Recent activity of the Be/X-ray binary system SAX J2103.5+4545
Recent activity of the Be/X-ray binary system SAX J2103.5+4545
Aims. We present a multiwavelength study of the Be/X-ray binary system SAX J2103.5+4545 with the goal of better characterizing the transient behaviour of this source. Methods. SAX J2103.5+4545 was observed by Swift/XRT four times in 2007 from April 25 to May 5, and during quiescence in 2012 August 31. In addition, this source has been monitored from the ground-based astronomical observatories of El Teide (Tenerife, Spain), Roque de los Muchachos (La Palma, Spain), and Sierra Nevada (Granada, Spain) since 2011 August, and from the TÜBTAK National Observatory (Antalya, Turkey) since 2009 June. We performed spectral and photometric temporal analyses to investigate the different states exhibited by SAX J2103.5+4545. Results. In X-rays, an absorbed power-law model provided the best fit for all the XRT spectra. An iron-line feature at ∼6.42 keV was present in all the observations except for that taken during quiescence in 2012. The photon indexes are consistent with previous studies of SAX J2103.5+4545 in high/low-luminosity states. Pulsations were found in all the XRT data from 2007 (2.839(2) mHz; MJD 54 222.02), but not during quiescence. The two optical outbursts in 2010 and 2012 lasted for about eight or nine months (as the one in 2007 probably did and the current one in 2014 might do) and were most probably caused by mass-ejection events from the Be star that eventually fed the circumstellar disc. All of these outbursts started about three months before the triggering of the X-ray activity, and at about the same period before the maximum of the Hα line equivalent width (in emission) was reached at only ∼-5 Å. The global correlation between the BV variability and the X-ray intensity was also observed at longer wavelengths in the IR domain.
Accretion accretion disks, Stars: emission-line Be, X-rays: binaries
Camero, A.
23dc935e-7909-4a87-889e-0fa75db5e21e
Zurita, C.
a54c6c5c-a599-4550-8596-050d925a0241
Gutiérrez-Soto, J.
4bb5e4a1-555a-4787-867a-9cd9e27b0969
Nespoli, E.
b3735ae2-57ed-4f27-ad08-234b76c812d2
Kiaeerad, F.
5d7c1a8a-da90-4bd4-a338-2f8aa758eec5
Beklen, E.
4108c1d4-4082-4bda-b1c3-76dd0a240912
García-Rojas, J.
6a410c3d-afe4-4fe6-909d-65fcf243145f
Caballero-García, M.
761b2e12-8f82-4297-ab53-44658887c19b
August 2014
Camero, A.
23dc935e-7909-4a87-889e-0fa75db5e21e
Zurita, C.
a54c6c5c-a599-4550-8596-050d925a0241
Gutiérrez-Soto, J.
4bb5e4a1-555a-4787-867a-9cd9e27b0969
Nespoli, E.
b3735ae2-57ed-4f27-ad08-234b76c812d2
Kiaeerad, F.
5d7c1a8a-da90-4bd4-a338-2f8aa758eec5
Beklen, E.
4108c1d4-4082-4bda-b1c3-76dd0a240912
García-Rojas, J.
6a410c3d-afe4-4fe6-909d-65fcf243145f
Caballero-García, M.
761b2e12-8f82-4297-ab53-44658887c19b
Camero, A., Zurita, C., Gutiérrez-Soto, J., Özbey Arabaci, M., Nespoli, E., Kiaeerad, F., Beklen, E., García-Rojas, J. and Caballero-García, M.
(2014)
Recent activity of the Be/X-ray binary system SAX J2103.5+4545.
Astronomy and Astrophysics, 568, [A115].
(doi:10.1051/0004-6361/201423452).
