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835 results on '"Ciardi B."'

101. The effect of minihaloes on cosmic reionization

Author: Ciardi, B., Scannapieco, E., Stoehr, F., Ferrara, A., Iliev, I. T., and Shapiro, P. R.
Subjects: Astrophysics
Abstract: One of the most debated issues in the theoretical modeling of cosmic reionization is the impact of small-mass gravitationally-bound structures. We carry out the first numerical investigation of the role of such sterile `minihaloes', which serve as self-shielding screens of ionizing photons. Minihaloes are too small to be properly resolved in current large-scale cosmological simulations, and thus we estimate their effects using a sub-grid model, considering two cases that bracket their effect within this framework. In the `extreme suppression' case in which minihalo formation ceases once a region is partially ionized, their effect on cosmic reionization is modest, reducing the volume-averaged ionization fraction by an overall factor of less than 15%. In the other extreme, in which minihalo formation is never suppressed, they delay complete reionization as much as Delta z~2, in rough agreement with the results from a previous semi-analytical study by the authors. Thus, depending on the details of the minihalo formation process, their effect on the overall progress of reionization can range from modest to significant, but the minihalo photon consumption is by itself insufficient to force an extended reionization epoch., Comment: 9 pages, 2 figures, accepted for pubblication in MNRAS
Published: 2005
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102. Constraints on the IMF of the first stars

Author: Schneider, R., Salvaterra, R., Ferrara, A., and Ciardi, B.
Subjects: Astrophysics
Abstract: Motivated by theoretical predictions that first stars were predominantly very massive, we investigate the physics of the transition from an early epoch dominated by massive Pop III stars to a later epoch dominated by familiar low-mass Pop II/I stars by means of a numerically-generated catalogue of dark matter halos coupled with a self-consistent treatment of chemical and radiative feedback. Depending on the strength of the chemical feedback, Pop III stars can contribute a substantial fraction (several percent) of the cosmic star formation activity even at moderate redshifts, z = 5. We find that the three z = 10 sources tentatively detected in NICMOS UDFs should be powered by Pop III stars, if these are massive; however, this scenario fails to reproduce the derived WMAP electron scattering optical depth. Instead, both the UDFs and WMAP constraints can be fulfilled if stars at any time form with a more standard, slightly top-heavy, Larson IMF in the range 1 Msun < M < 100 Msun., Comment: 11 pages, 8 figures, submitted to MNRAS
Published: 2005
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103. Reionization History from Coupled CMB/21cm Line Data

Author: Salvaterra, R., Ciardi, B., Ferrara, A., and Baccigalupi, C.
Subjects: Astrophysics
Abstract: We study CMB secondary anisotropies produced by inhomogeneous reionization by means of cosmological simulations coupled with the radiative transfer code CRASH. The reionization history is consistent with the WMAP Thomson optical depth determination. We find that the signal arising from this process dominates over the primary CMB component for l > 4000 and reaches a maximum amplitude of l(l+1)C_l/2\pi ~ 1.6 x 10^{-13} on arcmin scale, i.e. l as large as several thousands. We then cross-correlate secondary CMB anisotropy maps with neutral hydrogen 21cm line emission fluctuations obtained from the same simulations. The two signals are highly anti-correlated on angular scales corresponding to the typical size of HII regions (including overlapping) at the 21cm map redshift. We show how the CMB/21cm cross-correlation can be used to: (a) study the nature of the reionization sources, (b) reconstruct the cosmic reionization history, (c) infer the mean cosmic ionization level at any redshift. We discuss the feasibility of the proposed experiment with forthcoming facilities., Comment: 7 pages, 5 figures, MNRAS in press
Published: 2005
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104. A Lyman alpha emitter at z = 6.5 found with slitless spectroscopy

Author: Kurk, J. D., Cimatti, A., Alighieri, S. di Serego, Vernet, J., Daddi, E., Ferrara, A., and Ciardi, B.
Subjects: Astrophysics
Abstract: We report the discovery of a Lyman alpha emitting galaxy at z = 6.518. The single line was found in the 43 square arcmin VLT/FORS field by slitless spectroscopy limited to the atmospheric window at 9100 A (sampling Lya at 6.4 < z < 6.6). Its counterpart is undetected in a deep I band image and the line has an asymmetric appearance in a deeper follow-up spectrum. There are no plausible line identifications except for Lya with a flux of 1.9x10^-17 erg/s/cm2 and rest frame equivalent width > 80 A. The lower limit to the star formation rate density at z = 6.5 derived from our complete sample is 5x10^-4 M_sol/year/Mpc^3, consistent with measurements in the Subaru Deep Field and Hubble Ultra Deep Field but approximately ten times higher than in the Large Area Lyman Alpha survey. This Lya emitter is among the very small sample of highest redshift galaxies known., Comment: Accepted as Letter by A&A, 5 pages, 7 figures, one typo corrected
Published: 2004
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105. CRASH: a Radiative Transfer Scheme

Author: Maselli, A., Ferrara, A., and Ciardi, B.
Subjects: Astrophysics
Abstract: We present a largely improved version of CRASH, a 3-D radiative transfer code that treats the effects of ionizing radiation propagating through a given inhomogeneous H/He cosmological density field, on the physical conditions of the gas. The code, based on a Monte Carlo technique, self-consistently calculates the time evolution of gas temperature and ionization fractions due to an arbitrary number of point/extended sources and/or diffuse background radiation with given spectra. In addition, the effects of diffuse ionizing radiation following recombinations of ionized atoms have been included. After a complete description of the numerical scheme, to demonstrate the performances, accuracy, convergency and robustness of the code we present four different test cases designed to investigate specific aspects of radiative transfer: (i) pure hydrogen isothermal Stromgren sphere; (ii) realistic Stromgren spheres; (iii) multiple overlapping point sources, and (iv) shadowing of background radiation by an intervening optically thick layer. When possible, detailed quantitative comparison of the results against either analytical solutions or 1-D standard photoionization codes has been made showing a good level of agreement. For more complicated tests the code yields physically plausible results, which could be eventually checked only by comparison with other similar codes. Finally, we briefly discuss future possible developments and cosmological applications of the code., Comment: 17 pages, 14 figures, accepted for pubblication in MNRAS, high res figures available at http://www.arcetri.astro.it/science/cosmology/IGM/radtrans.html
Published: 2003
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106. Probing Beyond the Epoch of Hydrogen Reionization with 21 Centimeter Radiation

Author: Ciardi, B. and Madau, P.
Subjects: Astrophysics
Abstract: We use numerical simulations of hydrogen reionization by stellar sources in the context of LCDM cosmogonies to investigate the 21 (1+z) cm radio signal expected from the diffuse intergalactic medium (IGM) prior to the epoch of reionization breakthrough at redshift z_ion. Two reionization scenarios are analyzed in details: an `early reionization' case with z_ion~13, consistent with the recent discovery by the WMAP satellite of a large optical depth to Thomson scattering, and a `late reionization' case with z_ion~8. It is a generic prediction of these models that the background of Lyalpha photons produced by the early generation of stars which ultimately ionize the universe will be sufficiently intense to make intergalactic neutral hydrogen visible against the cosmic microwave background during the `grey age', i.e. z_ion
Published: 2003
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107. Early Reionization by the First Galaxies

Author: Ciardi, B., Ferrara, A., and White, S. D. M.
Subjects: Astrophysics
Abstract: Large-scale polarization of the cosmic microwave background measured by the WMAP satellite requires a mean optical depth to Thomson scattering, tau_e ~ 0.17. The reionization of the universe must therefore have begun at relatively high redshift. We have studied the reionization process using supercomputer simulations of a large and representative region of a universe which has cosmological parameters consistent with the WMAP results. Our simulations follow both the radiative transfer of ionizing photons and the formation and evolution of the galaxy population which produces them. A previously published model with a standard stellar IMF, with a moderate photon escape fraction from galaxies and with ionizing photon production as expected for zero metallicity stars produces tau_e = 0.104, which is within 1.0 to 1.5-sigma of the ``best'' WMAP value. Values up to 0.16 can be produced by taking larger escape fractions or a top heavy IMF. The data do not require a separate populations of ``miniquasars'' or of stars forming in objects with total masses below 10^9 M_sun. Reconciling such early reionization with the observed Gunn-Peterson troughs in z>6 quasars may be challenging. Possible resolutions of this problem are discussed., Comment: 5 pages, 3 figures, MNRAS submitted
Published: 2003
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108. Simulating IGM Reionization

Author: Ciardi, B., Stoehr, F., and White, S. D. M.
Subjects: Astrophysics
Abstract: We have studied the IGM reionization process in its full cosmological context including structure evolution and a realistic galaxy population. We have used a combination of high-resolution N-body simulations (to describe the dark matter and diffuse gas component), a semi-analytic model of galaxy formation (to track the evolution of the sources of ionizing radiation) and the Monte Carlo radiative transfer code CRASH (to follow the propagation of ionizing photons into the IGM). The process has been followed in the largest volume ever used for this kind of study, a field region of the universe with a comoving length of L~20/h Mpc, embedded in a much larger cosmological simulation. To assess the effect of environment on the reionization process, the same radiative transfer simulations have been performed on a 10/h Mpc comoving box, centered on a clustered region. We find that, to account for the all ionizing radiation, objects with total masses of M~10^9 Msun must be resolved. In this case, the simulated stellar population produces a volume averaged ionization fraction x_v=0.999 by z~8, consistent with observations without requiring any additional sources of ionization. We also find that environment substantially affects the reionization process. In fact, although the simulated proto-cluster occupies a smaller volume and produces a higher number of ionizing photons, it gets totally ionized later. This is because high density regions, which are more common in the proto-cluster, are difficult to ionize because of their high recombination rates., Comment: 10 pages, 9 figures, minor revisions, in press, MNRAS 343 (2003) 1101-1109
Published: 2003
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109. Needle-like structures discovered on positively charged lightning branches

Author: Hare, B. M., Scholten, O., Dwyer, J., Trinh, T. N. G., Buitink, S., ter Veen, S., Bonardi, A., Corstanje, A., Falcke, H., Hörandel, J. R., Huege, T., Mitra, P., Mulrey, K., Nelles, A., Rachen, J. P., Rossetto, L., Schellart, P., Winchen, T., Anderson, J., Avruch, I. M., Bentum, M. J., Blaauw, R., Broderick, J. W., Brouw, W. N., Brüggen, M., Butcher, H. R., Ciardi, B., Fallows, R. A., de Geus, E., Duscha, S., Eislöffel, J., Garrett, M. A., Grießmeier, J. M., Gunst, A. W., van Haarlem, M. P., Hessels, J. W. T., Hoeft, M., van der Horst, A. J., Iacobelli, M., Koopmans, L. V. E., Krankowski, A., Maat, P., Norden, M. J., Paas, H., Pandey-Pommier, M., Pandey, V. N., Pekal, R., Pizzo, R., Reich, W., Rothkaehl, H., Röttgering, H. J. A., Rowlinson, A., Schwarz, D. J., Shulevski, A., Sluman, J., Smirnov, O., Soida, M., Tagger, M., Toribio, M. C., van Ardenne, A., Wijers, R. A. M. J., van Weeren, R. J., Wucknitz, O., Zarka, P., and Zucca, P.
Published: 2019
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110. Lyman Continuum Escape from Inhomogeneous ISM

