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88 results on '"Buckley, D.A.H."'

1. The transient event in NGC 1566 from 2017 to 2019. I. An eccentric accretion disk and a turbulent, disk-dominated broad-line region unveiled by double-peaked Ca II and O I lines

Author

Ochmann, M.W., primary, Kollatschny, W., additional, Probst, M.A., additional, Romero-Colmenero, E., additional, Buckley, D.A.H., additional, Chelouche, D., additional, Chini, R., additional, Grupe, D., additional, Haas, M., additional, Kaspi, S., additional, Komossa, S., additional, Parker, M.L., additional, Santos-Lleo, M., additional, Schartel, N., additional, and Famula, P., additional

Published
2024
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2. Microquasar V404 Cyg /GS 2023+338: MASTER optical observations during the June and December 2015 super-outbursts

Author

Lipunov, V.M., Gorbovskoy, E., Kuznetsov, A., Vlasenko, D., Kornilov, V.G., Zimnukhov, D., Vladimirov, V., Giovannelli, F., Titarchuk, L.G., Shakura, N.I., Rebolo, R., Serra-Ricart, M., Buckley, D.A.H., Tiurina, N., Budnev, N.M., Gress, O., Hongbo, H., Wang, X., Krushinsky, V., Tlatov, A., Balanutsa, P., Gabovich, A., Yurkov, V., Ershova, O., and Grinshpun, V.

Published
2019
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4. Swift Deep Galactic Plane Survey classification of Swift J170800−402551.8 as a candidate intermediate polar cataclysmic variable

Author

O’Connor, B., Göğüş, E., Hare, J., Mukai, K., Huppenkothen, D., Brink, J., Buckley, D.A.H., Levan, Andrew, Baring, M.G., Stewart, R., Kouveliotou, C., Woudt, P., Bellm, E., Cenko, S.B., Evans, P.A., Granot, J., Hailey, C., Harrison, F., Hartmann, D., Horst, A.J. van der, Kaper, L., Kennea, J.A., Potter, S.B., Slane, P.O., Stern, D., Wijers, R.A.M.J., Younes, G., O’Connor, B., Göğüş, E., Hare, J., Mukai, K., Huppenkothen, D., Brink, J., Buckley, D.A.H., Levan, Andrew, Baring, M.G., Stewart, R., Kouveliotou, C., Woudt, P., Bellm, E., Cenko, S.B., Evans, P.A., Granot, J., Hailey, C., Harrison, F., Hartmann, D., Horst, A.J. van der, Kaper, L., Kennea, J.A., Potter, S.B., Slane, P.O., Stern, D., Wijers, R.A.M.J., and Younes, G.

Abstract

Item does not contain fulltext

Published
2023

5. Identification of 1RXS J165424.6-433758 as a Polar Cataclysmic Variable

Author

O’Connor, B., Brink, J., Buckley, D.A.H., Mukai, K., Kouveliotou, C., Göğüş, E., Potter, S.B., Woudt, P., Lien, A., Levan, A.J., Kargaltsev, O., Baring, M.G., Bellm, E., Cenko, S.B., Evans, P.A., Granot, J., Hailey, C., Harrison, F., Hartmann, D., Horst, A.J. van der, Huppenkothen, D., Kaper, L., Kennea, J.A., Slane, P.O., Stern, D., Troja, E., Wijers, R.A.M.J., Younes, G., O’Connor, B., Brink, J., Buckley, D.A.H., Mukai, K., Kouveliotou, C., Göğüş, E., Potter, S.B., Woudt, P., Lien, A., Levan, A.J., Kargaltsev, O., Baring, M.G., Bellm, E., Cenko, S.B., Evans, P.A., Granot, J., Hailey, C., Harrison, F., Hartmann, D., Horst, A.J. van der, Huppenkothen, D., Kaper, L., Kennea, J.A., Slane, P.O., Stern, D., Troja, E., Wijers, R.A.M.J., and Younes, G.

Abstract

Item does not contain fulltext

Published
2023

6. Deciphering the extreme X-ray variability of the nuclear transient eRASSt J045650.3-203750: A likely repeating partial tidal disruption event

Author

Liu, Z., Malyali, A., Krumpe, M., Homan, D., Goodwin, Adelle, Grotova, I., Kawka, A., Rau, A., Merloni, A., Anderson, Gemma, Miller-Jones, James, Markowitz, A.G., Ciroi, S., Di Mille, F., Schramm, M., Tang, S., Buckley, D.A.H., Gromadzki, M., Jin, C., Buchner, J., Liu, Z., Malyali, A., Krumpe, M., Homan, D., Goodwin, Adelle, Grotova, I., Kawka, A., Rau, A., Merloni, A., Anderson, Gemma, Miller-Jones, James, Markowitz, A.G., Ciroi, S., Di Mille, F., Schramm, M., Tang, S., Buckley, D.A.H., Gromadzki, M., Jin, C., and Buchner, J.

Abstract

Context. During its all-sky survey, the extended ROentgen Survey with an Imaging Telescope Array (eROSITA) on board the Spectrum-Roentgen-Gamma (SRG) observatory has uncovered a growing number of X-ray transients associated with the nuclei of quiescent galaxies. Benefitting from its large field of view and excellent sensitivity, the eROSITA window into time-domain X-ray astrophysics yields a valuable sample of X-ray selected nuclear transients. Multi-wavelength follow-up enables us to gain new insights into understanding the nature and emission mechanism of these phenomena. Aims. We present the results of a detailed multi-wavelength analysis of an exceptional repeating X-ray nuclear transient, eRASSt J045650.3-203750 (hereafter J0456-20), uncovered by SRG/eROSITA in a quiescent galaxy at a redshift of z ∼ 0:077. We aim to understand the radiation mechanism at different luminosity states of J0456-20, and provide further evidence that similar accretion processes are at work for black hole accretion systems at different black hole mass scales. Methods. We describe our temporal analysis, which addressed both the long- and short-term variability of J0456-20. A detailed X-ray spectral analysis was performed to investigate the X-ray emission mechanism. Results. Our main findings are that (1) J0456-20 cycles through four distinctive phases defined based on its X-ray variability: an X-ray rising phase leading to an X-ray plateau phase that lasts for abouttwo months. This is terminated by a rapid X-ray flux drop phase during which the X-ray flux can drop drastically by more than a factor of 100 within one week, followed by an X-ray faint state for about two months before the X-ray rising phase starts again. (2) The X-ray spectra are generally soft in the rising phase, with a photon index & 3:0, and they become harder as the X-ray flux increases. There is evidence of a multi-colour disk with a temperature of Tin ∼ 70 eV in the inner region at the beginning of the X-ray rising

Published
2023

8. Stokes Imaging of the Accretion Region in Magnetic Cataclysmic Variables

Author

Potter, S., Romero-Colmenero, E., Buckley, D.A.H., Cropper, M., Hakala, P., Beig, R., editor, Ehlers, J., editor, Frisch, U., editor, Hepp, K., editor, Hillebrandt, W., editor, Imboden, D., editor, Jaffe, R. L., editor, Kippenhahn, R., editor, Lipowsky, R., editor, Löhneysen, H. v., editor, Ojima, I., editor, Weidenmüller, H. A., editor, Wess, J., editor, Zittartz, J., editor, Boffin, Henri M.J., editor, Cuypers, Jan, editor, and Steeghs, Danny, editor

Published
2001
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9. An accreting white dwarf displaying fast transitional mode switching

Author

Scaringi, S., Martino, D. de, Buckley, D.A.H., Groot, P.J., Knigge, C., Fratta, M., Littlefield, C., Papitto, A., Scaringi, S., Martino, D. de, Buckley, D.A.H., Groot, P.J., Knigge, C., Fratta, M., Littlefield, C., and Papitto, A.

