASA
Published: 2020
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25. Science with the Murchison Widefield Array: Phase I results and Phase II opportunities – Corrigendum

Author: B. W. Meyers, M. D. Filipovic, Tessa Vernstrom, S. Yoshiura, Ray P. Norris, Bryan Gaensler, D. Kenney, R. B. Wayth, Paul Hancock, David Emrich, W. W. Tian, M. Walker, L. Horsley, C. J. Lonsdale, C. J. Riseley, G. Gürkan, Steven Tingay, D. A. Leahy, Melanie Johnston-Hollitt, Christene Lynch, R. C. Joseph, Patrick I. McCauley, Judd D. Bowman, Iver H. Cairns, Marcin Sokolowski, Chenoa D. Tremblay, John Morgan, Divya Oberoi, Jonathan C. Pober, S. W. Duchesne, A. P. Beardsley, O. I. Wong, Nick Seymour, Keitaro Takahashi, James Miller-Jones, Brian Crosse, S. Kitaeff, Ivan S. Bojičić, K. Steele, S. J. McSweeney, T. M. O. Franzen, G. E. Anderson, Daniel Jacobs, Jai Verdhan Chauhan, Andrew R. Williams, D. Pallot, George Heald, Mengyao Xue, Cathryn M. Trott, Miguel F. Morales, S. D. Croft, H. Su, C. W. James, Joseph R. Callingham, Natasha Hurley-Walker, W. Li, Chen Wu, David L. Kaplan, and N. D. R. Bhat
Subjects: Physics, Optics, Space and Planetary Science, business.industry, Phase (waves), Astronomy and Astrophysics, Murchison Widefield Array, business
Published: 2020
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26. A pulsar-based time-scale from the International Pulsar Timing Array

Author: Sourav Chatterjee, Daniel J. Reardon, Ismaël Cognard, Gemma H. Janssen, Sarah Burke-Spolaor, Zaven Arzoumanian, Michael T. Lam, Kejia Lee, Michael Kramer, Benetge Perera, J. B. Wang, L. Guo, Renée Spiewak, Ryan Shannon, David J. Nice, Richard N. Manchester, N. D. R. Bhat, D. Matsakis, E. Graikou, Joseph Simon, Ingrid H. Stairs, R. N. Caballero, Shi Dai, Matthew Bailes, Christopher J. Russell, Alberto Sesana, Robert D. Ferdman, Lucas Guillemot, Delphine Perrodin, Xing-Jiang Zhu, Andrew Lyne, Chiara M. F. Mingarelli, C. G. Bassa, Benjamin Stappers, A. Brazier, R. van Haasteren, Timothy T. Pennucci, J. W. McKee, Yue-Fei Wang, Maura McLaughlin, Michael Keith, L. Toomey, Matthew Kerr, William A. Coles, Timothy Dolch, Stefan Oslowski, M. L. Tong, Stephen Taylor, D. J. Champion, Kang Liu, S. A. Sanidas, George Hobbs, J. K. Swiggum, Gregory Desvignes, Gilles Theureau, A. Possenti, T. J. W. Lazio, R. S. Lynch, G. Shaifullah, Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Centre National d’Études Spatiales [Paris] (CNES), Unité Scientifique de la Station de Nançay (USN), Université d'Orléans (UO)-Observatoire des Sciences de l'Univers en région Centre (OSUC), PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Univers et Théories (LUTH (UMR_8102)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Hobbs, G, Guo, L, Caballero, R, Coles, W, Lee, K, Manchester, R, Reardon, D, Matsakis, D, Tong, M, Arzoumanian, Z, Bailes, M, Bassa, C, Bhat, N, Brazier, A, Burke-Spolaor, S, Champion, D, Chatterjee, S, Cognard, I, Dai, S, Desvignes, G, Dolch, T, Ferdman, R, Graikou, E, Guillemot, L, Janssen, G, Keith, M, Kerr, M, Kramer, M, Lam, M, Liu, K, Lyne, A, Lazio, T, Lynch, R, Mckee, J, Mclaughlin, M, Mingarelli, C, Nice, D, Osłowski, S, Pennucci, T, Perera, B, Perrodin, D, Possenti, A, Russell, C, Sanidas, S, Sesana, A, Shaifullah, G, Shannon, R, Simon, J, Spiewak, R, Stairs, I, Stappers, B, Swiggum, J, Taylor, S, Theureau, G, Toomey, L, van Haasteren, R, Wang, J, Wang, Y, Zhu, X, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS), ITA, USA, GBR, FRA, DEU, AUS, CAN, NLD, CHN, and HUN
Subjects: Astronomy, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astrophysics, Astronomy & Astrophysics, 01 natural sciences, Stability (probability), general [pulsars], Pulsar, Millisecond pulsar, Observatory, pulsars: general, 0103 physical sciences, [PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], Instrumentation and Methods for Astrophysics (astro-ph.IM), 010303 astronomy & astrophysics, time, Physics, 010308 nuclear & particles physics, Gravitational wave, Spectral density, Astronomy and Astrophysics, Atomic clock, 13. Climate action, Space and Planetary Science, [SDU]Sciences of the Universe [physics], Astrophysics - Instrumentation and Methods for Astrophysics, Noise (radio), Astronomical and Space Sciences
Abstract: We have constructed a new timescale, TT(IPTA16), based on observations of radio pulsars presented in the first data release from the International Pulsar Timing Array (IPTA). We used two analysis techniques with independent estimates of the noise models for the pulsar observations and different algorithms for obtaining the pulsar timescale. The two analyses agree within the estimated uncertainties and both agree with TT(BIPM17), a post-corrected timescale produced by the Bureau International des Poids et Mesures (BIPM). We show that both methods could detect significant errors in TT(BIPM17) if they were present. We estimate the stability of the atomic clocks from which TT(BIPM17) is derived using observations of four rubidium fountain clocks at the US Naval Observatory. Comparing the power spectrum of TT(IPTA16) with that of these fountain clocks suggests that pulsar-based timescales are unlikely to contribute to the stability of the best timescales over the next decade, but they will remain a valuable independent check on atomic timescales. We also find that the stability of the pulsar-based timescale is likely to be limited by our knowledge of solar-system dynamics, and that errors in TT(BIPM17) will not be a limiting factor for the primary goal of the IPTA, which is to search for the signatures of nano-Hertz gravitational waves., Comment: accepted by MNRAS
Published: 2020
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27. The High Time Resolution Universe Pulsar Survey - XVI. Discovery and timing of 40 pulsars from the southern Galactic plane

Author: Cherry Ng, Samuel Bates, Caterina Tiburzi, N. D. R. Bhat, W. van Straten, Benjamin Stappers, Vishnu Balakrishnan, Chris Flynn, Jingwen Wu, Michael Kramer, Lina Levin, D. J. Champion, Michael Keith, Andrew Lyne, A. D. Cameron, C. G. Bassa, Andrew Jameson, Shivani Bhandari, Simon Johnston, David A. Smith, A. Possenti, Matthew Bailes, M. Burgay, Ewan Barr, E. Petroff, Sarah Burke-Spolaor, Centre d'Etudes Nucléaires de Bordeaux Gradignan (CENBG), and Université Sciences et Technologies - Bordeaux 1-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)
Subjects: media_common.quotation_subject, Astrophysics::High Energy Astrophysical Phenomena, Population, FOS: Physical sciences, Astrophysics, 01 natural sciences, Binary pulsar, Luminosity, stars: neutron, Pulsar, surveys, Millisecond pulsar, pulsars: general, 0103 physical sciences, education, 010303 astronomy & astrophysics, media_common, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), education.field_of_study, 010308 nuclear & particles physics, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy and Astrophysics, Galactic plane, Orbital period, Universe, Space and Planetary Science, Astrophysics - High Energy Astrophysical Phenomena, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract: We present the results of processing an additional 44% of the High Time Resolution Universe South Low Latitude (HTRU-S LowLat) pulsar survey, the most sensitive blind pulsar survey of the southern Galactic plane to date. Our partially-coherent segmented acceleration search pipeline is designed to enable the discovery of pulsars in short, highly-accelerated orbits, while our 72-min integration lengths will allow us to discover pulsars at the lower end of the pulsar luminosity distribution. We report the discovery of 40 pulsars, including three millisecond pulsar-white dwarf binary systems (PSRs J1537-5312, J1547-5709 and J1618-4624), a black-widow binary system (PSR J1745-23) and a candidate black-widow binary system (PSR J1727-2951), a glitching pulsar (PSR J1706-4434), an eclipsing binary pulsar with a 1.5-yr orbital period (PSR J1653-45), and a pair of long spin-period binary pulsars which display either nulling or intermittent behaviour (PSRs J1812-15 and J1831-04). We show that the total population of 100 pulsars discovered in the HTRU-S LowLat survey to date represents both an older and lower-luminosity population, and indicates that we have yet to reach the bottom of the luminosity distribution function. We present evaluations of the performance of our search technique and of the overall yield of the survey, considering the 94% of the survey which we have processed to date. We show that our pulsar yield falls below earlier predictions by approximately 25% (especially in the case of millisecond pulsars), and discuss explanations for this discrepancy as well as future adaptations in RFI mitigation and searching techniques which may address these shortfalls., Comment: 28 pages, 9 figures, 13 tables
Published: 2020
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28. Modelling annual and orbital variations in the scintillation of the relativistic binary PSR J1141-6545

Author: Matthew Bailes, George Hobbs, N. D. R. Bhat, Daniel J. Reardon, Stephen M. Ord, V. Venkatraman Krishnan, Matthew Kerr, and William A. Coles
Subjects: Longitude of the ascending node, Proper motion, Epoch (astronomy), Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astrophysics, Astronomy & Astrophysics, 01 natural sciences, Declination, general [pulsars], Binary pulsar, Orbital inclination, Pulsar, 0103 physical sciences, individual [pulsars], 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, general [ISM], 010308 nuclear & particles physics, scattering, Astronomy and Astrophysics, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, astrometry, Astrophysics::Earth and Planetary Astrophysics, structure [ISM], Astrophysics - High Energy Astrophysical Phenomena, Right ascension, Astronomical and Space Sciences
Abstract: We have observed the relativistic binary pulsar PSR J1141$-$6545 over a period of $\sim$6 years using the Parkes 64 m radio telescope, with a focus on modelling the diffractive intensity scintillations to improve the accuracy of the astrometric timing model. The long-term scintillation, which shows orbital and annual variations, allows us to measure parameters that are difficult to measure with pulsar timing alone. These include: the orbital inclination $i$; the longitude of the ascending node $\Omega$; and the pulsar system transverse velocity. We use the annual variations to resolve the previous ambiguity in the sense of the inclination angle. Using the correct sense, and a prior probability distribution given by a constraint from pulsar timing ($i=73\pm3^\circ$), we find $\Omega=24.8\pm1.8^\circ$ and we estimate the pulsar distance to be $D=10^{+4}_{-3}$ kpc. This then gives us an estimate of this pulsar's proper motion of $\mu_{\alpha}\cos{\delta}=2.9\pm1.0$ mas yr$^{-1}$ in right ascension and $\mu_{\delta}=1.8\pm0.6$ mas yr$^{-1}$ in declination. Finally, we obtain measurements of the spatial structure of the interstellar electron density fluctuations, including: the spatial scale and anisotropy of the diffraction pattern; the distribution of scattering material along the line of sight; and spatial variation in the strength of turbulence from epoch to epoch. We find that the scattering is dominated by a thin screen at a distance of $(0.724\pm0.008)D$, with an anisotropy axial ratio $A_{\rm r} = 2.14\pm0.11$., Comment: 17 pages, 8 figures, 2 tables. Accepted for publication in MNRAS
Published: 2019

29. Probing pulsar scattering between 120 and 280 MHz with the MWA

Author: S. E. Tremblay, B. W. Meyers, Stephen M. Ord, N. D. R. Bhat, F. Kirsten, and Jean-Pierre Macquart
Subjects: Physics, High Energy Astrophysical Phenomena (astro-ph.HE), 010504 meteorology & atmospheric sciences, Scattering, Crab Pulsar, Astrophysics::High Energy Astrophysical Phenomena, Gum Nebula, Astrophysics::Instrumentation and Methods for Astrophysics, FOS: Physical sciences, Astronomy and Astrophysics, Murchison Widefield Array, Astrophysics, Vela, 01 natural sciences, Pulse (physics), Pulsar, Space and Planetary Science, 0103 physical sciences, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Instrumentation and Methods for Astrophysics, 010303 astronomy & astrophysics, Scaling, Instrumentation and Methods for Astrophysics (astro-ph.IM), 0105 earth and related environmental sciences
Abstract: The high sensitivity and wide frequency coverage of the Murchison Widefield Array allow for the measurement of the spectral scaling of the pulsar scattering timescale, $\alpha$, from a single observation. Here we present three case studies targeted at bright, strongly scattered pulsars J0534+2200 (the Crab pulsar), J0835-4510 (the Vela pulsar) and J0742-2822. We measure the scattering spectral indices to be $-3.8\pm0.2$, $-4.0\pm1.5$, and $-2.5\pm0.6$ for the Crab, Vela, and J0742-2822, respectively. We find that the scattered profiles of both Vela and J0742-2822 are best described by a thin screen model where the Gum Nebula likely contributes most of the observed scattering delay. For the Crab pulsar we see characteristically different pulse shapes compared to higher frequencies, for which none of the scattering screen models we explore are found to be optimal. The presence of a finite inner scale to the turbulence can possibly explain some of the discrepancies., Comment: 14 pages, 8 figures, accepted for publication in ApJ
Published: 2019

