Studying the presence of magnetic fields in a sample of high-mass X-ray binaries
Swetlana Hubrig, Alexander F. Kholtygin, Lara Sidoli, Markus Schöller, Silva P. Jarvinen
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5 pages, 1 table, 6 figures, to appear in IAU Symposium 346 "High-mass X-ray binaries: illuminating the passage from massive binaries to merging compact objects", 2018 August 27-31, Vienna, Austria
Previous circular polarization observations obtained with the ESO FOcal Reducer low dispersion spectrograpgh at the VLT in 2007-2008 revealed the presence of a weak longitudinal magnetic field on the surface of the optical component of the X-ray binary Cyg X-1, which contains a black hole and an O9.7Iab supergiant on a 5.6d orbit. In this contribution we report on recently acquired FORS2 spectropolarimetric observations of Cyg X-1 along with measurements of a few additional high-mass X-ray binaries.
The author presented the results on the evolution of NS LMXBs and the formation of UCXBs(Ma & Li 2009 for details), and proposed a scenario for the formation of UCXBs from L/IMXBs with the aid of a CB disk in this work.
Many high-mass X-ray binaries (HMXBs) are runaways. Stellar wind and radiation of donor stars in HMXBs along with outflows and jets from accretors interact with the local interstellar medium and produce curious circumstellar structures. Several such structures are presented and discussed in this contribution.
We present results of a long-term photometric multicolor optical monitoring project of selected low-mass and high-mass X-ray binaries carried out at the TÜBİTAK National Observatory (TUG). New long-term $VRI$ multicolor observations of three selected X-ray binaries with neutron star components (HZ Her, ScoX-1, SAX J2103.5+4545) were observed between 2015 and 2019 with the TUG 60-cm telescope. The light variations of the systems are presented and discussed.
We present photometric observations of the field around the optical counterparts of high-mass X-ray binaries. Our aim is to study the long-term photometric variability in correlation with their X-ray activity and derive a set of secondary standard stars that can be used for time series analysis. We find that the donors in Be/X-ray binaries exhibit larger amplitude changes in the magnitudes and colours than those hosting a supergiant companion. The amplitude of variability increases with wavelength in Be/X-ray binaries and remains fairly constant in supergiant systems. When time scales of years…
We present the results of our monitoring program to study the long-term variability of the Halpha line in high-mass X-ray binaries. We have carried out the most complete optical spectroscopic study of the global properties of high-mass X-ray binaries so far with the analysis of more than 1100 spectra of 20 sources. Our aim is to characterise the optical variability timescales and study the interaction between the neutron star and the accreting material. 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 orbita…
The X-ray binary population of the Small Magellanic Cloud (SMC) contains a large number of massive X-ray binaries and the recent survey of the SMC by XMM-Newton has resulted in almost 50 more tentative high mass X-ray binary candidates. Using probability parameters from Haberl & Sturm (2016) together with the optical spectra and timing in this work, we confirm six new massive X-ray binaries in the SMC. We also report two very probable binary periods; of 36.4d in XMM 1859 and of 72.2 d in XMM 2300. These Be X-ray binaries are likely part of the general SMC population which rarely undergoes an X…
High mass X-ray binary luminosity function (XLF) is an important tool for studying binary evolution processes and also the mass loss and consequent evolution in massive stars. We calculate the XLF for neutron star binaries using the standard scenario for formation and evolution of these systems. A one to one relation between primordial binary parameters and the HMXB parameters is established. The probability density function is then transformed using the standard Jacobian formalism. It is shown that the model successfully explains some basic properties of the observed XLF.
We investigate the anisotropy of stellar winds in binaries to improve the models of accretion in high-mass X-ray binaries. We model numerically the stellar wind from a supergiant component of a binary in radial and three-dimensional radiation hydrodynamic approximation taking into account the Roche potential, Coriolis force, and radiative pressure in the continuum and spectral lines. The Coriolis force influences substantially the mass loss and thus also the accretion rate. The focusing of the stellar wind by the gravitational field of the compact companion leads to the formation of a gaseous …
Theoretical expectations for high-mass X-ray binaries, supernova remnants, and their evolutionary paths: An overview talk for LIAC41: the eventful life of stellar multiples
In the Milky Way, $\sim$18 Wolf-Rayet+O (WR+O) binaries are known with estimates of their stellar and orbital parameters. Whereas black hole+O (BH+O) binaries are thought to evolve from the former, only one such system is known in the Milky Way. To resolve this disparity, it was suggested that upon core collapse, the WR stars receive large kicks such that most of the binaries are disrupted. We reassess this issue, with emphasis on the uncertainty in the formation of an accretion disk around wind-accreting BHs in BH+O binaries, which is key to identifying such systems. We follow the methodology…
INTEGRAL observations of the Small Magellanic Cloud region have resulted in the serendipitous detection of two transient hard X-ray sources in the Magellanic Bridge. In this paper we present the timing and spectral characteristics of these sources across the 2-100 keV energy range, which, in conjunction with their optical counterparts, demonstrate that they are high mass X-ray binaries in the Magellanic Bridge. Together with one previously known high mass X-ray binary system, and three candidates, these sources represent an emerging population of X-ray binaries in the Bridge, probably initiate…
Theoretical population number studies of binaries with at least one black hole (BH) component are obviously depending on whether or not BHs receive a (natal) kick during their formation. Several observational facts seem to indicate that indeed BHs receive a kick during their formation. In the present paper we discuss additional evidence. The progenitors of wind fed high mass X-ray binaries (HMXB) with a BH component (BH HMXB) are WR+OB binaries where the Wolf-Rayet (WR) star will finally collapse and form the BH. Starting from the observed population of WR+OB binaries in the Solar Neighborhood…