Abstract

Contains fulltext : 246923.pdf (Publisher’s version ) (Closed access)

Published
2022

10. Localized thermonuclear bursts from accreting magnetic white dwarfs

Author

Scaringi, S., Groot, P.J., Knigge, C., Bird, A.J., Breedt, E., Buckley, D.A.H., Cavecchi, Y., Degenaar, N.D., Martino, D. de, Done, C., Fratta, M., Iłkiewicz, K., Koerding, E., Lasota, J.P., Littlefield, C., Manara, C.F., O'Brien, M., Szkody, P., Timmes, F.X., Scaringi, S., Groot, P.J., Knigge, C., Bird, A.J., Breedt, E., Buckley, D.A.H., Cavecchi, Y., Degenaar, N.D., Martino, D. de, Done, C., Fratta, M., Iłkiewicz, K., Koerding, E., Lasota, J.P., Littlefield, C., Manara, C.F., O'Brien, M., Szkody, P., and Timmes, F.X.

Abstract

Contains fulltext : 249212.pdf (Publisher’s version ) (Closed access) Contains fulltext : 249212.pdf (Author’s version preprint ) (Open Access)

Published
2022

11. SXP 15.6 - an accreting pulsar close to spin equilibrium?

Author

Coe, M.J., Monageng, I.M., Kennea, J.A., Buckley, D.A.H., Evans, P.A., Udalski, A., Groot, P., Bloemen, Steven, Vreeswijk, Paul, Klein-Wolt, M., Woudt, P.A., Körding, Elmar, Poole, R. Le, Pieterse, D.L.A., Coe, M.J., Monageng, I.M., Kennea, J.A., Buckley, D.A.H., Evans, P.A., Udalski, A., Groot, P., Bloemen, Steven, Vreeswijk, Paul, Klein-Wolt, M., Woudt, P.A., Körding, Elmar, Poole, R. Le, and Pieterse, D.L.A.

Abstract

Contains fulltext : 250897.pdf (Publisher’s version ) (Open Access)

Published
2022

13. Optical, X-ray, and γ-ray observations of the candidate transitional millisecond pulsar 4FGL J0427.8-6704

Author

Kennedy, M.R., Breton, R.P., Clark, C.J., Dhillon, V.S., Kerr, M., Buckley, D.A.H., Potter, S.B., Mata Sánchez, D., Stringer, J.G., and Marsh, T.R.

Abstract

We present an optical, X-ray, and γ-ray study of 1SXPS J042749.2-670434, an eclipsing X-ray binary that has an associated γ-ray counterpart, 4FGL J0427.8-6704. This association has led to the source being classified as a transitional millisecond pulsar (tMSP) in an accreting state. We analyse 10.5 yr of Fermi LAT data and detect a γ-ray eclipse at the same phase as optical and X-ray eclipses at the >5 σ level, a significant improvement on the 2.8 σ level of the previous detection. The confirmation of this eclipse solidifies the association between the X-ray source and the γ-ray source, strengthening the tMSP classification. However, analysis of several optical data sets and an X-ray observation do not reveal a change in the source’s median brightness over long time-scales or a bi-modality on short time-scales. Instead, the light curve is dominated by flickering, which has a correlation time of 2.6 min alongside a potential quasi-periodic oscillation at ∼21 min. The mass of the primary and secondary stars is constrained to be M1=1.43+0.33−0.19 M⊙ and M2=0.3+0.17−0.12 M⊙ through modelling of the optical light curve. While this is still consistent with a white dwarf primary, we favour the tMSP in a low accretion state classification due to the significance of the γ-ray eclipse detection.

Published
2020

14. A major optical and X-ray outburst from the Magellanic Bridge source RX J0209.6-7427

Author

Coe, Malcolm, Monageng, I.M., Bartlett, E.S., Buckley, D.A.H., and Udalski, A.

Subjects
Astrophysics::High Energy Astrophysical Phenomena, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Galaxy Astrophysics
Abstract

RX J0209.6-7427 is an X-ray source in the Magellanic Bridge that was first detected in 1993, but not seen again till 2019. It has been identified as a member of the Be/X-ray binary class, a category of objects that are well established as bright, often-unpredictable transients. Such systems are rarely known in the Bridge, possibly because they lie outside the area most commonly studied by X-ray telescopes. Whatever the reason for the sparse number of such systems in the Bridge, they can provide useful tools for trying to understand the result of the tidal dynamics of the two Magellanic Clouds. In this paper the nature of the object is explored with the help of new data obtained during the latest outburst. In particular, the first optical spectrum of the counterpart is presented to help classify the star, plus measurements of the Balmer emission lines over several years are used to investigate changes in the size and structure of the circumstellar disk.

Published
2020

15. A spectroscopic, photometric, polarimetric, and radio study of the eclipsing polar UZ Fornacis: the first simultaneous SALT and MeerKAT observations

Author

Khangale, Z.N., Potter, S.B., Woudt, P., Buckley, D.A.H., Semena, A.N., Kotze, E.J., Groenewald, D.N., Hewitt, D.M., Pretorius, M.L., Fender, R.P., Groot, P.J., Bloemen, S., Klein-Wolt, M., Körding, E., Le Poole, R., McBride, V.A., Townsend, L., Paterson, K., Pieterse, D.L.A., Vreeswijk, P., Khangale, Z.N., Potter, S.B., Woudt, P., Buckley, D.A.H., Semena, A.N., Kotze, E.J., Groenewald, D.N., Hewitt, D.M., Pretorius, M.L., Fender, R.P., Groot, P.J., Bloemen, S., Klein-Wolt, M., Körding, E., Le Poole, R., McBride, V.A., Townsend, L., Paterson, K., Pieterse, D.L.A., and Vreeswijk, P.

Abstract

Contains fulltext : 216860.pdf (publisher's version ) (Open Access)

Published
2020

16. An extremely powerful long-lived superluminal ejection from the black hole MAXI J1820+070

Author

Bright, J.S., Fender, R.P., Motta, S.E., Williams, D.R.A., Moldon, J., Plotkin, Richard, Miller-Jones, James, Heywood, I., Tremou, E., Beswick, R., Sivakoff, G.R., Corbel, S., Buckley, D.A.H., Homan, J., Gallo, E., Tetarenko, A.J., Russell, T.D., Green, D.A., Titterington, D., Woudt, P.A., Armstrong, R.P., Groot, P.J., Horesh, A., Horst, A.J.V.D., Körding, E.G., McBride, V.A., Rowlinson, A., Wijers, R.A.M.J., Bright, J.S., Fender, R.P., Motta, S.E., Williams, D.R.A., Moldon, J., Plotkin, Richard, Miller-Jones, James, Heywood, I., Tremou, E., Beswick, R., Sivakoff, G.R., Corbel, S., Buckley, D.A.H., Homan, J., Gallo, E., Tetarenko, A.J., Russell, T.D., Green, D.A., Titterington, D., Woudt, P.A., Armstrong, R.P., Groot, P.J., Horesh, A., Horst, A.J.V.D., Körding, E.G., McBride, V.A., Rowlinson, A., and Wijers, R.A.M.J.

Abstract

Black holes in binary systems execute patterns of outburst activity where two characteristic X-ray states are associated with different behaviours observed at radio wavelengths. The hard state is associated with radio emission indicative of a continuously replenished, collimated, relativistic jet, whereas the soft state is rarely associated with radio emission, and never continuously, implying the absence of a quasi-steady jet. Here we report radio observations of the black hole transient MAXI J1820+070 during its 2018 outburst. As the black hole transitioned from the hard to soft state, we observed an isolated radio flare, which, using high-angular-resolution radio observations, we connect with the launch of bipolar relativistic ejecta. This flare occurs as the radio emission of the core jet is suppressed by a factor of over 800. We monitor the evolution of the ejecta over 200 days and to a maximum separation of 10″, during which period it remains detectable due to in situ particle acceleration. Using simultaneous radio observations sensitive to different angular scales, we calculate an accurate estimate of energy content of the approaching ejection. This energy estimate is far larger than that derived from the state transition radio flare, suggesting a systematic underestimate of jet energetics.

Published
2020

18. Discovery and follow-up of the unusual nuclear transient OGLE17aaj

Author

Gromadzki, M., Hamanowicz, A., Wyrzykowski, L., Sokolovsky, K.V., Fraser, M., Kozlowski, S., Jonker, P.G., Onori, F., Angus, C.R., Buckley, D.A.H., Gromadzki, M., Hamanowicz, A., Wyrzykowski, L., Sokolovsky, K.V., Fraser, M., Kozlowski, S., Jonker, P.G., Onori, F., Angus, C.R., and Buckley, D.A.H.

