Long-term variability of high-mass X-ray binaries

Reig, P.; Fabregat, J.

doi:10.1051/0004-6361/201425008

Cited by 47 publications

(62 citation statements)

References 43 publications

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“…Although KS 1947+300 does show a small decrease of about 10-15% immediately after the peak of the outburst both in the 2000 and 2013 events and displays a long-term gradual decrease of EW(Hα) between the outbursts, which is in excellent agreement with the fading of the photometric magnitudes (Reig & Fabregat 2015), the pre-outburst level is quickly recovered. We did not find any more data after the X-ray activity phase in the literature.…”

Section: Circumstellar Disk and X-ray Variabilitysupporting

confidence: 69%

“…However, it is worth mentioning that our work constitutes the first attempt to explain the long-term optical variability of BeXB as a group using the largest data set so far analysed. 9 Note that in Reig & Fabregat (2015) there is an erratum,Ṁ should read 5.4 × 10 16 g s −1 instead of 2.7 × 10 17 g s −1 . This does not affect the conclusion stated therein because the subsequent calculations are correct.…”

Section: Discussionmentioning

confidence: 99%

“…For information about the photometric observations and data, see Reig & Fabregat (2015). The constant m z (V) = 21.10 = −2.5 log (3.631 × 10 −9 ) is the zero-point magnitude for the V band in erg s −1 cm −2 Å −1 (Bessell et al 1998).…”

Section: Measuring Variabilitymentioning

confidence: 99%

“…JHK photometry has been performed since 2009 and optical polarimetry in the R-band has been regularly obtained since 2013. The results from the photometric study were presented in Reig & Fabregat (2015). In this work, we present the results of the spectroscopic observations.…”

Section: Introductionmentioning

confidence: 96%

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Long-term optical variability of high-mass X-ray binaries

Reig

Nersesian

Zezas

et al. 2016

A&A

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Context. High-mass X-ray binaries are bright X-ray sources. The high-energy emission is caused by the accretion of matter from the massive companion onto a neutron star. The accreting material comes from either the strong stellar wind in binaries with supergiant companions or the cirscumstellar disk in Be/X-ray binaries. In either case, the Hα line stands out as the main source of information about the state of the accreting material. Aims. We present the results of our monitoring program to study the long-term variability of the Hα line in high-mass X-ray binaries. Our aim is to characterise the optical variability timescales and study the interaction between the neutron star and the accreting material. Methods. We fitted the Hα line with Gaussian profiles and obtained the line parameters and equivalent width. The peak separation in split profiles was used to determine the disk velocity law and estimate the disk radius. The relative intensity of the two peaks (V/R ratio) allowed us to investigate the distribution of gas particles in the disk. The equivalent width was used to characterise the degree of variability of the systems. We also studied the variability of the Hα line in correlation with the X-ray activity. Results. Our results can be summarised as follows: i) we find that Be/X-ray binaries with narrow orbits are more variable than systems with long orbital periods; ii) we show that a Keplerian distribution of gas particles provides a good description of the disks in Be/X-ray binaries, as it does in classical Be stars; iii) a decrease in the Hα equivalent width is generally observed after major X-ray outbursts; iv) we confirm that the Hα equivalent width correlates with disk radius; v) while systems with supergiant companions display multistructured profiles, most of the Be/X-ray binaries show, at some epoch, double-peak asymmetric profiles, which indicates that density inhomogeneities is a common property in the disk of Be/X-ray binaries; vi) the profile variability (V/R ratio) timescales are shorter and the Hα equivalent widths are smaller in Be/X-ray binaries than in isolated Be stars; and vii) we provide new evidence that the disk in Be/X-ray binaries is, on average, denser than in classical Be stars. Conclusions. We carried out the most complete optical spectroscopic study of the global properties of high-mass X-ray binaries with the analysis of more than 1100 spectra from 20 sources. Our results provide further evidence for the truncation of the disk in Be/X-ray binaries. We conclude that the interaction between the compact object and the Be-type star works in two directions: the massive companion provides the source of matter for accretion, affecting the surroundings of the compact object, and the continuous revolution of the neutron star around the optical counterpart also produces the truncation of the Be star's equatorial disk.

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Section: Circumstellar Disk and X-ray Variabilitysupporting

confidence: 69%

Section: Discussionmentioning

confidence: 99%

Section: Measuring Variabilitymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 96%

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Long-term optical variability of high-mass X-ray binaries

Reig

Nersesian

Zezas

et al. 2016

A&A

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“…outburst (Reig & Fabregat 2015). The duration (∼50 days) and hard spectral index (Γ ∼ 0) of the progeny of SN 2010da are consistent with a Type II outburst (Reig & Nespoli 2013).…”

Section: Sn 2010da As a Hmxbmentioning

confidence: 62%

The Intermediate Luminosity Optical Transient Sn 2010da: The Progenitor, Eruption, and Aftermath of a Peculiar Supergiant High-Mass X-Ray Binary

Villar

Berger

Chornock

et al. 2016

ApJ

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We present optical spectroscopy, ultraviolet-to-infrared imaging,and X-ray observations of the intermediate luminosity optical transient (ILOT) SN 2010da in NGC 300 (d = 1.86 Mpc) spanning from −6 to +6 years relative to the time of outburst in 2010. Based on the light-curve and multi-epoch spectral energy distributions of SN 2010da, we conclude that the progenitor of SN 2010da is a ≈10-12 M e yellow supergiant possibly transitioning into a blue-loop phase. During outburst, SN 2010da had a peak absolute magnitude of M bol −10.4 mag, dimmer than other ILOTs and supernova impostors. We detect multi-component hydrogen Balmer, Paschen, and Ca II emission lines in our high-resolution spectra, which indicate a dusty and complex circumstellar environment. Since the 2010 eruption, the star has brightened by a factor of ≈5 and remains highly variable in the optical. Furthermore, we detect SN 2010da in archival Swift and Chandra observations as an ultraluminous X-ray source (L X ≈ 6 × 10 39 erg s −1). We additionally attribute He II 4686 Å and coronal Fe emission lines in addition to a steady X-ray luminosity of ≈10 37 erg s −1 to the presence of a compact companion.

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