A short observational view of black hole X-ray binaries with INTEGRAL
V. Grinberg
备注：
Solicited review; to appear in Proceedings of the 12th INTEGRAL conference and 1st AHEAD Gamma-ray Workshop, Geneva (Switzerland), 11-15 February 2019, Ed. C. Ferrigno, E. Bozzo, P. von Balmoos
Accreting black holes are unique tools to understand the physics under extreme gravity. While black hole X-ray binaries differ vastly in mass from AGN, their accretion and ejection flows are assumed to be essentially similar. Black hole X-ray binaries or microquasars are, however, quasars for the impatient as variability timescales scale directly with mass. State changes, i.e., strong variations in emission properties, in black hole X-ray binaries can happen within hours and whole outburst cycles within months to years. But our understanding of the drivers of such changes and the contributions of individual accretion and ejection components to the overall emission is still lacking. Here, I highlight some of the INTEGRAL's unique contributions to the understanding of black hole X-ray binaries through its coverage of the energies above the spectral cutoff, its long uninterrupted monitoring observations and the measurements of hard X-ray / soft $γ$-ray polarization.
Gamma-ray binaries are X-ray binaries with gamma-ray emissions. Their multi-wavelength emissions range from radio, optical, X-ray and to very high energy (TeV). X-ray emissions are crucial to understand the nature of gamma-ray binaries. INTEGRAL and RXTE have covered and monitored most of the gamma-ray binaries in hard and soft X-rays. Here we report the results of several gamma-ray binaries and possible gamma-ray binaries from INTEGRAL and RXTE.
Currently available information on fast variability of the X-ray emission from accreting collapsed objects constitutes a complex phenomenology which is difficult to interpret. We review the current observational standpoint for black-hole binaries and survey models that have been proposed to interpret it. Despite the complex structure of the accretion flow, key observational diagnostics have been identified which can provide direct access to the dynamics of matter motions in the close vicinity of black holes and thus to the some of fundamental properties of curved spacetimes, where strong-field…
In this chapter, I present the main X-ray observational characteristics of black-hole binaries and low magnetic field neutron-star binaries, concentrating on what can be considered similarities or differences, with particular emphasis on their fast-timing behaviour.
A common assumption used in the study of accretion disks is that the magnetic energy density and the kinetic energy density should be in equipartition. This assumption relies on the faster growth rate of the magnetic field strength against the kinetic energy of the particles in the flow, for decreasing radius, combined with a dissipation mechanism that tends towards equipartition. In this paper, we examine this assumption by modeling the radio, mm and optical spectra of several black hole binaries in their quiescent state. We use a standard two-component disk model, consisting of an inner geom…
Gamma-ray emitting binaries (GREBs) are complex systems. Its study became in the last years a major endeavour for the high-energy astrophysics community, both from an observational and a theoretical perspective. Whereas the accumulation of observation time for most Galactic gamma-ray sources is typically leading to highly accurate descriptions of their steady phenomenology, GREBs keep providing "exceptions to the rule" either through long-term monitoring of known systems or in the discovery of new sources of this class. Moreover, many GREBs have been identified as powerful radio, optical and X…
Gravitationally bound supermassive black hole binaries (SBHBs) are thought to be a natural product of galactic mergers and growth of the large scale structure in the universe. They however remain observationally elusive, thus raising a question about characteristic observational signatures associated with these systems. In this conference proceeding I discuss current theoretical understanding and latest advances and prospects in observational searches for SBHBs.