30. Relativistic spin precession in the binary PSR J1141$-$6545

Author: Matthew Bailes, Stefan Oslowski, Chris Flynn, Michael Kramer, V. Venkatraman Krishnan, Evan Keane, W. van Straten, and N. D. R. Bhat
Subjects: Physics, Rotation period, High Energy Astrophysical Phenomena (astro-ph.HE), Brightness, 010504 meteorology & atmospheric sciences, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, General Relativity and Quantum Cosmology (gr-qc), 01 natural sciences, Binary pulsar, General Relativity and Quantum Cosmology, Dipole, Pulsar, Space and Planetary Science, 0103 physical sciences, Precession, Astrophysics - High Energy Astrophysical Phenomena, 010303 astronomy & astrophysics, Scale factor (cosmology), Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences, Spin-½
Abstract: PSR J1141$-$6545 is a precessing binary pulsar that has the rare potential to reveal the two-dimensional structure of a non-recycled pulsar emission cone. It has undergone $\sim 25 \deg$ of relativistic spin precession in the $\sim18$ years since its discovery. In this paper, we present a detailed Bayesian analysis of the precessional evolution of the width of the total intensity profile, to understand the changes to the line-of-sight impact angle ($\beta$) of the pulsar using four different physically motivated prior distribution models. Although we cannot statistically differentiate between the models with confidence, the temporal evolution of the linear and circular polarisations strongly argue that our line-of-sight crossed the magnetic pole around MJD 54000 and that only two models remain viable. For both these models, it appears likely that the pulsar will precess out of our line-of-sight in the next $3-5$ years, assuming a simple beam geometry. Marginalising over $\beta$ suggests that the pulsar is a near-orthogonal rotator and provides the first polarization-independent estimate of the scale factor ($\mathbb{A}$) that relates the pulsar beam opening angle ($\rho$) to its rotational period ($P$) as $\rho = \mathbb{A}P^{-0.5}$ : we find it to be $> 6 \rm~deg~s^{0.5}$ at 1.4 GHz with 99\% confidence. If all pulsars emit from opposite poles of a dipolar magnetic field with comparable brightness, we might expect to see evidence of an interpulse arising in PSR J1141$-$6545, unless the emission is patchy., Comment: Accepted for publication in Astrophysical Journal Letters
Published: 2019

31. The International Pulsar Timing Array: Second data release

Author: Sarah Burke-Spolaor, Robert D. Ferdman, Stephen Taylor, Lei Zhang, Janna Goldstein, Caterina Tiburzi, Alberto Sesana, Ingrid H. Stairs, Elizabeth C. Ferrara, N. D. R. Bhat, Benetge Perera, Aditya Parthasarathy, Michael Kramer, H. Hu, Richard N. Manchester, Joseph Simon, L. Lentati, Matthew Kerr, Shi Dai, R. N. Caballero, Megan E. DeCesar, Paul Demorest, A. Possenti, Xing-Jiang Zhu, Kathryn Crowter, Weiwei Zhu, C. G. Bassa, Emmanuel Fonseca, Kejia Lee, Scott M. Ransom, Michael Keith, Stefan Oslowski, Chiara M. F. Mingarelli, D. J. Champion, Ramesh Karuppusamy, David J. Nice, Andrew Lyne, Timothy T. Pennucci, Timothy Dolch, J. K. Swiggum, Benjamin Stappers, K. Islo, Lucas Guillemot, Michele Vallisneri, J. B. Wang, X. Siemens, Gregory Desvignes, Gilles Theureau, James M. Cordes, Ismaël Cognard, Renée Spiewak, Siyuan Chen, Jing Luo, S. A. Sanidas, P. T. Baker, A. Brazier, Songbo Zhang, Alberto Vecchio, George Hobbs, Delphine Perrodin, Michael T. Lam, Jeffrey S. Hazboun, M. Burgay, Daniel J. Reardon, Zaven Arzoumanian, G. Shaifullah, J. W. McKee, Maura McLaughlin, Christopher J. Russell, Sourav Chatterjee, Kang Liu, Matthew Bailes, Gemma H. Janssen, Ryan Shannon, E. Graikou, Unité Scientifique de la Station de Nançay (USN), Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO), Franche-Comté Électronique Mécanique, Thermique et Optique - Sciences et Technologies (UMR 6174) (FEMTO-ST), Université de Technologie de Belfort-Montbeliard (UTBM)-Ecole Nationale Supérieure de Mécanique et des Microtechniques (ENSMM)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Univers et Théories (LUTH (UMR_8102)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7), Perera, B, Decesar, M, Demorest, P, Kerr, M, Lentati, L, Nice, D, Osłowski, S, Ransom, S, Keith, M, Arzoumanian, Z, Bailes, M, Baker, P, Bassa, C, Bhat, N, Brazier, A, Burgay, M, Burke-Spolaor, S, Caballero, R, Champion, D, Chatterjee, S, Chen, S, Cognard, I, Cordes, J, Crowter, K, Dai, S, Desvignes, G, Dolch, T, Ferdman, R, Ferrara, E, Fonseca, E, Goldstein, J, Graikou, E, Guillemot, L, Hazboun, J, Hobbs, G, Hu, H, Islo, K, Janssen, G, Karuppusamy, R, Kramer, M, Lam, M, Lee, K, Liu, K, Luo, J, Lyne, A, Manchester, R, Mckee, J, Mclaughlin, M, Mingarelli, C, Parthasarathy, A, Pennucci, T, Perrodin, D, Possenti, A, Reardon, D, Russell, C, Sanidas, S, Sesana, A, Shaifullah, G, Shannon, R, Siemens, X, Simon, J, Spiewak, R, Stairs, I, Stappers, B, Swiggum, J, Taylor, S, Theureau, G, Tiburzi, C, Vallisneri, M, Vecchio, A, Wang, J, Zhang, S, Zhang, L, Zhu, W, Zhu, X, Université d'Orléans (UO)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-Centre National de la Recherche Scientifique (CNRS), Université de Franche-Comté (UFC)-Centre National de la Recherche Scientifique (CNRS)-Ecole Nationale Supérieure de Mécanique et des Microtechniques (ENSMM)-Université de Technologie de Belfort-Montbeliard (UTBM), PSL Research University (PSL)-PSL Research University (PSL)-Centre National d’Études Spatiales [Paris] (CNES), PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS), and PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Ephemeris, 01 natural sciences, Pulsar timing array, stars: neutron, neutron [stars], Pulsar, Millisecond pulsar, Observatory, pulsars: general, 0103 physical sciences, 010303 astronomy & astrophysics, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], 010308 nuclear & particles physics, Gravitational wave, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy, Astronomy and Astrophysics, methods: data analysis, European Pulsar Timing Array, gravitational waves, Space and Planetary Science, [SDU]Sciences of the Universe [physics], pulsars, Astrophysics - High Energy Astrophysical Phenomena, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Noise (radio), Methods: data analysi
Abstract: In this paper, we describe the International Pulsar Timing Array second data release, which includes recent pulsar timing data obtained by three regional consortia: the European Pulsar Timing Array, the North American Nanohertz Observatory for Gravitational Waves, and the Parkes Pulsar Timing Array. We analyse and where possible combine high-precision timing data for 65 millisecond pulsars which are regularly observed by these groups. A basic noise analysis, including the processes which are both correlated and uncorrelated in time, provides noise models and timing ephemerides for the pulsars. We find that the timing precisions of pulsars are generally improved compared to the previous data release, mainly due to the addition of new data in the combination. The main purpose of this work is to create the most up-to-date IPTA data release. These data are publicly available for searches for low-frequency gravitational waves and other pulsar science., Comment: Submitted to MNRAS and in review, 23 pages, 5 figures
Published: 2019
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32. The frequency-dependent behaviour of subpulse drifting: I. Carousel geometry and emission heights of PSR B0031-07

Author: G. A. E. Wright, N. D. R. Bhat, S. E. Tremblay, Sanjay Kudale, and S. J. McSweeney
Subjects: Physics, High Energy Astrophysical Phenomena (astro-ph.HE), Astrophysics - Solar and Stellar Astrophysics, Pulsar, Space and Planetary Science, FOS: Physical sciences, Astronomy and Astrophysics, Relativistic aberration, Astrophysics, Astrophysics - High Energy Astrophysical Phenomena, Solar and Stellar Astrophysics (astro-ph.SR)
Abstract: The carousel model of pulsar emission attributes the phenomenon of subpulse drifting to a set of discrete sparks located very near the stellar surface rotating around the magnetic axis. Here, we investigate the subpulse drifting behaviour of PSR B0031-07 in the context of the carousel model. We show that B0031-07's three drift modes (A, B, and C) can be understood in terms of a single carousel rotation rate if the number of sparks is allowed to change by an integral number, and where the different drift rates are due to (first-order) aliasing effects. This also results in harmonically-related values for P 3 (the time it takes a subpulse to reappear at the same pulse phase), which we confirm for B0031-07. A representative solution has [n_A, n_B, n_C] = [15, 14, 13] sparks and a carousel rotation period of P_4 = 16.4 P_1. We also investigate the frequency dependence of B0031-07's subpulse behaviour. We extend the carousel model to include the dual effects of aberration and retardation, including the time it takes the information about the surface spark configuration to travel from the surface up to the emission point. Assuming these effects dominate at B0031-07's emission heights, we derive conservative emission height differences of $\lesssim 2000$ km for mode A and $\lesssim 1000$ km for modes B and C as seen between 185 MHz and 610 MHz. This new method of measuring emission heights is independent of others that involve average profile components or the polarisation position angle curve, and thus provides a potentially strong test of the carousel model., Comment: This paper has been accepted for publication in ApJ
Published: 2019
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33. Science with the Murchison Widefield Array: Phase I results and Phase II opportunities

Author: D. L. Kaplan, Judd D. Bowman, Iver H. Cairns, Daniel C. Jacobs, B. W. Meyers, D. Pallot, Mengyao Xue, Joseph R. Callingham, Natasha Hurley-Walker, W. Li, James Miller-Jones, Shintaro Yoshiura, Keitaro Takahashi, Chen Wu, Adam P. Beardsley, Miroslav Filipovic, Thomas M. O. Franzen, W. W. Tian, Christene Lynch, R. C. Joseph, G. E. Anderson, C. J. Riseley, Steven Tingay, Nick Seymour, S. J. McSweeney, Colin J. Lonsdale, Melanie Johnston-Hollitt, L. Horsley, Chenoa D. Tremblay, Cathryn M. Trott, Bryan Gaensler, O. I. Wong, Patrick I. McCauley, N. D. R. Bhat, Miguel F. Morales, S. Kitaeff, Andrew Williams, Divya Oberoi, S. W. Duchesne, David Emrich, Randall B. Wayth, Steve Croft, Ivan S. Bojičić, Ray P. Norris, George Heald, Mark Walker, Denis Leahy, G. Gürkan, Tessa Vernstrom, Paul Hancock, John Morgan, Jai Verdhan Chauhan, H. Su, Brian Crosse, K. Steele, C. W. James, Jonathan C. Pober, D. Kenney, and Marcin Sokolowski
Subjects: Physics, 010308 nuclear & particles physics, Epoch (reference date), media_common.quotation_subject, Phase (waves), FOS: Physical sciences, Astronomy, Astronomy and Astrophysics, Murchison Widefield Array, 01 natural sciences, law.invention, Telescope, Upgrade, Space and Planetary Science, Sky, law, 0103 physical sciences, Ionosphere, Astrophysics - Instrumentation and Methods for Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), 010303 astronomy & astrophysics, media_common
Abstract: The Murchison Widefield Array (MWA) is an open access telescope dedicated to studying the low frequency (80$-$300 MHz) southern sky. Since beginning operations in mid 2013, the MWA has opened a new observational window in the southern hemisphere enabling many science areas. The driving science objectives of the original design were to observe 21\,cm radiation from the Epoch of Reionisation (EoR), explore the radio time domain, perform Galactic and extragalactic surveys, and monitor solar, heliospheric, and ionospheric phenomena. All together 60$+$ programs recorded 20,000 hours producing 146 papers to date. In 2016 the telescope underwent a major upgrade resulting in alternating compact and extended configurations. Other upgrades, including digital back-ends and a rapid-response triggering system, have been developed since the original array was commissioned. In this paper we review the major results from the prior operation of the MWA, and then discuss the new science paths enabled by the improved capabilities. We group these science opportunities by the four original science themes, but also include ideas for directions outside these categories., Comment: 38 pages, 12 figures, accepted for publication in PASA
Published: 2019

34. The High Time Resolution Universe Pulsar Survey – XV. Completion of the intermediate-latitude survey with the discovery and timing of 25 further pulsars

