Detection of a large Be circumstellar disk during X-ray quiescence of XTE J1946 + 274
Detection of a large Be circumstellar disk during X-ray quiescence of XTE J1946 + 274
Aims. We present a multiwavelength study of the Be/X-ray binary system XTE J1946+274 with the main goal of better characterizing its behavior during X-ray quiescence. We also aim to shed light on the possible mechanisms which trigger the X-ray activity for this source. Methods. XTE J1946+274 was observed by Chandra-ACIS during quiescence in 2013 March 12. 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 September, and from the TÜBITAK National Observatory (Antalya, Turkey) since 2005 April. We have performed spectral and photometric temporal analyses in order to investigate the quiescent state and transient behavior of this binary system. Results. Our optical study revealed that a long mass ejection event from the Be star took place in 2006, lasting for about seven years, and another one is currently ongoing. We also found that a large Be circumstellar disk is present during quiescence, although major X-ray activity is not observed. We made an attempt to explain this by assuming the permanently presence of a tilted (sometimes warped) Be decretion disk. The 0.3-10 keV X-ray spectrum of the neutron star during quiescence was well fitted with either an absorbed black-body or an absorbed power-law models. The main parameters obtained for these models were kT = 1.43 ± 0.17 and Γ = 0.9 ± 0.4 (with NH ∼ 2-7 × 1022 cm-2). The 0.3-10 keV flux of the source was ∼0.8-1 × 10-12 erg-1 cm-2 s-1. Pulsations were found with Ppulse = 15.757(1) s (epoch MJD 56 363.115) and an rms pulse fraction of 32.1(3)%. The observed X-ray luminosity during quiescent periods was close to that of expected in supersonic propeller regimen.
accretion, accretion disks, pulsars: individual: XTE J1946+274, stars: emission-line, Be, X-rays: binaries
Camero-Arranz, A.
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Zurita, C.
a54c6c5c-a599-4550-8596-050d925a0241
Gutiérrez-Soto, J.
4bb5e4a1-555a-4787-867a-9cd9e27b0969
Nespoli, E.
b3735ae2-57ed-4f27-ad08-234b76c812d2
Suso, J.
c3cbc9b7-fa04-4db1-b91c-7e2d84056de9
Kiaeerad, F.
5d7c1a8a-da90-4bd4-a338-2f8aa758eec5
García-Rojas, J.
6a410c3d-afe4-4fe6-909d-65fcf243145f
Kiziloʇlu,
fcb5db24-35a7-4659-b11b-ca7190ef41d9
1 October 2015
Camero-Arranz, 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
Suso, J.
c3cbc9b7-fa04-4db1-b91c-7e2d84056de9
Kiaeerad, F.
5d7c1a8a-da90-4bd4-a338-2f8aa758eec5
García-Rojas, J.
6a410c3d-afe4-4fe6-909d-65fcf243145f
Kiziloʇlu,
fcb5db24-35a7-4659-b11b-ca7190ef41d9
Özbey Arabacl, M., Camero-Arranz, A., Zurita, C., Gutiérrez-Soto, J., Nespoli, E., Suso, J., Kiaeerad, F., García-Rojas, J. and Kiziloʇlu,
(2015)
Detection of a large Be circumstellar disk during X-ray quiescence of XTE J1946 + 274.
Astronomy and Astrophysics, 582, [A53].
(doi:10.1051/0004-6361/201425488).
Abstract
Aims. We present a multiwavelength study of the Be/X-ray binary system XTE J1946+274 with the main goal of better characterizing its behavior during X-ray quiescence. We also aim to shed light on the possible mechanisms which trigger the X-ray activity for this source. Methods. XTE J1946+274 was observed by Chandra-ACIS during quiescence in 2013 March 12. 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 September, and from the TÜBITAK National Observatory (Antalya, Turkey) since 2005 April. We have performed spectral and photometric temporal analyses in order to investigate the quiescent state and transient behavior of this binary system. Results. Our optical study revealed that a long mass ejection event from the Be star took place in 2006, lasting for about seven years, and another one is currently ongoing. We also found that a large Be circumstellar disk is present during quiescence, although major X-ray activity is not observed. We made an attempt to explain this by assuming the permanently presence of a tilted (sometimes warped) Be decretion disk. The 0.3-10 keV X-ray spectrum of the neutron star during quiescence was well fitted with either an absorbed black-body or an absorbed power-law models. The main parameters obtained for these models were kT = 1.43 ± 0.17 and Γ = 0.9 ± 0.4 (with NH ∼ 2-7 × 1022 cm-2). The 0.3-10 keV flux of the source was ∼0.8-1 × 10-12 erg-1 cm-2 s-1. Pulsations were found with Ppulse = 15.757(1) s (epoch MJD 56 363.115) and an rms pulse fraction of 32.1(3)%. The observed X-ray luminosity during quiescent periods was close to that of expected in supersonic propeller regimen.
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Published date: 1 October 2015
Additional Information:
Funding Information:
We thank the anonymous referee for his/her helpful comments and suggestions. 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 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. 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. The scientific results reported in this article are based in part on data obtained from the Chandra Data Archive. 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. A.C. was supported by the AYA2012-39303, SGR2009-811 and iLINK2011-0303 grants. M.Ö. A. acknowledges support from TÜBİTAK, The Scientific and Technological Research Council of Turkey, through the research project 106T040. We thank the anonymous refree for his/her helplful comments dans suggestions.
Publisher Copyright:
© ESO, 2015.
Keywords:
accretion, accretion disks, pulsars: individual: XTE J1946+274, stars: emission-line, Be, X-rays: binaries
Identifiers
Local EPrints ID: 486366
URI: http://eprints.soton.ac.uk/id/eprint/486366
ISSN: 0004-6361
PURE UUID: 365e961f-87f2-43ed-b094-9b420c9efa34
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Date deposited: 18 Jan 2024 19:26
Last modified: 11 Sep 2024 17:23
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Contributors
Author:
M. Özbey Arabacl
Author:
A. Camero-Arranz
Author:
C. Zurita
Author:
J. Gutiérrez-Soto
Author:
E. Nespoli
Author:
J. Suso
Author:
F. Kiaeerad
Author:
J. García-Rojas
Author:
Kiziloʇlu
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