The purpose of this work is to review the observational properties of Be/X-ray binaries. The open questions in Be/X-ray binaries include those related to the Be star companion, that is, the so-called "Be phenomenon", such as, timescales associated to the formation and dissipation of the equatorial disc, mass-ejection mechanisms, V/R variability, and rotation rates; those related to the neutron star, such as, mass determination, accretion physics, and spin period evolution; but also, those that result from the interaction of the two constituents, such as, disc truncation and mass transfer. Unti…
The magnetic inclination angle $χ$, namely the angle between the spin and magnetic axes of a neutron star (NS), plays a vital role in its observational characteristics. However, there are few systematic investigations on its long-term evolution, especially for accreting NSs in binary systems. Applying the model of \citet{2021MNRAS.505.1775B} and the binary evolution code \mesa{}, we simultaneously simulate the evolution of the accretion rate, spin period, magnetic field, and magnetic inclination angle of accreting NSs in intermediate/low X-ray binaries (I/LMXBs). We show that the evolution of …
X-ray flux from the inner hot region around central compact object in a binary system illuminates the upper surface of an accretion disc and it behaves like a corona. This region can be photoionised by the illuminating radiation, thus can emit different emission lines. We study those line spectra in black hole X-ray binaries for different accretion flow parameters including its geometry. The varying range of model parameters captures maximum possible observational features. We also put light on the routinely observed Fe line emission properties based on different model parameters, ionization r…
The X-ray emission from accreting black-holes and neutron stars features strong variability on sub-second time scales, with very complex and broad phenomenology. From high-frequency quasi-periodic oscillations to rapidly changing X-ray burst oscillations to millisecond pulsations, these are weak signals immersed in strong noise and their study is pushing instrument capabilities to their limit. The scientific significance of fast time variability studies are both astronomical (properties of accretion flows, nature and evolution of sources) and physical (effects of General Relativity, equation o…
Detection of electromagnetic (EM) counterparts of pre-coalescence binaries has very important implications for our understanding of the evolution of these systems as well as the associated accretion physics. In addition, a combination of EM and gravitational wave signatures observed from coalescing supermassive black hole binaries (SBHBs) would provide independent measurements of redshift and luminosity distance, thus allowing for high precision cosmological measurements. However, a statistically significant sample of these objects is yet to be attained and finding them observationally has pro…
The majority of known Galactic black holes reside in low-mass X-ray binaries. They are rare and fascinating objects, providing unique information on strong gravity, accretion disc physics, and stellar and binary evolution. There is no doubt that our understanding of the formation of black hole low-mass X-ray binaries has significantly advanced in the past decade. However, some key issues are still unresolved. In this paper we briefly summarize the observational clues and theoretical progress on the formation of black hole low-mass X-ray binaries.
The explosive transition of a massive neutron star to a quark star (the Quark-Nova, QN) releases in excess of ~ 10^52 erg in kinetic energy which can drastically impact the surrounding environment of the QN. A QN is triggered when a neutron star gains enough mass to reach the critical value for quark deconfinement to happen in the core. In binaries, a neutron star has access to mass reservoirs (e.g. accretion from a companion or from a Common Envelope, CE). We explain observed light-curves of hydrogen-poor superluminous Supernovae (SLSNe Ia) in the context of a QN occurring in the second CE ph…
Accreting white dwarfs (WDs) constitute a significant fraction of the hard X-ray sources detected by the INTEGRAL observatory. Most of them are magnetic Cataclysmic Variables (CVs) of the intermediate polar (IP) and polar types, but the contribution of the Nova-likes systems and the systems with optically thin boundary layers, Dwarf Novae (DNs) and Symbiotic Binaries (or Symbiotic Stars, SySs) in quiescence is also not negligible. Here we present a short review of the results obtained from the observations of cataclysmic variables and symbiotic binaries by INTEGRAL. The highlight results inclu…
Gamma-ray binaries (GBs) have been object of intense studies in the last decade. From an observational perspective, GBs are phenomenologically similar to most X-ray binary systems in terms of their broad-band emission across the entire electromagnetic spectrum, being segregated from this source population by showing a maximum of their spectral energy distribution in the gamma-ray band, either at high-energies (HE: 100 MeV - 100 GeV) or very-high energies (VHE: above 100 GeV). From a theoretical perspective, the broad-band emission from GBs is a unique case in which particle acceleration and em…
