New insights on accretion in supergiant fast X-ray transients from XMM–Newton and INTEGRAL observations of IGR J17544−2619

Drave, S. P.; Bird, A. J.; Sidoli, L.; Sguera, V.; Bazzano, A.; Hill, A. B.; Goossens, Marcel

doi:10.1093/mnras/stu110

Cited by 31 publications

(34 citation statements)

References 48 publications

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“…This confirms previous findings that most of the outbursts displayed by IGR J17544-2619 occur when the neutron star is closer to the supergiant companion and that the orbit of this system could be characterized by a non-negligible eccentricity (see, e.g., Drave et al 2014;Romano 2015, and references therein). Although this eccentricity could help in enhancing the X-ray dynamic range achievable by IGR J17544-2619, it cannot be the only explanation for the extreme behavior displayed by this source, as the system orbital period is relatively short and only a limited eccentricity of 0.2-0.3 can be expected (Walter et al 2015;Giménez-García et al 2016).…”

Section: Discussionsupporting

confidence: 91%

Multi-wavelength observations of IGR J17544-2619 from quiescence to outburst

Bozzo

Bhalerao

Pradhan

et al. 2016

A&A

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In this paper we report on a long multi-wavelength observational campaign of the supergiant fast X-ray transient prototype IGR J17544-2619. A 150 ks-long observation was carried out simultaneously with XMM-Newton and NuSTAR, catching the source in an initial faint X-ray state and then undergoing a bright X-ray outburst lasting approximately 7 ks. We studied the spectral variability during outburst and quiescence by using a thermal and bulk Comptonization model that is typically adopted to describe the X-ray spectral energy distribution of young pulsars in high mass X-ray binaries. Although the statistics of the collected X-ray data were relatively high, we could neither confirm the presence of a cyclotron line in the broad-band spectrum of the source (0.5-40 keV), nor detect any of the previously reported tentative detections of the source spin period. The monitoring carried out with Swift /XRT during the same orbit of the system observed by XMM-Newton and NuSTAR revealed that the source remained in a low emission state for most of the time, in agreement with the known property of all supergiant fast X-ray transients being significantly sub-luminous compared to other supergiant X-ray binaries. Optical and infrared observations were carried out for a total of a few thousand seconds during the quiescence state of the source detected by XMM-Newton and NuSTAR. The measured optical and infrared magnitudes were slightly lower than previous values reported in the literature, but compatible with the known micro-variability of supergiant stars. UV observations obtained with the UVOT telescope on-board Swift did not reveal significant changes in the magnitude of the source in this energy domain compared to previously reported values.

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Section: Discussionsupporting

confidence: 91%

Multi-wavelength observations of IGR J17544-2619 from quiescence to outburst

Bozzo

Bhalerao

Pradhan

et al. 2016

A&A

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“…Romano et al (2015) inspected Swift observations of the source experiencing an extraordinarily bright outburst (peak luminosity ∼10 38 erg/s), and reported the detection of X-ray pulsations with P spin = 11.60 s, also at a statistical significance of about 4σ. However, these results contrast with the analyses of XMM-Newton and NuSTAR observations performed by Drave et al (2014) and Bhalerao et al (2015) respectively. These authors do not find any evidence of pulsations for time scales of 1-2000 s.…”

Section: Igr J17544-2619contrasting

confidence: 96%

Measuring the stellar wind parameters in IGR J17544-2619 and Vela X-1 constrains the accretion physics in supergiant fast X-ray transient and classical supergiant X-ray binaries

