Radio detections of the neutron star X-ray binaries 4U 1820 - 30 and Ser X-1 in soft X-ray states

We present the analysis of simultaneous X-ray (RXTE) and radio (VLA) observations of two atoll-type neutron star X-ray binaries: 4U 1820 - 30 and Ser X-1. Both sources were steadily in the soft (`banana') X-ray state during the observations. We have detected the radio counterpart of 4U 1820 - 3...

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Authors: Migliari, Simone, Fender, R. P., Rupen, M. P., Wachter, S., Jonker, P. G., Homan, J., Van der Klis, M.
Format: article
Status:Published version
Publication Date:2004
Country:España
Institution:Universidad de Barcelona
Repository:Dipòsit Digital de la UB
OAI Identifier:oai:diposit.ub.edu:2445/99393
Online Access:https://hdl.handle.net/2445/99393
Access Level:Open access
Keyword:Estels binaris de raigs X
Estels de neutrons
Astronomia de raigs X
X-ray binaries
Neutron stars
X-ray astronomy
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spelling Radio detections of the neutron star X-ray binaries 4U 1820 - 30 and Ser X-1 in soft X-ray statesMigliari, SimoneFender, R. P.Rupen, M. P.Wachter, S.Jonker, P. G.Homan, J.Van der Klis, M.Estels binaris de raigs XEstels de neutronsAstronomia de raigs XX-ray binariesNeutron starsX-ray astronomyWe present the analysis of simultaneous X-ray (RXTE) and radio (VLA) observations of two atoll-type neutron star X-ray binaries: 4U 1820 - 30 and Ser X-1. Both sources were steadily in the soft (`banana') X-ray state during the observations. We have detected the radio counterpart of 4U 1820 - 30 at 4.86 and 8.46 GHz at a flux density of ~0.1 mJy. This radio source is positionally coincident with the radio pulsar PSR 1820 - 30A. However, the radio emission of the pulsar falls rapidly with frequency (~ν-3), and we argue that the radio emission of the X-ray binary is dominant above ~2 GHz. Supporting this interpretation, comparison with previous observations reveals variability at the higher radio frequencies that is likely to be due to the X-ray binary. We have detected for the first time the radio counterpart of Ser X-1 at 8.46 GHz, also at a flux density of ~0.1 mJy. The position of the radio counterpart has allowed us to identify its optical counterpart unambiguously. We briefly discuss similarities and differences between the disc-jet coupling in neutron star and black hole X-ray binaries. In particular, we draw attention to the fact that, contrary to other states, neutron star X-ray binaries seem to be more radio-loud than persistent black hole candidates when the emission is `quenched' in the soft state.Royal Astronomical Society2004info:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersionapplication/pdfhttps://hdl.handle.net/2445/99393Articles publicats en revistes (Física Quàntica i Astrofísica)reponame:Dipòsit Digital de la UBinstname:Universidad de BarcelonaInglésReproducció del document publicat a: http://dx.doi.org/10.1111/j.1365-2966.2004.07768.xMonthly Notices of the Royal Astronomical Society, 2004, vol. 351, num. 1, p. 186-192http://dx.doi.org/10.1111/j.1365-2966.2004.07768.x(c) Migliari, Simone et al., 2004info:eu-repo/semantics/openAccessoai:diposit.ub.edu:2445/993932026-05-27T06:46:51Z
dc.title.none.fl_str_mv Radio detections of the neutron star X-ray binaries 4U 1820 - 30 and Ser X-1 in soft X-ray states
title Radio detections of the neutron star X-ray binaries 4U 1820 - 30 and Ser X-1 in soft X-ray states
spellingShingle Radio detections of the neutron star X-ray binaries 4U 1820 - 30 and Ser X-1 in soft X-ray states
Migliari, Simone
Estels binaris de raigs X
Estels de neutrons
Astronomia de raigs X
X-ray binaries
Neutron stars
X-ray astronomy
title_short Radio detections of the neutron star X-ray binaries 4U 1820 - 30 and Ser X-1 in soft X-ray states