Author: Ciardi, B., Bianchi, S., and Ferrara, A.
Subjects: Astrophysics
Abstract: We have studied the effects of gas density inhomogeneities on the escape of ionising Lyman continuum (Lyc) photons from Milky Way-type galaxies via 3D numerical simulations using the Monte Carlo radiative transfer code CRASH (Ciardi et al. 2001). To this aim a comparison between a smooth Gaussian distribution (GDD) and an inhomogeneous, fractal one (FDD) has been made with realistic assumptions for the ionising stellar sources based on available data in the solar neighborhood. In both cases the escape fraction f_esc increases with ionisation rate N_gamma (although for the FDD with a flatter slope) and they become equal at N_gamma = 2*10^50 s^-1 where f_esc = 0.11. FDD allows escape fractions of the same order also at lower N_gamma, when Lyc photon escape is sharply suppressed by GDD. Values of the escape fraction as high as 0.6 can be reached (GDD) for N_gamma ~ 9*10^50 s^-1, corresponding to a star formation rate (SFR) of roughly 2 M_o yr^-1; at this ionising luminosity the FDD is less transparent (f_esc ~ 0.28). If high redshift galaxies have gas column densities similar to local ones, are characterized by such high SFRs and by a predominantly smooth (i.e.turbulence free) interstellar medium, our results suggest that they should considerably contribute to - and possibly dominate - the cosmic UV background., Comment: 12 pages, 9 figures, MNRAS accepted
Published: 2001
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111. Cosmological Reionization Around the First Stars: Monte Carlo Radiative Transfer

Author: Ciardi, B., Ferrara, A., Marri, S., and Raimondo, G.
Subjects: Astrophysics
Abstract: We study the evolution of ionization fronts around the first proto-galaxies by using high resolution numerical cosmological (Lambda+CDM model) simulations and Monte Carlo radiative transfer methods. We present the numerical scheme in detail and show the results of test runs from which we conclude that the scheme is both fast and accurate. As an example of interesting cosmological application, we study the reionization produced by a stellar source of total mass M=2 10^8 M_\odot turning on at z=12, located at a node of the cosmic web. The study includes a Spectral Energy Distribution of a zero-metallicity stellar population, and two Initial Mass Functions (Salpeter/Larson). The expansion of the I-front is followed as it breaks out from the galaxy and it is channeled by the filaments into the voids, assuming, in a 2D representation, a characteristic butterfly shape. The ionization evolution is very well tracked by our scheme, as realized by the correct treatment of the channeling and shadowing effects due to overdensities. We confirm previous claims that both the shape of the IMF and the ionizing power metallicity dependence are important to correctly determine the reionization of the universe., Comment: 8 pages, 8 figures. Revised version, accepted for publication by MNRAS
Published: 2000
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112. Feedback Processes in the Early Universe

Author: Ferrara, A., Ciardi, B., Marri, S., and Todini, P.
Subjects: Astrophysics
Abstract: Feedback effects due to massive stars and supernovae in the first objects are shown to strongly regulate both galaxy formation/evolution and the reionization process. Here we review the most important ones in some detail. We discuss how Type II supernovae can be used as tracers of the first objects and detected with NGST, for which we predict supernova number counts including the effects of gravitational lensing. Preliminary results on the formation of dust in the ejecta of supernovae of primordial composition are also presented. We finally turn to the consideration of the process of inhomogeneous reionization due to primordial stellar sources by means of high resolution numerical simulations, allowing for a self-consistent treatment of the above feedback processes. These simulations allow us to draw conclusions on the evolution and epoch of reionization and about the fate of reionizing objects. We conclude that a large fraction (~ 99%) of collapsed objects must be dark at redshift around eight., Comment: 8 pages, EslabStyle.cls, LaTeX, 7 figures
Published: 2000

113. CMB Anisotropies due to Feedback-Regulated Inhomogeneous Reionization

Author: Bruscoli, M., Ferrara, A., Fabbri, R., and Ciardi, B.
Subjects: Astrophysics
Abstract: We calculate the secondary anisotropies in the CMB produced by inhomogeneous reionization from simulations in which the effects of radiative and stellar feedback effects on galaxy formation have been included. This allows to self-consistently determine the beginning ($z_i\approx 30$), the duration ($ \delta z\approx 20$) and the (nonlinear) evolution of the reionization process for a critical density CDM model. In addition, from the simulated spatial distribution of ionized regions, we are able to calculate the evolution of the two-point ionization correlation function, $C_\chi$, and obtain the power spectrum of the anisotropies, $C_\ell$, in the range $5000 < \ell < 10^6$. The power spectrum has a broad maximum around $\ell \approx 30000$, where it reaches the value $2\times 10^{-12}$. We also show that the angular correlation function $C(\theta)$ is not Gaussian, but at separation angles $% \theta \lower.5ex\hbox{\ltsima} 10^{-4}$ rad it can be approximated by a modified Lorentzian shape; at larger separations an anticorrelation signal is predicted. Detection of signals as above will be possible with future mm-wavelength interferometers like ALMA, which appears as an optimum instrument to search for signatures of inhomogeneous reionization., Comment: 14 pages, aaspp4.sty, LaTeX, 4 figures. MNRAS, submitted
Published: 1999
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114. Gravitational Waves Signals from the Collapse of the First Stars

Author: Schneider, R., Ferrara, A., Ciardi, B., Ferrari, V., and Matarrese, S.
Subjects: Astrophysics
Abstract: We study the gravitational wave emission from the first stars which are assumed to be Very Massive Objects (VMOs). We take into account various feedback (both radiative and stellar) effects regulating the collapse of objects in the early universe and thus derive the VMO initial mass function and formation rate. If the final fate of VMOs is to collapse, leaving very massive black hole remnants, then the gravitational waves emitted during each collapse would be seen as a stochastic background. The predicted spectral strain amplitude in a critical density Cold Dark Matter universe peaks in the frequency range \approx 5 \times 10^{-4}-5 \times 10^{-3} Hz where it has a value in the range \approx 10^{-20}-10^{-19} Hz^{-1/2}, and might be detected by LISA. The expected emission rate is roughly 4000 events/yr, resulting in a stationary, discrete sequence of bursts, i.e. a shot--noise signal., Comment: 10 pages, including 5 figures, submitted to MNRAS
Published: 1999
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115. Inhomogeneous Reionization Regulated by Radiative and Stellar Feedbacks

Author: Ciardi, B., Ferrara, A., Governato, F., and Jenkins, A.
Subjects: Astrophysics
Abstract: We study the inhomogeneous reionization in a critical density CDM universe due to stellar sources, including Population III objects. The spatial distribution of the sources is obtained from high resolution numerical N-body simulations. We calculate the source properties taking into account a self-consistent treatment of both radiative (ie ionizing and H2 -photodissociating photons) and stellar (ie SN explosions) feedbacks regulated by massive stars. This allows us to describe the topology of the ionized and dissociated regions at various cosmic epochs and derive the evolution of H, He, and H2 filling factors, soft UV background, cosmic star formation rate and the final fate of ionizing objects. The main results are: (i) galaxies reionize the IGM by z~10 (with some uncertainty related to the gas clumping factor), whereas H2 is completely dissociated already by z~25; (ii) reionization is mostly due to the relatively massive objects which collapse via H line cooling, while objects whose formation relies on H2 cooling alone are insufficient to this aim; (iii) the diffuse soft UV background is the major source of radiative feedback effects for z<15; at higher z direct flux from neighboring objects dominates; (iv) the match of the calculated cosmic star formation history with the one observed at lower redshifts suggests that the conversion efficiency of baryons into stars is ~1%; (v) we find that a very large population of dark objects which failed to form stars is present by z~8. We discuss and compare our results with similar previous studies., Comment: 34 pages, emulateapj.sty, LaTeX, 13 figures. MNRAS, submitted
Published: 1999
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116. AMADA—Analysis of multidimensional astronomical datasets

Author: de Souza, R.S. and Ciardi, B.
Published: 2015
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117. The LOFAR Tied-Array All-Sky Survey: Timing of 35 radio pulsars and an overview of the properties of the LOFAR pulsar discoveries

Author: van der Wateren, E., primary, Bassa, C. G., additional, Cooper, S., additional, Grießmeier, J.-M., additional, Stappers, B. W., additional, Hessels, J. W. T., additional, Kondratiev, V. I., additional, Michilli, D., additional, Tan, C. M., additional, Tiburzi, C., additional, Weltevrede, P., additional, Bak Nielsen, A.-S., additional, Carozzi, T. D., additional, Ciardi, B., additional, Cognard, I., additional, Dettmar, R.-J., additional, Karastergiou, A., additional, Kramer, M., additional, Künsemöller, J., additional, Osłowski, S., additional, Serylak, M., additional, Vocks, C., additional, and Wucknitz, O., additional
Published: 2023
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118. Assessing the impact of two independent direction-dependent calibration algorithms on the LOFAR 21 cm signal power spectrum

Author: Gan, H., primary, Mertens, F. G., additional, Koopmans, L. V. E., additional, Offringa, A. R., additional, Mevius, M., additional, Pandey, V. N., additional, Brackenhoff, S. A., additional, Ceccotti, E., additional, Ciardi, B., additional, Gehlot, B. K., additional, Ghara, R., additional, Giri, S. K., additional, Iliev, I. T., additional, and Munshi, S., additional
Published: 2022
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119. The impact of solar wind variability on pulsar timing

Author: Tiburzi, C, Shaifullah, G, Bassa, C, Zucca, P, Verbiest, J, Porayko, N, Van Der Wateren, E, Fallows, R, Main, R, Janssen, G, Anderson, J, Bak Nielsen, A, Donner, J, Keane, E, Kunsemoller, J, Oslowski, S, Griessmeier, J, Serylak, M, Bruggen, M, Ciardi, B, Dettmar, R, Hoeft, M, Kramer, M, Mann, G, Vocks, C, Tiburzi C., Shaifullah G. M., Bassa C. G., Zucca P., Verbiest J. P. W., Porayko N. K., Van Der Wateren E., Fallows R. A., Main R. A., Janssen G. H., Anderson J. M., Bak Nielsen A. -S., Donner J. Y., Keane E. F., Kunsemoller J., Oslowski S., Griessmeier J. -M., Serylak M., Bruggen M., Ciardi B., Dettmar R. -J., Hoeft M., Kramer M., Mann G., Vocks C., Tiburzi, C, Shaifullah, G, Bassa, C, Zucca, P, Verbiest, J, Porayko, N, Van Der Wateren, E, Fallows, R, Main, R, Janssen, G, Anderson, J, Bak Nielsen, A, Donner, J, Keane, E, Kunsemoller, J, Oslowski, S, Griessmeier, J, Serylak, M, Bruggen, M, Ciardi, B, Dettmar, R, Hoeft, M, Kramer, M, Mann, G, Vocks, C, Tiburzi C., Shaifullah G. M., Bassa C. G., Zucca P., Verbiest J. P. W., Porayko N. K., Van Der Wateren E., Fallows R. A., Main R. A., Janssen G. H., Anderson J. M., Bak Nielsen A. -S., Donner J. Y., Keane E. F., Kunsemoller J., Oslowski S., Griessmeier J. -M., Serylak M., Bruggen M., Ciardi B., Dettmar R. -J., Hoeft M., Kramer M., Mann G., and Vocks C.
Abstract: Context. High-precision pulsar timing requires accurate corrections for dispersive delays of radio waves, parametrized by the dispersion measure (DM), particularly if these delays are variable in time. In a previous paper, we studied the solar wind (SW) models used in pulsar timing to mitigate the excess of DM that is annually induced by the SW and found these to be insufficient for high-precision pulsar timing. Here we analyze additional pulsar datasets to further investigate which aspects of the SW models currently used in pulsar timing can be readily improved, and at what levels of timing precision SW mitigation is possible. Aims. Our goals are to verify: (a) whether the data are better described by a spherical model of the SW with a time-variable amplitude, rather than a time-invariant one as suggested in literature, and (b) whether a temporal trend of such a model's amplitudes can be detected. Methods. We use the pulsar timing technique on low-frequency pulsar observations to estimate the DM and quantify how this value changes as the Earth moves around the Sun. Specifically, we monitor the DM in weekly to monthly observations of 14 pulsars taken with parts of the LOw-Frequency ARray (LOFAR) across time spans of up to 6 years. We develop an informed algorithm to separate the interstellar variations in the DM from those caused by the SW and demonstrate the functionality of this algorithm with extensive simulations. Assuming a spherically symmetric model for the SW density, we derive the amplitude of this model for each year of observations. Results. We show that a spherical model with a time-variable amplitude models the observations better than a spherical model with a constant amplitude, but that both approaches leave significant SW-induced delays uncorrected in a number of pulsars in the sample. The amplitude of the spherical model is found to be variable in time, as opposed to what has been previously suggested.
Published: 2021