Abstract

Contains fulltext : 200918.pdf (publisher's version ) (Open Access) Contains fulltext : 200918.pdf (preprint version ) (Open Access)

Published
2019

19. Puzzling blue dips in the black hole candidate Swift J1357.2 − 0933, from ULTRACAM, SALT, ATCA, Swift, and NuSTAR

Author

Paice, J.A., Gandhi, P., Charles, P.A., Dhillon, V.S., Marsh, T.R., Buckley, D.A.H., Kotze, M.M., Beri, A., Altamirano, D., Middleton, M.J., Plotkin, Richard, Miller-Jones, James, Russell, D.M., Tomsick, J., Díaz-Merced, W., Misra, R., Paice, J.A., Gandhi, P., Charles, P.A., Dhillon, V.S., Marsh, T.R., Buckley, D.A.H., Kotze, M.M., Beri, A., Altamirano, D., Middleton, M.J., Plotkin, Richard, Miller-Jones, James, Russell, D.M., Tomsick, J., Díaz-Merced, W., and Misra, R.

Abstract

© 2019 The Author(s). We present rapid, multiwavelength photometry of the low-mass X-ray binary Swift J1357.2-0933 during its 2017 outburst. Using several sets of quasi-simultaneous ULTRACAM/NTT (optical), NuSTAR (X-ray), XRT/Swift (X-ray), SALT (optical), and ATCA (radio) observations taken during outburst decline, we confirm the frequent optical dipping that has previously been noted both in outburst and in quiescence. We also find: (1) that the dip frequency decreases as the outburst decays, similar to what was seen in the previous outburst, (2) that the dips produce a shape similar to that in binary systems with partial disc occultations, (3) that the source becomes significantly bluer during these dips, indicating an unusual geometry compared to other LMXB dippers, and (4) that dip superposition analysis confirms the lack of an X-ray response to the optical dips. These very unusual properties appear to be unique to Swift J1357.2−0933, and are likely the result of a high binary inclination, as inferred from features such as its very low outburst X-ray luminosity. From this analysis as well as X-ray/optical timing correlations, we suggest a model with multicomponent emission/absorption features with differing colours. This could include the possible presence of a sporadically occulted jet base and a recessed disc. This source still hosts many puzzling features, with consequences for the very faint X-ray transients population.

Published
2019

22. SALT spectroscopic classification of transient Gaia17bur as a likely dwarf nova

Author

Gromadzki, M., Wyrzykowski, L., Mroz, P., Hamanowicz, A., Kostrzewa-Rutkowska, Z.P., Buckley, D.A.H., Romero-Colmenero, E., Gromadzki, M., Wyrzykowski, L., Mroz, P., Hamanowicz, A., Kostrzewa-Rutkowska, Z.P., Buckley, D.A.H., and Romero-Colmenero, E.

Abstract

Item does not contain fulltext

Published
2017

23. SALT observations of the optical counterpart of MAXI J1957+032

Author

Buckley, D.A.H., Kotze, M.M., Charles, P.A., Sanchez, D.M., Munoz-Darias, T., Israel, G., Masetti, E.J.M.N., Jonker, P.G., Buckley, D.A.H., Kotze, M.M., Charles, P.A., Sanchez, D.M., Munoz-Darias, T., Israel, G., Masetti, E.J.M.N., and Jonker, P.G.

Abstract

Item does not contain fulltext

Published
2016

25. The XMM-Newton survey of the small Magellanic cloud: The X-ray point-source catalogue

Author

Sturm, R. Haberl, F. Pietsch, W. Ballet, J. Hatzidimitriou, D. Buckley, D.A.H. Coe, M. Ehle, M. Filipović, M.D. La Palombara, N. Tiengo, A.

Abstract

Context. Local-Group galaxies provide access to samples of X-ray source populations of whole galaxies. The XMM-Newton survey of the Small Magellanic Cloud (SMC) completely covers the bar and eastern wing with a 5.6 deg2 area in the (0.2?12.0) keV band. Aims. To characterise the X-ray sources in the SMC field, we created a catalogue of point sources and sources with moderate extent. Sources with high extent (≤40'') have been presented in a companion paper. Methods. We searched for point sources in the EPIC images using sliding-box and maximum-likelihood techniques and classified the sources using hardness ratios, X-ray variability, and their multi-wavelength properties. Results. The catalogue comprises 3053 unique X-ray sources with a median position uncertainty of 1.3" down to a flux limit for point sources of ∼10?14 erg cm?2 s?1 in the (0.2?4.5) keV band, corresponding to 5 × 1033 erg s?1 for sources in the SMC.We discuss statistical properties, like the spatial distribution, X-ray colour diagrams, luminosity functions, and time variability. We identified 49 SMC high-mass X-ray binaries (HMXB), four super-soft X-ray sources (SSS), 34 foreground stars, and 72 active galactic nuclei (AGN) behind the SMC. In addition, we found candidates for SMC HMXBs (45) and faint SSSs (8) as well as AGN (2092) and galaxy clusters (13). Conclusions. We present the most up-to-date catalogue of the X-ray source population in the SMC field. In particular, the known population of X-ray binaries is greatly increased. We find that the bright-end slope of the luminosity function of Be/X-ray binaries significantly deviates from the expected universal high-mass X-ray binary luminosity function. © ESO 2013.

Published
2013

26. IKT 16: A composite supernova remnant in the Small Magellanic Cloud

Author

Owen, R.A. Filipović, M.D. Ballet, J. Haberl, F. Crawford, E.J. Payne, J.L. Sturm, R. Pietsch, W. Mereghetti, S. Ehle, M. Tiengo, A. Coe, M.J. Hatzidimitriou, D. Buckley, D.A.H.

Subjects
Astrophysics::High Energy Astrophysical Phenomena, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics::Galaxy Astrophysics
Abstract

Aims. IKT 16 is an X-ray and radio-faint supernova remnant (SNR) in the Small Magellanic Cloud (SMC). A previous X-ray study of this SNR found a hard X-ray source near its centre. Using all available archival and proprietary XMM-Newton data, alongside new multi-frequency radio-continuum surveys and optical observations at Hα and forbidden [SII] and [OIII] lines, we aim to constrain the properties of the SNR and discover the nature of the hard source within. Methods. We combine XMM-Newton datasets to produce the highest quality X-ray image of IKT 16 to date. We use this, in combination with radio and optical images, to conduct a multi-wavelength morphological analysis of the remnant. We extract separate spectra from the SNR and the bright source near its centre, and conduct spectral fitting of both regions. Results. We find IKT 16 to have a radius of 37 ± 3 pc, with the bright source located 8 ± 2 pc from the centre. This is the largest known SNR in the SMC. The large size of the remnant suggests it is likely in the Sedov-adiabatic phase of evolution. Using a Sedov model to fit the SNR spectrum, we find an electron temperature kT of 1.03 ± 0.12 keV and an age of 14700 yr. The absorption found requires the remnant to be located deep within the SMC. The bright source is fit with a power law with index Γ = 1.58 ± 0.07, and is associated with diffuse radio emission extending towards the centre of the SNR. We argue that this source is likely to be the neutron star remnant of the supernova explosion, and infer its transverse kick velocity to be 580 ± 100 km s -1. The X-ray and radio properties of this source strongly favour a pulsar wind nebula (PWN) origin. © 2011 ESO.

Published
2011

27. The XMM-newton survey of the small magellanic cloud: Discovery of the 11.866s Be/X-ray binary pulsar XMMU J004814.0-732204 (SXP11.87)

Author

Sturm, R. Haberl, F. Coe, M.J. Bartlett, E.S. Buckley, D.A.H. Corbet, R.H.D. Ehle, M. Filipović, M.D. Hatzidimitriou, D. Mereghetti, S. La Palombara, N. Pietsch, W. Tiengo, A. Townsend, L.J. Udalski, A.