Abstract
Aims. We present a multiwavelength study of the Be/X-ray binary system SAX J2103.5+4545 with the goal of better characterizing the transient behaviour of this source. Methods. SAX J2103.5+4545 was observed by Swift/XRT four times in 2007 from April 25 to May 5, and during quiescence in 2012 August 31. In addition, this source has been monitored from the ground-based astronomical observatories of El Teide (Tenerife, Spain), Roque de los Muchachos (La Palma, Spain), and Sierra Nevada (Granada, Spain) since 2011 August, and from the TÜBTAK National Observatory (Antalya, Turkey) since 2009 June. We performed spectral and photometric temporal analyses to investigate the different states exhibited by SAX J2103.5+4545. Results. In X-rays, an absorbed power-law model provided the best fit for all the XRT spectra. An iron-line feature at ∼6.42 keV was present in all the observations except for that taken during quiescence in 2012. The photon indexes are consistent with previous studies of SAX J2103.5+4545 in high/low-luminosity states. Pulsations were found in all the XRT data from 2007 (2.839(2) mHz; MJD 54 222.02), but not during quiescence. The two optical outbursts in 2010 and 2012 lasted for about eight or nine months (as the one in 2007 probably did and the current one in 2014 might do) and were most probably caused by mass-ejection events from the Be star that eventually fed the circumstellar disc. All of these outbursts started about three months before the triggering of the X-ray activity, and at about the same period before the maximum of the Hα line equivalent width (in emission) was reached at only ∼-5 Å. The global correlation between the BV variability and the X-ray intensity was also observed at longer wavelengths in the IR domain.
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Published date: August 2014
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Funding Information:
This article is partially based on service observations made with the IAC80 and TCS telescopes operated on the island of Tenerife by the Instituto de Astrofísica de Canarias (IAC) in the Spanish Observatorio del Teide. The authors are grateful to the IAC support astronomers and the telescope operators for having made the observations with the IAC facilities. The present work is also based on observations made with the Nordic Optical Telescope, operated by the Nordic Optical Telescope Scientific Association at the Observatorio del Roque de los Muchachos (IAC), La Palma, Spain. The Albireo spectrograph at the 1.5 m telescope is operated by the Instituto de Astrofísica de Andalucía at the Sierra Nevada Observatory. M.Ö.A. acknowledges support from TÜBİTAK, The Scientific and Technological Research Council of Turkey, through the research project 106T040. We thank TÜBİTAK and ROTSE collaboration for partial support in using the RTT 150 and ROTSEIIId Telescopes with project numbers TUG-RTT150.08.45, 12ARTT150-264-1 and ROTSE-40. We also thank Ü. Kızıloǧlu for providing all the available ROTSE data on SAX J2103.5+4545 for this study. We thank H. BilalÖzcan for the most recent optical spectroscopic observations obtained with the RTT150. We appreciate to A. Papitto for useful discussions about spin-down processes in neutron stars systems. We also acknowledge Terry Mahoney for revising the English text. This study made use of data supplied by the UK Swift Science Data Centre at the University of Leicester. The work of J.G.S. is supported by the Spanish Programa Nacional de Astronomía y Astrofísica under contract AYA2012-39246-C02-01. E.N. acknowledges a VALi+d postdoctoral grant from the Generalitat Valenciana and was supported by the Spanish Ministry of Economy and Competitiveness under contract AYA 2010-18352. M.C.G. is supported by the European social fund within the framework of “Support of inter-sectoral mobility and quality enhancement of research teams at Czech Technical University in Prague”, CZ.1.07/2.3.00/30.0034. A.C. was supported by the AYA2012-39303, SGR2009-811 and iLINK2011-0303 grants.
Keywords:
Accretion accretion disks, Stars: emission-line Be, X-rays: binaries
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Local EPrints ID: 486365
URI: http://eprints.soton.ac.uk/id/eprint/486365
ISSN: 0004-6361
PURE UUID: d93665ba-d33e-4551-bffe-0bbf4607fb42
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Date deposited: 18 Jan 2024 19:25
Last modified: 11 Sep 2024 17:23
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Contributors
Author:
A. Camero
Author:
C. Zurita
Author:
J. Gutiérrez-Soto
Author:
M. Özbey Arabaci
Author:
E. Nespoli
Author:
F. Kiaeerad
Author:
E. Beklen
Author:
J. García-Rojas
Author:
M. Caballero-García
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