120. Synchronous X-ray and Radio Mode Switches: A Rapid Global Transformation of the Pulsar Magnetosphere

Author: Hermsen, W., Hessels, J. W. T., Kuiper, L., van Leeuwen, J., Mitra, D., de Plaa, J., Rankin, J. M., Stappers, B. W., Wright, G. A. E., Basu, R., Alexov, A., Coenen, T., Grießmeier, J.-M., Hassall, T. E., Karastergiou, A., Keane, E., Kondratiev, V. I., Kramer, M., Kuniyoshi, M., Noutsos, A., Serylak, M., Pilia, M., Sobey, C., Weltevrede, P., Zagkouris, K., Asgekar, A., Avruch, I. M., Batejat, F., Bell, M. E., Bell, M. R., Bentum, M. J., Bernardi, G., Best, P., Bîrzan, L., Bonafede, A., Breitling, F., Broderick, J., Brüggen, M., Butcher, H. R., Ciardi, B., Duscha, S., Eislöffel, J., Falcke, H., Fender, R., Ferrari, C., Frieswijk, W., Garrett, M. A., de Gasperin, F., de Geus, E., Gunst, A. W., Heald, G., Hoeft, M., Horneffer, A., Iacobelli, M., Kuper, G., Maat, P., Macario, G., Markoff, S., McKean, J. P., Mevius, M., Miller-Jones, J. C. A., Morganti, R., Munk, H., Orrú, E., Paas, H., Pandey-Pommier, M., Pandey, V. N., Pizzo, R., Polatidis, A. G., Rawlings, S., Reich, W., Röttgering, H., Scaife, A. M. M., Schoenmakers, A., Shulevski, A., Sluman, J., Steinmetz, M., Tagger, M., Tang, Y., Tasse, C., Veen, S. ter, Vermeulen, R., van de Brink, R. H., van Weeren, R. J., Wijers, R. A. M. J., Wise, M. W., Wucknitz, O., Yatawatta, S., and Zarka, P.
Published: 2013
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121. Statistical analysis of the causes of excess variance in the 21 cm signal power spectra obtained with the Low-Frequency Array

Author: Gan, H., primary, Koopmans, L. V. E., additional, Mertens, F. G., additional, Mevius, M., additional, Offringa, A. R., additional, Ciardi, B., additional, Gehlot, B. K., additional, Ghara, R., additional, Ghosh, A., additional, Giri, S. K., additional, Iliev, I. T., additional, Mellema, G., additional, Pandey, V. N., additional, and Zaroubi, S., additional
Published: 2022
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122. Sub-arcsecond imaging with the International LOFAR Telescope: II. Completion of the LOFAR Long-Baseline Calibrator Survey

Author: Jackson, N., Badole, S., Morgan, J., Chhetri, R., Prūsis, K., Nikolajevs, A., Morabito, L., Brentjens, M., Sweijen, F., Iacobelli, M., Orrù, E., Sluman, J., Blaauw, R., Mulder, H., van Dijk, P., Mooney, S., Deller, A., Moldon, J., Callingham, J.R., Harwood, J., Hardcastle, M., Heald, G., Drabent, A., Mckean, J.P., Asgekar, A., Avruch, I.M., Bentum, M.J., Bonafede, A., Brouw, W.N., Brüggen, M., Butcher, H.R., Ciardi, B., Coolen, A., Corstanje, A., Damstra, S., Duscha, S., Eislöffel, J., Falcke, H., Garrett, M., De Gasperin, F., Griessmeier, J.M., Gunst, A.W., van Haarlem, M.P., Hoeft, M., van der Horst, A.J., Jütte, E., Koopmans, L.V.E., Krankowski, A., Maat, P., Mann, G., Miley, G.K., Nelles, A., Norden, M., Paas, M., Pandey, V.N., Pandey-Pommier, M., Pizzo, R.F., Reich, W., Rothkaehl, H., Rowlinson, A., Ruiter, M., Shulevski, A., Schwarz, D.J., Smirnov, O., Tagger, M., Vocks, C., van Weeren, R.J., Wijers, R., Wucknitz, O., Zarka, P., Zensus, J.A., Zucca, P., Jackson, N., Badole, S., Morgan, J., Chhetri, R., Prūsis, K., Nikolajevs, A., Morabito, L., Brentjens, M., Sweijen, F., Iacobelli, M., Orrù, E., Sluman, J., Blaauw, R., Mulder, H., van Dijk, P., Mooney, S., Deller, A., Moldon, J., Callingham, J.R., Harwood, J., Hardcastle, M., Heald, G., Drabent, A., Mckean, J.P., Asgekar, A., Avruch, I.M., Bentum, M.J., Bonafede, A., Brouw, W.N., Brüggen, M., Butcher, H.R., Ciardi, B., Coolen, A., Corstanje, A., Damstra, S., Duscha, S., Eislöffel, J., Falcke, H., Garrett, M., De Gasperin, F., Griessmeier, J.M., Gunst, A.W., van Haarlem, M.P., Hoeft, M., van der Horst, A.J., Jütte, E., Koopmans, L.V.E., Krankowski, A., Maat, P., Mann, G., Miley, G.K., Nelles, A., Norden, M., Paas, M., Pandey, V.N., Pandey-Pommier, M., Pizzo, R.F., Reich, W., Rothkaehl, H., Rowlinson, A., Ruiter, M., Shulevski, A., Schwarz, D.J., Smirnov, O., Tagger, M., Vocks, C., van Weeren, R.J., Wijers, R., Wucknitz, O., Zarka, P., Zensus, J.A., and Zucca, P.
Abstract: The Low-Frequency Array (LOFAR) Long-Baseline Calibrator Survey (LBCS) was conducted between 2014 and 2019 in order to obtain a set of suitable calibrators for the LOFAR array. In this paper, we present the complete survey, building on the preliminary analysis published in 2016 which covered approximately half the survey area. The final catalogue consists of 30 006 observations of 24 713 sources in the northern sky, selected for a combination of high low-frequency radio flux density and flat spectral index using existing surveys (WENSS, NVSS, VLSS, and MSSS). Approximately one calibrator per square degree, suitable for calibration of ≥200 km baselines is identified by the detection of compact flux density, for declinations north of 30° and away from the Galactic plane, with a considerably lower density south of this point due to relative difficulty in selecting flat-spectrum candidate sources in this area of the sky. The catalogue contains indicators of degree of correlated flux on baselines between the Dutch core and each of the international stations, involving a maximum baseline length of nearly 2000 km, for all of the observations. Use of the VLBA calibrator list, together with statistical arguments by comparison with flux densities from lower-resolution catalogues, allow us to establish a rough flux density scale for the LBCS observations, so that LBCS statistics can be used to estimate compact flux densities on scales between 300 mas and 2′, for sources observed in the survey. The survey is used to estimate the phase coherence time of the ionosphere for the LOFAR international baselines, with median phase coherence times of about 2 min varying by a few tens of percent between the shortest and longest baselines. The LBCS can be used to assess the structures of point sources in lower-resolution surveys, with significant reductions in the degree of coherence in these sources on scales between 2′ and 300 mas. The LBCS survey sources show a greater incidence of
Published: 2022

123. Subarcsecond view on the high-redshift blazar GB 1508+5714 by the International LOFAR Telescope

Author: Ministerio de Ciencia e Innovación (España), European Commission, Kappes, A., Burd, P. R., Kadler, M., Ghisellini, G., Bonnassieux, E., Perucho, M., Brüggen, M., Cheung, C. C., Ciardi, B., Gallo, E., Haardt, F., Morabito, L. K., Sbarrato, T., Drabent, A., Harwood, J., Jackson, N., Moldón, Javier, Ministerio de Ciencia e Innovación (España), European Commission, Kappes, A., Burd, P. R., Kadler, M., Ghisellini, G., Bonnassieux, E., Perucho, M., Brüggen, M., Cheung, C. C., Ciardi, B., Gallo, E., Haardt, F., Morabito, L. K., Sbarrato, T., Drabent, A., Harwood, J., Jackson, N., and Moldón, Javier
Abstract: Context. Studies of the most distant active galactic nuclei (AGNs) allow us to test our current understanding of the physics present in radio-jetted AGNs across a range of environments, and probe their interactions with these environments. The decrease in apparent luminosity with distance is the primary difficulty to overcome in the study of these distant AGNs, which requires highly sensitive instruments. Aims. Our goal is to employ new long wavelength radio data to better parametrise the broad-band spectral energy distribution (SED) of GB 1508+5714, a high-redshift (z = 4.30) AGN. Its high redshift, high intrinsic luminosity and classification as a blazar allow us to test emission models that consider the efficient cooling of jet electrons via inverse Compton losses in interactions with the dense cosmic microwave background (CMB) photon field at high redshifts. A significant detection of this effect in GB 1508+5714 may partly explain the apparent sparsity of high-redshift radio galaxies in wide-field surveys, detections of this kind are only becoming possible with the current generation of Square Kilometre Array (SKA) precursors. Methods. We used the LOw-Frequency ARray (LOFAR) to image the long wavelength radio emission around the high-redshift blazar GB 1508+5714 on arcsecond scales at frequencies between 128 and 160 MHz. This allowed us to compare the spatially resolved structure with higher frequency observations, and construct spectral index maps to study the spectral properties of the different components. Results. The LOFAR image shows a compact unresolved core and two resolved emission regions around 2 arcsec to the east and to the west of the radio core. We find structure consistent with previous Very Large Array (VLA) observations, as well as a previously unreported emission region to the east. The region in the west shows a spectral index of −1.2−0.2+0.4 while the region in the east indicates a spectral index of ≲−1.1. The radio core features aflat spect
Published: 2022

124. Subarcsecond view on the high-redshift blazar GB 1508+5714 by the International LOFAR Telescope

Author: Kappes, A., primary, Burd, P. R., additional, Kadler, M., additional, Ghisellini, G., additional, Perucho, M., additional, Brüggen, M., additional, Cheung, C. C., additional, Ciardi, B., additional, Gallo, E., additional, Haardt, F., additional, Morabito, L. K., additional, Sbarrato, T., additional, Bonnassieux, E., additional, Drabent, A., additional, Harwood, J., additional, Jackson, N., additional, and Moldon, J., additional
Published: 2022
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125. Sub-arcsecond imaging with the International LOFAR Telescope