In the recent papers by Gusakov, Chugunov, and Kantor (2014) a new scenario describing evolution of rapidly rotating neutron stars in low-mass X-ray binaries was proposed. The scenario accounts for a resonant interaction of normal r modes with superfluid inertial modes at some specific internal stellar temperatures ("resonance temperatures"). This interaction results in an enhanced damping of r mode and appearance of the "stability peaks" in the temperature -- spin frequency plane, which split the r-mode instability window in the vicinity of the resonance temperatures. The scenario suggests th…
Vela X-1 is an eclipsing high mass X-ray binary (HMXB) consisting of a 283s accreting X-ray pulsar in a close orbit of 8.964 days around the B0.5Ib supergiant HD77581 at a distance of just 2.4 kpc. The system is considered a prototype of wind-accreting HMXB and it has been used as a baseline in different theoretical or modelling studies. We discuss the observational properties of the system and the use of the observational data as laboratory to test recent developments in modelling the accretion process in High-Mass X-ray Binaries (e.g., Sander et al. 2018; El Mellah et al. 2018), which range …
In the last decade, X-ray spectroscopy has enabled a wealth of discoveries of photoionised absorbers in X-ray binaries. Studies of such accretion disc atmospheres and winds are of fundamental importance to understand accretion processes and possible feedback mechanisms to the environment. In this work, we review the current observational state and theoretical understanding of accretion disc atmospheres and winds in low-mass X-ray binaries, focusing on the wind launching mechanisms and on the dependence on accretion state. We conclude with issues that deserve particular attention.
In our self-similar, analytical, magneto-hydrodynamic (MHD) accretion-ejection solution, the density at the base of the outflow is explicitly dependent on the disk accretion rate - a unique property of this class of solutions. We had earlier found that the ejection index $p >\sim 0.1 (\dot{M}_{acc} \propto r^p ) $ is a key MHD parameter that decides if the flow can cause absorption lines in the high resolution X-ray spectra of black hole binaries. Here we choose 3 dense warm solutions with $p = 0.1, 0.3, 0.45$ and carefully develop a methodology to generate spectra which are convolved with the…
INTEGRAL is an ESA mission in fundamental astrophysics that was launched in October 2002. It has been in orbit for over 18 years, during which it has been observing the high-energy sky with a set of instruments specifically designed to probe the emission from hard X-ray and soft gamma-ray sources. This paper is devoted to the subject of black hole binaries, which are among the most important sources that populate the high-energy sky. We present a review of the scientific literature based on INTEGRAL data, which has significantly advanced our knowledge in the field of relativistic astrophysics.…
Binary black holes as the recently detected sources of gravitational waves can be formed from massive stellar binaries in the field or by dynamical interactions in clusters of high stellar density, if the black holes are the remnants of massive stars that collapsed without natal kicks that would disrupt the binary system or eject the black holes from the cluster before binary black hole formation. Here are summarized and discussed the kinematics in three dimensions of space of five Galactic black hole X-ray binaries. For Cygnus X-1 and GRS 1915+105 it is found that the black holes of ~15 and ~…
We describe here the nature, formation and evolution of the supergiant high mass X-ray binary (HMXB) population, i.e. systems accreting the stellar wind of supergiant stars. There are now many new observations, from the high-energy side (mainly from the INTEGRAL satellite), complemented by multi-wavelength observations (mainly in the optical, near and mid-infrared from ESO facilities), showing that a new population of supergiant HMXBs has been recently revealed. We report here on the observational facts about the different categories of HMXBs, allowing to build a consistent scenario explaining…
There are few observed high-mass X-ray binaries (HMXBs) that harbor massive black holes, and none are likely to result in a binary black hole (BBH) that merges within a Hubble time; however, we know that massive merging BBHs exist from gravitational-wave observations. We investigate the role that X-ray and gravitational-wave observational selection effects play in determining the properties of their respective detected binary populations. We find that, as a result of selection effects, detectable HMXBs and detectable BBHs form at different redshifts and metallicities, with detectable HMXBs for…
A large population of X-ray binaries (XRBs) was recently discovered within the central parsec of the Galaxy by Hailey et al. While the presence of compact objects on this scale due to radial mass segregation is, in itself, unsurprising, the fraction of binaries would naively be expected to be small because of how easily primordial binaries are dissociated in the dynamically hot environment of the nuclear star cluster (NSC). We propose that the formation of XRBs in the central parsec is dominated by the tidal capture of stars by black holes (BHs) and neutron stars (NSs). We model the time-depen…
We investigate the kilohertz quasi-periodic oscillations of low-mass X-ray binaries within the Hartle-Thorne spacetime. On the basis the relativistic precession model we extract the total mass $M$, angular momentum $J$, and quadrupole moment $Q$ of a compact object in a low-mass X-ray binary by analyzing the data of the Z -source GX 5-1. In view of the recent neutron star model we compute the radius, angular velocity and other parameters of this source by imposing the observational and theoretical constraints on the mass-radius relation.