title_full Radio detections of the neutron star X-ray binaries 4U 1820 - 30 and Ser X-1 in soft X-ray states
title_fullStr Radio detections of the neutron star X-ray binaries 4U 1820 - 30 and Ser X-1 in soft X-ray states
title_full_unstemmed Radio detections of the neutron star X-ray binaries 4U 1820 - 30 and Ser X-1 in soft X-ray states
title_sort Radio detections of the neutron star X-ray binaries 4U 1820 - 30 and Ser X-1 in soft X-ray states
dc.creator.none.fl_str_mv Migliari, Simone
Fender, R. P.
Rupen, M. P.
Wachter, S.
Jonker, P. G.
Homan, J.
Van der Klis, M.
author Migliari, Simone
author_facet Migliari, Simone
Fender, R. P.
Rupen, M. P.
Wachter, S.
Jonker, P. G.
Homan, J.
Van der Klis, M.
author_role author
author2 Fender, R. P.
Rupen, M. P.
Wachter, S.
Jonker, P. G.
Homan, J.
Van der Klis, M.
author2_role author
author
author
author
author
author
dc.subject.none.fl_str_mv Estels binaris de raigs X
Estels de neutrons
Astronomia de raigs X
X-ray binaries
Neutron stars
X-ray astronomy
topic Estels binaris de raigs X
Estels de neutrons
Astronomia de raigs X
X-ray binaries
Neutron stars
X-ray astronomy
description We present the analysis of simultaneous X-ray (RXTE) and radio (VLA) observations of two atoll-type neutron star X-ray binaries: 4U 1820 - 30 and Ser X-1. Both sources were steadily in the soft (`banana') X-ray state during the observations. We have detected the radio counterpart of 4U 1820 - 30 at 4.86 and 8.46 GHz at a flux density of ~0.1 mJy. This radio source is positionally coincident with the radio pulsar PSR 1820 - 30A. However, the radio emission of the pulsar falls rapidly with frequency (~ν-3), and we argue that the radio emission of the X-ray binary is dominant above ~2 GHz. Supporting this interpretation, comparison with previous observations reveals variability at the higher radio frequencies that is likely to be due to the X-ray binary. We have detected for the first time the radio counterpart of Ser X-1 at 8.46 GHz, also at a flux density of ~0.1 mJy. The position of the radio counterpart has allowed us to identify its optical counterpart unambiguously. We briefly discuss similarities and differences between the disc-jet coupling in neutron star and black hole X-ray binaries. In particular, we draw attention to the fact that, contrary to other states, neutron star X-ray binaries seem to be more radio-loud than persistent black hole candidates when the emission is `quenched' in the soft state.
publishDate 2004
dc.date.none.fl_str_mv 2004
dc.type.none.fl_str_mv info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
format article
status_str publishedVersion
dc.identifier.none.fl_str_mv https://hdl.handle.net/2445/99393
url https://hdl.handle.net/2445/99393
dc.language.none.fl_str_mv Inglés
language_invalid_str_mv Inglés
dc.relation.none.fl_str_mv Reproducció del document publicat a: http://dx.doi.org/10.1111/j.1365-2966.2004.07768.x
Monthly Notices of the Royal Astronomical Society, 2004, vol. 351, num. 1, p. 186-192
http://dx.doi.org/10.1111/j.1365-2966.2004.07768.x
dc.rights.none.fl_str_mv (c) Migliari, Simone et al., 2004
info:eu-repo/semantics/openAccess
rights_invalid_str_mv (c) Migliari, Simone et al., 2004
eu_rights_str_mv openAccess
dc.format.none.fl_str_mv application/pdf
dc.publisher.none.fl_str_mv Royal Astronomical Society
publisher.none.fl_str_mv Royal Astronomical Society
dc.source.none.fl_str_mv Articles publicats en revistes (Física Quàntica i Astrofísica)
reponame:Dipòsit Digital de la UB
instname:Universidad de Barcelona
instname_str Universidad de Barcelona
reponame_str Dipòsit Digital de la UB
collection Dipòsit Digital de la UB
repository.name.fl_str_mv
repository.mail.fl_str_mv
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score 15.300719

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