Author: Jackson, N., primary, Badole, S., additional, Morgan, J., additional, Chhetri, R., additional, Prūsis, K., additional, Nikolajevs, A., additional, Morabito, L., additional, Brentjens, M., additional, Sweijen, F., additional, Iacobelli, M., additional, Orrù, E., additional, Sluman, J., additional, Blaauw, R., additional, Mulder, H., additional, van Dijk, P., additional, Mooney, S., additional, Deller, A., additional, Moldon, J., additional, Callingham, J. R., additional, Harwood, J., additional, Hardcastle, M., additional, Heald, G., additional, Drabent, A., additional, McKean, J. P., additional, Asgekar, A., additional, Avruch, I. M., additional, Bentum, M. J., additional, Bonafede, A., additional, Brouw, W. N., additional, Brüggen, M., additional, Butcher, H. R., additional, Ciardi, B., additional, Coolen, A., additional, Corstanje, A., additional, Damstra, S., additional, Duscha, S., additional, Eislöffel, J., additional, Falcke, H., additional, Garrett, M., additional, de Gasperin, F., additional, Griessmeier, J.-M., additional, Gunst, A. W., additional, van Haarlem, M. P., additional, Hoeft, M., additional, van der Horst, A. J., additional, Jütte, E., additional, Koopmans, L. V. E., additional, Krankowski, A., additional, Maat, P., additional, Mann, G., additional, Miley, G. K., additional, Nelles, A., additional, Norden, M., additional, Paas, M., additional, Pandey, V. N., additional, Pandey-Pommier, M., additional, Pizzo, R. F., additional, Reich, W., additional, Rothkaehl, H., additional, Rowlinson, A., additional, Ruiter, M., additional, Shulevski, A., additional, Schwarz, D. J., additional, Smirnov, O., additional, Tagger, M., additional, Vocks, C., additional, van Weeren, R. J., additional, Wijers, R., additional, Wucknitz, O., additional, Zarka, P., additional, Zensus, J. A., additional, and Zucca, P., additional
Published: 2022
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126. Sub-arcsecond imaging with the International LOFAR Telescope

Author: Morabito, L. K., primary, Jackson, N. J., additional, Mooney, S., additional, Sweijen, F., additional, Badole, S., additional, Kukreti, P., additional, Venkattu, D., additional, Groeneveld, C., additional, Kappes, A., additional, Bonnassieux, E., additional, Drabent, A., additional, Iacobelli, M., additional, Croston, J. H., additional, Best, P. N., additional, Bondi, M., additional, Callingham, J. R., additional, Conway, J. E., additional, Deller, A. T., additional, Hardcastle, M. J., additional, McKean, J. P., additional, Miley, G. K., additional, Moldon, J., additional, Röttgering, H. J. A., additional, Tasse, C., additional, Shimwell, T. W., additional, van Weeren, R. J., additional, Anderson, J. M., additional, Asgekar, A., additional, Avruch, I. M., additional, van Bemmel, I. M., additional, Bentum, M. J., additional, Bonafede, A., additional, Brouw, W. N., additional, Butcher, H. R., additional, Ciardi, B., additional, Corstanje, A., additional, Coolen, A., additional, Damstra, S., additional, de Gasperin, F., additional, Duscha, S., additional, Eislöffel, J., additional, Engels, D., additional, Falcke, H., additional, Garrett, M. A., additional, Griessmeier, J., additional, Gunst, A. W., additional, van Haarlem, M. P., additional, Hoeft, M., additional, van der Horst, A. J., additional, Jütte, E., additional, Kadler, M., additional, Koopmans, L. V. E., additional, Krankowski, A., additional, Mann, G., additional, Nelles, A., additional, Oonk, J. B. R., additional, Orru, E., additional, Paas, H., additional, Pandey, V. N., additional, Pizzo, R. F., additional, Pandey-Pommier, M., additional, Reich, W., additional, Rothkaehl, H., additional, Ruiter, M., additional, Schwarz, D. J., additional, Shulevski, A., additional, Soida, M., additional, Tagger, M., additional, Vocks, C., additional, Wijers, R. A. M. J., additional, Wijnholds, S. J., additional, Wucknitz, O., additional, Zarka, P., additional, and Zucca, P., additional
Published: 2022
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127. A numerical study of 21-cm signal suppression and noise increase in direction-dependent calibration of LOFAR data

Author: Mevius, M, primary, Mertens, F, additional, Koopmans, L V E, additional, Offringa, A R, additional, Yatawatta, S, additional, Brentjens, M A, additional, Chapman, E, additional, Ciardi, B, additional, Gan, H, additional, Gehlot, B K, additional, Ghara, R, additional, Ghosh, A, additional, Giri, S K, additional, Iliev, I T, additional, Mellema, G, additional, Pandey, V N, additional, and Zaroubi, S, additional
Published: 2021
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128. SPACE: the spectroscopic all-sky cosmic explorer

Author: Cimatti, A., Robberto, M., Baugh, C., Beckwith, S. V. W., Content, R., Daddi, E., De Lucia, G., Garilli, B., Guzzo, L., Kauffmann, G., Lehnert, M., Maccagni, D., Martínez-Sansigre, A., Pasian, F., Reid, I. N., Rosati, P., Salvaterra, R., Stiavelli, M., Wang, Y., Osorio, M. Zapatero, Balcells, M., Bersanelli, M., Bertoldi, F., Blaizot, J., Bottini, D., Bower, R., Bulgarelli, A., Burgasser, A., Burigana, C., Butler, R. C., Casertano, S., Ciardi, B., Cirasuolo, M., Clampin, M., Cole, S., Comastri, A., Cristiani, S., Cuby, J.-G., Cuttaia, F., De Rosa, A., Sanchez, A. Diaz, Di Capua, M., Dunlop, J., Fan, X., Ferrara, A., Finelli, F., Franceschini, A., Franx, M., Franzetti, P., Frenk, C., Gardner, Jonathan P., Gianotti, F., Grange, R., Gruppioni, C., Gruppuso, A., Hammer, F., Hillenbrand, L., Jacobsen, A., Jarvis, M., Kennicutt, R., Kimble, R., Kriek, M., Kurk, J., Kneib, J.-P., Le Fevre, O., Macchetto, D., MacKenty, J., Madau, P., Magliocchetti, M., Maino, D., Mandolesi, N., Masetti, N., McLure, R., Mennella, A., Meyer, M., Mignoli, M., Mobasher, B., Molinari, E., Morgante, G., Morris, S., Nicastro, L., Oliva, E., Padovani, P., Palazzi, E., Paresce, F., Garrido, A. Perez, Pian, E., Popa, L., Postman, M., Pozzetti, L., Rayner, J., Rebolo, R., Renzini, A., Röttgering, H., Schinnerer, E., Scodeggio, M., Saisse, M., Shanks, T., Shapley, A., Sharples, R., Shea, H., Silk, J., Smail, I., Spanó, P., Steinacker, J., Stringhetti, L., Szalay, A., Tresse, L., Trifoglio, M., Urry, M., Valenziano, L., Villa, F., Perez, I. Villo, Walter, F., Ward, M., White, R., White, S., Wright, E., Wyse, R., Zamorani, G., Zacchei, A., Zeilinger, W. W., and Zerbi, F.
Published: 2009
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129. The LOFAR Two-meter Sky Survey: Deep Fields Data Release 1

Author: Sabater, J., Best, P. N., Tasse, C., Hardcastle, M. J., Shimwell, T. W., Nisbet, D., Jelić, Vibor, Callingham, J. R., Röttgering, H. J. A., Bonato, M., Bondi, M., Ciardi, B., Cochrane, R. K., Jarvis, M. J., Kondapally, R., Koopmans, L. V. E., O’Sullivan, S. P., Prandoni, I., Schwarz, D. J., Smith, D. J. B., Wang, L., Williams, W. L., and Zaroubi, S.
Subjects: surveys, catalogs, radio continuum: general, radio continuum: galaxies, Physics, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics
Abstract: The LOFAR Two-metre Sky Survey (LoTSS) will cover the full northern sky and, additionally, aims to observe the LoTSS deep fields to a noise level of ≲10 μJy beam−1 over several tens of square degrees in areas that have the most extensive ancillary data. This paper presents the ELAIS-N1 deep field, the deepest of the LoTSS deep fields to date. With an effective observing time of 163.7 h, it reaches a root mean square noise level of ≲20 μJy beam−1 in the central region (and below 30 μJy beam−1 over 10 square degrees). The resolution is ~6 arcsecs and 84 862 radio sources were detected in the full area (68 square degrees) with 74 127 sources in the highest quality area at less than 3 degrees from the pointing centre. The observation reaches a sky density of more than 5000 sources per square degree in the central region (~5 square degrees). We present the calibration procedure, which addresses the special configuration of some observations and the extended bandwidth covered (115-177 MHz ; central frequency 146.2 MHz) compared to standard LoTSS. We also describe the methods used to calibrate the flux density scale using cross-matching with sources detected by other radio surveys in the literature. We find the flux density uncertainty related to the flux density scale to be ~6.5 per cent. By studying the variations of the flux density measurements between different epochs, we show that relative flux density calibration is reliable out to about a 3 degree radius, but that additional flux density uncertainty is present for all sources at about the 3 per cent level ; this is likely to be associated with residual calibration errors, and is shown to be more significant in datasets with poorer ionosphere conditions. We also provide intra-band spectral indices, which can be useful to detect sources with unusual spectral properties. The final uncertainty in the flux densities is estimated to be ~10 per cent for ELAIS-N1.
Published: 2021

130. Exploration of the high-redshift universe enabled by THESEUS

Author: Tanvir, N. R., primary, Le Floc’h, E., additional, Christensen, L., additional, Caruana, J., additional, Salvaterra, R., additional, Ghirlanda, G., additional, Ciardi, B., additional, Maio, U., additional, D’Odorico, V., additional, Piedipalumbo, E., additional, Campana, S., additional, Noterdaeme, P., additional, Graziani, L., additional, Amati, L., additional, Bagoly, Z., additional, Balázs, L. G., additional, Basa, S., additional, Behar, E., additional, De Cia, A., additional, Valle, M. Della, additional, De Pasquale, M., additional, Frontera, F., additional, Gomboc, A., additional, Götz, D., additional, Horvath, I., additional, Hudec, R., additional, Mereghetti, S., additional, O’Brien, P. T., additional, Osborne, J. P., additional, Paltani, S., additional, Rosati, P., additional, Sergijenko, O., additional, Stanway, E. R., additional, Szécsi, D., additional, Tot́h, L. V., additional, Urata, Y., additional, Vergani, S., additional, and Zane, S., additional
Published: 2021
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131. Improved upper limits on the 21 cm signal power spectrum of neutral hydrogen at z approximate to 9.1 from LOFAR

Author: Mertens, F. G., Mevius, M., Koopmans, L. V. E., Offringa, A. R., Mellema, G., Zaroubi, S., Brentjens, M. A., Gan, H., Gehlot, B. K., Pandey, V. N., Sardarabadi, A. M., Vedantham, H. K., Yatawatta, S., Asad, K. M. B., Ciardi, B., Chapman, E., Gazagnes, S., Ghara, R., Ghosh, A., Giri, S. K., Iliev, I. T., Jelic, Ratomir, Kooistra, R., Mondal, R., Schaye, J., Silva, M. B., Kapteyn Astronomical Institute, Astronomy, and Research unit Nuclear & Hadron Physics
Subjects: EPOCH, CALIBRATION, IMPACT, COSMIC DAWN, methods: data analysis, SIMULATIONS, REIONIZATION WINDOWS, techniques: interferometric, cosmology: observations, dark ages, reionization, first stars, HIGH-REDSHIFT, SKY SURVEY, POLARIZATION LEAKAGE, 21-CM SIGNAL
Abstract: A new upper limit on the 21 cm signal power spectrum at a redshift of z approximate to 9.1 is presented, based on 141 h of data obtained with the Low-Frequency Array (LOFAR). The analysis includes significant improvements in spectrally smooth gain-calibration, Gaussian Process Regression (GPR) foreground mitigation and optimally weighted power spectrum inference. Previously seen 'excess power' due to spectral structure in the gain solutions has markedly reduced but some excess power still remains with a spectral correlation distinct from thermal noise. This excess has a spectral coherence scale of 0.25-0.45 MHz and is partially correlated between nights, especially in the foreground wedge region. The correlation is stronger between nights covering similar local sidereal times. A best 2-sigma upper limit of Delta(2)(21)
Published: 2020