Subjects
Astrophysics::High Energy Astrophysical Phenomena, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics::Galaxy Astrophysics
Abstract

Aims. One of the goals of the XMM-Newton survey of the Small Magellanic Cloud is to study the Be/X-ray binary population. During one of our first survey observations, a bright new transient - XMMU J004814.0-732204 - was discovered. Methods. We present the analysis of the EPIC X-ray data, together with optical observations, to investigate the spectral and temporal characteristics of XMMU J004814.0-732204. Results. We found coherent X-ray pulsations in the EPIC data with a period of (11.86642 ± 0.00017) s. The X-ray spectrum can be modelled by an absorbed power law with an indication for a soft excess. Depending on the modelling of the soft X-ray spectrum, the photon index ranges between 0.53 and 0.66. We identify the optical counterpart as a B = 14.9 mag star that was monitored during the MACHO and OGLE-III projects. The optical light curves show regular outbursts by ∼0.5 mag in B and R and up to 0.9 mag in I, which repeat on a time scale of about 1000 days. The OGLE-III optical colours of the star are consistent with an early B spectral type. An optical spectrum obtained at the 1.9 m telescope of the South African Astronomical Observatory in December 2009 shows Hα emission with an equivalent width of 3.5 ± 0.6 Å. Conclusions. The X-ray spectrum and the detection of pulsations suggest that XMMU J004814.0-732204is a new high-mass X-ray binary pulsar in the SMC. The long term variability and the Hα emission line in the spectrum of the optical counterpart identify it as a Be/X-ray binary system. © 2011 ESO.

Published
2011

30. Observational detection of eight mutual eclipses and occultations between the satellites of Uranus

Author

Christou, A.A. Lewis, F. Roche, P. Hashimoto, Y. O'Donoghue, D. Worters, H. Buckley, D.A.H. Michalowski, T. Asher, D.J. Bitsaki, A. Psalidas, A. Tsamis, V. Gourgouliatos, K.N. Liakos, A. Hidas, M.G. Brown, T.M.

Subjects
Astrophysics::Earth and Planetary Astrophysics
Abstract

Aims. We carried out observations, with five different instruments ranging in aperture from 0.4 m to 10 m, of the satellites of Uranus during that planet's 2007 Equinox. Our observations covered specific intervals of time when mutual eclipses and occultations were predicted. Methods. The observations were carried out in the near-infrared part of the spectrum to mitigate the glare from the planet. Frames were acquired at rates >1/min. Following modelling and subtraction of the planetary source from these frames, differential aperture photometry was carried out on the satellite pairs involved in the predicted events. In all cases but one, nearby bright satellites were used as reference sources. Results. We have obtained fifteen individual lightcurves, eight of which show a clear drop in the flux from the satellite pair, indicating that a mutual event took place. Three of these involve the faint satellite Miranda. All eight lightcurves were model-fitted to yield best estimates of the time of maximum flux drop and the impact parameter. In three cases best-fit albedo ratios were also derived. We used these estimates to generate intersatellite astrometric positions with typical formal uncertainties of

Published
2009

31. The discovery of a persistent quasi-periodic oscillation in the intermediate polar TX Col

Author

Mhlahlo, N., Buckley, D.A.H., Dhillon, V.S., Potter, S.B., Warner, B., Woudt, P., Bolt, G., McCormick, J., Rea, R., Sullivan, D.J., and Velhuis, F.

Subjects
Astrophysics::High Energy Astrophysical Phenomena, Astrophysics (astro-ph), FOS: Physical sciences, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Astrophysics, Astrophysics::Galaxy Astrophysics
Abstract

We report on the detection of an ~5900 s quasi-periodic variation in the extensive photometry of TX Col spanning 12 years. We discuss five different models to explain this period. We favour a mechanism where the quasi-periodic variation results from the beating of the Keplerian frequency of the `blobs' orbiting in the outer accretion disc with the spin frequency, and from modulated accretion of these `blobs' taking place in a shocked region near the disc/magnetosphere boundary., 9 pages, 6 figures, 3 tables. Accepted by the Monthly Notices of the Royal Astronomical Society

Published
2007

32. Spectroscopic observations of the intermediate polar EX Hydrae in quiescence

Author

Mhlahlo, N., Buckley, D.A.H., Dhillon, V.S., Potter, S.B., Warner, B., and Woudt, P.A.

Subjects
Astrophysics::High Energy Astrophysical Phenomena, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Astrophysics::Galaxy Astrophysics
Abstract

Results from spectroscopic observations of the intermediate polar (IP) EX Hya in quiescence during 1991 and 2001 are presented. Spin-modulated radial velocities consistent with an outer disc origin were detected for the first time in an IP. The spin pulsation was modulated with velocities near ∼500–600 km s−1. These velocities are consistent with those of the material circulating at the outer edge of the accretion disc, suggesting co-rotation of the accretion curtain with the material near the Roche lobe radius. Furthermore, spin Doppler tomograms have revealed evidence of the accretion curtain emission extending from velocities of ∼500 to ∼1000 km s−1. These findings have confirmed the theoretical model predictions for EX Hya, which predict large accretion curtains that extend to a distance close to the Roche lobe radius in this system.\ud \ud Evidence for overflow stream of material falling on to the magnetosphere was observed, confirming the result of Belle et al. that disc overflow in EX Hya is present during quiescence as well as outburst.\ud \ud It appears that the Hβ and Hγ spin radial velocities originated from the rotation of the funnel at the outer disc edge, while those of Hα were produced due to the flow of the material along the field lines far from the white dwarf (narrow component) and close to the white dwarf (broad-base component), in agreement with the accretion curtain model.

Published
2007

35. Two new hot white dwarfs in a region of exceptionally low hi density

Author

Barstow, M.A., primary, Wesemael, F., additional, Holberg, J.B., additional, Werner, K., additional, Buckley, D.A.H., additional, Stobie, R.S., additional, Fontaine, G., additional, Rosen, S.R., additional, Demers, S., additional, Lamontagne, R., additional, Irwin, M.J., additional, Bergeron, P., additional, Kepler, S.O., additional, and Vennes, S., additional

Published
1993
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36. The masses of the cataclysmic variables AC Cancri and V363 Aurigae.

Author

Thoroughgood, T.D., Dhillon, V.S., Watson, C.A., Buckley, D.A.H., Steeghs, D., and Stevenson, M.J.

Subjects
CATACLYSMIC variable stars, BINARY stars, VARIABLE stars, STAR observations, MASS transfer, ASTRONOMICAL observations
Abstract

We present time-resolved spectroscopy and photometry of the double-lined eclipsing cataclysmic variables AC Cnc and V363 Aur (= Lanning 10). There is evidence of irradiation on the inner hemisphere of the secondary star in both systems, which we correct for using a model that reproduces the observations remarkably well. We find the radial velocity of the secondary star in AC Cnc to be KR = 176 ± 3 km s-1 and its rotational velocity to be v sin i = 135 ± 3 km s-1. From these parameters we obtain masses of M1 = 0.76 ± 0.03 M⊙ for the whitedwarf primary and M2 = 0.77 ± 0.05 M⊙ for the K2 ± 1V secondary star, giving a mass ratio of q = 1.02 ± 0.04. We measure the radial and rotational velocities of the G7 ± 2V secondary star in V363 Aur to be KR = 168 ± 5 km s-1 and v sin i = 143 ± 5 km s-1, respectively. The component masses of V363 Aur are M1 = 0.90 ± 0.06 M⊙ and M2 = 1.06 ± 0.11 M⊙, giving a mass ratio of q = 1.17 ± 0.07. The mass ratios for AC Cnc and V363 Aur fall within the theoretical limits for dynamically and thermally stable mass transfer. Both systems are similar to the SW Sex stars, exhibiting single-peaked emission lines with transient absorption features, high-velocity S-wave components and phase-offsets in their radial-velocity curves. The Balmer lines in V363 Aur show a rapid increase in flux around phase 0 followed by a rapid decrease, which we attribute to the eclipse of an optically thick region at the centre of the disc. This model could also account for the behaviour of other SW Sex stars where the Balmer lines show only a shallow eclipse compared to the continuum. [ABSTRACT FROM AUTHOR]

Published
2004
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37. Spectroscopy and polarimetry of the AM Herculis system RX J1313.32-3259.