In this chapter I will review the status of our phenomenological understanding of the relation between accretion and outflows in accreting black hole systems. This understanding arises primarily from observing the relation between X-ray and longer wavelength (infrared, radio) emission. The view is necessarily a biased one, beginning with observations of X-ray binary systems, and attempting to see if they match with the general observational properties of active galactic nuclei.
When a core-collapse supernova explodes in a binary star system, the ejecta might encounter an overdense shell, where the stellar winds of the two stars previously collided. In this work, we investigate effects of such interactions on supernova light curves on time-scales from the early flash ionization signatures to approximately one year after the explosion. We construct a model of the colliding-wind shell in an orbiting binary star system and we provide an analytical expression for the shell thickness and density, which we calibrate with three-dimensional adaptive mesh refinement hydrodynam…
Flip-flop states in X-ray binaries and changing-state AGN
Texas Tech University（德克萨斯理工大学）；Vanderbilt University（范德堡大学）；University of Turku（图尔库大学）；Coventry University（考文垂大学）；INAF—Istituto di Astrofisica e Planetologia Spaziali（意大利国家天体物理研究所空间天体物理学和行星科学研究所）；University of Southampton（南安普顿大学）
Instituto de Astrofísica de Canarias（加那利天体物理研究所）；Universidad de La Laguna（拉古纳大学）；European Southern Observatory (ESO)（欧洲南方天文台）；University of Durham（杜伦大学）；INAF–Osservatorio Astronomico di Brera（意大利国家天体物理研究所布里耶拉天文台）；Max-Planck-Institut für Extraterrestrische Physik（马克斯·普朗克地外物理研究所）；Università degli Studi dell’Insubria（因苏布里亚大学）；Osaka University（大阪大学）
Low Mass X-ray binaries (LMXBs) are binary systems where one of the components is either a black hole or a neutron star and the other is a less massive star. It is challenging to unambiguously determine whether a LMXB hosts a black hole or a neutron star. In the last few decades, multiple observational works have tried, with different levels of success, to address this problem. In this paper, we explore the use of machine learning to tackle this observational challenge. We train a random forest classifier to identify the type of compact object using the energy spectrum in the energy range 5-25…
Although General Relativity (GR) has been tested extensively in the weak gravity regime, similar tests in the strong gravity regime are still missing. In this paper we explore the possibility to use X-ray spectropolarimetric observations of black holes in X-ray binaries to distinguish between the Kerr metric and the phenomenological metrics introduced by Johannsen and Psaltis (2011) (which are not vacuum solutions of Einstein's equation) and thus to test the no-hair theorem of GR. To this end, we have developed a numerical code that calculates the radial brightness profiles of accretion disks …
There are increasing interests in binary supermassive black holes (SMBHs), but merging binaries with separations smaller than ~1 light days (~10^2 gravitational radii for 10^8 Msun), which are rapidly evolving under control of gravitational waves, are elusive in observations. In this paper, we discuss fates of mini-disks around component SMBHs for three regimes: 1) low rates (advection-dominated accretion flows: ADAFs); 2) intermediate rates; 3) super-Eddington accretion rates. Mini-disks with intermediate rates are undergoing evaporation through thermal conduction of hot corona forming a hybr…
Wind-fed supergiant X-ray binaries are precious laboratories not only to study accretion under extreme gravity and magnetic field conditions, but also to probe still highly debated properties of massive star winds. These includes the so-called clumps, originated from the inherent instability of line driven winds, and larger structures. In this paper, we report on the results of the last (and not yet published) monitoring campaigns that our group has been carrying out since 2007 with both XMM-Newton and the Swift Neil Gehrels observatory. Data collected with the EPIC cameras on-board XMM-Newton…
This contribution summarizes, as of early 2008, the observational and theoretical understanding of the origin, physics, and emission properties of short gamma-ray bursts in both electromagnetic and gravitational waves.