Giménez-García

Shenar

Torrejón

et al. 2016

A&A

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Context. Classical supergiant X-ray binaries (SGXBs) and supergiant fast X-ray transients (SFXTs) are two types of high-mass X-ray binaries (HMXBs) that present similar donors but, at the same time, show very different behavior in the X-rays. The reason for this dichotomy of wind-fed HMXBs is still a matter of debate. Among the several explanations that have been proposed, some of them invoke specific stellar wind properties of the donor stars. Only dedicated empiric analysis of the donors' stellar wind can provide the required information to accomplish an adequate test of these theories. However, such analyses are scarce. Aims. To close this gap, we perform a comparative analysis of the optical companion in two important systems: IGR J17544-2619 (SFXT) and Vela X-1 (SGXB). We analyze the spectra of each star in detail and derive their stellar and wind properties. As a next step, we compare the wind parameters, giving us an excellent chance of recognizing key differences between donor winds in SFXTs and SGXBs. Methods. We use archival infrared, optical and ultraviolet observations, and analyze them with the non-local thermodynamic equilibrium (NLTE) Potsdam Wolf-Rayet model atmosphere code. We derive the physical properties of the stars and their stellar winds, accounting for the influence of X-rays on the stellar winds. Results. We find that the stellar parameters derived from the analysis generally agree well with the spectral types of the two donors: O9I (IGR J17544-2619) and B0.5Iae (Vela X-1). The distance to the sources have been revised and also agree well with the estimations already available in the literature. In IGR J17544-2619 we are able to narrow the uncertainty to d = 3.0 ± 0.2 kpc. From the stellar radius of the donor and its X-ray behavior, the eccentricity of IGR J17544-2619 is constrained to e < 0.25. The derived chemical abundances point to certain mixing during the lifetime of the donors. An important difference between the stellar winds of the two stars is their terminal velocities ( ∞ = 1500 km s −1 in IGR J17544-2619 and ∞ = 700 km s −1 in Vela X-1), which have important consequences on the X-ray luminosity of these sources. Conclusions. The donors of IGR J17544-2619 and Vela X-1 have similar spectral types as well as similar parameters that physically characterize them and their spectra. In addition, the orbital parameters of the systems are similar too, with a nearly circular orbit and short orbital period. However, they show moderate differences in their stellar wind velocity and the spin period of their neutron star which has a strong impact on the X-ray luminosity of the sources. This specific combination of wind speed and pulsar spin favors an accretion regime with a persistently high luminosity in Vela X-1, while it favors an inhibiting accretion mechanism in IGR J17544-2619. Our study demonstrates that the relative wind velocity is critical in class determination for the HMXBs hosting a supergiant donor, given that it may shift the accretion mechanism from direct accretion...

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“…The companion star was spectroscopically identified by Pellizza et al (2006) (but see also Rahoui et al, 2008a) and the orbital period was measured at 4.92 days . A possible indication of pulsations from the direction of the source at 71 s was reported by Drave et al (2012) by using the RXTE/PCA, but then retracted (Drave et al, 2014). The deepest observation available was performed with the XIS on-board Suzaku (Rampy et al, 2009).…”

Section: Discussionmentioning

confidence: 99%

“…-IGR J17544-2619: Drave et al (2014) and Romano et al (2014a) observed that its X-ray luminosity varies mostly in the range 10 33−35 erg/s with some flares reaching few 10 36 erg/s. The source activity shows a clear peak at periastron, reminiscent of the building up of a tidal stream, and a minimum at apastron.…”

Section: Fast Transients Reaching Anomalously Low Luminositiesmentioning

confidence: 99%

High-mass X-ray binaries in the Milky Way

Walter

Lutovinov

Bozzo

et al. 2015

Astron Astrophys Rev

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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New insights on accretion in supergiant fast X-ray transients from XMM–Newton and INTEGRAL observations of IGR J17544−2619

Cited by 31 publications

References 48 publications

Multi-wavelength observations of IGR J17544-2619 from quiescence to outburst

Multi-wavelength observations of IGR J17544-2619 from quiescence to outburst

Measuring the stellar wind parameters in IGR J17544-2619 and Vela X-1 constrains the accretion physics in supergiant fast X-ray transient and classical supergiant X-ray binaries

High-mass X-ray binaries in the Milky Way

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