Author

van der Heyden, K.J., Potter, S.B., and Buckley, D.A.H.

Subjects
POLARIZATION (Nuclear physics), SPECTRUM analysis, POLARIMETRY
Abstract

We present polarimetric and spectroscopic observations of the ROSAT source RX J1313.32-3259, recently identified as a polar. Circular polarization is modulated over the orbital period with an amplitude of ∼10 per cent. A brief reversal in circular polarization is detected at phase ∼0.0, when the main accretion region is seen face on to the observer. We deduce that the main cyclotron emission is absorbed by the accretion shock and/or stream at this phase, allowing a second accretion shock, located at the opposite ends of the field lines that feed the main pole, to be seen. Linear polarization is also detected with possible linear pulses at orbital phases where the accretion region is expected to be on the limb of the white dwarf. The general morphology of the photopolarimetry arises as a result of a combination of the absorption of cyclotron radiation by the accretion shock/stream and projection/cyclotron beaming effects of a main cyclotron emission region as the white dwarf rotates. The main cyclotron emission region remains on the visible hemisphere of the white dwarf throughout the orbit. Doppler maps of the emission lines show emission at or near the expected location of the secondary star and an extended arc-like feature coincident with the ballistic and possibly the magnetically confined accretion stream. [ABSTRACT FROM AUTHOR]

Published
2002
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38. Indirect imaging of the accretion stream in eclipsing polars – IV. V895 Cen.

Author

Salvi, N., Ramsay, G., Cropper, M., Buckley, D.A.H., and Stobie, R.S.

Subjects
IMAGING systems in astronomy, WHITE dwarf stars
Abstract

We present spectroscopic and high-speed photometric data of the eclipsing polar V895 Cen. We find that the eclipsed component is consistent with it being the accretion regions on the white dwarf. This is in contrast to Stobie et al. who concluded that the eclipsed component was not the white dwarf. Further, we find no evidence for an accretion disc in our data. From our Doppler tomography results, we find that the white dwarf has M≳0.7 M[sub ⊙]. Our indirect imaging of the accretion stream suggests that the stream is brightest close to the white dwarf. When we observed V895 Cen in its highest accretion state, emission was concentrated along field lines leading to the upper pole. There is no evidence for enhanced emission at the magnetic coupling region. [ABSTRACT FROM AUTHOR]

Published
2002
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39. Optical studies of two Large Magellanic Cloud X-ray transients: RX J0544.1–7100 and RX J0520.5–6932.

Author

Coe, M.J., Negueruela, I., Buckley, D.A.H., Haigh, N.J., and Laycock, S.G.T.

Subjects
STAR observations, B stars, ASTRONOMICAL observations
Abstract

We report observations that confirm the identities of the optical counterparts to the transient sources RX J0544.1–7100 and RX J0520.5–6932. The counterparts are suggested to be B-type stars. Optical data from the observations carried out at ESO and SAAO, together with results from the OGLE data base, are presented. In addition, X-ray data from the RXTE All-Sky Monitor are investigated for long-term periodicities. A strong suggestion for a binary period of 24.4 d is seen in RX J0520.5–6932 from the OGLE data. [ABSTRACT FROM AUTHOR]

Published
2001
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40. Multiwavelength monitoring of QS Tel.

Author

Rosen, S.R., Rainger, J.F., Burleigh, M.R., Mittaz, J.P.D., Buckley, D.A.H., Sirk, M., Lieu, R., Howell, S.B., and de Martino, D.

Subjects
ACCRETION (Astrophysics), BINARY stars
Abstract

Multiwavelength monitoring observations of the AM Her system, QS Tel, are presented, the centrepiece being a coordinated campaign with the ASCA, EUVE and HST satellites and optical observations on 1996 September 28–29. The star was initially observed in an intermediate brightness, single pole state in 1996 April by ROSAT. However two EUVE snapshots of the system in August found it in a deep low state, the light curves appearing to retain a bright and faint phase morphology although the bright interval showed significant phase drifts compared with the earlier ROSAT data. At this time, the system appeared optically bright, while polarimetry pointed to one active pole. A modest recovery of intensity, albeit accompanied by an apparently chaotic extreme ultraviolet (EUV) light curve, was subsequently recorded during the coordinated run in late September. This brightening was confirmed by a second ROSAT pointing in early October, although the EUV brightening is matched by a marked decay in its optical output. These observations, all of which found the system in a fainter EUV state than seen in 1993, add to the catalogue of accretion mode behaviour in QS Tel. However, as yet, the data base of observations does not allow us to establish whether the accretion mode is dictated by accretion-rate dependent penetration of the magnetosphere or asynchronous rotation. The ASCA spectrum obtained during the coordinated observation is adequately described by a thermal spectrum with a temperature of about 4.4 keV and an absorbing column density of less than 8×10[sup 20] cm[sup -2]. At the same time, the 1150–2600 Å UV HST spectrum shows a strong, broad Lyα absorption profile which we attribute to the white dwarf. We infer an effective temperature of 16 000–19 000 K and a mass between 0.5 and 0.93 M[sub ⊙] for the white dwarf, at least some of the uncertainty arising because the profile is very probably contaminated and broadened by Zeeman features. The orbital variation seen by HST can be matched by a blackbody-like spectrum with a temperature above 24 000 K. The near UV part of the spectrum contains evidence of phase-variable cyclotron harmonics. [ABSTRACT FROM AUTHOR]

Published
2001
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41. Multiwaveband studies of the hard ROSAT SMC transient 1WGA J0053.8--7226: a new X-ray pulsar.

Author

Buckley, D.A.H., Coe, M.J., Stevens, J.B., van der Heyden, K., Angelini, L., White, N., and Giommi, P.

Subjects
*MAGELLANIC clouds, *X-ray astronomy, *ARTIFICIAL satellites
Abstract

Focuses on the X-ray source in the Small Magellanic Cloud (SMC) from the ROSAT Positions Sensitive Proportional Counter archive. Luminosity of SMC; Identification of the source as an X-ray pulsar; Estimation of the absolute magnitude of the SMC system.

Published
2001
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42. Polarimetry and spectroscopy of RX J1141.3-6410: a single-pole AM Her system.

Author

Buckley, D.A.H., Cropper, M., van der Heyden, K., Potter, S.B., and Wickramasinghe, D.T.

Subjects
*ARTIFICIAL satellites, *STARS, *ASTRONOMICAL observations
Abstract

We present polarimetric and spectroscopic observations of the ROSAT source RX J1141.3-6410, recently identified as a polar. The detection of circular polarization variations, with an amplitude of 10 per cent, over a 3.16-h period confirms that the system is a polar (AM Herculis star). Supporting evidence comes from the nature of the emission lines and their radial velocity variability. In addition, we observe continuum slope changes in the far-red spectral region (∼6000–8200 Å), indicative of phase dependent cyclotron emission. Polarimetric modelling at two wavelengths establishes RX J1141.3-6410 as a single-pole system, with i∼β∼70°. The accretion region is extended in magnetic longitude, and is totally self-occulted for ∼25 per cent of the orbit. The radial velocity curves derived from the emission lines show a phasing with maximum blueshift occurring with Δφ∼0.05 of maximum intensity and circular polarisation. In addition, the broader component of the lines exhibit a substantial radial velocity phase shift with respect to the narrower component, in the sense that the broad component preceeds the narrow. This can be readily understood if the narrower component is principally a result of orbital motion of the stream material and the broad component mainly a result of streaming motion near the coupling region. The phasing of the Ca ii near-infrared line radial velocities also supports this general picture. [ABSTRACT FROM AUTHOR]

Published
2000
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43. Simultaneous optical polarimetry and X-ray data of the near-synchronous polar RX J2115–5840.

Author

Ramsay, G., Potter, S., Cropper, M., Buckley, D.A.H., and Harrop-Allin, M.K.