Author: Samuel Bates, Chris Flynn, Simon Johnston, D. J. Champion, Benjamin Stappers, Michael Kramer, M. Burgay, Matthew Bailes, Andrew Jameson, Michael Keith, Cherry Ng, Lina Levin, W. van Straten, L. Bondonneau, Ralph Eatough, Caterina Tiburzi, N. D. R. Bhat, Ewan Barr, Andrew Lyne, E. Petroff, A. D. Cameron, A. Possenti, Evan Keane, Sarah Burke-Spolaor, Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES)
Subjects: media_common.quotation_subject, J1757−1500, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, 01 natural sciences, J1826−2415, Latitude, Pulsar, J1837−0822, J1638−4233, 0103 physical sciences, Total count, 010303 astronomy & astrophysics, Line (formation), media_common, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], 010308 nuclear & particles physics, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy, Astronomy and Astrophysics, Time resolution, Universe, Space and Planetary Science, Sky, [SDU]Sciences of the Universe [physics], Glitch (astronomy), [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Astrophysics - High Energy Astrophysical Phenomena, pulsars: individual: J1635−2616
Abstract: We report on the latest six pulsars discovered through our standard pipeline in the intermediate-latitude region (|b| < 15 deg) of the Parkes High Time Resolution Universe Survey (HTRU). We also present timing solutions for the new discoveries and for 19 further pulsars for which only discovery parameters were previously published. Highlights of the presented sample include the isolated millisecond pulsar J1826-2415, the long-period binary pulsar J1837-0822 in a mildly eccentric 98-day orbit with a > 0.27 M_sun companion, and the nulling pulsar J1638-4233, detected only 10% of the time. Other interesting objects are PSR J1757-1500, exhibiting sporadic mode changes, and PSR J1635-2616 showing one glitch over 6 years. The new discoveries bring the total count of HTRU intermediate-latitude pulsars to 113, 25% of which are recycled pulsars. This is the higest ratio of recycled over ordinary pulsars discoveries of all recent pulsar surveys in this region of the sky. Among HTRU recycled pulsars, four are isolated objects. Comparing the characteristics of Galactic fully-recycled isolated MSPs with those of eclipsing binaries ('spiders'), from which the former are believed to have formed, we highlight a discrepancy in their spatial distribution. This may reflect a difference in the natal kick, hence, possibly, a different formation path. On the other hand, however, isolated fully-recycled MSPs spin periods are, on average, longer than those of spiders, in line with what one would expect, from simple magnetic-dipole spin-down, if the former were indeed evolved from the latter., Accepted for publication in MNRAS; 12 pages, 9 figures, 7 tables
Published: 2019
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35. The emission and scintillation properties of RRAT J2325-0530 at 154 MHz and 1.4 GHz

Author: Ryan Shannon, Stephen M. Ord, Melanie Johnston-Hollitt, B. W. Meyers, N. D. R. Bhat, Charlotte Sobey, S. E. Tremblay, Mark Walker, and Randall B. Wayth
Subjects: Physics, High Energy Astrophysical Phenomena (astro-ph.HE), Spectral index, Scintillation, education.field_of_study, Astrophysics::High Energy Astrophysical Phenomena, Population, Astrophysics::Instrumentation and Methods for Astrophysics, FOS: Physical sciences, Astronomy and Astrophysics, Context (language use), Murchison Widefield Array, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Radio telescope, Pulsar, Space and Planetary Science, 0103 physical sciences, Broadband, education, Astrophysics - High Energy Astrophysical Phenomena, 010303 astronomy & astrophysics
Abstract: Rotating Radio Transients (RRATs) represent a relatively new class of pulsar, primarily characterised by their sporadic bursting emission of single pulses on time scales of minutes to hours. In addition to the difficulty involved in detecting these objects, low-frequency ($, Comment: 18 pages, 8 figures, 5 tables, accepted for publication in PASA
Published: 2019
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36. MWA tied-array processing II: Polarimetric verification and analysis of two bright southern pulsars

Author: S. E. Tremblay, Charlotte Sobey, S. J. McSweeney, Mengyao Xue, N. D. R. Bhat, Stephen M. Ord, N. A. Swainston, and B. W. Meyers
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE), Physics, 010504 meteorology & atmospheric sciences, Aperture, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics::Instrumentation and Methods for Astrophysics, Polarimetry, FOS: Physical sciences, Array processing, Astronomy and Astrophysics, Murchison Widefield Array, Astrophysics, 01 natural sciences, Pulsar, Space and Planetary Science, 0103 physical sciences, Astronomical interferometer, Radio frequency, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Instrumentation and Methods for Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), 010303 astronomy & astrophysics, Zenith, 0105 earth and related environmental sciences
Abstract: Polarimetric studies of pulsars at low radio frequencies provide important observational insights into the pulsar emission mechanism and beam models, and probe the properties of the magneto-ionic interstellar medium (ISM). Aperture arrays are the main form of next-generation low-frequency telescopes, including the Murchison Widefield Array (MWA). These require a distinctly different approach to data processing (e.g. calibration and beamforming) compared to traditional dish antennas. As the second paper of this series, we present a verification of the MWA's pulsar polarimetry capability, using two bright southern pulsars, PSRs J0742-2822 and J1752-2806. Our observations simultaneously cover multiple frequencies (76-313 MHz) and were taken at multiple zenith angles during a single night for each pulsar. We show that the MWA can be reliably calibrated for zenith angles < 45 degree and frequencies < 270 MHz. We present the polarimetric profiles for PSRs J0742-2822 and J1752-2806 at frequencies lower than 300 MHz for the first time, along with an analysis of the linear polarisation degree and pulse profile evolution with frequency. For PSR J0742-2822, the measured degree of linear polarisation shows a rapid decrease at low frequencies, in contrast with the generally expected trend, which can be attributed to depolarisation effects from small-scale, turbulent, magneto-ionic ISM components. This effect has not been widely explored for pulsars in general, and will be further investigated in future work., accepted for publication in PASA
Published: 2019
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37. From spin noise to systematics: stochastic processes in the first International Pulsar Timing Array data release

Author: R. van Haasteren, Scott M. Ransom, S. Babak, Antoine Petiteau, Paul Demorest, L. Toomey, Gemma H. Janssen, Alberto Sesana, Marjorie Gonzalez, Sourav Chatterjee, A. Lassus, Ryan Shannon, Justin A. Ellis, Glenn Jones, E. Graikou, J. W. McKee, Kang Liu, Kejia Lee, Matthew Kerr, Sarah Burke-Spolaor, William A. Coles, Maura McLaughlin, G. Shaifullah, Stephen Taylor, Weiwei Zhu, P. Lazarus, S. A. Sanidas, D. J. Champion, Delphine Perrodin, R. N. Caballero, Kevin Stovall, Joris P. W. Verbiest, Benetge Perera, Richard N. Manchester, C. G. Bassa, Emmanuel Fonseca, Jonathan R. Gair, George Hobbs, D. R. Madison, R. Smits, Alberto Vecchio, Daniel R. Stinebring, Michael T. Lam, Daniel J. Reardon, X. P. You, Zaven Arzoumanian, Paul D. Lasky, Yue-Fei Wang, Lucas Guillemot, R. S. Lynch, Pablo Rosado, Lina Levin, Xing-Jiang Zhu, Chiara M. F. Mingarelli, L. Lentati, Benjamin Stappers, A. Possenti, T. J. W. Lazio, Robert D. Ferdman, Stefan Oslowski, J. K. Swiggum, X. Siemens, Gregory Desvignes, Gilles Theureau, Ramesh Karuppusamy, Ismaël Cognard, M. Burgay, Timothy T. Pennucci, Michele Vallisneri, J. B. Wang, James M. Cordes, Sean T. McWilliams, David J. Nice, P. Brem, W. van Straten, Caterina Tiburzi, N. D. R. Bhat, Shi Dai, Jason W. T. Hessels, Ingrid H. Stairs, Timothy Dolch, Michael Kramer, Michael Keith, Lentati, L, Shannon, R, Coles, W, Verbiest, J, van Haasteren, R, Ellis, J, Caballero, R, Manchester, R, Arzoumanian, Z, Babak, S, Bassa, C, Bhat, N, Brem, P, Burgay, M, Burke-Spolaor, S, Champion, D, Chatterjee, S, Cognard, I, Cordes, J, Dai, S, Demorest, P, Desvignes, G, Dolch, T, Ferdman, R, Fonseca, E, Gair, J, Gonzalez, M, Graikou, E, Guillemot, L, Hessels, J, Hobbs, G, Janssen, G, Jones, G, Karuppusamy, R, Keith, M, Kerr, M, Kramer, M, Lam, M, Lasky, P, Lassus, A, Lazarus, P, Lazio, T, Lee, K, Levin, L, Liu, K, Lynch, R, Madison, D, Mckee, J, Mclaughlin, M, Mcwilliams, S, Mingarelli, C, Nice, D, Osłowski, S, Pennucci, T, Perera, B, Perrodin, D, Petiteau, A, Possenti, A, Ransom, S, Reardon, D, Rosado, P, Sanidas, S, Sesana, A, Shaifullah, G, Siemens, X, Smits, R, Stairs, I, Stappers, B, Stinebring, D, Stovall, K, Swiggum, J, Taylor, S, Theureau, G, Tiburzi, C, Toomey, L, Vallisneri, M, van Straten, W, Vecchio, A, Wang, J, Wang, Y, You, X, Zhu, W, Zhu, X, High Energy Astrophys. & Astropart. Phys (API, FNWI), Cavendish Laboratory, University of Cambridge [UK] (CAM), CSIRO Astronomy and Space Science, Commonwealth Scientific and Industrial Research Organisation [Canberra] (CSIRO), University of California, University of California (UC), Max-Planck-Institut für Radioastronomie (MPIFR), Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), NASA Goddard Space Flight Center (GSFC), Max-Planck-Institut für Gravitationsphysik ( Albert-Einstein-Institut ) (AEI), Max-Planck-Gesellschaft, Netherlands Institute for Radio Astronomy (ASTRON), Curtin University [Perth], Planning and Transport Research Centre (PATREC), INAF - Osservatorio Astronomico di Cagliari (OAC), Istituto Nazionale di Astrofisica (INAF), National Radio Astronomy Observatory (NRAO), Center for Radiophysics and Space Research [Ithaca] (CRSR), Cornell University [New York], Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Department of Astronomy [Ithaca], Department of Physics, Hillsdale College, Unité Scientifique de la Station de Nançay (USN), Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), University of British Columbia (UBC), Vancouver Coastal Health, Department of Nuclear Medicine, Netherlands Institute for Radio Astronomy ( ASTRON ), ARC Centre of Excellence for Coral Reef Studies (CoralCoE), James Cook University (JCU), Jodrell Bank Centre for Astrophysics, University of Manchester [Manchester], Vrije Universiteit Medical Centre (VUMC), Vrije Universiteit Amsterdam [Amsterdam] (VU), Kavli Institute for Astronomy and Astrophysics [Beijing] (KIAA-PKU), Peking University [Beijing], National Radio Astronomy Observatory [Green Bank] (NRAO), Jodrell Bank Centre for Astrophysics (JBCA), Department of Physics, West Virginia University, West Virginia University, Theoretical Astrophysics [Pasadena] (TAPIR), California Institute of Technology (CALTECH), Physics Department, Lafayette College, Lafayette College [Easton], Department of Astronomy [Charlottesville], University of Virginia, APC - Gravitation (APC-Gravitation), AstroParticule et Cosmologie (APC (UMR_7164)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Max-Planck-Institut für Gravitationsphysik ( Albert-Einstein-Institut ) (AEI), Max-Planck-Gesellschaft-Max-Planck-Gesellschaft, Laboratoire de glaciologie et géophysique de l'environnement (LGGE), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Centre for Astrophysics and Supercomputing [Swinburne] (CAS), Swinburne University of Technology [Melbourne], Anton Pannekoek Institute for Astronomy, University of Amsterdam [Amsterdam] (UvA), University of Wisconsin - Milwaukee, Department of Physics and Astronomy, University of British Columbia, Department of Physics and Astronomy [Oberlin], Oberlin College, Institute of Meteoritics [Albuquerque] (IOM), The University of New Mexico [Albuquerque], Department of Physics and Astronomy, West Virginia University, West Virginia University [Morgantown], Birmingham City University (BCU), Xinjiang Astronomical Observatory, Chinese Academy of Sciences [Beijing] (CAS), Huazhong University of Science and Technology [Wuhan] (HUST), School of Physical Science and Technology, Southwest University [Chongqing], Australian Research Council Discovery Project DP140102578NASA through Einstein Fellowship grant PF3-140116West Light Foundation of CAS XBBS201322 and NSFC project no.11403086National Science Fundation of China (NSFC) award number 11503007NNSF of China (U1231120) and FRFCU (XDJK2015B012), European Project: 337062,EC:FP7:ERC,ERC-2013-StG,DRAGNET(2014), European Project: 227947,EC:FP7:ERC,ERC-2008-AdG,LEAP(2009), European Project: 610058,EC:FP7:ERC,ERC-2013-SyG,BLACKHOLECAM(2014), Cornell University, Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Centre National d’Études Spatiales [Paris] (CNES), Université d'Orléans (UO)-Observatoire des Sciences de l'Univers en région Centre (OSUC), PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-Centre National de la Recherche Scientifique (CNRS), Division of Physics, Mathematics and Astronomy [Pasadena], California Institute of Technology (CALTECH)-California Institute of Technology (CALTECH), Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Max-Planck-Institut für Gravitationsphysik ( Albert-Einstein-Institut ) (AEI), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Max-Planck-Institut für Gravitationsphysik ( Albert-Einstein-Institut ) (AEI), California Institute of Technology (CALTECH)-NASA, Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO), University of Virginia [Charlottesville], Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Max-Planck-Institut für Gravitationsphysik ( Albert-Einstein-Institut ) (AEI)
Subjects: Astrophysics::High Energy Astrophysical Phenomena, data analysis, pulsars: general [methods], FOS: Physical sciences, General Relativity and Quantum Cosmology (gr-qc), Methods: Data analysi, Astrophysics, Astronomy & Astrophysics, general [pulsars], 01 natural sciences, General Relativity and Quantum Cosmology, pulsars:individual, Binary pulsar, Pulsar, 0103 physical sciences, data analysis [methods], Coherence (signal processing), Sensitivity (control systems), Instrumentation and Methods for Astrophysics (astro-ph.IM), 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), High Energy Astrophysical Phenomena (astro-ph.HE), Physics, 010308 nuclear & particles physics, Stochastic process, Noise (signal processing), Model selection, Pulsars: General, Astronomy and Astrophysics, methods: data analysis, LIGO, Computational physics, Astrophysics - Solar and Stellar Astrophysics, [SDU]Sciences of the Universe [physics], 13. Climate action, Space and Planetary Science, Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - High Energy Astrophysical Phenomena, Astronomical and Space Sciences
Abstract: We analyse the stochastic properties of the 49 pulsars that comprise the first International Pulsar Timing Array (IPTA) data release. We use Bayesian methodology, performing model selection to determine the optimal description of the stochastic signals present in each pulsar. In addition to spin-noise and dispersion-measure (DM) variations, these models can include timing noise unique to a single observing system, or frequency band. We show the improved radio-frequency coverage and presence of overlapping data from different observing systems in the IPTA data set enables us to separate both system and band-dependent effects with much greater efficacy than in the individual PTA data sets. For example, we show that PSR J1643$-$1224 has, in addition to DM variations, significant band-dependent noise that is coherent between PTAs which we interpret as coming from time-variable scattering or refraction in the ionised interstellar medium. Failing to model these different contributions appropriately can dramatically alter the astrophysical interpretation of the stochastic signals observed in the residuals. In some cases, the spectral exponent of the spin noise signal can vary from 1.6 to 4 depending upon the model, which has direct implications for the long-term sensitivity of the pulsar to a stochastic gravitational-wave (GW) background. By using a more appropriate model, however, we can greatly improve a pulsar's sensitivity to GWs. For example, including system and band-dependent signals in the PSR J0437$-$4715 data set improves the upper limit on a fiducial GW background by $\sim 60\%$ compared to a model that includes DM variations and spin-noise only., Comment: 29 pages. 16 figures. Accepted for publication in MNRAS
Published: 2016
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38. The International Pulsar Timing Array: First data release