132. The LOFAR Two-meter Sky Survey: Deep Fields Data Release 1

Author: Sabater, J., primary, Best, P. N., additional, Tasse, C., additional, Hardcastle, M. J., additional, Shimwell, T. W., additional, Nisbet, D., additional, Jelic, V., additional, Callingham, J. R., additional, Röttgering, H. J. A., additional, Bonato, M., additional, Bondi, M., additional, Ciardi, B., additional, Cochrane, R. K., additional, Jarvis, M. J., additional, Kondapally, R., additional, Koopmans, L. V. E., additional, O’Sullivan, S. P., additional, Prandoni, I., additional, Schwarz, D. J., additional, Smith, D. J. B., additional, Wang, L., additional, Williams, W. L., additional, and Zaroubi, S., additional
Published: 2021
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133. The impact of solar wind variability on pulsar timing

Author: Tiburzi, C., primary, Shaifullah, G. M., additional, Bassa, C. G., additional, Zucca, P., additional, Verbiest, J. P. W., additional, Porayko, N. K., additional, van der Wateren, E., additional, Fallows, R. A., additional, Main, R. A., additional, Janssen, G. H., additional, Anderson, J. M., additional, Bak Nielsen, A.-S., additional, Donner, J. Y., additional, Keane, E. F., additional, Künsemöller, J., additional, Osłowski, S., additional, Grießmeier, J.-M., additional, Serylak, M., additional, Brüggen, M., additional, Ciardi, B., additional, Dettmar, R.-J., additional, Hoeft, M., additional, Kramer, M., additional, Mann, G., additional, and Vocks, C., additional
Published: 2021
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134. Dispersion measure variability for 36 millisecond pulsars at 150 MHz with LOFAR

Author: Donner, J. Y., primary, Verbiest, J. P. W., additional, Tiburzi, C., additional, Osłowski, S., additional, Künsemöller, J., additional, Bak Nielsen, A.-S., additional, Grießmeier, J.-M., additional, Serylak, M., additional, Kramer, M., additional, Anderson, J. M., additional, Wucknitz, O., additional, Keane, E., additional, Kondratiev, V., additional, Sobey, C., additional, McKee, J. W., additional, Bilous, A. V., additional, Breton, R. P., additional, Brüggen, M., additional, Ciardi, B., additional, Hoeft, M., additional, van Leeuwen, J., additional, and Vocks, C., additional
Published: 2020
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135. Comparing foreground removal techniques for recovery of the LOFAR-EoR 21 cm power spectrum

Author: Hothi, Ian, primary, Chapman, Emma, additional, Pritchard, Jonathan R, additional, Mertens, F G, additional, Koopmans, L V E, additional, Ciardi, B, additional, Gehlot, B K, additional, Ghara, R, additional, Ghosh, A, additional, Giri, S K, additional, Iliev, I T, additional, Jelić, V, additional, and Zaroubi, S, additional
Published: 2020
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136. Tight constraints on the excess radio background at z = 9.1 from LOFAR

Author: Mondal, R, primary, Fialkov, A, additional, Fling, C, additional, Iliev, I T, additional, Barkana, R, additional, Ciardi, B, additional, Mellema, G, additional, Zaroubi, S, additional, Koopmans, L V E, additional, Mertens, F G, additional, Gehlot, B K, additional, Ghara, R, additional, Ghosh, A, additional, Giri, S K, additional, Offringa, A, additional, and Pandey, V N, additional
Published: 2020
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137. LOFAR 144-MHz follow-up observations of GW170817

Author: Broderick, J W, primary, Shimwell, T W, primary, Gourdji, K, primary, Rowlinson, A, primary, Nissanke, S, primary, Hotokezaka, K, primary, Jonker, P G, primary, Tasse, C, primary, Hardcastle, M J, primary, Oonk, J B R, primary, Fender, R P, primary, Wijers, R A M J, primary, Shulevski, A, primary, Stewart, A J, primary, ter Veen, S, primary, Moss, V A, primary, van der Wiel, M H D, primary, Nichols, D A, primary, Piette, A, primary, Bell, M E, primary, Carbone, D, primary, Corbel, S, primary, Eislöffel, J, primary, Grießmeier, J-M, primary, Keane, E F, primary, Law, C J, primary, Muñoz-Darias, T, primary, Pietka, M, primary, Serylak, M, primary, van der Horst, A J, primary, van Leeuwen, J, primary, Wijnands, R, primary, Zarka, P, primary, Anderson, J M, primary, Bentum, M J, primary, Blaauw, R, primary, Brouw, W N, primary, Brüggen, M, primary, Ciardi, B, primary, de Vos, M, primary, Duscha, S, primary, Fallows, R A, primary, Franzen, T M O, primary, Garrett, M A, primary, Gunst, A W, primary, Hoeft, M, primary, Hörandel, J R, primary, Iacobelli, M, primary, Jütte, E, primary, Koopmans, L V E, primary, Krankowski, A, primary, Maat, P, primary, Mann, G, primary, Mulder, H, primary, Nelles, A, primary, Paas, H, primary, Pandey-Pommier, M, primary, Pekal, R, primary, Reich, W, primary, Röttgering, H J A, primary, Schwarz, D J, primary, Smirnov, O, primary, Soida, M, primary, Toribio, M C, primary, van Haarlem, M P, primary, van Weeren, R J, primary, Vocks, C, primary, Wucknitz, O, primary, and Zucca, P, primary
Published: 2020
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138. The assembly of dusty galaxies at z ≥ 4: statistical properties

Author: Graziani, L, primary, Schneider, R, primary, Ginolfi, M, primary, Hunt, L K, primary, Maio, U, primary, Glatzle, M, primary, and Ciardi, B, primary
Published: 2020
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139. Cassiopeia A, Cygnus A, Taurus A, and Virgo A at ultra-low radio frequencies

Author: de Gasperin, F., primary, Vink, J., additional, McKean, J. P., additional, Asgekar, A., additional, Avruch, I., additional, Bentum, M. J., additional, Blaauw, R., additional, Bonafede, A., additional, Broderick, J. W., additional, Brüggen, M., additional, Breitling, F., additional, Brouw, W. N., additional, Butcher, H. R., additional, Ciardi, B., additional, Cuciti, V., additional, de Vos, M., additional, Duscha, S., additional, Eislöffel, J., additional, Engels, D., additional, Fallows, R. A., additional, Franzen, T. M. O., additional, Garrett, M. A., additional, Gunst, A. W., additional, Hörandel, J., additional, Heald, G., additional, Hoeft, M., additional, Iacobelli, M., additional, Koopmans, L. V. E., additional, Krankowski, A., additional, Maat, P., additional, Mann, G., additional, Mevius, M., additional, Miley, G., additional, Morganti, R., additional, Nelles, A., additional, Norden, M. J., additional, Offringa, A. R., additional, Orrú, E., additional, Paas, H., additional, Pandey, V. N., additional, Pandey-Pommier, M., additional, Pekal, R., additional, Pizzo, R., additional, Reich, W., additional, Rowlinson, A., additional, Rottgering, H. J. A., additional, Schwarz, D. J., additional, Shulevski, A., additional, Smirnov, O., additional, Sobey, C., additional, Soida, M., additional, Steinmetz, M., additional, Tagger, M., additional, Toribio, M. C., additional, van Ardenne, A., additional, van der Horst, A. J., additional, van Haarlem, M. P., additional, van Weeren, R. J., additional, Vocks, C., additional, Wucknitz, O., additional, Zarka, P., additional, and Zucca, P., additional
Published: 2020
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140. The THESEUS space mission concept: science case, design and expected performances

