A Suzaku observation of the low-mass X-ray binary GS 1826−238 in the hard state

Ono, Ko; Sakurai, S.; Zhang, Zhongli; Nakazawa, K.; Makishima, Kazuo

doi:10.1093/pasj/psw003

Cited by 9 publications

(11 citation statements)

References 29 publications

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“…Considering the large value of R in , it suggests that the corona is centrally localized, and the disk intrudes into only the outer part of the corona. Similar results were obtained by Ono et al (2016) on GS 1826−238, that only an inner region of a truncated accretion disk is Comptonized.…”

Section: The Spectral Modeling Of Exo 0748−676supporting

confidence: 87%

“…Among them, the six observations of Aql X−1 (ObsID from 402053020 to 402053070) were previously analyzed by Sakurai et al (2014) and were updated by Sakurai (2015). Besides, GS 1826−238 was further studied in detail by Ono et al (2016), of which the results are quoted in the present paper.…”

Section: Suzaku Archived Sample Of Non-dipping Lmxbsmentioning

confidence: 93%

“…In seven observations with L X 0.01L edd , forming category 2 (C2), the disk was detected but it did not need to be Comptonized. Finally, in the four most luminous observations with L X ∼ 0.1L edd , to be called category 3 (C3), the disk emission was also strongly Comptonized by a corona that can be considered either to be the same (with the same kT e and τ values) as for the NS Comptonization (406010010 of Aql X−1 and 4U 1705−44), or to have a lower temperature (GS 1826−238;Ono et al 2016). The luminosity of EXO 0748−676 is higher than in most of the LMXBs in C2, and lower than (ignoring the inclination effect) in all LMXBs in C3.…”

Section: The Spectral Modeling Of Exo 0748−676mentioning

confidence: 99%

“…b R in is corrected for the inclination factor √ cos(i), assuming i = 45 • . c Results of this source are quoted from Ono et al (2016), in which a partially Comptonized disk blackbody model dkbbfth is applied.…”

Section: Properties Of the Comptonizing Coronamentioning

confidence: 99%

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Suzaku Observation of the High-Inclination Binary EXO 0748-676 in the Hard State

Zhang,

Sakurai,

Makishima

et al. 2016

Preprint

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Utilizing an archived Suzaku data acquired on 2007 December 25 for 46 ks, Xray spectroscopic properties of the dipping and eclipsing low-mass X-ray binary EXO 0748−676 were studied. At an assumed distance of 7.1 kpc, the data gave a persistent unabsorbed luminosity of 3.4 × 10 36 erg cm −2 s −1 in 0.6 − 55 keV. The source was in a relatively bright low/hard state, wherein the 0.6 − 55 keV spectrum can be successfully explained by a "double-seed" Comptonization model, incorporating a common corona with an electron temperature of ∼ 13 keV. The seed photons are thought to be supplied from both the neutron star surface, and a cooler truncated disk. Compared to a sample of non-dipping low-mass X-ray binaries in the low/hard state, the spectrum is subject to stronger Comptonization, with a relatively larger Comptonizing y-parameter of ∼ 1.4 and a larger coronal optical depth of ∼ 5. This result, when attributed to the high inclination of EXO 0748−676, suggests that the Comptonizing corona may elongate along the disk plane, and give a longer path for the seed photons when viewed from edge-on inclinations.

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Section: The Spectral Modeling Of Exo 0748−676supporting

confidence: 87%

Section: Suzaku Archived Sample Of Non-dipping Lmxbsmentioning

confidence: 93%

Section: The Spectral Modeling Of Exo 0748−676mentioning

confidence: 99%

Section: Properties Of the Comptonizing Coronamentioning

confidence: 99%

See 2 more Smart Citations

Suzaku Observation of the High-Inclination Binary EXO 0748-676 in the Hard State

Zhang,

Sakurai,

Makishima

et al. 2016

Preprint

Self Cite

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“…A double Comptonization corona was also observed in 4U1915−05 (but see also Gambino et al 2019 for a different interpretation) and MAXIJ0556-332 in the soft state (Sugizaki et al 2013;Zhang et al 2014), in GS1826−238 in the low/ hard state and in AqlX-1 in the low hard state just before it made a transition into the soft state (Ono et al 2016). In the last two cases, the sources were at the highest luminosity end of the hard state (L L 0.1 Edd ), at the same luminosity level as the very hard state of 1RXSJ180408.9−342058.…”