Subjects
POLARIMETRY, SPACE probes
Abstract

We present simultaneous optical polarimetry and X-ray data of the near-synchronous polar RX J2115–5840. We model the polarization data using the Stokes imaging technique of Potter et al. We find that the data are best modelled using a relatively high binary inclination and a small angle between the magnetic and spin axes. We find that, for all spin–orbit beat phases, a significant proportion of the accretion flow is directed on to the lower hemisphere of the white dwarf, producing negative circular polarization. Only for a small fraction of the beat cycle is a proportion of the flow directed on to the upper hemisphere. However, the accretion flow never occurs near the upper magnetic pole, whatever the orientation of the magnetic poles. This indicates the presence of a non-dipole field with the field strength at the upper pole significantly higher. We find that the brightest parts of the hard X-ray emitting region and the cyclotron region are closely coincident. [ABSTRACT FROM AUTHOR]

Published
2000
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44. Normal modes and discovery of high-order cross-frequencies in the DBV white dwarf GD 358.

Author

Vuille, F., O’Donoghue, D., Buckley, D.A.H., Massacand, C., Solheim, J.E., Bard, S., Vauclair, G., Giovannini, O., Kepler, S.O., Kanaan, A., Provencal, J.L., Wood, M.A., Clemens, J.C., Kleinman, S.J., O’Brien, M.S., Nather, R.E., Winget, D.E., Nitta, A., Klumpe, E.W., and Montgomery, M.H.

Subjects
WHITE dwarf stars, FREQUENCY spectra
Abstract

We present a detailed mode identification performed on the 1994 Whole Earth Telescope (WET) run on GD 358. The results are compared with that obtained for the same star from the 1990 WET data. The two temporal spectra show very few qualitative differences, although amplitude changes are seen in most modes, including the disappearance of the mode identified as k=14 in the 1990 data. The excellent coverage and signal-to-noise ratio obtained during the 1994 run lead to the secure identification of combination frequencies up to fourth order, i.e. peaks that are sums or differences of up to four parent frequencies, including a virtually complete set of second-order frequencies, as expected from harmonic distortion. We show how the third-order frequencies are expected to affect the triplet structure of the normal modes by back-interacting with them. Finally, a search for ℓ=2 modes was unsuccessful, not verifying the suspicion that such modes had been uncovered in the 1990 data set. [ABSTRACT FROM AUTHOR]

Published
2000
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45. Orbital period of the dwarf nova HL Canis Majoris.

Author

Still, M.D., Steeghs, D., Dhillon, V.S., and Buckley, D.A.H.

Subjects
DWARF novae, ORBITS (Astronomy), EXCITATION (Physiology), ACCRETION (Astrophysics)
Abstract

We present a small sample of time-resolved optical spectroscopy of the dwarf nova HL CMa during an outburst state. By combining radial velocity measurements with published data we show that the previously quoted value is not the only candidate for the orbital period of this system. We reduce the significance of daily aliasing but cannot distinguish between two periods at 0.2146±0.0004 and 0.2212±0.0005 d. We show that the low-excitation emission lines are composites from an accretion disc and the companion star, and that high-excitation emission originates in the disc or outflowing material associated with the accreting white dwarf. [ABSTRACT FROM AUTHOR]

Published
1999
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46. The optical counterparts to Be/X-ray binaries in the Magellanic Clouds.

Author

Stevens, J.B., Coe, M.J., and Buckley, D.A.H.

Subjects
BINARY stars, MAGELLANIC clouds, ASTRONOMICAL observations
Abstract

The fields of eight X-ray sources in the Magellanic Clouds believed to be Be/X-ray binaries have been searched for possible Be-star counterparts. BVR[sub c] and Hα CCD imaging was employed to identify early-type emission stars through colour indices and Hα fluxes. Spectroscopy of five sources confirms the presence of Hα emission in each case. Based on the positional coincidence of emission-line objects with the X-ray sources, we identify Be-star counterparts to the ROSAT sources RX J0032.9-7348, RX J0049.1-7250, RX J0054.9-7226 and RX J0101.0-7206, and to the recently discovered ASCA source AX J0051-722. We confirm the Be star nature of the counterpart to the HEAO1 source H0544-66. In the field of the ROSAT source RX J0051.8-7231 we find that there are three possible counterparts, each showing evidence for Hα emission. We find a close double in the error circle of the EXOSAT source EXO 0531.1-6609, each component of which could be a Be star associated with the X-ray source. [ABSTRACT FROM AUTHOR]

Published
1999
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47. Simultaneous optical polarimetry and X-ray observations of the magnetic CV CP Tuc (AX J2315-592).

Author

Ramsay, G., Potter, S.B., Buckley, D.A.H., and Wheatley, P.J.

Subjects
MAGNETIC fields, OPTICAL properties, X-ray binaries
Abstract

CP Tuc (AX J2315–592) shows a dip in X-rays which lasts for approximately half the binary orbit and is deeper in soft X-rays compared with hard X-rays. It has been proposed that this dip is due to the accretion stream obscuring the accretion region from view. If CP Tuc were a polar, as has been suggested, then the length of such a dip would make it unique amongst polars since in those polars in which a dip is seen in hard X-rays the dip lasts for only 0.1 of the orbit. We present optical polarimetry and RXTE observations of CP Tuc which show circular polarization levels of ∼10 per cent and find evidence for only one photometric period. These data confirm CP Tuc as a polar. Our modelling of the polarization data implies that the X-ray dip is due to the bulk of the primary accretion region being self-eclipsed by the white dwarf. The energy dependence of the dip is due to a combination of this self-eclipse and also the presence of an X-ray temperature gradient over the primary accretion region. [ABSTRACT FROM AUTHOR]

Published
1999
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48. Follow up of GW170817 and its electromagnetic counterpart by Australian-led observing programmes