Author: Amati, L, O'Brien, P, Götz, D, Bozzo, E, Tenzer, C, Frontera, F, Ghirlanda, G, Labanti, C, Osborne, J, Stratta, G, Tanvir, N, Willingale, R, Attina, P, Campana, R, Castro-Tirado, A, Contini, C, Fuschino, F, Gomboc, A, Hudec, R, Orleanski, P, Renotte, E, Rodic, T, Bagoly, Z, Blain, A, Callanan, P, Covino, S, Ferrara, A, Le Floch, E, Marisaldi, M, Mereghetti, S, Rosati, P, Vacchi, A, D'Avanzo, P, Giommi, P, Piranomonte, S, Piro, L, Reglero, V, Rossi, A, Santangelo, A, Salvaterra, R, Tagliaferri, G, Vergani, S, Vinciguerra, S, Briggs, M, Campolongo, E, Ciolfi, R, Connaughton, V, Cordier, B, Morelli, B, Orlandini, M, Adami, C, Argan, A, Atteia, J, Auricchio, N, Balazs, L, Baldazzi, G, Basa, S, Basak, R, Bellutti, P, Bernardini, M, Bertuccio, G, Braga, J, Branchesi, M, Brandt, S, Brocato, E, Budtz-Jorgensen, C, Bulgarelli, A, Burderi, L, Camp, J, Capozziello, S, Caruana, J, Casella, P, Cenko, B, Chardonnet, P, Ciardi, B, Colafrancesco, S, Dainotti, M, D'Elia, V, De Martino, D, De Pasquale, M, Del Monte, E, Della Valle, M, Drago, A, Evangelista, Y, Feroci, M, Finelli, F, Fiorini, M, Fynbo, J, Gal-Yam, A, Gendre, B, Ghisellini, G, Grado, A, Guidorzi, C, Hafizi, M, Hanlon, L, Hjorth, J, Izzo, L, Kiss, L, Kumar, P, Kuvvetli, I, Lavagna, M, Li, T, Longo, F, Lyutikov, M, Maio, U, Maiorano, E, Malcovati, P, Malesani, D, Margutti, R, Martin-Carrillo, A, Masetti, N, Mcbreen, S, Mignani, R, Morgante, G, Mundell, C, Nargaard-Nielsen, H, Nicastro, L, Palazzi, E, Paltani, S, Panessa, F, Pareschi, G, Pe'Er, A, Penacchioni, A, Pian, E, Piedipalumbo, E, Piran, T, Rauw, G, Razzano, M, Read, A, Rezzolla, L, Romano, P, Ruffini, R, Savaglio, S, Sguera, V, Schady, P, Skidmore, W, Song, L, Stanway, E, Starling, R, Topinka, M, Troja, E, van Putten, M, Vanzella, E, Vercellone, S, Wilson-Hodge, C, Yonetoku, D, Zampa, G, Zampa, N, Zhang, B, Zhang, S, Antonelli, A, Bianco, F, Boci, S, Boer, M, Botticella, M, Boulade, O, Butler, C, Campana, S, Capitanio, F, Celotti, A, Chen, Y, Colpi, M, Comastri, A, Cuby, J, Dadina, M, De Luca, A, Dong, Y, Ettori, S, Gandhi, P, Geza, E, Greiner, J, Guiriec, S, Harms, J, Hernanz, M, Hornstrup, A, Hutchinson, I, Israel, G, Jonker, P, Kaneko, Y, Kawai, N, Wiersema, K, Korpela, S, Lebrun, V, Lu, F, Macfadyen, A, Malaguti, G, Maraschi, L, Melandri, A, Modjaz, M, Morris, D, Omodei, N, Paizis, A, Páta, P, Petrosian, V, Rachevski, A, Rhoads, J, Ryde, F, Sabau-Graziati, L, Shigehiro, N, Sims, M, Soomin, J, Szécsi, D, Urata, Y, Uslenghi, M, Valenziano, L, Vianello, G, Vojtech, S, Watson, D, Zicha, J, Amati, L., O'Brien, P., Götz, D., Bozzo, E., Tenzer, C., Frontera, F., Ghirlanda, G., Labanti, C., Osborne, J. P., Stratta, G., Tanvir, N., Willingale, R., Attina, P., Campana, R., Castro-Tirado, A. J., Contini, C., Fuschino, F., Gomboc, A., Hudec, R., Orleanski, P., Renotte, E., Rodic, T., Bagoly, Z., Blain, A., Callanan, P., Covino, S., Ferrara, A., Le Floch, E., Marisaldi, M., Mereghetti, S., Rosati, P., Vacchi, A., D'Avanzo, P., Giommi, P., Piranomonte, S., Piro, L., Reglero, V., Rossi, A., Santangelo, A., Salvaterra, R., Tagliaferri, G., Vergani, S., Vinciguerra, S., Briggs, M., Campolongo, E., Ciolfi, R., Connaughton, V., Cordier, B., Morelli, B., Orlandini, M., Adami, C., Argan, A., Atteia, J. -L., Auricchio, N., Balazs, L., Baldazzi, G., Basa, S., Basak, R., Bellutti, P., Bernardini, M. G., Bertuccio, G., Braga, J., Branchesi, M., Brandt, S., Brocato, E., Budtz-Jorgensen, C., Bulgarelli, A., Burderi, L., Camp, J., Capozziello, S., Caruana, J., Casella, P., Cenko, B., Chardonnet, P., Ciardi, B., Colafrancesco, S., Dainotti, M. G., D'Elia, V., De Martino, D., De Pasquale, M., Del Monte, E., Della Valle, M., Drago, A., Evangelista, Y., Feroci, M., Finelli, F., Fiorini, M., Fynbo, J., Gal-Yam, A., Gendre, B., Ghisellini, G., Grado, A., Guidorzi, C., Hafizi, M., Hanlon, L., Hjorth, J., Izzo, L., Kiss, L., Kumar, P., Kuvvetli, I., Lavagna, M., Li, T., Longo, F., Lyutikov, M., Maio, U., Maiorano, E., Malcovati, P., Malesani, D., Margutti, R., Martin-Carrillo, A., Masetti, N., McBreen, S., Mignani, R., Morgante, G., Mundell, C., Nargaard-Nielsen, H. U., Nicastro, L., Palazzi, E., Paltani, S., Panessa, F., Pareschi, G., Pe'er, A., Penacchioni, A. V., Pian, E., Piedipalumbo, E., Piran, T., Rauw, G., Razzano, M., Read, A., Rezzolla, L., Romano, P., Ruffini, R., Savaglio, S., Sguera, V., Schady, P., Skidmore, W., Song, L., Stanway, E., Starling, R., Topinka, M., Troja, E., van Putten, M., Vanzella, E., Vercellone, S., Wilson-Hodge, C., Yonetoku, D., Zampa, G., Zampa, N., Zhang, B., Zhang, B. B., Zhang, S., Zhang, S. -N., Antonelli, A., Bianco, F., Boci, S., Boer, M., Botticella, M. T., Boulade, O., Butler, C., Campana, S., Capitanio, F., Celotti, A., Chen, Y., Colpi, M., Comastri, A., Cuby, J. -G., Dadina, M., De Luca, A., Dong, Y. -W., Ettori, S., Gandhi, P., Geza, E., Greiner, J., Guiriec, S., Harms, J., Hernanz, M., Hornstrup, A., Hutchinson, I., Israel, G., Jonker, P., Kaneko, Y., Kawai, N., Wiersema, K., Korpela, S., Lebrun, V., Lu, F., MacFadyen, A., Malaguti, G., Maraschi, L., Melandri, A., Modjaz, M., Morris, D., Omodei, N., Paizis, A., Páta, P., Petrosian, V., Rachevski, A., Rhoads, J., Ryde, F., Sabau-Graziati, L., Shigehiro, N., Sims, M., Soomin, J., Szécsi, D., Urata, Y., Uslenghi, M., Valenziano, L., Vianello, G., Vojtech, S., Watson, D., Zicha, J., Amati, L, O'Brien, P, Götz, D, Bozzo, E, Tenzer, C, Frontera, F, Ghirlanda, G, Labanti, C, Osborne, J, Stratta, G, Tanvir, N, Willingale, R, Attina, P, Campana, R, Castro-Tirado, A, Contini, C, Fuschino, F, Gomboc, A, Hudec, R, Orleanski, P, Renotte, E, Rodic, T, Bagoly, Z, Blain, A, Callanan, P, Covino, S, Ferrara, A, Le Floch, E, Marisaldi, M, Mereghetti, S, Rosati, P, Vacchi, A, D'Avanzo, P, Giommi, P, Piranomonte, S, Piro, L, Reglero, V, Rossi, A, Santangelo, A, Salvaterra, R, Tagliaferri, G, Vergani, S, Vinciguerra, S, Briggs, M, Campolongo, E, Ciolfi, R, Connaughton, V, Cordier, B, Morelli, B, Orlandini, M, Adami, C, Argan, A, Atteia, J, Auricchio, N, Balazs, L, Baldazzi, G, Basa, S, Basak, R, Bellutti, P, Bernardini, M, Bertuccio, G, Braga, J, Branchesi, M, Brandt, S, Brocato, E, Budtz-Jorgensen, C, Bulgarelli, A, Burderi, L, Camp, J, Capozziello, S, Caruana, J, Casella, P, Cenko, B, Chardonnet, P, Ciardi, B, Colafrancesco, S, Dainotti, M, D'Elia, V, De Martino, D, De Pasquale, M, Del Monte, E, Della Valle, M, Drago, A, Evangelista, Y, Feroci, M, Finelli, F, Fiorini, M, Fynbo, J, Gal-Yam, A, Gendre, B, Ghisellini, G, Grado, A, Guidorzi, C, Hafizi, M, Hanlon, L, Hjorth, J, Izzo, L, Kiss, L, Kumar, P, Kuvvetli, I, Lavagna, M, Li, T, Longo, F, Lyutikov, M, Maio, U, Maiorano, E, Malcovati, P, Malesani, D, Margutti, R, Martin-Carrillo, A, Masetti, N, Mcbreen, S, Mignani, R, Morgante, G, Mundell, C, Nargaard-Nielsen, H, Nicastro, L, Palazzi, E, Paltani, S, Panessa, F, Pareschi, G, Pe'Er, A, Penacchioni, A, Pian, E, Piedipalumbo, E, Piran, T, Rauw, G, Razzano, M, Read, A, Rezzolla, L, Romano, P, Ruffini, R, Savaglio, S, Sguera, V, Schady, P, Skidmore, W, Song, L, Stanway, E, Starling, R, Topinka, M, Troja, E, van Putten, M, Vanzella, E, Vercellone, S, Wilson-Hodge, C, Yonetoku, D, Zampa, G, Zampa, N, Zhang, B, Zhang, S, Antonelli, A, Bianco, F, Boci, S, Boer, M, Botticella, M, Boulade, O, Butler, C, Campana, S, Capitanio, F, Celotti, A, Chen, Y, Colpi, M, Comastri, A, Cuby, J, Dadina, M, De Luca, A, Dong, Y, Ettori, S, Gandhi, P, Geza, E, Greiner, J, Guiriec, S, Harms, J, Hernanz, M, Hornstrup, A, Hutchinson, I, Israel, G, Jonker, P, Kaneko, Y, Kawai, N, Wiersema, K, Korpela, S, Lebrun, V, Lu, F, Macfadyen, A, Malaguti, G, Maraschi, L, Melandri, A, Modjaz, M, Morris, D, Omodei, N, Paizis, A, Páta, P, Petrosian, V, Rachevski, A, Rhoads, J, Ryde, F, Sabau-Graziati, L, Shigehiro, N, Sims, M, Soomin, J, Szécsi, D, Urata, Y, Uslenghi, M, Valenziano, L, Vianello, G, Vojtech, S, Watson, D, Zicha, J, Amati, L., O'Brien, P., Götz, D., Bozzo, E., Tenzer, C., Frontera, F., Ghirlanda, G., Labanti, C., Osborne, J. P., Stratta, G., Tanvir, N., Willingale, R., Attina, P., Campana, R., Castro-Tirado, A. J., Contini, C., Fuschino, F., Gomboc, A., Hudec, R., Orleanski, P., Renotte, E., Rodic, T., Bagoly, Z., Blain, A., Callanan, P., Covino, S., Ferrara, A., Le Floch, E., Marisaldi, M., Mereghetti, S., Rosati, P., Vacchi, A., D'Avanzo, P., Giommi, P., Piranomonte, S., Piro, L., Reglero, V., Rossi, A., Santangelo, A., Salvaterra, R., Tagliaferri, G., Vergani, S., Vinciguerra, S., Briggs, M., Campolongo, E., Ciolfi, R., Connaughton, V., Cordier, B., Morelli, B., Orlandini, M., Adami, C., Argan, A., Atteia, J. -L., Auricchio, N., Balazs, L., Baldazzi, G., Basa, S., Basak, R., Bellutti, P., Bernardini, M. G., Bertuccio, G., Braga, J., Branchesi, M., Brandt, S., Brocato, E., Budtz-Jorgensen, C., Bulgarelli, A., Burderi, L., Camp, J., Capozziello, S., Caruana, J., Casella, P., Cenko, B., Chardonnet, P., Ciardi, B., Colafrancesco, S., Dainotti, M. G., D'Elia, V., De Martino, D., De Pasquale, M., Del Monte, E., Della Valle, M., Drago, A., Evangelista, Y., Feroci, M., Finelli, F., Fiorini, M., Fynbo, J., Gal-Yam, A., Gendre, B., Ghisellini, G., Grado, A., Guidorzi, C., Hafizi, M., Hanlon, L., Hjorth, J., Izzo, L., Kiss, L., Kumar, P., Kuvvetli, I., Lavagna, M., Li, T., Longo, F., Lyutikov, M., Maio, U., Maiorano, E., Malcovati, P., Malesani, D., Margutti, R., Martin-Carrillo, A., Masetti, N., McBreen, S., Mignani, R., Morgante, G., Mundell, C., Nargaard-Nielsen, H. U., Nicastro, L., Palazzi, E., Paltani, S., Panessa, F., Pareschi, G., Pe'er, A., Penacchioni, A. V., Pian, E., Piedipalumbo, E., Piran, T., Rauw, G., Razzano, M., Read, A., Rezzolla, L., Romano, P., Ruffini, R., Savaglio, S., Sguera, V., Schady, P., Skidmore, W., Song, L., Stanway, E., Starling, R., Topinka, M., Troja, E., van Putten, M., Vanzella, E., Vercellone, S., Wilson-Hodge, C., Yonetoku, D., Zampa, G., Zampa, N., Zhang, B., Zhang, B. B., Zhang, S., Zhang, S. -N., Antonelli, A., Bianco, F., Boci, S., Boer, M., Botticella, M. T., Boulade, O., Butler, C., Campana, S., Capitanio, F., Celotti, A., Chen, Y., Colpi, M., Comastri, A., Cuby, J. -G., Dadina, M., De Luca, A., Dong, Y. -W., Ettori, S., Gandhi, P., Geza, E., Greiner, J., Guiriec, S., Harms, J., Hernanz, M., Hornstrup, A., Hutchinson, I., Israel, G., Jonker, P., Kaneko, Y., Kawai, N., Wiersema, K., Korpela, S., Lebrun, V., Lu, F., MacFadyen, A., Malaguti, G., Maraschi, L., Melandri, A., Modjaz, M., Morris, D., Omodei, N., Paizis, A., Páta, P., Petrosian, V., Rachevski, A., Rhoads, J., Ryde, F., Sabau-Graziati, L., Shigehiro, N., Sims, M., Soomin, J., Szécsi, D., Urata, Y., Uslenghi, M., Valenziano, L., Vianello, G., Vojtech, S., Watson, D., and Zicha, J.
Abstract: THESEUS is a space mission concept aimed at exploiting Gamma-Ray Bursts for investigating the early Universe and at providing a substantial advancement of multi-messenger and time-domain astrophysics. These goals will be achieved through a unique combination of instruments allowing GRB and X-ray transient detection over a broad field of view (more than 1sr) with 0.5–1 arcmin localization, an energy band extending from several MeV down to 0.3 keV and high sensitivity to transient sources in the soft X-ray domain, as well as on-board prompt (few minutes) follow-up with a 0.7 m class IR telescope with both imaging and spectroscopic capabilities. THESEUS will be perfectly suited for addressing the main open issues in cosmology such as, e.g., star formation rate and metallicity evolution of the inter-stellar and intra-galactic medium up to redshift ∼10, signatures of Pop III stars, sources and physics of re-ionization, and the faint end of the galaxy luminosity function. In addition, it will provide unprecedented capability to monitor the X-ray variable sky, thus detecting, localizing, and identifying the electromagnetic counterparts to sources of gravitational radiation, which may be routinely detected in the late ’20s/early ’30s by next generation facilities like aLIGO/ aVirgo, eLISA, KAGRA, and Einstein Telescope. THESEUS will also provide powerful synergies with the next generation of multi-wavelength observatories (e.g., LSST, ELT, SKA, CTA, ATHENA).
Published: 2018