Author: Lucas Guillemot, Sourav Chatterjee, N. Garver-Daniels, D. R. Madison, Scott M. Ransom, J. K. Swiggum, Daniel R. Stinebring, Delphine Perrodin, Ingrid H. Stairs, Alberto Vecchio, Timothy Dolch, X. Siemens, Gregory Desvignes, Antoine Petiteau, Gilles Theureau, W. van Straten, J. B. Wang, X. P. You, Jason W. T. Hessels, Renée Spiewak, R. N. Caballero, Alberto Sesana, Stefan Oslowski, R. S. Lynch, Xing-Jiang Zhu, C. G. Bassa, Emmanuel Fonseca, Daniel J. Reardon, Yue-Fei Wang, Chiara M. F. Mingarelli, Benjamin Stappers, Kejia Lee, Stanislav Babak, Benetge Perera, Pablo Rosado, Zaven Arzoumanian, Richard N. Manchester, Paul Demorest, A. Brazier, Jonathan R. Gair, R. van Haasteren, Nipuni Palliyaguru, Lina Levin, R. Smits, Joseph Simon, P. Brem, Michele Vallisneri, Michael Kramer, James M. Cordes, Andrew Lyne, L. Lentati, Weiwei Zhu, Matthew Kerr, Peter A. Gentile, Michael Keith, A. Possenti, D. J. Champion, Caterina Tiburzi, T. J. W. Lazio, N. D. R. Bhat, A. Lassus, Stephen Taylor, Linqing Wen, Ryan Shannon, Glenn Jones, Shi Dai, E. Graikou, Gemma H. Janssen, S. J. Chamberlin, Kevin Stovall, Kang Liu, P. Lazarus, Ramesh Karuppusamy, S. A. Sanidas, Ismaël Cognard, George Hobbs, Robert D. Ferdman, Timothy T. Pennucci, M. Burgay, Sean T. McWilliams, David J. Nice, B. Christy, G. Shaifullah, L. Toomey, Justin A. Ellis, J. W. McKee, Maura McLaughlin, Paul D. Lasky, Michael T. Lam, Sarah Burke-Spolaor, Joris P. W. Verbiest, Marjorie Gonzalez, High Energy Astrophys. & Astropart. Phys (API, FNWI), Verbiest, J, Lentati, L, Hobbs, G, van Haasteren, R, Demorest, P, Janssen, G, Wang, J, Desvignes, G, Caballero, R, Keith, M, Champion, D, Arzoumanian, Z, Babak, S, Bassa, C, Bhat, N, Brazier, A, Brem, P, Burgay, M, Burke-Spolaor, S, Chamberlin, S, Chatterjee, S, Christy, B, Cognard, I, Cordes, J, Dai, S, Dolch, T, Ellis, J, Ferdman, R, Fonseca, E, Gair, J, Garver-Daniels, N, Gentile, P, Gonzalez, M, Graikou, E, Guillemot, L, Hessels, J, Jones, G, Karuppusamy, R, Kerr, M, Kramer, M, Lam, M, Lasky, P, Lassus, A, Lazarus, P, Lazio, T, Lee, K, Levin, L, Liu, K, Lynch, R, Lyne, A, Mckee, J, Mclaughlin, M, Mcwilliams, S, Madison, D, Manchester, R, Mingarelli, C, Nice, D, Osłowski, S, Palliyaguru, N, Pennucci, T, Perera, B, Perrodin, D, Possenti, A, Petiteau, A, Ransom, S, Reardon, D, Rosado, P, Sanidas, S, Sesana, A, Shaifullah, G, Shannon, R, Siemens, X, Simon, J, Smits, R, Spiewak, R, Stairs, I, Stappers, B, Stinebring, D, Stovall, K, Swiggum, J, Taylor, S, Theureau, G, Tiburzi, C, Toomey, L, Vallisneri, M, van Straten, W, Vecchio, A, Wang, Y, Wen, L, You, X, Zhu, W, Zhu, X, Max-Planck-Institut für Radioastronomie (MPIFR), Cavendish Laboratory, University of Cambridge [UK] (CAM), CSIRO Astronomy and Space Science, Commonwealth Scientific and Industrial Research Organisation [Canberra] (CSIRO), Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), National Radio Astronomy Observatory [Socorro] (NRAO), National Radio Astronomy Observatory (NRAO), Netherlands Institute for Radio Astronomy (ASTRON), Xinjiang Astronomical Observatory, Chinese Academy of Sciences [Beijing] (CAS), Jodrell Bank Centre for Astrophysics, University of Manchester [Manchester], NASA Goddard Space Flight Center (GSFC), Max-Planck-Institut für Gravitationsphysik ( Albert-Einstein-Institut ) (AEI), Max-Planck-Gesellschaft, Curtin University [Perth], Planning and Transport Research Centre (PATREC), Cornell Center for Astrophysics and Planetary Science (CCAPS), Cornell University [New York], INAF - Osservatorio Astronomico di Cagliari (OAC), Istituto Nazionale di Astrofisica (INAF), Pennsylvania State University (Penn State), Penn State System, Center for Radiophysics and Space Research [Ithaca] (CRSR), University of Maryland [College Park], University of Maryland System, Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National d’Études Spatiales [Paris] (CNES), Unité Scientifique de la Station de Nançay (USN), Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université d'Orléans (UO), Department of Astronomy [Ithaca], Department of Physics, Hillsdale College, University of British Columbia (UBC), University of Edinburgh, Department of Physics and Astronomy, West Virginia University, West Virginia University [Morgantown], Vancouver Coastal Health, Department of Nuclear Medicine, Department of Physics, Columbia University, Columbia University [New York], Monash Centre for Astrophysics (MoCA), Monash University [Clayton], Kavli Institute for Astronomy and Astrophysics [Beijing] (KIAA-PKU), Peking University [Beijing], National Radio Astronomy Observatory [Green Bank] (NRAO), Theoretical Astrophysics [Pasadena] (TAPIR), Division of Physics, Mathematics and Astronomy [Pasadena], California Institute of Technology (CALTECH)-California Institute of Technology (CALTECH), Physics Department, Lafayette College, Lafayette College [Easton], Physics Department, Texas Tech University, Texas Tech University [Lubbock] (TTU), Department of Astronomy [Charlottesville], University of Virginia [Charlottesville], APC - Gravitation (APC-Gravitation), AstroParticule et Cosmologie (APC (UMR_7164)), Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Max-Planck-Institut für Gravitationsphysik ( Albert-Einstein-Institut ) (AEI), Max-Planck-Gesellschaft-Max-Planck-Gesellschaft, Centre for Astrophysics and Supercomputing [Swinburne] (CAS), Swinburne University of Technology [Melbourne], Anton Pannekoek Institute for Astronomy, University of Amsterdam [Amsterdam] (UvA), University of Wisconsin - Milwaukee, Center for Gravitation, Cosmology and Astrophysics, Netherlands Institute for Radio Astronomy ( ASTRON ), Department of Physics and Astronomy, University of British Columbia, Department of Physics and Astronomy [Oberlin], Oberlin College, Department of Physics and Astronomy [Albuquerque], The University of New Mexico [Albuquerque], Birmingham City University (BCU), School of Physics [HUST], Huazhong University of Science and Technology [Wuhan] (HUST), School of Physics (University of Western Australia), Université, School of Physical Science and Technology, Southwest University [Chongqing], European Project: 337062,EC:FP7:ERC,ERC-2013-StG,DRAGNET(2014), Max-Planck-Institut für Radioastronomie, Cavendish Laboratory - University of Cambridge, University of Cambridge [UK] ( CAM ), CSIRO Astronomy and Space Science, PO BOX 76, NSW 1710, Australia, Jet Propulsion Laboratory ( JPL ), NASA-California Institute of Technology ( CALTECH ), National Radio Astronomy Observatory [Socorro] ( NRAO ), National Radio Astronomy Observatory ( NRAO ), Netherlands Institute for Radio Astronomy, Chinese Academy of Sciences [Beijing] ( CAS ), NASA Goddard Space Flight Center ( GSFC ), Albert Einstein Institute, Max-Planck-Institut für Gravitationsphysik, Curtin University, Perth, Australia, Cornell Center for Astrophysics and Planetary Science ( CCAPS ), Cornell University, MPI for Gravitational Physics (Albert Einstein Institute), INAF-Osservatorio di Cagliari, PennState University [Pennsylvania] ( PSU ), Center for Radiophysics and Space Research [Ithaca] ( CRSR ), Laboratoire de Physique et Chimie de l'Environnement et de l'Espace ( LPC2E ), Institut national des sciences de l'Univers ( INSU - CNRS ) -Université d'Orléans ( UO ) -Centre National de la Recherche Scientifique ( CNRS ), Unité Scientifique de la Station de Nançay ( USN ), Institut national des sciences de l'Univers ( INSU - CNRS ) -Observatoire de Paris-Université d'Orléans ( UO ) -Centre National de la Recherche Scientifique ( CNRS ), University of British Columbia ( UBC ), University of Edimburgh, Kavli Institute for Astronomy and Astrophysics, National Radio Astronomy Observatory [Green Bank] ( NRAO ), Commonwealth Scientific and Industrial Research Organisation [Canberra] ( CSIRO ), TAPIR (Theoretical Astrophysics), California Institute of Technology, Texas Tech University [Lubbock] ( TTU ), Osservatorio Astronomico di Cagliari, Ist Nazl Astrofis, Osservatorio Astronomico di Cagliari, APC - Gravitation ( APC-Gravitation ), AstroParticule et Cosmologie ( APC - UMR 7164 ), Centre National de la Recherche Scientifique ( CNRS ) -Institut National de Physique Nucléaire et de Physique des Particules du CNRS ( IN2P3 ) -Observatoire de Paris-Université Paris Diderot - Paris 7 ( UPD7 ) -Commissariat à l'énergie atomique et aux énergies alternatives ( CEA ) -Centre National de la Recherche Scientifique ( CNRS ) -Institut National de Physique Nucléaire et de Physique des Particules du CNRS ( IN2P3 ) -Observatoire de Paris-Université Paris Diderot - Paris 7 ( UPD7 ) -Commissariat à l'énergie atomique et aux énergies alternatives ( CEA ) -Max-Planck-Institut für Gravitationsphysik (Albert-Einstein-Institut), Max-Planck-Institut-Max-Planck-Institut, Centre for Astrophysics and Supercomputing [Swinburne] ( CAS ), Anton Pannekoek Institute for Astronomy, University of Amsterdam, Max Planck Institut für Gravitationsphysik, Albert Einstein Institut, Physics and Astronomy Department [Oberlin], Center for Gravitational Wave Astronomy, The University of Texas at Brownsville and Texas Southmost College, Birmingham City University ( BCU ), School of Physics, Huazhong University of Science and Technology, Huazhong University of Science and Technology, School of Physics ( University of Western Australia ), European Project : 337062,EC:FP7:ERC,ERC-2013-StG,DRAGNET ( 2014 ), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), California Institute of Technology (CALTECH), University of Virginia, Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Max-Planck-Institut für Gravitationsphysik ( Albert-Einstein-Institut ) (AEI), PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Centre National d’Études Spatiales [Paris] (CNES), Université d'Orléans (UO)-Observatoire des Sciences de l'Univers en région Centre (OSUC), PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-Centre National de la Recherche Scientifique (CNRS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, and PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Max-Planck-Institut für Gravitationsphysik ( Albert-Einstein-Institut ) (AEI)
Subjects: data analysis, data analysis, pulsars: general [methods], FOS: Physical sciences, Methods: Data analysi, general [pulsars], 01 natural sciences, 7. Clean energy, Set (abstract data type), Pulsar timing array, Pulsar, 0103 physical sciences, data analysis [methods], Instrumentation and Methods for Astrophysics (astro-ph.IM), 010303 astronomy & astrophysics, instrumentation, Physics, [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], 010308 nuclear & particles physics, Gravitational wave, Astrophysics::Instrumentation and Methods for Astrophysics, Pulsars: General, Astronomy, Astronomy and Astrophysics, methods: data analysis, Data set, European Pulsar Timing Array, Neutron star, gravitational waves, Space and Planetary Science, pulsars, Measurement uncertainty, Astrophysics - Instrumentation and Methods for Astrophysics, [ SDU.ASTR.SR ] Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Algorithm, astro-ph.IM
Abstract: The highly stable spin of neutron stars can be exploited for a variety of (astro-)physical investigations. In particular arrays of pulsars with rotational periods of the order of milliseconds can be used to detect correlated signals such as those caused by gravitational waves. Three such "Pulsar Timing Arrays" (PTAs) have been set up around the world over the past decades and collectively form the "International" PTA (IPTA). In this paper, we describe the first joint analysis of the data from the three regional PTAs, i.e. of the first IPTA data set. We describe the available PTA data, the approach presently followed for its combination and suggest improvements for future PTA research. Particular attention is paid to subtle details (such as underestimation of measurement uncertainty and long-period noise) that have often been ignored but which become important in this unprecedentedly large and inhomogeneous data set. We identify and describe in detail several factors that complicate IPTA research and provide recommendations for future pulsar timing efforts. The first IPTA data release presented here (and available online) is used to demonstrate the IPTA's potential of improving upon gravitational-wave limits placed by individual PTAs by a factor of ~2 and provides a 2-sigma limit on the dimensionless amplitude of a stochastic GWB of 1.7x10^{-15} at a frequency of 1 yr^{-1}. This is 1.7 times less constraining than the limit placed by (Shannon et al. 2015), due mostly to the more recent, high-quality data they used., 25 pages, 6 tables, 5 figures. Accepted for publication in MNRAS
Published: 2016
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39. The host galaxy of a fast radio burst