Section: Continuum Emissionmentioning

confidence: 80%

Quasi-simultaneous INTEGRAL, SWIFT, and NuSTAR Observations of the New X-Ray Clocked Burster 1RXS J180408.9-342058

Fiocchi

Bazzano

Bruni

et al. 2019

ApJ

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We report the quasi-simultaneous INTEGRAL, SWIFT, and NuSTAR observations showing spectral state transitions in the neutron star low-mass X-ray binary 1RXSJ180408.9−342058 during its 2015 outburst. We present results of the analysis of high-quality broad energy band (0.8-200 keV) data in three different spectral states: high/soft, low/very-hard, and transitional state. The broadband spectra can be described in general as the sum of thermal Comptonization and reflection due to illumination of an optically thick accretion disk. During the high/soft state, blackbody emission is generated from the accretion disk and the surface of the neutron star. This emission, measured at a temperature of kT bb ∼1.2 keV, is then Comptonized by a thick corona with an electron temperature of ∼2.5keV. For the transitional and low/very-hard state, the spectra are successfully explained with emission from a double Comptonizing corona. The first component is described by thermal Comptonization of seed disk/ neutron star photons (kT bb ∼1.2 keV) by a cold corona cloud with kT e ∼8-10 keV, while the second one originates from lower temperature blackbody photons (kT bb 0.1 keV) Comptonized by a hot corona (kT e ∼ 35 keV). Finally, from NuSTAR observations, there is evidence that the source is a new clocked burster. The average time between two successive X-ray bursts corresponds to ∼7.9 and ∼4.0 ks when the persistent emission decreases by a factor of ∼2, moving from a very hard to transitional state. The accretion rate (☉´-M 4 10 yr 9 1) and the decay time of the X-ray bursts longer than ∼30 s suggest that the thermonuclear emission is due to mixed H/He burning triggered by thermally unstable He ignition. Unified Astronomy Thesaurus concepts: Binary stars (154); Low-mass X-ray binary stars (939); X-ray astronomy (1810); Gamma-ray bursters (1878); Gamma-ray astronomy (628)

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Burst-induced coronal cooling in GS 1826–24

Sánchez–Fernández

Kajava

Poutanen

et al. 2020

A&A

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Type I X-ray bursts in GS 1826-24, and in several other systems, may induce cooling of the hot inner accretion flow that surrounds the bursting neutron star. Given that GS 1826-24 remained persistently in the hard state over the period 2003-2008 and presented regular bursting properties, we stacked the spectra of the X-ray bursts detected by INTEGRAL (JEM-X and ISGRI) and XMM-Newton (RGS) during that period to study the effect of the burst photons on the properties of the Comptonizing medium. The extended energy range provided by these instruments allows the simultaneous observation of the burst and persistent emission spectra. We detect an overall change in the shape of the persistent emission spectrum in response to the burst photon shower. For the first time, we observe simultaneously a drop in the hard X-ray emission, together with a soft X-ray excess with respect to the burst blackbody emission. The hard X-ray drop can be explained by burst-induced coronal cooling, while the bulk of the soft X-ray excess can be described by fitting the burst emission with an atmosphere model, instead of a simple blackbody model. Traditionally, the persistent emission was assumed to be invariant during X-ray bursts, and more recently to change only in normalization but not in spectral shape; the observed change in the persistent emission level during X-ray bursts may thus trigger the revision of existing neutron star massradius constraints, as the derived values rely on the assumption that the persistent emission does not change during X-ray bursts. The traditional burst fitting technique leads to up to a 10% overestimation of the bolometric burst flux in GS 1826-24, which significantly hampers the comparisons of the KEPLER and MESA model against this 'textbook burster'.

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A Suzaku observation of the low-mass X-ray binary GS 1826−238 in the hard state

Cited by 9 publications

References 29 publications

Suzaku Observation of the High-Inclination Binary EXO 0748-676 in the Hard State

Suzaku Observation of the High-Inclination Binary EXO 0748-676 in the Hard State

Quasi-simultaneous INTEGRAL, SWIFT, and NuSTAR Observations of the New X-Ray Clocked Burster 1RXS J180408.9-342058

Burst-induced coronal cooling in GS 1826–24

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