Observations with the INTEGRAL satellite have quadrupled the population of supergiant High Mass X-ray Binaries (HMXBs), revealed a previously hidden population of obscured supergiant HMXBs, and allowed the discovery of huge and fast transient flares in supergiant HMXBs. Apart from these 3 observational facts, has INTEGRAL allowed us to better understand these supergiant HMXBs? Do we have now a better understanding of the 3 populations of HMXBs, and of their accretion process, separated in the so-called Corbet diagram? Do we better apprehend the accretion process in the supergiant HMXBs, and wh…
High Mass X-ray Binaries (HMXBs) are interesting objects that provide a wide range of observational probes to the nature of the two stellar components, accretion process, stellar wind and orbital parameters of the systems. A large fraction of the transient HMXBs are found to be Be/X-ray binaries in which the companion Be star with its circumstellar disk governs the outburst. These outbursts are understood to be due to the sudden enhanced mass accretion to the neutron star and is likely to be associated with changes in the circumstellar disk of the companion. In the recent years, another class …
Dynamical interactions that take place between objects in dense stellar systems lead to frequent formation of exotic stellar objects, unusual binaries, and systems of higher multiplicity. They are most important for the formation of binaries with neutron stars and black holes, which are usually observationally revealed in mass-transferring binaries. Here we review the current understanding of compact object's retention, of the metallicity dependence on the formation of low-mass X-ray binaries with neutron stars, and how mass-transferring binaries with a black hole and a white dwarf can be form…
Recently, a large number of low-mass (<0.30 M_sun) helium white dwarfs (He WDs) have been discovered as a result of several surveys campaigns such as WASP, ELM, Kepler or SDSS. The far majority of them have as companion another compact object. There appears to be discrepancies between current theoretical modelling of low-mass He WDs and a number of key observational cases indicating that some details of their formation scenario yet remain to be understood.