Author: Mansi M. Kasliwal, Andrew Jameson, Tsuyoshi Terai, Naoki Yasuda, N. D. R. Bhat, Andrew Williams, Poonam Chandra, Ralph Eatough, W. van Straten, Delphine Perrodin, Yuu Niino, E. D. Barr, Matthew Bailes, Steven Tingay, M. Burgay, M. Caleb, Tomoki Morokuma, Hajime Sugai, Evan Keane, Jacob E. Jencson, Ben Stappers, Shotaro Yamasaki, Takashi Hattori, A. Possenti, Mitchell B. Mickaliger, Randall B. Wayth, Michael Kramer, Jeff Cooke, M. Berezina, Mareki Honma, Tomonori Totani, C. G. Bassa, R. Allen, David L. Kaplan, Shivani Bhandari, Nozomu Tominaga, Simon Johnston, Hisanori Furusawa, E. Petroff, Sarah Burke-Spolaor, and Chris Flynn
Subjects: Physics, Multidisciplinary, 010308 nuclear & particles physics, Radio galaxy, Fast radio burst, Astrophysics::High Energy Astrophysical Phenomena, Canadian Hydrogen Intensity Mapping Experiment, Astronomy, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Redshift survey, 01 natural sciences, Redshift, Galaxy, Interstellar medium, X-shaped radio galaxy, 0103 physical sciences, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics
Abstract: In recent years, millisecond-duration radio signals originating in distant galaxies appear to have been discovered in the so-called fast radio bursts. These signals are dispersed according to a precise physical law and this dispersion is a key observable quantity, which, in tandem with a redshift measurement, can be used for fundamental physical investigations. Every fast radio burst has a dispersion measurement, but none before now have had a redshift measurement, because of the difficulty in pinpointing their celestial coordinates. Here we report the discovery of a fast radio burst and the identification of a fading radio transient lasting ~6 days after the event, which we use to identify the host galaxy; we measure the galaxy’s redshift to be z = 0.492 ± 0.008. The dispersion measure and redshift, in combination, provide a direct measurement of the cosmic density of ionized baryons in the intergalactic medium of ΩIGM = 4.9 ± 1.3 per cent, in agreement with the expectation from the Wilkinson Microwave Anisotropy Probe, and including all of the so-called ‘missing baryons’. The ~6-day radio transient is largely consistent with the radio afterglow of a short γ-ray burst, and its existence and timescale do not support progenitor models such as giant pulses from pulsars, and supernovae. This contrasts with the interpretation of another recently discovered fast radio burst, suggesting that there are at least two classes of bursts.
Published: 2016
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40. The SUrvey for Pulsars and Extragalactic Radio Bursts – II. New FRB discoveries and their follow-up