Author

Andreoni, I., Ackley, K., Cooke, J., Acharyya, A., Allison, J.R., Anderson, G.E., Ashley, M.C.B., Baade, D., Bailes, M., Bannister, K., Beardsley, A., Bessell, M.S., Bian, F., Bland, P.A., Boer, M., Booler, T., Brandeker, A., Brown, I.S., Buckley, D.A.H., Chang, S.-W., Coward, D.M., Crawford, S., Crisp, H., Crosse, B., Cucchiara, A., Cupák, M., de Gois, J.S., Deller, A., Devillepoix, H.A.R., Dobie, D., Elmer, E., Emrich, D., Farah, W., Farrell, T.J., Franzen, T., Gaensler, B.M., Galloway, D.K., Gendre, B., Giblin, T., Goobar, A., Green, J., Hancock, P.J., Hartig, B.A.D., Howell, E.J., Horsley, L., Hotan, A., Howie, R.M., Hu, L., Hu, Y., James, C.W., Johnston, S., Johnston-Hollitt, M., Kaplan, D.L., Kasliwal, M., Keane, E.F., Kenney, D., Klotz, A., Lau, R., Laugier, R., Lenc, E., Li, X., Liang, E., Lidman, C., Luvaul, L.C., Lynch, C., Ma, B., Macpherson, D., Mao, J., McClelland, D.E., McCully, C., Möller, A., Morales, M.F., Morris, D., Murphy, T., Noysena, K., Onken, C.A., Orange, N.B., Osłowski, S., Pallot, D., Paxman, J., Potter, S.B., Pritchard, T., Raja, W., Ridden-Harper, R., Romero-Colmenero, E., Sadler, E.M., Sansom, E.K., Scalzo, R.A., Schmidt, B.P., Scott, S.M., Seghouani, N., Shang, Z., Shannon, R.M., Shao, L., Shara, M.M., Sharp, R., Sokolowski, M., Sollerman, J., Staff, J., Steele, K., Sun, T., Suntzeff, N.B., Tao, C., Tingay, S., Towner, M.C., Thierry, P., Trott, C., Tucker, B.E., Väisänen, P., Krishnan, V. Venkatraman, Walker, M., Wang, L., Wang, X., Wayth, R., Whiting, M., Williams, A., Williams, T., Wolf, C., Wu, C., Wu, X., Yang, J., Yuan, X., Zhang, H., Zhou, J., Zovaro, H., Andreoni, I., Ackley, K., Cooke, J., Acharyya, A., Allison, J.R., Anderson, G.E., Ashley, M.C.B., Baade, D., Bailes, M., Bannister, K., Beardsley, A., Bessell, M.S., Bian, F., Bland, P.A., Boer, M., Booler, T., Brandeker, A., Brown, I.S., Buckley, D.A.H., Chang, S.-W., Coward, D.M., Crawford, S., Crisp, H., Crosse, B., Cucchiara, A., Cupák, M., de Gois, J.S., Deller, A., Devillepoix, H.A.R., Dobie, D., Elmer, E., Emrich, D., Farah, W., Farrell, T.J., Franzen, T., Gaensler, B.M., Galloway, D.K., Gendre, B., Giblin, T., Goobar, A., Green, J., Hancock, P.J., Hartig, B.A.D., Howell, E.J., Horsley, L., Hotan, A., Howie, R.M., Hu, L., Hu, Y., James, C.W., Johnston, S., Johnston-Hollitt, M., Kaplan, D.L., Kasliwal, M., Keane, E.F., Kenney, D., Klotz, A., Lau, R., Laugier, R., Lenc, E., Li, X., Liang, E., Lidman, C., Luvaul, L.C., Lynch, C., Ma, B., Macpherson, D., Mao, J., McClelland, D.E., McCully, C., Möller, A., Morales, M.F., Morris, D., Murphy, T., Noysena, K., Onken, C.A., Orange, N.B., Osłowski, S., Pallot, D., Paxman, J., Potter, S.B., Pritchard, T., Raja, W., Ridden-Harper, R., Romero-Colmenero, E., Sadler, E.M., Sansom, E.K., Scalzo, R.A., Schmidt, B.P., Scott, S.M., Seghouani, N., Shang, Z., Shannon, R.M., Shao, L., Shara, M.M., Sharp, R., Sokolowski, M., Sollerman, J., Staff, J., Steele, K., Sun, T., Suntzeff, N.B., Tao, C., Tingay, S., Towner, M.C., Thierry, P., Trott, C., Tucker, B.E., Väisänen, P., Krishnan, V. Venkatraman, Walker, M., Wang, L., Wang, X., Wayth, R., Whiting, M., Williams, A., Williams, T., Wolf, C., Wu, C., Wu, X., Yang, J., Yuan, X., Zhang, H., Zhou, J., and Zovaro, H.

Abstract

The discovery of the first electromagnetic counterpart to a gravitational wave signal has generated follow-up observations by over 50 facilities world-wide, ushering in the new era of multi-messenger astronomy. In this paper, we present follow-up observations of the gravitational wave event GW170817 and its electromagnetic counterpart SSS17a/DLT17ck (IAU label AT2017gfo) by 14 Australian telescopes and partner observatories as part of Australian-based and Australian-led research programs. We report early- to late-time multi-wavelength observations, including optical imaging and spectroscopy, mid-infrared imaging, radio imaging, and searches for fast radio bursts. Our optical spectra reveal that the transient source emission cooled from approximately 6 400 K to 2 100 K over a 7-d period and produced no significant optical emission lines. The spectral profiles, cooling rate, and photometric light curves are consistent with the expected outburst and subsequent processes of a binary neutron star merger. Star formation in the host galaxy probably ceased at least a Gyr ago, although there is evidence for a galaxy merger. Binary pulsars with short (100 Myr) decay times are therefore unlikely progenitors, but pulsars like PSR B1534+12 with its 2.7 Gyr coalescence time could produce such a merger. The displacement (~2.2 kpc) of the binary star system from the centre of the main galaxy is not unusual for stars in the host galaxy or stars originating in the merging galaxy, and therefore any constraints on the kick velocity imparted to the progenitor are poor.

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49. Follow up of GW170817 and its electromagnetic counterpart by Australian-led observing programmes

Author

Andreoni, I., Ackley, K., Cooke, J., Acharyya, A., Allison, J.R., Anderson, G.E., Ashley, M.C.B., Baade, D., Bailes, M., Bannister, K., Beardsley, A., Bessell, M.S., Bian, F., Bland, P.A., Boer, M., Booler, T., Brandeker, A., Brown, I.S., Buckley, D.A.H., Chang, S.-W., Coward, D.M., Crawford, S., Crisp, H., Crosse, B., Cucchiara, A., Cupák, M., de Gois, J.S., Deller, A., Devillepoix, H.A.R., Dobie, D., Elmer, E., Emrich, D., Farah, W., Farrell, T.J., Franzen, T., Gaensler, B.M., Galloway, D.K., Gendre, B., Giblin, T., Goobar, A., Green, J., Hancock, P.J., Hartig, B.A.D., Howell, E.J., Horsley, L., Hotan, A., Howie, R.M., Hu, L., Hu, Y., James, C.W., Johnston, S., Johnston-Hollitt, M., Kaplan, D.L., Kasliwal, M., Keane, E.F., Kenney, D., Klotz, A., Lau, R., Laugier, R., Lenc, E., Li, X., Liang, E., Lidman, C., Luvaul, L.C., Lynch, C., Ma, B., Macpherson, D., Mao, J., McClelland, D.E., McCully, C., Möller, A., Morales, M.F., Morris, D., Murphy, T., Noysena, K., Onken, C.A., Orange, N.B., Osłowski, S., Pallot, D., Paxman, J., Potter, S.B., Pritchard, T., Raja, W., Ridden-Harper, R., Romero-Colmenero, E., Sadler, E.M., Sansom, E.K., Scalzo, R.A., Schmidt, B.P., Scott, S.M., Seghouani, N., Shang, Z., Shannon, R.M., Shao, L., Shara, M.M., Sharp, R., Sokolowski, M., Sollerman, J., Staff, J., Steele, K., Sun, T., Suntzeff, N.B., Tao, C., Tingay, S., Towner, M.C., Thierry, P., Trott, C., Tucker, B.E., Väisänen, P., Krishnan, V. Venkatraman, Walker, M., Wang, L., Wang, X., Wayth, R., Whiting, M., Williams, A., Williams, T., Wolf, C., Wu, C., Wu, X., Yang, J., Yuan, X., Zhang, H., Zhou, J., Zovaro, H., Andreoni, I., Ackley, K., Cooke, J., Acharyya, A., Allison, J.R., Anderson, G.E., Ashley, M.C.B., Baade, D., Bailes, M., Bannister, K., Beardsley, A., Bessell, M.S., Bian, F., Bland, P.A., Boer, M., Booler, T., Brandeker, A., Brown, I.S., Buckley, D.A.H., Chang, S.-W., Coward, D.M., Crawford, S., Crisp, H., Crosse, B., Cucchiara, A., Cupák, M., de Gois, J.S., Deller, A., Devillepoix, H.A.R., Dobie, D., Elmer, E., Emrich, D., Farah, W., Farrell, T.J., Franzen, T., Gaensler, B.M., Galloway, D.K., Gendre, B., Giblin, T., Goobar, A., Green, J., Hancock, P.J., Hartig, B.A.D., Howell, E.J., Horsley, L., Hotan, A., Howie, R.M., Hu, L., Hu, Y., James, C.W., Johnston, S., Johnston-Hollitt, M., Kaplan, D.L., Kasliwal, M., Keane, E.F., Kenney, D., Klotz, A., Lau, R., Laugier, R., Lenc, E., Li, X., Liang, E., Lidman, C., Luvaul, L.C., Lynch, C., Ma, B., Macpherson, D., Mao, J., McClelland, D.E., McCully, C., Möller, A., Morales, M.F., Morris, D., Murphy, T., Noysena, K., Onken, C.A., Orange, N.B., Osłowski, S., Pallot, D., Paxman, J., Potter, S.B., Pritchard, T., Raja, W., Ridden-Harper, R., Romero-Colmenero, E., Sadler, E.M., Sansom, E.K., Scalzo, R.A., Schmidt, B.P., Scott, S.M., Seghouani, N., Shang, Z., Shannon, R.M., Shao, L., Shara, M.M., Sharp, R., Sokolowski, M., Sollerman, J., Staff, J., Steele, K., Sun, T., Suntzeff, N.B., Tao, C., Tingay, S., Towner, M.C., Thierry, P., Trott, C., Tucker, B.E., Väisänen, P., Krishnan, V. Venkatraman, Walker, M., Wang, L., Wang, X., Wayth, R., Whiting, M., Williams, A., Williams, T., Wolf, C., Wu, C., Wu, X., Yang, J., Yuan, X., Zhang, H., Zhou, J., and Zovaro, H.