We develop a method for identifying a compact object in binary systems with astrometric measurements and apply it to some binaries. Compact objects in some high-mass X-ray binaries and gamma-ray binaries are unknown, which is responsible for the fact that emission mechanisms in such systems have not yet confirmed. The accurate estimate of the mass of the compact object allows us to identify the compact object in such systems. Astrometric measurements are expected to enable us to estimate the masses of the compact objects in the binary systems via a determination of a binary orbit. We aim to ev…
It is generally believed that Ultracompact X-ray binaries (UCXBs) evolved from binaries consisting of a neutron star accreting from a low-mass white dwarf or helium star where mass transfer is driven by gravitational radiation. However, the standard white-dwarf evolutionary channel cannot produce the relatively long-period ($40 - 60$\,min) UCXBs with high time-averaged mass-transfer rate. In this work, we explore an alternative evolutionary route toward UCXBs where the companions evolve from intermediate-mass Ap/Bp stars with an anomalously strong magnetic field ($100 - 10000$\,G). Including t…
Ultra-compact X-ray binaries (UCXBs) are accreting systems with periods less than 1 hour, which qualifies them to contain a degenerate donor-companion. One would expect such systems to have the easiest theoretical explanation, compared to other kinds of X-ray binaries. Nonetheless, current theory fails to explain high mass transfer (MT) rates in three recently well observed long-period UCXBs. We find that this range of MT rates can be maintained if the donor is a remnant of an out-of-thermal-equilibrium naked core of a giant which was revealed in a very recent episode of a common envelope (CE)…
The INTEGRAL archive developed at INAF-IASF Milano with the available public observations from late 2002 to 2016 is investigated to extract the X-ray properties of 58 High Mass X-ray Binaries (HMXBs). This sample consists of sources hosting either a Be star (Be/XRBs) or an early-type supergiant companion (SgHMXBs), including the Supergiant Fast X-ray Transients (SFXTs). INTEGRAL light curves (sampled at 2 ks) are used to build their hard X-ray luminosity distributions, returning the source duty cycles, the range of variability of the X-ray luminosity and the time spent in each luminosity state…
LS I +61 303 and LS 5039 are two of only a handful of known high mass X-ray binaries (HMXBs) that exhibit very high energy emission in the MeV-TeV range, and these "gamma-ray binaries" are of renewed interest due to the recent launch of the Fermi Gamma-ray Space Telescope. Here we present new radial velocities of both systems based on recent red and blue optical spectra. Both systems have somewhat discrepant orbital solutions available in the literature, and our new measurements result in improved orbital elements and resolve the disagreements. The improved geometry of each orbit will aid in s…
Type I outbursts in Be/X-ray binaries are usually associated with the eccentricity of the binary orbit. The neutron star accretes gas from the outer parts of the decretion disk around the Be star at each periastron passage. However, this mechanism cannot explain type I outbursts that have been observed in nearly circular orbit Be/X-ray binaries. With hydrodynamical simulations and analytic estimates we find that in a circular orbit binary, a nearly coplanar disk around the Be star can become eccentric. The extreme mass ratio of the binary leads to the presence of the 3:1 Lindblad resonance ins…
This paper summarizes our recent results on tidal interaction in high mass X-ray binaries and symbiotic stars. We demonstrate that the giant in symbiotic stars with orbital periods <1200 d are co-rotating (synchronized). The symbiotics MWC 560 and CD-4314304 probably have high orbital eccentricity. The giants in symbiotic binaries rotate faster than the field giants, likely their rotation is accelerated by the tidal force of the white dwarf. The giant/supergiant High mass X-ray binaries with orbital periods <40 d are synchronized. However the Be/X-ray binaries are not synchronized. In the Be/X…
The mass transfer efficiency during the evolution of massive binaries is still uncertain. We model the mass transfer processes in a grid of binaries to investigate the formation of Wolf-Rayet+O (WR+O) binaries, taking into account two kinds of non-conservative mass transfer models: Model I with rotation-dependent mass accretion and Model II of half mass accretion. Generally the mass transfer in Model I is more inefficient, with the average efficiency in a range of $\sim0.2-0.7$ and $ \lesssim0.2 $ for Case A and Case B mass transfer, respectively. We present the parameter distributions for the…
The birth kicks of black holes, arising from asymmetric mass ejection or neutrino emission during core-collapse supernovae, are of great interest for both observationally constraining supernova models and population-synthesis studies of binary evolution. Recently, several efforts were undertaken to estimate black hole birth kicks from observations of black-hole low-mass X-ray binaries. We follow up on this work, specifically focussing on the highest estimated black-hole kick velocities. We find that existing observations do not require black hole birth kicks in excess of approximately 100 km/s…
In the Galaxy and in the Magellanic Clouds there are 170 Be X-ray binaries known to-date. Out of those, 111 host a neutron star, and for the reminder the nature of a companion is not known. None, so far, is known to host a black hole. This disparity is referred to as a missing Be -- black hole X-ray binary problem. The stellar population synthesis calculations following the formation of Be X-ray binaries in the Galaxy (Belczynski and Ziolkowski 2009) demonstrate that there is no problem of the missing Be+BH X-ray binaries for the Galaxy (the expected number of Be -- black hole X-ray binaries i…
The radial velocity curves of optical components in X-ray binary systems can differ from the radial velocity curves of their barycenters due to tidal distortion, gravitational darkening, X-ray heating, etc. This motivated us to investigate how the semiamplitudes of the radial velocity curves of these optical components can depend on the binary-system parameters in a Roche model. The K-correction is taken to be the ratio of the radial velocity semiamplitude for a star in the Roche model to the corresponding value for the stellar barycenter. K-corrections are tabulated for the optical stars in t…