Author: Matthew Bailes, T. A. Pritchard, Mitchell B. Mickaliger, A. Trovato, C. Lachaud, Maurizio Spurio, A.J. Heijboer, M. Anghinolfi, N. El Khayati, Ivan Felis, Daniele Vivolo, S. Loucatos, Utane Sawangwit, M. Marcelin, R. Coniglione, Paolo Sapienza, A. Klotz, J. Zúñiga, S.F. Biagi, Dominique Lefèvre, Jörn Wilms, J. Hofestädt, Alba Domi, C. Racca, Silvia Celli, D. Dornic, S. Basa, M. de Jong, I. El Bojaddaini, A. Marinelli, V. Popa, Dominik Elsässer, Tomonori Totani, V. Bertin, M. Circella, Timothée Grégoire, A. Ettahiri, A. Sánchez-Losa, C. Pellegrino, Anne Deschamps, Yann Hello, Matteo Sanguineti, Eric Howell, Steffen Hallmann, J. Carr, Annarita Margiotta, Antoine Kouchner, M. Saldaña, M.C. Bouwhuis, J. A. Green, Michel André, F. Schüssler, I. Salvadori, D. Turpin, Paolo Piattelli, R. Bormuth, Thomas Eberl, Sarah Burke-Spolaor, Richard Wilson, R. Mele, C. Perrina, Alessandro Corongiu, Tommaso Chiarusi, G.E. Păvălaş, Hervé Glotin, V. Van Elewyck, J. Busto, Pablo Torne, P. Jaroenjittichai, E. Petroff, E. Nezri, V. Venkatraman Krishnan, M. Jongen, V. Morello, P. Migliozzi, A. Creusot, G. De Bonis, Joao Coelho, R. Bruijn, J. Hößl, T. Avgitas, Jürgen Brunner, D. Kießling, Federico Versari, M. Organokov, C. Distefano, Juan José Hernández-Rey, O. Kalekin, D. F. E. Samtleben, M. Taiuti, C. Tönnis, A. Enzenhöfer, Giulia Illuminati, I. Di Palma, J.A. Martínez-Mora, Alexis Coleiro, M. Caleb, C. Hugon, C. Sieger, Michael Kramer, H. Brânzaş, J-J. Aubert, Emanuele Leonora, Antonio F. Díaz, P. Coyle, Poonam Chandra, L. Caramete, Giorgio Riccobene, F. Jankowski, Richard Dodson, Th. Stolarczyk, J.D. Zornoza, B. Vallage, Alessio Trois, Vladimir Kulikovskiy, Miguel Ardid, B. Belhorma, Chris Flynn, M. Kreter, Gisela Anton, A. Jameson, A. Vizzocca, V. Giordano, A. Capone, H. van Haren, Timothy Butterley, T. Pradier, R. Cherkaoui El Moursli, Evan Keane, S. Bourret, Ralph Eatough, David Coward, W. van Straten, S. Navas, Delphine Perrodin, U. F. Katz, V. S. Dhillon, Farida Fassi, I. Andreoni, E. D. Barr, C. W. James, Kay Graf, Karel Melis, Jeff Cooke, S. P. Littlefair, Arnauld Albert, Caterina Tiburzi, T. R. Marsh, N. D. R. Bhat, L. K. Hardy, Abdelilah Moussa, Doriane Drouhin, Benjamin Stappers, I. Kreykenbohm, Yuu Niino, Bruny Baret, Simon Johnston, Robert Lahmann, A. Possenti, L. Quinn, Shivani Bhandari, Nozomu Tominaga, Yahya Tayalati, R. Gracia-Ruiz, Tsuyoshi Terai, H. Costantini, J. Barrios-Martí, Luigi Antonio Fusco, Matthias Kadler, T. Michael, T. W. B. Muxlow, M. Burgay, C. Donzaud, Institut de recherche en astrophysique et planétologie (IRAP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Groupe de Recherche en Physique des Hautes Energies (GRPHE), Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut Universitaire de Technologie de Colmar, Centre de Physique des Particules de Marseille (CPPM), Aix Marseille Université (AMU)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), AstroParticule et Cosmologie (APC (UMR_7164)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Observatoire de la Côte d'Azur (OCA), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Université Paris-Sud - Paris 11 (UP11), Laboratoire de Physique de Clermont (LPC), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA), Laboratoire des Sciences de l'Information et des Systèmes (LSIS), Centre National de la Recherche Scientifique (CNRS)-Arts et Métiers Paristech ENSAM Aix-en-Provence-Université de Toulon (UTLN)-Aix Marseille Université (AMU), Institut Universitaire de France (IUF), Ministère de l'Education nationale, de l’Enseignement supérieur et de la Recherche (M.E.N.E.S.R.), Institut méditerranéen d'océanologie (MIO), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Toulon (UTLN)-Centre National de la Recherche Scientifique (CNRS), Département de Physique des Particules (ex SPP) (DPP), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Institut Pluridisciplinaire Hubert Curien (IPHC), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS), ANTARES, Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Aix Marseille Université (AMU), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), Centre National de la Recherche Scientifique (CNRS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Clermont Auvergne (UCA)-Centre National de la Recherche Scientifique (CNRS), Aix Marseille Université (AMU)-Université de Toulon (UTLN)-Arts et Métiers Paristech ENSAM Aix-en-Provence-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université de Toulon (UTLN)-Aix Marseille Université (AMU)-Institut de Recherche pour le Développement (IRD), Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-IUT de Colmar, Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Département de Physique des Particules (ex SPP) (DPhP), Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Institut de recherche en astrophysique et planétologie ( IRAP ), Université Paul Sabatier - Toulouse 3 ( UPS ) -Observatoire Midi-Pyrénées ( OMP ) -Centre National de la Recherche Scientifique ( CNRS ), Centre de Physique des Particules de Marseille ( CPPM ), Centre National de la Recherche Scientifique ( CNRS ) -Institut National de Physique Nucléaire et de Physique des Particules du CNRS ( IN2P3 ) -Aix Marseille Université ( AMU ), AstroParticule et Cosmologie ( APC - UMR 7164 ), Centre National de la Recherche Scientifique ( CNRS ) -Institut National de Physique Nucléaire et de Physique des Particules du CNRS ( IN2P3 ) -Observatoire de Paris-Université Paris Diderot - Paris 7 ( UPD7 ) -Commissariat à l'énergie atomique et aux énergies alternatives ( CEA ), Laboratoire d'Astrophysique de Marseille ( LAM ), Aix Marseille Université ( AMU ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National d'Etudes Spatiales ( CNES ) -Centre National de la Recherche Scientifique ( CNRS ), Observatoire de la Côte d'Azur ( OCA ), Centre National de la Recherche Scientifique ( CNRS ), Université Paris-Sud - Paris 11 ( UP11 ), Laboratoire de Physique de Clermont ( LPC ), Institut National de Physique Nucléaire et de Physique des Particules du CNRS ( IN2P3 ) -Université Clermont Auvergne ( UCA ) -Centre National de la Recherche Scientifique ( CNRS ), Laboratoire des Sciences de l'Information et des Systèmes ( LSIS ), Aix Marseille Université ( AMU ) -Université de Toulon ( UTLN ) -Arts et Métiers Paristech ENSAM Aix-en-Provence-Centre National de la Recherche Scientifique ( CNRS ), Institut méditerranéen d'océanologie ( MIO ), Centre National de la Recherche Scientifique ( CNRS ) -Université de Toulon ( UTLN ) -Aix Marseille Université ( AMU ) -Institut de Recherche pour le Développement ( IRD ), Département de Physique des Particules (ex SPP) ( DPP ), Institut de Recherches sur les lois Fondamentales de l'Univers ( IRFU ), Commissariat à l'énergie atomique et aux énergies alternatives ( CEA ) -Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives ( CEA ) -Université Paris-Saclay, Institut Pluridisciplinaire Hubert Curien ( IPHC ), Centre National de la Recherche Scientifique ( CNRS ) -Université de Strasbourg ( UNISTRA ), Centre Tecnològic de Vilanova i la Geltrú, Universitat Politècnica de Catalunya. LAB - Laboratori d'Aplicacions Bioacústiques, Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS), KM3NeT (IHEF, IoP, FNWI), Bhandari, S, Keane, Ef, Barr, Ed, Jameson, A, Petroff, E, Johnston, S, Bailes, M, Bhat, Ndr, Burgay, M, Burke-Spolaor, S, Caleb, M, Eatough, Rp, Flynn, C, Green, Ja, Jankowski, F, Kramer, M, Krishnan, Vv, Morello, V, Possenti, A, Stappers, B, Tiburzi, C, van Straten, W, Andreoni, I, Butterley, T, Chandra, P, Cooke, J, Corongiu, A, Coward, Dm, Dhillon, V, Dodson, R, Hardy, Lk, Howell, Ej, Jaroenjittichai, P, Klotz, A, Littlefair, Sp, Marsh, Tr, Mickaliger, M, Muxlow, T, Perrodin, D, Pritchard, T, Sawangwit, U, Terai, T, Tominaga, N, Torne, P, Totani, T, Trois, A, Turpin, D, Niino, Y, Wilson, Rw, Albert, A, Andre, M, Anghinolfi, M, Anton, G, Ardid, M, Aubert, Jj, Avgitas, T, Baret, B, Barrios-Marti, J, Basa, S, Belhorma, B, Bertin, V, Biagi, S, Bormuth, R, Bourret, S, Bouwhuis, Mc, Branzas, H, Bruijn, R, Brunner, J, Busto, J, Capone, A, Caramete, L, Carr, J, Celli, S, El Moursli, Rc, Chiarusi, T, Circella, M, Coelho, Jab, Coleiro, A, Coniglione, R, Costantini, H, Coyle, P, Creusot, A, Diaz, Af, Deschamps, A, De Bonis, G, Distefano, C, Di Palma, I, Domi, A, Donzaud, C, Dornic, D, Drouhin, D, Eberl, T, El Bojaddaini, I, Khayati, N, Elasser, D, Enzenhoefer, A, Ettahiri, A, Fassi, F, Felis, I, Fusco, La, Gay, P, Giordano, V, Glotin, H, Gregoire, T, Gracia-Ruiz, R, Graf, K, Hallmann, S, van Haren, H, Heijboer, Aj, Hello, Y, Hernandez-Rey, Jj, Hossl, J, Hofestadt, J, Hugon, C, Illuminati, G, James, Cw, de Jong, M, Jongen, M, Kadler, M, Kalekin, O, Katz, U, Kiessling, D, Kouchner, A, Kreter, M, Kreykenbohm, I, Kulikovskiy, V, Lachaud, C, Lahmann, R, Lefevere, D, Leonora, E, Loucatos, S, Marcelin, M, Margiotta, A, Marinelli, A, Martinez-Mora, Ja, Mele, R, Melis, K, Michael, T, Migliozzi, P, Moussa, A, Navas, S, Nezri, E, Organokov, M, Pavalas, Ge, Pellegrino, C, Perrina, C, Piattelli, P, Popa, V, Pradier, T, Quinn, L, Racca, C, Riccobene, G, Sanchez-Losa, A, Saldana, M, Salvadori, I, Samtleben, Dfe, Sanguineti, M, Sapienza, P, Schussler, F, Sieger, C, Spurio, M, Stolarczyk, T, Taiuti, M, Tayalati, Y, Trovato, A, Tonnis, C, Vallage, B, Van Elewyck, V, Versari, F, Vivolo, D, Vizzocca, A, Wilms, J, Zornoza, Jd, Zuniga, J, Bhandari, S., Keane, E.F., Barr, E.D., Jameson, A., Petroff, E., Johnston, S., Bailes, M., Bhat, N.D.R., Burgay, M., Burke-Spolaor, S., Caleb, M., Eatough, R.P., Flynn, C., Green, J.A., Jankowski, F., Kramer, M., Venkatraman Krishnan, V., Morello, V., Possenti, A., Stappers, B., Tiburzi, C., van Straten, W., Andreoni, I., Butterley, T., Chandra, P., Cooke, J., Corongiu, A., Coward, D.M., Dhillon, V.S., Dodson, R., Hardy, L.K., Howell, E.J., Jaroenjittichai, P., Klotz, A., Littlefair, S.P., Marsh, T.R., Mickaliger, M., Muxlow, T., Perrodin, D., Pritchard, T., Sawangwit, U., Terai, T., Tominaga, N., Torne, P., Totani, T., Trois, A., Turpin, D., Niino, Y., Wilson, R.W., Albert, A., André, M., Anghinolfi, M., Anton, G., Ardid, M., Aubert, J.-J., Avgitas, T., Baret, B., Barrios-Martí, J., Basa, S., Belhorma, B., Bertin, V., Biagi, S., Bormuth, R., Bourret, S., Bouwhuis, M.C., Brănzas, H., Bruijn, R., Brunner, J., Busto, J., Capone, A., Caramete, L., Carr, J., Celli, S., El Moursli, R. Cherkaoui, Chiarusi, T., Circella, M., Coelho, J.A.B., Coleiro, A., Coniglione, R., Costantini, H., Coyle, P., Creusot, A., Díaz, A.F., Deschamps, A., De Bonis, G., Distefano, C., Di Palma, I., Domi, A., Donzaud, C., Dornic, D., Drouhin, D., Eberl, T., El Bojaddaini, I., El Khayati, N., Elsässer, D., Enzenhöfer, A., Ettahiri, A., Fassi, F., Felis, I., Fusco, L.A., Gay, P., Giordano, V., Glotin, H., Gregoire, T., Gracia-Ruiz, R., Graf, K., Hallmann, S., van Haren, H., Heijboer, A.J., Hello, Y., Hernández-Rey, J.J., Hößl, J., Hofestädt, J., Hugon, C., Illuminati, G., James, C.W., de Jong, M., Jongen, M., Kadler, M., Kalekin, O., Katz, U., Kießling, D., Kouchner, A., Kreter, M., Kreykenbohm, I., Kulikovskiy, V., Lachaud, C., Lahmann, R., Lefevre, D., Leonora, E., Loucatos, S., Marcelin, M., Margiotta, A., Marinelli, A., Martínez-Mora, J.A., Mele, R., Melis, K., Michael, T., Migliozzi, P., Moussa, A., Navas, S., Nezri, E., Organokov, M., Pavalas, G.E., Pellegrino, C., Perrina, C., Piattelli, P., Popa, V., Pradier, T., Quinn, L., Racca, C., Riccobene, G., Sánchez-Losa, A., Saldana, M., Salvadori, I., Samtleben, D.F.E., Sanguineti, M., Sapienza, P., Schüssler, F., Sieger, C., Spurio, M., Stolarczyk, Th., Taiuti, M., Tayalati, Y., Trovato, A., Tönnis, C., Vallage, B., Van Elewyck, V., Versari, F., Vivolo, D., Vizzocca, A., Wilms, J., Zornoza, J.D., Zúniga, J., Keane, E. F., Barr, E. D., Bhat, N. D. R., Eatough, R. P., Green, J. A., Coward, D. M., Dhillon, V. S., Hardy, L. K., Howell, E. J., Littlefair, S. P., Marsh, T. R., Wilson, R. W., Andre, M., Aubert, J. -J., Barrios-Marti, J., Bouwhuis, M. C., Branzas, H., El Moursli, R. C., Coelho, J. A. B., Diaz, A. F., Elsasser, D., Enzenhofer, A., Fusco, L. A., Heijboer, A. J., Hernandez-Rey, J. J., Hossl, J., Hofestadt, J., James, C. W., Kiessling, D., Martinez-Mora, J. A., Pavalas, G. E., Sanchez-Losa, A., Samtleben, D. F. E., Schussler, F., Stolarczyk, T., Tonnis, C., Zornoza, J. D., and Zuniga, J.
Subjects: surveys – intergalactic medium, [ PHYS.ASTR ] Physics [physics]/Astrophysics [astro-ph], data analysis, Astrophysics, Surveys, 7. Clean energy, 01 natural sciences, radiation mechanisms, observational surveys, intergalactic medium, radio continuum, Astronomical observatories, Methods: Data analysis, Survey, data analysis [Methods], 010303 astronomy & astrophysics, media_common, general [Radiation mechanisms], Physics, High Energy Astrophysical Phenomena (astro-ph.HE), Fast radio burst, general [Radio continuum], Canadian Hydrogen Intensity Mapping Experiment, Intergalactic medium, Methods: Observational, Radiation mechanisms: General, Radio continuum: General, Neutrino, Observatoris astronòmics, Astrophysics - High Energy Astrophysical Phenomena, general [adio continuum], media_common.quotation_subject, FOS: Physical sciences, Methods: Data analysi, Radio telescope, Pulsar, 0103 physical sciences, Radiation mechanisms, observational [Methods], Source counts, Telescopis, Astronomy and Astrophysics, Space and Planetary Science, 010308 nuclear & particles physics, radiation mechanisms: general, methods: data analysis, methods: observational, radio continuum: general, Astronomy, Astronomy and Astrophysic, Afterglow, Radio continuum, 13. Climate action, Sky, FISICA APLICADA, Física::Astronomia i astrofísica [Àrees temàtiques de la UPC], data analysi [methods], [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Telescopes
Abstract: SB would like to thank Tara Murphy, Martin Bell, Paul Hancock, Keith Bannister, Chris Blake and Bing Zhang for useful discussions., We report the discovery of four Fast Radio Bursts (FRBs) in the ongoing SUrvey for Pulsars and Extragalactic Radio Bursts at the Parkes Radio Telescope: FRBs 150610, 151206, 151230 and 160102. Our real-time discoveries have enabled us to conduct extensive, rapid multimessenger follow-up at 12 major facilities sensitive to radio, optical, X-ray, gamma-ray photons and neutrinos on time-scales ranging from an hour to a few months post-burst. No counterparts to the FRBs were found and we provide upper limits on afterglow luminosities. None of the FRBs were seen to repeat. Formal fits to all FRBs show hints of scattering while their intrinsic widths are unresolved in time. FRB 151206 is at low Galactic latitude, FRB 151230 shows a sharp spectral cut-off, and FRB 160102 has the highest dispersion measure (DM = 2596.1 ± 0.3 pc cm−3) detected to date. Three of the FRBs have high dispersion measures (DM > 1500 pc cm−3), favouring a scenario where the DM is dominated by contributions from the intergalactic medium. The slope of the Parkes FRB source counts distribution with fluences >2 Jy ms is α=−2.2+0.6−1.2 and still consistent with a Euclidean distribution (α = −3/2). We also find that the all-sky rate is 1.7+1.5−0.9×103 FRBs/(4π sr)/day above ∼2Jyms and there is currently no strong evidence for a latitude-dependent FRB sky rate., The Parkes radio telescope and the Australia Telescope Compact Array are part of the Australia Telescope National Facility which is funded by the Commonwealth of Australia for operation as a National Facility managed by CSIRO. Parts of this research were conducted by the Australian Research Council Centre of Excellence for All-sky Astrophysics (CAASTRO), through project number CE110001020. The GMRT is run by the National Centre for Radio Astrophysics of the Tata Institute of Fundamental Research. VLAis run by theNational Radio Astronomy Observatory (NRAO). NRAO is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. This work was performed on the gSTAR national facility at Swinburne University of Technology. gSTAR is funded by Swinburne and the Australian Government’s Education Investment Fund. This work is also based on data collected at Subaru Telescope, which is operated by the National Astronomical Observatory of Japan. We thank the LSST Project for making their code available as free software at http://dm.lsstcorp.org. Funding from the European Research Council under the European Union’s Seventh Framework Programme (FP/2007-2013) / ERC Grant Agreement n. 617199 (EP). Access to the Lovell Telescope is supported through an STFC consolidated grant. The 100-m telescope in Effelsberg is operation by the Max- Planck-Institut für Radioastronomie with funds of the Max-Planck Society. The Sardinia Radio Telescope (SRT) is funded by the Department of University and Research (MIUR), the Italian Space Agency (ASI), and the Autonomous Region of Sardinia (RAS) and is operated as National Facility by the National Institute for Astrophysics (INAF). TB and RWW are grateful to the STFC for financial support (grant reference ST/P000541/1). Research support to IA is provided by the Australian Astronomical Observatory. The ANTARES authors acknowledge the financial support of the funding agencies: Centre National de la Recherche Scientifique (CNRS), Commissariat à l’énergie atomique et aux énergies alternatives (CEA), Commission Européenne (FEDER fund and Marie Curie Program), Institut Universitaire de France (IUF), IdEx program and UnivEarthS Labex program at Sorbonne Paris Cité (ANR-10- LABX-0023 and ANR-11-IDEX-0005-02), Labex OCEVU (ANR- 11-LABX-0060) and the A*MIDEX project (ANR-11-IDEX-0001- 02), Région Île-de-France (DIM-ACAV), Région Alsace (contrat CPER), Région Provence-Alpes-Côte d’Azur, Département du Var and Ville de La Seyne-sur-Mer, France; Bundesministerium für Bildung und Forschung (BMBF), Germany; IstitutoNazionale di Fisica Nucleare (INFN), Italy; Stichting voor Fundamenteel Onderzoek der Materie (FOM), Nederlandse organisatie voor Wetenschappelijk Onderzoek (NWO), the Netherlands; Council of the President of the Russian Federation for young scientists and leading scientific schools supporting grants, Russia; National Authority for Scientific Research (ANCS), Romania; Ministerio de Economía y Competitividad (MINECO): Plan Estatal de Investigación (refs. FPA2015- 65150-C3-1-P, -2-P and -3-P, (MINECO/FEDER)), Severo Ochoa Centre of Excellence and MultiDark Consolider (MINECO), and Prometeo and Grisolía programs (Generalitat Valenciana), Spain; Ministry of Higher Education, Scientific Research and Professional Training, Morocco. We also acknowledge the technical support of Ifremer, AIM and Foselev Marine for the sea operation and the CC-IN2P3 for the computing facilities. This work made use of data supplied by the UK Swift Science Data Centre at the University of Leicester. This research has made use of data, software and/or web tools obtained from the High Energy Astrophysics Science Archive Research Center (HEASARC), a service of the Astrophysics Science Division at NASA/GSFC and of the Smithsonian Astrophysical Observatory’s High Energy Astrophysics Division. This work is based in part on data collected at Subaru Telescope, which is operated by the National Astronomical Observatory of Japan. This paper makes use of software developed for the Large Synoptic Survey Telescope. We thank the LSST Project for making their code available as free software at http://dm.lsstcorp.org. RPE/MK gratefully acknowledges support from ERC Synergy Grant "BlackHoleCam" Grant Agreement Number 610058
Published: 2018
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41. MeerTime - the MeerKAT Key Science Program on Pulsar Timing

