Sigma detection of hard X-ray emission from the soft transient type I X-ray burster KS 1731 - 260

Barret, D.; Bouchet, L.; Mandrou, P.; Roques, J. P.; Cordier, B.; Laurent, P.; Lebrun, F.; Paul, J.; Sunyaev, R.; Churazov, E.; Gilfanov, M.; Diachkov, A.; Khavenson, N.; Novikov, B.; Chulkov, I.; Kuznetsov, A.

doi:10.1086/171615

Cited by 40 publications

(16 citation statements)

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“…The spectrum was well fit by a bremsstrahlung spectrum with k T br ∼ 6 keV; X-ray bursts were also observed (Sunyaev et al 1990). KS 1731-260 was also detected by ART-P, SIGMA (revealing a hard energy tail extending up to energies of ∼ 40 keV; Barret et al 1992) and during the ROSAT all-sky survey (see e.g. Smith, Morgan & Bradt 1997).…”

Section: Ks 1731-260mentioning

confidence: 94%

The neutron stars of Soft X-ray Transients

Campana

Colpi

Mereghetti

et al. 1998

Astronomy and Astrophysics Review

263

387

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Abstract. Soft X-ray Transients (SXRTs) have long been suspected to contain old, weakly magnetic neutron stars that have been spun up by accretion torques. After reviewing their observational properties, we analyse the different regimes that likely characterise the neutron stars in these systems across the very large range of mass inflow rates, from the peak of the outbursts to the quiescent emission. While it is clear that close to the outburst maxima accretion onto the neutron star surface takes place, as the mass inflow rate decreases, accretion might stop at the magnetospheric boundary because of the centrifugal barrier provided by the neutron star. For low enough mass inflow rates (and sufficiently short rotation periods), the radio pulsar mechanism might turn on and sweep the inflowing matter away. The origin of the quiescent emission, observed in a number of SXRTs at a level of ∼ 10 32 − 10 33 erg s −1 , plays a crucial role in constraining the neutron star magnetic field and spin period. Accretion onto the neutron star surface is an unlikely mechanism for the quiescent emission of SXRTs, as it requires very low magnetic fields and/or long spin periods. Thermal radiation from a cooling neutron star surface in between the outbursts can be ruled out as the only cause of the quiescent emission.We find that accretion onto the neutron star magnetosphere and shock emission powered by an enshrouded radio pulsar provide far more plausible models. In the latter case the range of allowed neutron star spin periods and magnetic fields is consistent with the values recently inferred from the properties of kHz quasi-periodic oscillation in low mass X-ray binaries. If quiescent SXRTs contain enshrouded radio pulsars, they provide a missing link between X-ray binaries and millisecond pulsars.

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Section: Ks 1731-260mentioning

confidence: 94%

The neutron stars of Soft X-ray Transients

Campana

Colpi

Mereghetti

et al. 1998

Astronomy and Astrophysics Review

263

387

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“…Renewed interest in the hard X-ray emission properties of NS LMXBs was motivated by the SIGMA/GRANAT discovery of a spectral component extending up to energies of ∼ 100 − 200 keV in Terzan 2 [3], KS 1731-260 [4], SLX 1735-269 [27] and Terzan 1 [10]. More recently, the presence of hard components in the X-ray spectra of LMXRBs was confirmed thanks to the broad band capabilities of BeppoSAX and RXTE.…”

Section: A Few Words On Lmxrbsmentioning

confidence: 99%

Hard X-ray emission from neutron star X-ray binaries

Salvo

Santangelo

Segreto

2004

Nuclear Physics B - Proceedings Supplements

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“…KS 1731[260 was discovered as a transient burster (Sunyaev 1989), but it has since been observed as a persistent source by Ginga, ROSAT , SIGMA, and RXT E (Yamauchi & Koyama 1990 ;Predehl & Schmitt 1995 ;Barret et al 1992Barret et al , 2000. The Mir-Kvant/TTM observation of KS 1731[260 found a 5.7 keV thermal bremsstrahlung spectrum absorbed by 2.2 ] 1022 cm~2 of neutral hydrogen (Sunyaev 1989).…”

Section: Introductionmentioning

confidence: 99%

ASCAObservations of GX 354−0 and KS 1731−260

Narita

Grindlay

Barret

2001

ApJ

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We report on ASCA observations of the low-mass X-ray binaries GX 354[0 and KS 1731[260. The spectrum of GX 354[0 is best described as a power law or a Comptonized spectrum with q D 5 and kT D 8 keV and a residual at D6.5 keV. The residual may be a disk reÑection or a Compton-broadened Gaussian line from the hot inner advection-dominated accretion ÑowÈlike coronal region. The absorption column density to the source is 2.9 ] 1022 cm~2. No soft thermal component was detected. The spectrum from KS 1731[260 is softer, and it is best Ðt with a two-component model with a column density of 1.1 ] 1022 cm~2. The likely interpretation is emission from a Comptonizing cloud with an optical depth q [ 12 and either a neutron star or a disk blackbody emission. We discuss the likely location of the Comptonizing cloud for both sources within the context of several proposed emission models.

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Sigma detection of hard X-ray emission from the soft transient type I X-ray burster KS 1731 - 260

Cited by 40 publications

References 0 publications

The neutron stars of Soft X-ray Transients

The neutron stars of Soft X-ray Transients

Hard X-ray emission from neutron star X-ray binaries

ASCAObservations of GX 354−0 and KS 1731−260

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