INTEGRAL observations of recurrent fast X-ray transient sources

Sguera, V.; Barlow, E. J.; Bird, A. J.; Clark, D. J.; Dean, Anthony J.; Hill, A. B.; Moran, Lisa; Shaw, S. E.; Willis, D. R.; Bazzano, A.; Ubertini, P.; Malizia, A.

doi:10.1051/0004-6361:20053103

Cited by 221 publications

(266 citation statements)

References 43 publications

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“…dynamic range ≥ 620 and duration of ∼1.5 days and ≥ 4 days from the two IBIS/ISGRI detected activities, respectively) could be typical of the Be HMXB class. In addition we note that mentioned X-ray characteristics are compatible as well with a Supergiant Fast X-ray Transients nature (SFXTs, Sguera et al 2008), which are a newly discovered class of HMXBs (Sguera et al 2005, Negueruela et al 2005 Although classical SFXTs usually display above 20 keV hard X-ray outbursts lasting much less than a day, a few other SFXTs are known to show unusually longer hard X-ray activity, exceptionally lasting several days (e.g. IGR J18483−0311, ; IGR J17354−3255, Sguera et al 2011), i.e.…”

Section: High Mass X-ray Binarymentioning

confidence: 63%

First hard X-ray detection and broad-band X-ray study of the unidentified transient AX J1949.8+2534

Sguera

Sidoli

Paizis

et al. 2017

Monthly Notices of the Royal Astronomical Society

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We present the results from INTEGRAL and Swift/XRT observations of the hitherto poorly studied unidentified X-ray transient AX J1949.8+2534, and on archival multiwavelength observations of field objects. Bright hard X-ray outbursts have been discovered above 20 keV for the first time, the measured duty cycle and dynamic range are of the order of ∼ 4% and ≥ 630, respectively. The source was also detected during a low soft X-ray state (∼ 2×10 −12 erg cm −2 s −1 ) thanks to a Swift/XRT followup, which allowed for the first time to perform a soft X-ray spectral analysis as well as significantly improve the source positional uncertainty from arcminute to arcsecond size. From archival near-infrared data, we pinpointed two bright objects as most likely counterparts whose photometric properties are compatible with an early type spectral nature. This strongly supports a High Mass X-ray Binary (HMXB) scenario for AX J1949.8+2534, specifically a Supergiant Fast X-ray Transient (more likely) or alternatively a Be HMXB.

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Section: High Mass X-ray Binarymentioning

confidence: 63%

First hard X-ray detection and broad-band X-ray study of the unidentified transient AX J1949.8+2534

Sguera

Sidoli

Paizis

et al. 2017

Monthly Notices of the Royal Astronomical Society

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“…Several outbursts from this source were detected with ASCA (Sakano et al, 2002), RXTE (Smith et al, 2006), INTEGRAL (Sunyaev et al, 2003a;Lutovinov et al, 2005b;Sguera et al, 2005Sguera et al, , 2006bBlay et al, 2008), and Swift /BAT (Sidoli et al, 2009a,c;Romano et al, 2009bRomano et al, , 2011b. The source was also observed during faint X-ray states by Chandra and XMM-Newton, revealing the typical variability of the SFXT sources (Smith et al, 2006;Bozzo et al, 2010;Bodaghee et al, 2011b).…”

Section: Discussionmentioning

confidence: 94%

High-mass X-ray binaries in the Milky Way

Walter

Lutovinov

Bozzo

et al. 2015

Astron Astrophys Rev

230

234

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High-mass X-ray binaries are fundamental in the study of stellar evolution, nucleosynthesis, structure and evolution of galaxies and accretion processes. Hard X-rays observations by INTEGRAL and Swift have broadened significantly our understanding in particular for the super-giant systems in the Milky Way, which number has increased by almost a factor of three. INTEGRAL played a crucial role in the discovery, study and understanding of heavily obscured systems and of fast X-ray transients. Most super-giant systems can now be classified in three categories: classical/obscured, eccentric and fast transient.The classical systems feature low eccentricity and variability factor of ∼ 10 3 , mostly driven by hydrodynamic phenomena occurring on scales larger than the accretion radius. Among them, systems with short orbital periods and close to Roche-Lobe overflow or with slow winds, appear highly obscured. In eccentric systems, the variability amplitude can reach even higher factors, because of the contrast of the wind density along the orbit. Four super-giant systems, featuring fast outbursts, very short orbital periods and anomalously low accretion rates, are not yet understood.Simulations of the accretion processes on relatively large scales have progressed and reproduce parts of the observations. The combined effects of wind

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“…Supergiant fast X-ray transients (SFXTs) are high mass X-ray binaries (HMXBs) hosting a neutron star (NS) and an OB supergiant companion (Sguera et al 2005;Negueruela et al 2006) which display X-ray flares reaching, for a few hours, 10 36 −10 37 erg s −1 (see Romano et al 2014c, for a recent review). This is at odds with normal supergiant HMXBs, which display a fairly constant average luminosity with typical variations of a factor of 10−50 on time scales of a few hundred to thousands of seconds; SFXTs are also significantly subluminous with respect to classical Sg-HMXBs like Vela X-1 (Bozzo et al 2015), and show a dynamical range up to 5 orders of magnitude, as their luminosities can be as low as ∼10 32 erg s −1 during quiescence (e.g.…”

Section: Introductionmentioning

confidence: 99%

Giant outburst from the supergiant fast X-ray transient IGR J17544−2619: accretion from a transient disc?

Romano

Bozzo

Mangano

et al. 2015

A&A

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Supergiant fast X-ray transients (SFXTs) are high mass X-ray binaries associated with OB supergiant companions and characterized by an X-ray flaring behaviour whose dynamical range reaches 5 orders of magnitude on time scales of a few hundred to thousands of seconds. Current investigations concentrate on finding possible mechanisms to inhibit accretion in SFXTs and to explain their unusually low average X-ray luminosity. We present the Swift observations of an exceptionally bright outburst displayed by the SFXT IGR J17544−2619 on 2014 October 10 when the source achieved a peak luminosity of 3 × 10 38 erg s −1 . This extends the total source dynamic range to > ∼ 10 6 , the largest (by a factor of 10) recorded so far from an SFXT. Tentative evidence for pulsations at a period of 11.6 s is also reported. We show that these observations challenge, for the first time, the maximum theoretical luminosity achievable by an SFXT and propose that this giant outburst was due to the formation of a transient accretion disc around the compact object.

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INTEGRAL observations of recurrent fast X-ray transient sources

Cited by 221 publications

References 43 publications

First hard X-ray detection and broad-band X-ray study of the unidentified transient AX J1949.8+2534

First hard X-ray detection and broad-band X-ray study of the unidentified transient AX J1949.8+2534

High-mass X-ray binaries in the Milky Way

Giant outburst from the supergiant fast X-ray transient IGR J17544−2619: accretion from a transient disc?

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