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The INTEGRAL long monitoring of persistent ultra compact X-ray bursters

The INTEGRAL long monitoring of persistent ultra compact X-ray bursters
The INTEGRAL long monitoring of persistent ultra compact X-ray bursters
Context: the combination of compact objects, short period variability and peculiar chemical composition of the ultra compact X-ray binaries make up a very interesting laboratory to study accretion processes and thermonuclear burning on the neutron star surface. Improved large optical telescopes and more sensitive X-ray satellites have increased the number of known ultra compact X-ray binaries allowing their study with unprecedented detail.
Aims. We analyze the average properties common to all ultra compact bursters observed by INTEGRAL from ~0.2 keV to ~150 keV.

Methods: we have performed a systematic analysis of the INTEGRAL public data and Key-Program proprietary observations of a sample of the ultra compact X-ray binaries. In order to study their average properties in a very broad energy band, we combined INTEGRAL with BeppoSAX and SWIFT data whenever possible. For sources not showing any significant flux variations along the INTEGRAL monitoring, we build the average spectrum by combining all available data; in the case of variable fluxes, we use simultaneous INTEGRAL and SWIFT observations when available. Otherwise we compared IBIS and PDS data to check the variability and combine BeppoSAX with INTEGRAL /IBIS data.

Results: all spectra are well represented by a two component model consisting of a disk-blackbody and Comptonised emission. The majority of these compact sources spend most of the time in a canonical low/hard state, with a dominating Comptonised component and accretion rate lower than ~ 10-9 yr, not depending on the model used to fit the data.
gamma rays: observations, stars: neutron, x-rays: binaries
0004-6361
557-563
Fiocchi, M.
74d63e71-f43d-494b-92ee-07dc83d18de1
Bazzano, A.
8eef0c6e-1a5f-4bcd-a034-9a5c3b29104d
Ubertini, P.
7035748e-152c-473e-8766-a2fa3ac49fcb
Bird, A.J.
045ee141-4720-46fd-a412-5aa848a91b32
Natalucci, L.
1a93c54f-3598-4523-9b3f-2871ad23af5f
Sguera, V.
371bb568-7e56-496e-a624-dba6de79d9e1
Fiocchi, M.
74d63e71-f43d-494b-92ee-07dc83d18de1
Bazzano, A.
8eef0c6e-1a5f-4bcd-a034-9a5c3b29104d
Ubertini, P.
7035748e-152c-473e-8766-a2fa3ac49fcb
Bird, A.J.
045ee141-4720-46fd-a412-5aa848a91b32
Natalucci, L.
1a93c54f-3598-4523-9b3f-2871ad23af5f
Sguera, V.
371bb568-7e56-496e-a624-dba6de79d9e1

Fiocchi, M., Bazzano, A., Ubertini, P., Bird, A.J., Natalucci, L. and Sguera, V. (2008) The INTEGRAL long monitoring of persistent ultra compact X-ray bursters. Astronomy & Astrophysics, 492 (2), 557-563. (doi:10.1051/0004-6361:200809715).

Record type: Article

Abstract

Context: the combination of compact objects, short period variability and peculiar chemical composition of the ultra compact X-ray binaries make up a very interesting laboratory to study accretion processes and thermonuclear burning on the neutron star surface. Improved large optical telescopes and more sensitive X-ray satellites have increased the number of known ultra compact X-ray binaries allowing their study with unprecedented detail.
Aims. We analyze the average properties common to all ultra compact bursters observed by INTEGRAL from ~0.2 keV to ~150 keV.

Methods: we have performed a systematic analysis of the INTEGRAL public data and Key-Program proprietary observations of a sample of the ultra compact X-ray binaries. In order to study their average properties in a very broad energy band, we combined INTEGRAL with BeppoSAX and SWIFT data whenever possible. For sources not showing any significant flux variations along the INTEGRAL monitoring, we build the average spectrum by combining all available data; in the case of variable fluxes, we use simultaneous INTEGRAL and SWIFT observations when available. Otherwise we compared IBIS and PDS data to check the variability and combine BeppoSAX with INTEGRAL /IBIS data.

Results: all spectra are well represented by a two component model consisting of a disk-blackbody and Comptonised emission. The majority of these compact sources spend most of the time in a canonical low/hard state, with a dominating Comptonised component and accretion rate lower than ~ 10-9 yr, not depending on the model used to fit the data.

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More information

Published date: 3 December 2008
Keywords: gamma rays: observations, stars: neutron, x-rays: binaries

Identifiers

Local EPrints ID: 144797
URI: http://eprints.soton.ac.uk/id/eprint/144797
ISSN: 0004-6361
PURE UUID: 000e5b0a-66cd-4ed3-af15-0c2ad98c99e6
ORCID for A.J. Bird: ORCID iD orcid.org/0000-0002-6888-8937

Catalogue record

Date deposited: 24 May 2010 13:50
Last modified: 09 Nov 2021 02:44

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Contributors

Author: M. Fiocchi
Author: A. Bazzano
Author: P. Ubertini
Author: A.J. Bird ORCID iD
Author: L. Natalucci
Author: V. Sguera

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