Author: V. M. Kaspi, Simon Johnston, Maura McLaughlin, Fernando Camilo, G. Theureau, Scott M. Ransom, Norbert Wex, Kavilan Moodley, W. van Straten, Jonathan Sievers, J. Brink, Benjamin Stappers, Aris Karastergiou, Michael Kramer, M. Burgay, M. Serylak, Michael Keith, Stefan Oslowski, N. D. R. Bhat, Matthew Bailes, Frederic A. Rasio, Ramesh Karuppusamy, Ewan Barr, Jason W. T. Hessels, D. J. Champion, A. Possenti, Ingrid H. Stairs, G. H. Jansseng, S. Buchner, Patrick Weltevrede, Andrew Jameson, Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Centre National d’Études Spatiales [Paris] (CNES), Unité Scientifique de la Station de Nançay (USN), Université d'Orléans (UO)-Observatoire des Sciences de l'Univers en région Centre (OSUC), PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Univers et Théories (LUTH (UMR_8102)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National d’Études Spatiales [Paris] (CNES), Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université d'Orléans (UO), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7), Laboratoire de Physique et Chimie de l'Environnement et de l'Espace ( LPC2E ), Centre National de la Recherche Scientifique ( CNRS ) -Université d'Orléans ( UO ) -Institut national des sciences de l'Univers ( INSU - CNRS ), Unité Scientifique de la Station de Nançay ( USN ), Institut national des sciences de l'Univers ( INSU - CNRS ) -Observatoire de Paris-Université d'Orléans ( UO ) -Centre National de la Recherche Scientifique ( CNRS ), Laboratoire Univers et Théories ( LUTH ), and Institut national des sciences de l'Univers ( INSU - CNRS ) -Observatoire de Paris-Université Paris Diderot - Paris 7 ( UPD7 ) -Centre National de la Recherche Scientifique ( CNRS )
Subjects: [ PHYS.ASTR ] Physics [physics]/Astrophysics [astro-ph], Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Magnetar, 7. Clean energy, 01 natural sciences, Pulsar, Millisecond pulsar, 0103 physical sciences, [PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], [ PHYS.PHYS.PHYS-INS-DET ] Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], Instrumentation and Methods for Astrophysics (astro-ph.IM), 010303 astronomy & astrophysics, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, Supermassive black hole, 010308 nuclear & particles physics, Gravitational wave, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy, Neutron star, Globular cluster, Glitch (astronomy), Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - High Energy Astrophysical Phenomena, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract: The MeerKAT telescope represents an outstanding opportunity for radio pulsar timing science with its unique combination of a large collecting area and aperture efficiency (effective area $\sim$7500 m$^2$), system temperature ($T, 15 pages, MeerKAT Science: On the Pathway to the SKA, 25-27 May, 2016, Stellenbosch, South Africa, available at: https://pos.sissa.it/277/011/pdf
Published: 2018
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42. The High Time Resolution Universe Pulsar Survey - XIII. PSR J1757-1854, the most accelerated binary pulsar

Author: Thomas M. Tauris, Michael Kramer, Paulo C. C. Freire, Duncan R. Lorimer, Caterina Tiburzi, A. D. Cameron, Matthew Bailes, Andrew Jameson, Benjamin Stappers, N. D. R. Bhat, Michael Keith, Lina Levin, Cherry Ng, Ramesh Karuppusamy, Ralph Eatough, Ewan Barr, Norbert Wex, Shivani Bhandari, Simon Johnston, Chris Flynn, D. J. Champion, Maura McLaughlin, A. Possenti, W. van Straten, C. G. Bassa, E. Petroff, Alessandro Ridolfi, M. Burgay, Sarah Burke-Spolaor, and Andrew Lyne
Subjects: astro-ph.SR, Astrophysics::High Energy Astrophysical Phenomena, Pulsar planet, FOS: Physical sciences, Astrophysics, General Relativity and Quantum Cosmology (gr-qc), 01 natural sciences, Binary pulsar, General Relativity and Quantum Cosmology, Gravitation, Pulsar, surveys, Millisecond pulsar, Tests of general relativity, 0103 physical sciences, 010306 general physics, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Physics, High Energy Astrophysical Phenomena (astro-ph.HE), astro-ph.HE, binaries: close, pulsars: individual: PSR, Astronomy, Astronomy and Astrophysics, J1757-1854, Neutron star, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, gravitation, Astrophysics::Earth and Planetary Astrophysics, Relativistic quantum chemistry, Astrophysics - High Energy Astrophysical Phenomena
Abstract: We report the discovery of PSR J1757$-$1854, a 21.5-ms pulsar in a highly-eccentric, 4.4-h orbit around a neutron star (NS) companion. PSR J1757$-$1854 exhibits some of the most extreme relativistic parameters of any known pulsar, including the strongest relativistic effects due to gravitational-wave (GW) damping, with a merger time of 76 Myr. Following a 1.6-yr timing campaign, we have measured five post-Keplerian (PK) parameters, yielding the two component masses ($m_\text{p}=1.3384(9)\,\text{M}_\odot$ and $m_\text{c}=1.3946(9)\,\text{M}_\odot$) plus three tests of general relativity (GR), which the theory passes. The larger mass of the NS companion provides important clues regarding the binary formation of PSR J1757$-$1854. With simulations suggesting 3-$\sigma$ measurements of both the contribution of Lense-Thirring precession to the rate of change of the semi-major axis and the relativistic deformation of the orbit within $\sim7-9$ years, PSR J1757$-$1854 stands out as a unique laboratory for new tests of gravitational theories., Comment: 6 pages, 2 figures, 2 tables
Published: 2017
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43. The SUrvey for Pulsars and Extragalactic Radio Bursts I: Survey Description and Overview

Author: Matthew Bailes, Shivani Bhandari, Michael Kramer, Caterina Tiburzi, N. D. R. Bhat, V. Morello, Ewan Barr, Simon Johnston, Cherry Ng, W. van Straten, E. Petroff, A. Jameson, Evan Keane, F. Jankowski, Ralph Eatough, M. Caleb, M. Burgay, Chris Flynn, Sarah Burke-Spolaor, Lina Levin, A. Possenti, and V. Venkatraman Krishnan
Subjects: media_common.quotation_subject, Astrophysics::High Energy Astrophysical Phenomena, Binary number, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Electromagnetic interference, Radio telescope, Pulsar, surveys, Millisecond pulsar, 0103 physical sciences, Eccentricity (behavior), 010303 astronomy & astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), media_common, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), 010308 nuclear & particles physics, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy, Astronomy and Astrophysics, Orbital period, methods: data analysis, Orbit, Space and Planetary Science, Astrophysics::Earth and Planetary Astrophysics, methods: observational, Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - High Energy Astrophysical Phenomena
Abstract: We describe the Survey for Pulsars and Extragalactic Radio Bursts (SUPERB), an ongoing pulsar and fast transient survey using the Parkes radio telescope. SUPERB involves real-time acceleration searches for pulsars and single-pulse searches for pulsars and fast radio bursts. We report on the observational setup, data analysis, multi-wavelength/messenger connections, survey sensitivities to pulsars and fast radio bursts and the impact of radio frequency interference. We further report on the first 10 pulsars discovered in the project. Among these is PSR~J1306$-$40, a millisecond pulsar in a binary system where it appears to be eclipsed for a large fraction of the orbit. PSR~J1421$-$4407 is another binary millisecond pulsar; its orbital period is $30.7$ days. This orbital period is in a range where only highly eccentric binaries are known, and expected by theory; despite this its orbit has an eccentricity of $10^{-5}$., Accepted for publication in MNRAS, 21 pages, 18 figures, 6 tables
Published: 2017

44. Comparison of Pulsar Positions from Timing and Very Long Baseline Astrometry

Author: Yuri Levin, Matthew Kerr, Stefan Oslowski, William A. Coles, Xing-Jiang Zhu, James Dempsey, Vikram Ravi, X. P. You, J. P. Yuan, Na Wang, Paul D. Lasky, Matthew Bailes, George Hobbs, Michael Keith, Christopher J. Russell, Linqing Wen, Ryan Shannon, W. van Straten, Pablo Rosado, N. D. R. Bhat, Shi Dai, Daniel J. Reardon, Richard N. Manchester, Renée Spiewak, J. B. Wang, and Lawrence Toomey
Subjects: astro-ph.GA, FOS: Physical sciences, Ephemeris, 01 natural sciences, Radio telescope, Pulsar, Axial tilt, 0103 physical sciences, Very-long-baseline interferometry, Instrumentation and Methods for Astrophysics (astro-ph.IM), 010303 astronomy & astrophysics, High Energy Astrophysical Phenomena (astro-ph.HE), Earth and Planetary Astrophysics (astro-ph.EP), Physics, astro-ph.HE, 010308 nuclear & particles physics, Astronomy, Astronomy and Astrophysics, Quasar, Astrometry, Astrophysics - Astrophysics of Galaxies, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), astro-ph.EP, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Instrumentation and Methods for Astrophysics, Reference frame, Astrophysics - Earth and Planetary Astrophysics, astro-ph.IM
Abstract: Pulsar positions can be measured with high precision using both pulsar timing methods and very-long-baseline interferometry (VLBI). Pulsar timing positions are referenced to a solar-system ephemeris, whereas VLBI positions are referenced to distant quasars. Here we compare pulsar positions from published VLBI measurements with those obtained from pulsar timing data from the Nanshan and Parkes radio telescopes in order to relate the two reference frames. We find that the timing positions differ significantly from the VLBI positions (and also differ between different ephemerides). A statistically significant change in the obliquity of the ecliptic of $2.16\pm0.33$\,mas is found for the JPL ephemeris DE405, but no significant rotation is found in subsequent JPL ephemerides. The accuracy with which we can relate the two frames is limited by the current uncertainties in the VLBI reference source positions and in matching the pulsars to their reference source. Not only do the timing positions depend on the ephemeris used in computing them, but also different segments of the timing data lead to varying position estimates. These variations are mostly common to all ephemerides, but slight changes are seen at the 10$\mu$as level between ephemerides., Comment: accepted by MNRAS,22 pages, 5 figures
Published: 2017
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45. A Census of Southern Pulsars at 185 MHz