Abstract

The discovery of the first electromagnetic counterpart to a gravitational wave signal has generated follow-up observations by over 50 facilities world-wide, ushering in the new era of multi-messenger astronomy. In this paper, we present follow-up observations of the gravitational wave event GW170817 and its electromagnetic counterpart SSS17a/DLT17ck (IAU label AT2017gfo) by 14 Australian telescopes and partner observatories as part of Australian-based and Australian-led research programs. We report early- to late-time multi-wavelength observations, including optical imaging and spectroscopy, mid-infrared imaging, radio imaging, and searches for fast radio bursts. Our optical spectra reveal that the transient source emission cooled from approximately 6 400 K to 2 100 K over a 7-d period and produced no significant optical emission lines. The spectral profiles, cooling rate, and photometric light curves are consistent with the expected outburst and subsequent processes of a binary neutron star merger. Star formation in the host galaxy probably ceased at least a Gyr ago, although there is evidence for a galaxy merger. Binary pulsars with short (100 Myr) decay times are therefore unlikely progenitors, but pulsars like PSR B1534+12 with its 2.7 Gyr coalescence time could produce such a merger. The displacement (~2.2 kpc) of the binary star system from the centre of the main galaxy is not unusual for stars in the host galaxy or stars originating in the merging galaxy, and therefore any constraints on the kick velocity imparted to the progenitor are poor.

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50. Follow up of GW170817 and its electromagnetic counterpart by Australian-led observing programmes

Author

Andreoni, I., Ackley, K., Cooke, J., Acharyya, A., Allison, J.R., Anderson, G.E., Ashley, M.C.B., Baade, D., Bailes, M., Bannister, K., Beardsley, A., Bessell, M.S., Bian, F., Bland, P.A., Boer, M., Booler, T., Brandeker, A., Brown, I.S., Buckley, D.A.H., Chang, S.-W., Coward, D.M., Crawford, S., Crisp, H., Crosse, B., Cucchiara, A., Cupák, M., de Gois, J.S., Deller, A., Devillepoix, H.A.R., Dobie, D., Elmer, E., Emrich, D., Farah, W., Farrell, T.J., Franzen, T., Gaensler, B.M., Galloway, D.K., Gendre, B., Giblin, T., Goobar, A., Green, J., Hancock, P.J., Hartig, B.A.D., Howell, E.J., Horsley, L., Hotan, A., Howie, R.M., Hu, L., Hu, Y., James, C.W., Johnston, S., Johnston-Hollitt, M., Kaplan, D.L., Kasliwal, M., Keane, E.F., Kenney, D., Klotz, A., Lau, R., Laugier, R., Lenc, E., Li, X., Liang, E., Lidman, C., Luvaul, L.C., Lynch, C., Ma, B., Macpherson, D., Mao, J., McClelland, D.E., McCully, C., Möller, A., Morales, M.F., Morris, D., Murphy, T., Noysena, K., Onken, C.A., Orange, N.B., Osłowski, S., Pallot, D., Paxman, J., Potter, S.B., Pritchard, T., Raja, W., Ridden-Harper, R., Romero-Colmenero, E., Sadler, E.M., Sansom, E.K., Scalzo, R.A., Schmidt, B.P., Scott, S.M., Seghouani, N., Shang, Z., Shannon, R.M., Shao, L., Shara, M.M., Sharp, R., Sokolowski, M., Sollerman, J., Staff, J., Steele, K., Sun, T., Suntzeff, N.B., Tao, C., Tingay, S., Towner, M.C., Thierry, P., Trott, C., Tucker, B.E., Väisänen, P., Krishnan, V. Venkatraman, Walker, M., Wang, L., Wang, X., Wayth, R., Whiting, M., Williams, A., Williams, T., Wolf, C., Wu, C., Wu, X., Yang, J., Yuan, X., Zhang, H., Zhou, J., Zovaro, H., Andreoni, I., Ackley, K., Cooke, J., Acharyya, A., Allison, J.R., Anderson, G.E., Ashley, M.C.B., Baade, D., Bailes, M., Bannister, K., Beardsley, A., Bessell, M.S., Bian, F., Bland, P.A., Boer, M., Booler, T., Brandeker, A., Brown, I.S., Buckley, D.A.H., Chang, S.-W., Coward, D.M., Crawford, S., Crisp, H., Crosse, B., Cucchiara, A., Cupák, M., de Gois, J.S., Deller, A., Devillepoix, H.A.R., Dobie, D., Elmer, E., Emrich, D., Farah, W., Farrell, T.J., Franzen, T., Gaensler, B.M., Galloway, D.K., Gendre, B., Giblin, T., Goobar, A., Green, J., Hancock, P.J., Hartig, B.A.D., Howell, E.J., Horsley, L., Hotan, A., Howie, R.M., Hu, L., Hu, Y., James, C.W., Johnston, S., Johnston-Hollitt, M., Kaplan, D.L., Kasliwal, M., Keane, E.F., Kenney, D., Klotz, A., Lau, R., Laugier, R., Lenc, E., Li, X., Liang, E., Lidman, C., Luvaul, L.C., Lynch, C., Ma, B., Macpherson, D., Mao, J., McClelland, D.E., McCully, C., Möller, A., Morales, M.F., Morris, D., Murphy, T., Noysena, K., Onken, C.A., Orange, N.B., Osłowski, S., Pallot, D., Paxman, J., Potter, S.B., Pritchard, T., Raja, W., Ridden-Harper, R., Romero-Colmenero, E., Sadler, E.M., Sansom, E.K., Scalzo, R.A., Schmidt, B.P., Scott, S.M., Seghouani, N., Shang, Z., Shannon, R.M., Shao, L., Shara, M.M., Sharp, R., Sokolowski, M., Sollerman, J., Staff, J., Steele, K., Sun, T., Suntzeff, N.B., Tao, C., Tingay, S., Towner, M.C., Thierry, P., Trott, C., Tucker, B.E., Väisänen, P., Krishnan, V. Venkatraman, Walker, M., Wang, L., Wang, X., Wayth, R., Whiting, M., Williams, A., Williams, T., Wolf, C., Wu, C., Wu, X., Yang, J., Yuan, X., Zhang, H., Zhou, J., and Zovaro, H.

Abstract

The discovery of the first electromagnetic counterpart to a gravitational wave signal has generated follow-up observations by over 50 facilities world-wide, ushering in the new era of multi-messenger astronomy. In this paper, we present follow-up observations of the gravitational wave event GW170817 and its electromagnetic counterpart SSS17a/DLT17ck (IAU label AT2017gfo) by 14 Australian telescopes and partner observatories as part of Australian-based and Australian-led research programs. We report early- to late-time multi-wavelength observations, including optical imaging and spectroscopy, mid-infrared imaging, radio imaging, and searches for fast radio bursts. Our optical spectra reveal that the transient source emission cooled from approximately 6 400 K to 2 100 K over a 7-d period and produced no significant optical emission lines. The spectral profiles, cooling rate, and photometric light curves are consistent with the expected outburst and subsequent processes of a binary neutron star merger. Star formation in the host galaxy probably ceased at least a Gyr ago, although there is evidence for a galaxy merger. Binary pulsars with short (100 Myr) decay times are therefore unlikely progenitors, but pulsars like PSR B1534+12 with its 2.7 Gyr coalescence time could produce such a merger. The displacement (~2.2 kpc) of the binary star system from the centre of the main galaxy is not unusual for stars in the host galaxy or stars originating in the merging galaxy, and therefore any constraints on the kick velocity imparted to the progenitor are poor.

Full Text
View/download PDF

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