141. Improved upper limits on the 21-cm signal power spectrum of neutral hydrogen at $\boldsymbol{z \approx 9.1}$ from LOFAR

Author: Mertens, F.G., Mevius, M., Koopmans, L.V.E, Offringa, A.R., Mellema, G., Zaroubi, S., Brentjens, M.A., Gan, H., Gehlot, B.K., Pandey, V.N., Sardarabadi, A.M., Vedantham, H.K., Yatawatta, S., Asad, K.M.B., Ciardi, B., Chapman, E., Gazagnes, S., Ghara, R., Ghosh, A., Giri, S.K., Iliev, I.T., Jelíc, V., Kooistra, R., Mondal, R., Schaye, J., Silva, M.B., Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA (UMR_8112)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-CY Cergy Paris Université (CY)
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO), techniques: interferometric, cosmology: observations, first stars, reionization, FOS: Physical sciences, dark ages, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], methods: data analysis, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract: A new upper limit on the 21-cm signal power spectrum at a redshift of $z \approx 9.1$ is presented, based on 141 hours of data obtained with the Low-Frequency Array (LOFAR). The analysis includes significant improvements in spectrally-smooth gain-calibration, Gaussian Process Regression (GPR) foreground mitigation and optimally-weighted power spectrum inference. Previously seen `excess power' due to spectral structure in the gain solutions has markedly reduced but some excess power still remains with a spectral correlation distinct from thermal noise. This excess has a spectral coherence scale of $0.25 - 0.45$\,MHz and is partially correlated between nights, especially in the foreground wedge region. The correlation is stronger between nights covering similar local sidereal times. A best 2-$\sigma$ upper limit of $\Delta^2_{21} < (73)^2\,\mathrm{mK^2}$ at $k = 0.075\,\mathrm{h\,cMpc^{-1}}$ is found, an improvement by a factor $\approx 8$ in power compared to the previously reported upper limit. The remaining excess power could be due to residual foreground emission from sources or diffuse emission far away from the phase centre, polarization leakage, chromatic calibration errors, ionosphere, or low-level radio-frequency interference. We discuss future improvements to the signal processing chain that can further reduce or even eliminate these causes of excess power., Comment: 27 pages, 14 figues, accepted in MNRAS (updated with reference to accompanying paper)
Published: 2020
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142. Corrigendum: A large light-mass component of cosmic rays at 10171017.5 electronvolts from radio observations

Author: Buitink, S., Corstanje, A., Falcke, H., Hrandel, J. R., Huege, T., Nelles, A., Rachen, J. P., Rossetto, L., Schellart, P., Scholten, O., ter Veen, S., Thoudam, S., Trinh, T. N. G., Anderson, J., Asgekar, A., Avruch, I. M., Bell, M. E., Bentum, M. J., Bernardi, G., Best, P., Bonafede, A., Breitling, F., Broderick, J. W., Brouw, W. N., Brggen, M., Butcher, H. R., Carbone, D., Ciardi, B., Conway, J. E., de Gasperin, F., de Geus, E., Deller, A., Dettmar, R.-J., van Diepen, G., Duscha, S., Eislffel, J., Engels, D., Enriquez, J. E., Fallows, R. A., Fender, R., Ferrari, C., Frieswijk, W., Garrett, M. A., Griemeier, J. M., Gunst, A. W., van Haarlem, M. P., Hassall, T. E., Heald, G., Hessels, J. W. T., Hoeft, M., Horneffer, A., Iacobelli, M., Intema, H., Juette, E., Karastergiou, A., Kondratiev, V. I., Kramer, M., Kuniyoshi, M., Kuper, G., van Leeuwen, J., Loose, G. M., Maat, P., Mann, G., Markoff, S., McFadden, R., McKay-Bukowski, D., McKean, J. P., Mevius, M., Mulcahy, D. D., Munk, H., Norden, M. J., Orru, E., Paas, H., Pandey-Pommier, M., Pandey, V. N., Pietka, M., Pizzo, R., Polatidis, A. G., Reich, W., Rttgering, H. J. A., Scaife, A. M. M., Schwarz, D. J., Serylak, M., Sluman, J., Smirnov, O., Stappers, B. W., Steinmetz, M., Stewart, A., Swinbank, J., Tagger, M., Tang, Y., Tasse, C., Toribio, M. C., Vermeulen, R., Vocks, C., Vogt, C., van Weeren, R. J., Wijers, R. A. M. J., Wijnholds, S. J., Wise, M. W., Wucknitz, O., Yatawatta, S., Zarka, P., and Zensus, J. A.
Abstract: Author(s): S. Buitink; A. Corstanje; H. Falcke; J. R. Hrandel; T. Huege; A. Nelles; J. P. Rachen; L. Rossetto; P. Schellart; O. Scholten; S. ter Veen; S. Thoudam; T. N. [...]
Published: 2016
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143. LOFAR 144-MHz follow-up observations of GW170817

Author: Broderick, J.W., Shimwell, T.W., Gourdji, K., Rowlinson, A., Nissanke, S., Hotokezaka, K., Jonker, P.G., Tasse, C., Hardcastle, M.J., Oonk, J.B.R., Fender, R.P., Wijers, R.A.M.J., Shulevski, A., Stewart, A.J., ter Veen, S., Moss, V.A., van der Wiel, M.H.D., Nichols, D., Piette, A., Bell, M.E., Carbone, D., Corbel, S., Eislöffel, J., Grießmeier, J.-M., Keane, E.F., Law, C.J., Muñoz-Darias, T., Pietka, M., Serylak, M, van der Horst, A.J., van Leeuwen, J., Wijnands, R., Zarka, P., Anderson, J.M., Bentum, M.J., Blaauw, R., Brouw, W.N., Brüggen, M., Ciardi, B., de Vos, M., Duscha, S., Fallows, R.A., Franzen, T.M.O., Garrett, M.A., Gunst, A.W., Hoeft, M., Hörandel, J.R., Iacobelli, M., Jütte, E., Koopmans, L.V.E., Krankowski, A., Maat, P., Mann, G., Mulder, H., Paas, H., Pandey-Pommier, M., Pekal, R., Reich, W., Röttgering, H.J.A., Schwarz, D.J., Smirnov, O., Soida, M., Toribio, M.C., van Haarlem, M.P., van Weeren, R.J., Vocks, C., Wucknitz, O., Zucca, P., Broderick, J.W., Shimwell, T.W., Gourdji, K., Rowlinson, A., Nissanke, S., Hotokezaka, K., Jonker, P.G., Tasse, C., Hardcastle, M.J., Oonk, J.B.R., Fender, R.P., Wijers, R.A.M.J., Shulevski, A., Stewart, A.J., ter Veen, S., Moss, V.A., van der Wiel, M.H.D., Nichols, D., Piette, A., Bell, M.E., Carbone, D., Corbel, S., Eislöffel, J., Grießmeier, J.-M., Keane, E.F., Law, C.J., Muñoz-Darias, T., Pietka, M., Serylak, M, van der Horst, A.J., van Leeuwen, J., Wijnands, R., Zarka, P., Anderson, J.M., Bentum, M.J., Blaauw, R., Brouw, W.N., Brüggen, M., Ciardi, B., de Vos, M., Duscha, S., Fallows, R.A., Franzen, T.M.O., Garrett, M.A., Gunst, A.W., Hoeft, M., Hörandel, J.R., Iacobelli, M., Jütte, E., Koopmans, L.V.E., Krankowski, A., Maat, P., Mann, G., Mulder, H., Paas, H., Pandey-Pommier, M., Pekal, R., Reich, W., Röttgering, H.J.A., Schwarz, D.J., Smirnov, O., Soida, M., Toribio, M.C., van Haarlem, M.P., van Weeren, R.J., Vocks, C., Wucknitz, O., and Zucca, P.
Abstract: Contains fulltext : 219289.pdf (publisher's version ) (Open Access)
Published: 2020

144. Tight constraints on the excess radio background at z=9.1 from LOFAR

Author: Mondal, Rajesh, Fialkov, A., Fling, C., Iliev, I. T., Barkana, R., Ciardi, B., Mellema, Garrelt, Zaroubi, S., Koopmans, L. V. E., Mertens, F. G., Gehlot, B. K., Ghara, Raghunath, Ghosh, A., Giri, Sambit K., Offringa, A., Pandey, V. N., Mondal, Rajesh, Fialkov, A., Fling, C., Iliev, I. T., Barkana, R., Ciardi, B., Mellema, Garrelt, Zaroubi, S., Koopmans, L. V. E., Mertens, F. G., Gehlot, B. K., Ghara, Raghunath, Ghosh, A., Giri, Sambit K., Offringa, A., and Pandey, V. N.
Abstract: The ARCADE2 and LWA1 experiments have claimed an excess over the cosmic microwave background (CMB) at low radio frequencies. If the cosmological high-redshift contribution to this radio background is between 0.1 per cent and 22 per cent of the CMB at 1.42 GHz, it could explain the tentative EDGES low-band detection of the anomalously deep absorption in the 21-cm signal of neutral hydrogen. We use the upper limit on the 21-cm signal from the Epoch of Reionization (z = 9.1) based on 141 h of observations with LOFAR to evaluate the contribution of the high-redshift Universe to the detected radio background. Marginalizing over astrophysical properties of star-forming haloes, we find (at 95 per cent CL) that the cosmological radio background can be at most 9.6 per cent of the CMB at 1.42 GHz. This limit rules out strong contribution of the high-redshift Universe to the ARCADE2 and LWA1 measurements. Even though LOFAR places limit on the extra radio background, excess of 0.1-9.6 per cent over the CMB (at 1.42 GHz) is still allowed and could explain the EDGES low-band detection. We also constrain the thermal and ionization state of the gas at z = 9.1, and put limits on the properties of the first star-forming objects. We find that, in agreement with the limits from EDGES high-band data, LOFAR data constrain scenarios with inefficient X-ray sources, and cases where the Universe was ionized by stars in massive haloes only.
Published: 2020
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145. Constraining the intergalactic medium at z approximate to 9.1 using LOFAR Epoch of Reionization observations