Author: Charlotte Sobey, N. A. Swainston, S. J. McSweeney, Mengyao Xue, N. D. R. Bhat, Stephen M. Ord, Simon Johnston, S. E. Tremblay, B. W. Meyers, and David L. Kaplan
Subjects: 0106 biological sciences, Astrophysics::High Energy Astrophysical Phenomena, media_common.quotation_subject, Phase (waves), FOS: Physical sciences, Murchison Widefield Array, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, law.invention, Telescope, Pulsar, Millisecond pulsar, Frequency resolution, law, 0103 physical sciences, Instrumentation and Methods for Astrophysics (astro-ph.IM), 010303 astronomy & astrophysics, media_common, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy, Astronomy and Astrophysics, Square kilometre array, Space and Planetary Science, Sky, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Instrumentation and Methods for Astrophysics, 010606 plant biology & botany
Abstract: The Murchison Widefield Array, and its recently developed Voltage Capture System, facilitates extending the low-frequency range of pulsar observations at high-time and -frequency resolution in the Southern Hemisphere, providing further information about pulsars and the ISM. We present the results of an initial time-resolved census of known pulsars using the Murchison Widefield Array. To significantly reduce the processing load, we incoherently sum the detected powers from the 128 Murchison Widefield Array tiles, which yields ~10% of the attainable sensitivity of the coherent sum. This preserves the large field-of-view (~450 deg2 at 185 MHz), allowing multiple pulsars to be observed simultaneously. We developed a WIde-field Pulsar Pipeline that processes the data from each observation and automatically folds every known pulsar located within the beam. We have detected 50 pulsars to date, 6 of which are millisecond pulsars. This is consistent with our expectation, given the telescope sensitivity and the sky coverage of the processed data (~17 000 deg2). For 10 pulsars, we present the lowest frequency detections published. For a subset of the pulsars, we present multi-frequency pulse profiles by combining our data with published profiles from other telescopes. Since the Murchison Widefield Array is a low-frequency precursor to the Square Kilometre Array, we use our census results to forecast that a survey using the low-frequency component of the Square Kilometre Array Phase 1 can potentially detect around 9 400 pulsars.
Published: 2017
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46. Low Frequency Observations of the Subpulse Drifter PSR J0034-0721 with the Murchison Widefield Array

Author: S. J. McSweeney, Avinash A. Deshpande, S. E. Tremblay, N. D. R. Bhat, and Stephen M. Ord
Subjects: Physics, High Energy Astrophysical Phenomena (astro-ph.HE), 010308 nuclear & particles physics, FOS: Physical sciences, Astronomy and Astrophysics, Murchison Widefield Array, Astrophysics, Low frequency, Rotation, 01 natural sciences, Pulse (physics), Drifter, Acceleration, Pulsar, Space and Planetary Science, 0103 physical sciences, Stochastic drift, Astrophysics - High Energy Astrophysical Phenomena, 010303 astronomy & astrophysics
Abstract: The phenomenon of subpulse drifting may hold the key to understanding the pulsar emission mechanism. Here, we report on new observations of PSR J0034-0721 (B0031-07), carried out with the Murchison Widefield Array at 185 MHz. We observe three distinct drift modes whose "vertical" drift band separations ($P_3$) and relative abundances are consistent with previous studies at similar and higher frequencies. The driftbands, however, are observed to change their slopes over the course of individual drift modes, which can be interpreted as a continuously changing drift rate. The implied acceleration of the intrinsic carousel rotation cannot easily be explained by plasma models based on ExB drift. Furthermore, we find that methods of classifying the drift modes by means of $P_3$ measurements can sometimes produce erroneous identifications in the presence of a changing drift rate. The "horizontal" separation between driftbands ($P_2$) is found to be larger at later rotation phases within the pulse window, which is inconsistent with the established effects of retardation, aberration, and the motion of the visible point. Longer observations spanning at least ~10,000 pulses are required to determine how the carousel rotation parameters change from one drift sequence to the next., Comment: Accepted for publication in ApJ, 11 pages, 6 figures
Published: 2017
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47. Searching for gravitational wave memory bursts with the Parkes Pulsar Timing Array

Author: Jing Wang, Sarah Burke-Spolaor, Matthew Bailes, W. van Straten, Stefan Oslowski, George Hobbs, Yuri Levin, Vikram Ravi, Na Wang, N. D. R. Bhat, L. Toomey, Shi Dai, Xing-Jiang Zhu, Richard N. Manchester, Linqing Wen, Ryan Shannon, Matthew Kerr, William A. Coles, Michael Keith, and D. R. Madison
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO), Gravitational-wave observatory, Astrophysics::High Energy Astrophysical Phenomena, media_common.quotation_subject, FOS: Physical sciences, Astrophysics, Astronomy & Astrophysics, general [pulsars], Gravitational-wave astronomy, Binary pulsar, Pulsar timing array, Pulsar, pulsars: general, data analysis [methods], Instrumentation and Methods for Astrophysics (astro-ph.IM), media_common, Physics, Supermassive black hole, Gravitational wave, Astronomy, Astronomy and Astrophysics, Astrophysics - Astrophysics of Galaxies, methods: data analysis, gravitational waves, Space and Planetary Science, Sky, Astrophysics of Galaxies (astro-ph.GA), Astrophysics - Instrumentation and Methods for Astrophysics, Astronomical and Space Sciences, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract: Anisotropic bursts of gravitational radiation produced by events such as super-massive black hole mergers leave permanent imprints on space. Such gravitational wave "memory" (GWM) signals are, in principle, detectable through pulsar timing as sudden changes in the apparent pulse frequency of a pulsar. If an array of pulsars is monitored as a GWM signal passes over the Earth, the pulsars would simultaneously appear to change pulse frequency by an amount that varies with their sky position in a quadrupolar fashion. Here we describe a search algorithm for such events and apply the algorithm to approximately six years of data from the Parkes Pulsar Timing Array. We find no GWM events and set an upper bound on the rate for events which could have been detected. We show, using simple models of black hole coalescence rates, that this non-detection is not unexpected., Accepted by MNRAS
Published: 2014
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48. The First Murchison Widefield Array low-frequency radio observations of cluster scale non-thermal emission: the case of Abell 3667

Author: Bryna J. Hazelton, Bryan Gaensler, Melanie Johnston-Hollitt, Thiagaraj Prabu, Martin Bell, Gianni Bernardi, Christopher L. Williams, Natasha Hurley-Walker, Emil Lenc, Bartosz Pindor, David L. Kaplan, Robert F. Goeke, A. Roshi, Daniel C. Jacobs, N. Udaya Shankar, K. S. Dwarakanath, Steven Tingay, Alan E. E. Rogers, David Emrich, Brian E. Corey, A. R. Offringa, Daniel A. Mitchell, Luke Hindson, Ettore Carretti, M. J. Lynch, N. D. R. Bhat, Lincoln J. Greenhill, Judd D. Bowman, J. Riding, Colin J. Lonsdale, Randall B. Wayth, Eric R. Morgan, Frank H. Briggs, Miguel F. Morales, Mark Waterson, Stephen M. Ord, Aaron Ewall-Wice, Benjamin McKinley, Alan R. Whitney, Justin C. Kasper, K. S. Srivani, Pietro Procopio, Divya Oberoi, Eric Kratzenberg, Andrew Williams, Avinash A. Deshpande, Roger J. Cappallo, John Morgan, K. Buckley, Rachel L. Webster, Nadia Kudryavtseva, Ravi Subrahmanyan, Stephen R. McWhirter, and Lu Feng
Subjects: Physics, FOS: Physical sciences, Astronomy, Astronomy and Astrophysics, Murchison Widefield Array, Astrophysics, Astrophysics - Astrophysics of Galaxies, 01 natural sciences, Galaxy, Radio relics, Radio halo, X-shaped radio galaxy, Abell 2744, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), 0103 physical sciences, Abell 520, 010306 general physics, 010303 astronomy & astrophysics, Galaxy cluster
Abstract: We present the first Murchison Widefield Array observations of the well-known cluster of galaxies Abell 3667 (A3667) between 105 and 241 MHz. A3667 is one of the best known examples of a galaxy cluster hosting a double radio relic and has been reported to contain a faint radio halo and bridge. The origins of radio halos, relics and bridges is still unclear, however galaxy cluster mergers seems to be an important factor. We clearly detect the North-West (NW) and South-East (SE) radio relics in A3667 and find an integrated flux density at 149 MHz of 28.1 +/- 1.7 and 2.4 +/- 0.1 Jy, respectively, with an average spectral index, between 120 and 1400 MHz, of -0.9 +/- 0.1 for both relics. We find evidence of a spatial variation in the spectral index across the NW relic steepening towards the centre of the cluster, which indicates an ageing electron population. These properties are consistent with higher frequency observations. We detect emission that could be associated with a radio halo and bridge. How- ever, due to the presence of poorly sampled large-scale Galactic emission and blended point sources we are unable to verify the exact nature of these features., 17 pages, 11 figures
Published: 2014
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49. The High Time Resolution Universe survey – IX. Polarimetry of long-period pulsars

Author: Caterina Tiburzi, N. D. R. Bhat, W. van Straten, Ben Stappers, Sarah Burke-Spolaor, S. Milia, Matthew Bailes, Simon Johnston, Michael Kramer, D. Thornton, Michael Keith, A. Possenti, Cherry Ng, D. Champion, Lina Levin, N. D'Amico, M. Burgay, Samuel Bates, and P. Coster
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE), Physics, Line-of-sight, Spiral galaxy, Astrophysics::High Energy Astrophysical Phenomena, Polarimetry, FOS: Physical sciences, Astronomy, Astronomy and Astrophysics, Time resolution, Astrophysics, Polarization (waves), Position angle, Magnetic field, Astrophysics - Solar and Stellar Astrophysics, Pulsar, Space and Planetary Science, Astrophysics - High Energy Astrophysical Phenomena, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics
Abstract: We present a polarimetric analysis of 49 long-period pulsars discovered as part of the High Time Resolution Universe (HTRU) southern survey. The sources exhibit the typical characteristics of "old" pulsars, with low fractional linear and circular polarisation and narrow, multicomponent profiles. Although the position angle swings are generally complex, for two of the analysed pulsars (J1622-3751 and J1710-2616) we obtained an indication of the geometry via the rotating vector model. We were able to determine a value of the rotation measure (RM) for 34 of the sources which, when combined with their dispersion measures (DM), yields an integrated magnetic field strength along the line of sight. With the data presented here, the total number of values of RM associated to pulsars discovered during the HTRU southern survey sums to 51. The RMs are not consistent with the hypothesis of a counter-clockwise direction of the Galactic magnetic field within an annulus included between 4 and 6 kpc from the Galactic centre. A partial agreement with a counter-clockwise sense of the Galactic magnetic field within the spiral arms is however found in the area of the Carina-Sagittarius arm., 18 pages, 5 figures, 2 tables, accepted by MNRAS
Published: 2013
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50. The High Time Resolution Universe Pulsar Survey –VIII. The Galactic millisecond pulsar population

Author: Cherry Ng, Andrew Jameson, Benjamin Stappers, N. D. R. Bhat, P. Coster, N. D'Amico, Samuel Bates, D. J. Champion, Simon Johnston, W. van Straten, A. Possenti, David J. Thornton, Benjamin R. Barsdell, S. Milia, Lina Levin, Sarah Burke-Spolaor, Michael Kramer, M. Burgay, Michael Keith, and Matthew Bailes
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE), Physics, education.field_of_study, Astrophysics::High Energy Astrophysical Phenomena, media_common.quotation_subject, Population, FOS: Physical sciences, Astronomy, Flux, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Universe, Galaxy, Luminosity, Astrophysics - Solar and Stellar Astrophysics, Pulsar, Space and Planetary Science, Millisecond pulsar, Astrophysics - High Energy Astrophysical Phenomena, education, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, Scale factor (cosmology), media_common
Abstract: We have used millisecond pulsars (MSPs) from the southern High Time Resolution Universe (HTRU) intermediate latitude survey area to simulate the distribution and total population of MSPs in the Galaxy. Our model makes use of the scale factor method, which estimates the ratio of the total number of MSPs in the Galaxy to the known sample. Using our best fit value for the z-height, z=500 pc, we find an underlying population of MSPs of 8.3(\pm 4.2)*10^4 sources down to a limiting luminosity of L_min=0.1 mJy kpc^2 and a luminosity distribution with a steep slope of d\log N/d\log L = -1.45(\pm 0.14). However, at the low end of the luminosity distribution, the uncertainties introduced by small number statistics are large. By omitting very low luminosity pulsars, we find a Galactic population above L_min=0.2 mJy kpc^2 of only 3.0(\pm 0.7)*10^4 MSPs. We have also simulated pulsars with periods shorter than any known MSP, and estimate the maximum number of sub-MSPs in the Galaxy to be 7.8(\pm 5.0)*10^4 pulsars at L=0.1 mJy kpc^2. In addition, we estimate that the high and low latitude parts of the southern HTRU survey will detect 68 and 42 MSPs respectively, including 78 new discoveries. Pulsar luminosity, and hence flux density, is an important input parameter in the model. Some of the published flux densities for the pulsars in our sample do not agree with the observed flux densities from our data set, and we have instead calculated average luminosities from archival data from the Parkes Telescope. We found many luminosities to be very different than their catalogue values, leading to very different population estimates. Large variations in flux density highlight the importance of including scintillation effects in MSP population studies., Comment: 13 pages, 5 figures, 5 tables. Accepted for publication in MNRAS
Published: 2013
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