Tidal dissipation in compact white dwarf (WD) binary systems significantly influences the physical conditions (such as surface temperature and rotation rate) of the WDs prior to mass transfer or merger. In these systems, the dominant tidal effects involve the excitation of gravity waves and their dissipation in the outer envelope of the star. We calculate the amplitude of tidally excited gravity waves in low-mass (0.3M_\odot) helium-core (He) WDs as a function of the tidal forcing frequency ω. Like carbon-oxygen (CO) WDs studied in our previous paper, we find that the dimensionless tidal torqu…
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…
Colliding wind binaries (CWBs) have been considered as a possible high energy $γ$-ray sources for some time, however no system other than $η$ Car has been detected. In the paper a sample of seven CWBs (WR 11, WR 70, WR 137, WR 140, WR 146, WR 147) which, by means of theoretic modelling, were deemed most promising candidates, was analyzed using almost 7 years of the Fermi-LAT data. WR 11 ($γ^2$ Vel) was detected at 6.1$σ$ confidence level with a photon flux in 0.1-100 GeV range $(1.8\pm0.6)\times10^{-9}~\mathrm{ph~cm^{-2}~s^{-1}}$ and an energy flux $(2.7\pm0.5)\times10^{-12}~~\mathrm{erg~cm^{-…
Several scenarios were suggested for the origins of gravitational-wave (GW) sources from mergers of stellar binary black holes (BBHs). Here we propose a novel origin through catalyzed formation of GW-sources from ultra-wide binaries in the field. Such binaries experience perturbations from random stellar fly-bys which excite their eccentricities. Once a wide-binary is driven to a sufficiently small peri-center approach, GW-emission becomes significant, and the binary inspirals and merges. We derive an analytic model and verify it with numerical calculation to compute the merger rate to be $\si…
Given the stellar density near the galactic center, close encounters between compact object binaries and the supermassive black hole are a plausible occurrence. We present results from a numerical study of close to 13 million such encounters. Consistent with previous studies, we corroborate that, for binary systems tidally disrupted by the black hole, the component of the binary remaining bound to the hole has eccentricity ~ 0.97 and circularizes dramatically by the time it enters the classical LISA band. Our results also show that the population of surviving binaries merits attention. These b…
Probing Boson Clouds with Supermassive Black Hole Binaries
Institute of High Energy Physics, Chinese Academy of Sciences（中国科学院高能物理研究所）；School of Physics Sciences, University of Chinese Academy of Sciences（中国科学院大学物理科学学院）；Center for High Energy Physics, Peking University（北京大学高能物理中心）
The influence of free-free absorption on the radio spectrum of Particle-Accelerating Colliding-Wind Binaries
University of Liège（列日大学）；Indian Institute for Space science and Technology (IIST)（印度空间科学与技术学院）；Instituto Argentino de Radioastronomía（阿根廷射电天文学研究所）；Peking University（北京大学）；Chalmers University of Technology（查尔姆斯理工大学）
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…
A neutron star low-mass X-ray binary is a binary stellar system with a neutron star and a low-mass companion star rotating around each other. In this system the neutron star accretes mass from the companion, and as this matter falls into the deep potential well of the neutron star, the gravitational potential energy is released primarily in the X-ray wavelengths. Such a source was first discovered in X-rays in 1962, and this discovery formally gave birth to the "X-ray astronomy". In the subsequent decades, our knowledge of these sources has increased enormously by the observations with several…
Pulsars are some of the most accurate clocks found in nature, while black holes offer a unique arena for the study of quantum gravity. As such, pulsar-black hole (PSR-BH) binaries provide ideal astrophysical systems for detecting the effects of quantum gravity. With the success of aLIGO and the advent of instruments like the SKA and eLISA, the prospects for the discovery of such PSR-BH binaries are very promising. We argue that PSR-BH binaries can serve as ready-made testing grounds for proposed resolutions to the black hole information paradox. We propose using timing signals from a pulsar be…
Since it was theorized by Kerr in 1963, determining the spin of black holes from observed data was paid very little attention until few years back. The main reasons behind this were the unavailability of adequate data and the lack of appropriate techniques. In this article, we explore determining/predicting the spin of several black holes in X-ray binaries and in the center of galaxies, using X-ray and gamma-ray satellite data. For X-ray binaries, in order to explain observed quasi-periodic oscillations, our model predicts the spin parameter of underlying black holes. On the other hand, the na…
Black hole-main sequence star (BH-MS) binaries are one of the targets of the future data releases of the astrometric satellite {\it Gaia}. They are supposed to be formed in two main sites: a galactic field and star clusters. However, previous work has never predicted the number of BH-MS binaries originating in the latter site. In this paper, we estimate the number of BH-MS binaries formed in open clusters and detectable with {\it Gaia} based on the results of {\it N}-body simulations. By considering interstellar extinction in the Milky Way (MW) and observational constraints, we predict $\sim 1…