Author: Ghara, Raghunath, Giri, Sambit K., Mellema, Garrelt, Ciardi, B., Zaroubi, S., Iliev, I. T., Koopmans, L. V. E., Chapman, E., Gazagnes, S., Gehlot, B. K., Ghosh, A., Jelic, V, Mertens, F. G., Mondal, R., Schaye, J., Silva, M. B., Asad, K. M. B., Kooistra, R., Mevius, M., Offringa, A. R., Pandey, V. N., Yatawatta, S., Ghara, Raghunath, Giri, Sambit K., Mellema, Garrelt, Ciardi, B., Zaroubi, S., Iliev, I. T., Koopmans, L. V. E., Chapman, E., Gazagnes, S., Gehlot, B. K., Ghosh, A., Jelic, V, Mertens, F. G., Mondal, R., Schaye, J., Silva, M. B., Asad, K. M. B., Kooistra, R., Mevius, M., Offringa, A. R., Pandey, V. N., and Yatawatta, S.
Abstract: We derive constraints on the thermal and ionization states of the intergalactic medium (IGM) at redshift approximate to 9.1 using new upper limits on the 21-cm power spectrum measured by the LOFAR radio telescope and a prior on the ionized fraction at that redshift estimated from recent cosmic microwave background (CMB) observations. We have used results from the reionization simulation code GRIZZLY and a Bayesian inference framework to constrain the parameters which describe the physical state of the IGM. We find that, if the gas heating remains negligible, an IGM with ionized fraction greater than or similar to 0.13 and a distribution of the ionized regions with a characteristic size greater than or similar to 8 h(-1) comoving megaparsec (Mpc) and a full width at half-maximum (FWHM) greater than or similar to 16 h(-1) Mpc is ruled out. For an IGM with a uniform spin temperature T-S greater than or similar to 3 K, no constraints on the ionized component can be computed. If the large-scale fluctuations of the signal are driven by spin temperature fluctuations, an IGM with a volume fraction less than or similar to 0.34 of heated regions with a temperature larger than CMB, average gas temperature 7-160 K, and a distribution of the heated regions with characteristic size 3.5-70 h(-1) Mpc and FWHM of less than or similar to 110 h(-1) Mpc is ruled out. These constraints are within the 95 per cent credible intervals. With more stringent future upper limits from LOFAR at multiple redshifts, the constraints will become tighter and will exclude an increasingly large region of the parameter space.
Published: 2020
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146. Constraining the intergalactic medium at z ≈ 9.1 using LOFAR Epoch of Reionization observations

Author: Ghara, R; https://orcid.org/0000-0001-9816-5070, Giri, S K; https://orcid.org/0000-0002-2560-536X, Mellema, G; https://orcid.org/0000-0002-2512-6748, Ciardi, B, Zaroubi, S, Iliev, I T; https://orcid.org/0000-0002-5174-1365, Koopmans, L V E, Chapman, E; https://orcid.org/0000-0002-5050-9847, Gazagnes, S, Gehlot, B K; https://orcid.org/0000-0002-3240-9228, Ghosh, A; https://orcid.org/0000-0002-8566-9955, Jelić, V; https://orcid.org/0000-0002-6034-8610, Mertens, F G; https://orcid.org/0000-0003-3802-4289, Mondal, R; https://orcid.org/0000-0001-7728-3756, Schaye, J; https://orcid.org/0000-0002-0668-5560, Silva, M B, Asad, K M B; https://orcid.org/0000-0002-2920-4117, Kooistra, R, Mevius, M, Offringa, A R, Pandey, V N, Yatawatta, S; https://orcid.org/0000-0001-5619-4017, Ghara, R; https://orcid.org/0000-0001-9816-5070, Giri, S K; https://orcid.org/0000-0002-2560-536X, Mellema, G; https://orcid.org/0000-0002-2512-6748, Ciardi, B, Zaroubi, S, Iliev, I T; https://orcid.org/0000-0002-5174-1365, Koopmans, L V E, Chapman, E; https://orcid.org/0000-0002-5050-9847, Gazagnes, S, Gehlot, B K; https://orcid.org/0000-0002-3240-9228, Ghosh, A; https://orcid.org/0000-0002-8566-9955, Jelić, V; https://orcid.org/0000-0002-6034-8610, Mertens, F G; https://orcid.org/0000-0003-3802-4289, Mondal, R; https://orcid.org/0000-0001-7728-3756, Schaye, J; https://orcid.org/0000-0002-0668-5560, Silva, M B, Asad, K M B; https://orcid.org/0000-0002-2920-4117, Kooistra, R, Mevius, M, Offringa, A R, Pandey, V N, and Yatawatta, S; https://orcid.org/0000-0001-5619-4017
Abstract: We derive constraints on the thermal and ionization states of the intergalactic medium (IGM) at redshift ≈ 9.1 using new upper limits on the 21-cm power spectrum measured by the LOFAR radio telescope and a prior on the ionized fraction at that redshift estimated from recent cosmic microwave background (CMB) observations. We have used results from the reionization simulation code grizzly and a Bayesian inference framework to constrain the parameters which describe the physical state of the IGM. We find that, if the gas heating remains negligible, an IGM with ionized fraction ≳0.13 and a distribution of the ionized regions with a characteristic size ≳ 8 h−1 comoving megaparsec (Mpc) and a full width at half-maximum (FWHM) ≳16 h−1 Mpc is ruled out. For an IGM with a uniform spin temperature TS ≳ 3 K, no constraints on the ionized component can be computed. If the large-scale fluctuations of the signal are driven by spin temperature fluctuations, an IGM with a volume fraction ≲0.34 of heated regions with a temperature larger than CMB, average gas temperature 7–160 K, and a distribution of the heated regions with characteristic size 3.5–70 h−1 Mpc and FWHM of ≲110 h−1 Mpc is ruled out. These constraints are within the 95 per cent credible intervals. With more stringent future upper limits from LOFAR at multiple redshifts, the constraints will become tighter and will exclude an increasingly large region of the parameter space.
Published: 2020

147. Tight constraints on the excess radio background at z = 9.1 from LOFAR

Author: Mondal, R; https://orcid.org/0000-0001-7728-3756, Fialkov, A, Fling, C, Iliev, I T; https://orcid.org/0000-0002-5174-1365, Barkana, R, Ciardi, B, Mellema, G; https://orcid.org/0000-0002-2512-6748, Zaroubi, S, Koopmans, L V E, Mertens, F G; https://orcid.org/0000-0003-3802-4289, Gehlot, B K; https://orcid.org/0000-0002-3240-9228, Ghara, R; https://orcid.org/0000-0001-9816-5070, Ghosh, A; https://orcid.org/0000-0002-8566-9955, Giri, S K; https://orcid.org/0000-0002-2560-536X, Offringa, A; https://orcid.org/0000-0002-5809-2783, Pandey, V N, Mondal, R; https://orcid.org/0000-0001-7728-3756, Fialkov, A, Fling, C, Iliev, I T; https://orcid.org/0000-0002-5174-1365, Barkana, R, Ciardi, B, Mellema, G; https://orcid.org/0000-0002-2512-6748, Zaroubi, S, Koopmans, L V E, Mertens, F G; https://orcid.org/0000-0003-3802-4289, Gehlot, B K; https://orcid.org/0000-0002-3240-9228, Ghara, R; https://orcid.org/0000-0001-9816-5070, Ghosh, A; https://orcid.org/0000-0002-8566-9955, Giri, S K; https://orcid.org/0000-0002-2560-536X, Offringa, A; https://orcid.org/0000-0002-5809-2783, and Pandey, V N
Abstract: The ARCADE2 and LWA1 experiments have claimed an excess over the cosmic microwave background (CMB) at low radio frequencies. If the cosmological high-redshift contribution to this radio background is between 0.1 per cent and 22 per cent of the CMB at 1.42 GHz, it could explain the tentative EDGES low-band detection of the anomalously deep absorption in the 21-cm signal of neutral hydrogen. We use the upper limit on the 21-cm signal from the Epoch of Reionization (z = 9.1) based on 141 h of observations with LOFAR to evaluate the contribution of the high-redshift Universe to the detected radio background. Marginalizing over astrophysical properties of star-forming haloes, we find (at 95 per cent CL) that the cosmological radio background can be at most 9.6 per cent of the CMB at 1.42 GHz. This limit rules out strong contribution of the high-redshift Universe to the ARCADE2 and LWA1 measurements. Even though LOFAR places limit on the extra radio background, excess of 0.1–9.6 per cent over the CMB (at 1.42 GHz) is still allowed and could explain the EDGES low-band detection. We also constrain the thermal and ionization state of the gas at z = 9.1, and put limits on the properties of the first star-forming objects. We find that, in agreement with the limits from EDGES high-band data, LOFAR data constrain scenarios with inefficient X-ray sources, and cases where the Universe was ionized by stars in massive haloes only.
Published: 2020

148. Is Reionization Regulated by H2 in the Early Universe?

Author: Ferrara, A., primary, Ciardi, B., additional, and Todini, P., additional
Published: 2000
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149. Constraining the intergalactic medium at z ≈ 9.1 using LOFAR Epoch of Reionization observations

Author: Ghara, R, primary, Giri, S K, primary, Mellema, G, primary, Ciardi, B, primary, Zaroubi, S, primary, Iliev, I T, primary, Koopmans, L V E, primary, Chapman, E, primary, Gazagnes, S, primary, Gehlot, B K, primary, Ghosh, A, primary, Jelić, V, primary, Mertens, F G, primary, Mondal, R, primary, Schaye, J, primary, Silva, M B, primary, Asad, K M B, primary, Kooistra, R, primary, Mevius, M, primary, Offringa, A R, primary, Pandey, V N, primary, and Yatawatta, S, primary
Published: 2020
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150. The LOFAR Tied-Array all-sky survey: Timing of 21 pulsars including the first binary pulsar discovered with LOFAR

Author: Tan, C M, primary, Bassa, C G, additional, Cooper, S, additional, Hessels, J W T, additional, Kondratiev, V I, additional, Michilli, D, additional, Sanidas, S, additional, Stappers, B W, additional, van Leeuwen, J, additional, Donner, J Y, additional, Grießmeier, J-M, additional, Kramer, M, additional, Tiburzi, C, additional, Weltevrede, P, additional, Ciardi, B, additional, Hoeft, M, additional, Mann, G, additional, Miskolczi, A, additional, Schwarz, D J, additional, Vocks, C, additional, and Wucknitz, O, additional
Published: 2020
Full Text: View/download PDF

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