BeppoSAX view of the NS-LMXB GS 1826-238
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In this article, the authors investigated the origin and the nature of the low energy emission of GS 1826−238 further, along with its contribution to the bolometric output of the source, dominated by the high-temperature thermally Comptonised radiation.Abstract:
Context. The spectroscopic characteristics of GS 1826−238, a neutron star in a low-mass X-ray binary system, have already been studied by sensitive, wide band X-ray telescopes (e.g. BeppoSAX, RXTE, INTEGRAL). Up to now, the source has always been observed in a low-hard spectral state, with two spectral components typically detected. The persistent high-energy (>10keV) emission is effectively explained by thermal Comptonisation by a hot electron cloud (kTe ∼ 20keV); a further low energy component, modelled either by pure blackbody emission or by Compton-modified blackbody radiation by a few keV electron plasma, is generally needed to yield acceptable fits in the soft X-ray band. Aims. The aimof the present work is to investigate the originand the nature of the low energy emission of GS 1826−238 further, along with its contribution to the bolometric output of the source, dominated by the high-temperature thermally Comptonised radiation. Methods. This kind of investigation needs sensitive data in the widest available energy band. Simultaneous covering of both the soft X-rays (below 1keV) and the hard X-rays (up to hundreds of keV) is crucial for an unbiased characterisation of the two spectral components, so we searched the whole BeppoSAX-NFI archive for all the available GS 1826−238observations. We analysed a total of six data sets, collected from 1997 to 2000; data analysis of two of them was still unpublished. In this study we applied both a wellestablished (comptt) and a more recent, updated Comptonisation model (comptb), in order to get the widest quantitative information about the physical parameters at work. Results. Our results confirmthat the0.1‐200keV emission of GS 1826−238 needs twocomponents tobe explained. In particular, two populations of soft seed photons, with different colour temperatures, are observed. One population is Comptonised to high energies by a hot electron cloud (temperatures in the range 19‐24keV, anticorrelated with the source luminosity), while the other is directly observed and can be modelled by a pure blackbody. We also propose an alternative model in which both the seed photon populations are Compton-modified by the electron plasma. This model explains the observed emission of GS 1826−238 as accurately as the traditional one and, moreover, fits well in a wider evolutionary scenario able to describe the state transitions observed in neutron-star low-mass X-ray binaries. The use of comptb also indicates that, in the case of GS 1826−238, the seed photons populations are not distributed as a pure blackbody.read more
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Accretion Geometry of the Low-Mass X-ray Binary Aquila X-1 in the Soft and Hard States
TL;DR: In this article, the authors used two out of the seven data sets to constrain the flux-dependent accretion geometry of this source over wider energy bands than employed in most of previous works.
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Accretion geometry of the Low-Mass X-Ray Binary Aquila X-1 in the soft and hard states
Soki Sakurai,Shinya Yamada,S. Torii,Hirofumi Noda,Kazuhiro Nakazawa,Kazuo Makishima,Hiromitsu Takahashi +6 more
TL;DR: In this article, the authors used two out of seven data sets from the Suzaku X-ray observatory to constrain the flux-dependent accretion geometry of this source over wider energy bands than employed in most previous studies.
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A SOFT X-RAY SPECTRAL EPISODE FOR THE CLOCKED BURSTER, GS 1826–24 AS MEASURED BY SWIFT AND NuSTAR
Jérôme Chenevez,Duncan K. Galloway,Duncan K. Galloway,J. J. M. in 't Zand,J. J. M. in 't Zand,John A. Tomsick,Didier Barret,Deepto Chakrabarty,Felix Fürst,S. E. Boggs,Finn Erland Christensen,Walter Craig,Walter Craig,C. J. Hailey,Fiona A. Harrison,P. Romano,Daniel Stern,William W. Zhang +17 more
TL;DR: In this paper, the authors report on NuSTAR and Swift observations of a soft state of the neutron star low-mass X-ray binary GS 1826-24, commonly known as the "clocked" burster.
Journal ArticleDOI
A Soft X-Ray Spectral Episode for the Clocked Burster, GS 1826-24 as Measured by Swift and NuSTAR
Jérôme Chenevez,Duncan K. Galloway,Duncan K. Galloway,J. J. M. in 't Zand,J. J. M. in 't Zand,John A. Tomsick,Didier Barret,Deepto Chakrabarty,Felix Fürst,S. E. Boggs,Finn Erland Christensen,Walter Craig,Walter Craig,C. J. Hailey,Fiona A. Harrison,P. Romano,Daniel Stern,William W. Zhang +17 more
TL;DR: In this article, the authors report on NuSTAR and Swift observations of a soft state of the neutron star low-mass X-ray binary GS 1826-24, commonly known as the "clocked" burster.
Journal ArticleDOI
New insights on the puzzling LMXB 1RXS J180408.9-342058: the intermediate state, the clocked type-I X-ray bursts, and much more
A. Marino,A. Marino,A. Marino,M. Del Santo,M. Cocchi,Antonino D'Ai,A. Segreto,Carlo Ferrigno,T. Di Salvo,Julien Malzac,R. Iaria,Luciano Burderi +11 more
TL;DR: In this paper, the authors presented a comprehensive X-ray study of a low-mass binary with a neutron star, which shows X-rays activity at very different mass-accretion regimes, from very faint to almost the Eddington luminosity.
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