High-mass microquasars may produce jets that will strongly interact with surrounding stellar winds on binary system spatial scales. We study the dynamics of the collision between a mildly relativistic hydrodynamical jet of supersonic nature and the wind of an OB star. We performed numerical 3D simulations of jets that cross the stellar wind with the code Ratpenat. The jet head generates a strong shock in the wind, and strong recollimation shocks occur due to the initial overpressure of the jet with its environment. These shocks can accelerate particles up to TeV energies and produce gamma-rays. The recollimation shock also strengthens jet asymmetric Kelvin-Helmholtz instabilities produced in the wind/jet contact discontinuity. This can lead to jet disruption even for jet powers of several times $10^{36}$ erg s$^{-1}$. High-mass microquasar jets likely suffer a strong recollimation shock that can be a site of particle acceleration up to very high energies, but also eventually lead to the disruption of the jet.
We studied the relation of accretion-jet power and disk luminosity, especially the jet efficiencies and disk radiative efficiencies for different accretion disks as well as black hole (BH) spin, in order to explore the origin of radio emission in black hole X-ray binaries (BHXBs). We found that jet efficiency increases more rapidly (efficient) than the nearly constant disk radiative efficiency for thin disk component in high accretion regime, which could account for the steep track ($μ>1$) in the observed radio and X-ray luminosity relations ($L_{\rm R}\propto L_{\rm X}^μ$), but the thin disk …
We study conditions for formation of recollimation shocks in jets interacting with stellar winds in high-mass X-ray binaries. We show the existence of a critical jet power, dependent on the wind rate and velocity and the jet velocity, above which a recollimation shock is not formed. For jet powers below critical, we derive the location of the shock. We show that surface shocks may still exist above the critical power, but only occupy a small volume of the jet and do not significantly alter the jet opening angle. We test these prediction by 3-D numerical simulations, which confirm the existence…
Over the past half century, X-ray and radio observations of accreting neutron stars and stellar mass black holes have yielded a rich observational picture with common features including state transitions and jet formation, but also sharp differences. While black hole X-ray binaries overwhelmingly suppress jets in so-called soft states, accreting neutron stars are less restrictive, with a soft state wind observed in some sources to co-exist with a jet. We propose an explanation for these differences that leads to a generalization of a foundational element, the hardness-intensity diagram of Fend…
We show that the jet power $P_j$ and geometrically corrected $γ$-ray luminosity $L_γ$ for the X-ray binaries (XRBs) Cygnus X-1, Cygnus X-3, and V404 Cygni, and $γ$-ray upper limits for GRS 1915+105 and GX339-4, follow the universal scaling for the energetics of relativistic jets from black hole (BH) systems found by Nemmen et al. (2012) for blazars and GRBs. The observed peak $γ$-ray luminosity for XRBs is geometrically corrected; and the minimum jet power is estimated from the peak flux density of radio flares and the flare rise time. The $L_γ-P_j$ correlation holds across $\sim 17$ orders of…
Jets powered by high-mass X-ray binaries must traverse the powerful wind of the companion star. We present the first global 3D simulations of jet-wind interaction in high-mass X-ray binaries. We show that the wind momentum flux intercepted by the jet can lead to significant bending of the jet and that jets propagating through a spherical wind will be bent to an asymptotic angle $ψ_{\infty}$. We derive simple expressions for $ψ_{\infty}$ as a function of jet power and wind thrust. For known wind parameters, measurements of $ψ_{\infty}$ can be used to constrain the jet power. In the case of Cygn…
Active Galactic Nucleus Feedback in an Elliptical Galaxy. IV. The Importance of the Jet Wind Coupling
Shanghai Astronomical Observatory, Chinese Academy of Sciences（中国科学院上海天文台）；ShanghaiTech University（上海科技大学）；University of Chinese Academy of Sciences（中国科学院大学）；Fudan University（复旦大学）；National Astronomical Observatories, Chinese Academy of Sciences（中国科学院国家天文台）
Neutron star X-ray binaries emit a compact, optically thick, relativistic radio jet during low-luminosity, usually hard states, as Galactic black-hole X-ray binaries do. When radio emission is bright, a hard power-law tail without evidence for an exponential cutoff is observed in most systems. We have developed a jet model that explains many spectral and timing properties of black-hole binaries in the states where a jet is present. Our goal is to investigate whether our jet model can reproduce the hard tail, with the correct range of photon index and the absence of a high-energy cutoff, in neu…
X-ray binary observations led to the interpretation that powerful compact jets, produced in the hard state, are quenched when the source transitions to its soft state. The aim of this paper is to discuss the possibility that a powerful dark jet is still present in the soft state. Using the black hole X-ray binaries GX339-4 and H1743-322 as test cases, we feed observed X-ray power density spectra in the soft state of these two sources to an internal shock jet model. Remarkably, the predicted radio emission is consistent with current upper-limits. Our results show that, for these two sources, a …
We propose a new model of Fast Radio Bursts (FRBs) based on stellar mass black hole-massive star binaries. We argue that the inhomogeneity of the circumstellar materials or/and the time varying wind activities of the stellar companion will cause the black hole to accrete at a transient super-Eddington rate. The collision among the clumpy ejecta in the resulted jet could trigger plasma instability. As a result, the plasma in the jet will emit coherent curvature radiation. When the jet cone aims toward the observer, the apparent luminosity can be $10^{41}-10^{42}$\,erg/s. The duration of the res…
We analyze the model of gamma-ray binaries, consisting of a massive star and a pulsar with ultrarelativistic wind. We consider radiation from energetic particles, accelerated at the pulsar wind termination shock, and feedback of this radiation on the wind through production of secondary electron-positron pairs. We show that the pair feedback limits the Lorentz factor of the pulsar wind and creates a population of very energetic pairs, whose radiation may be responsible for the observed gamma-ray signal.
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.
Jets are a commonly observed phenomenon in post-asymptotic giant branch (post-AGB) binaries. Due to the orbital motion of the binary, the jet causes variable absorption in the Balmer profiles. In previous work, we have developed spatio-kinematic and radiative transfer models to reproduce the observed Balmer line variability and derive the spatio-kinematic structure of the jet and its mass-loss rate. Here, we apply our jet model to five post-AGB binaries with distinct Hα line variability and diverse orbital properties. Our models fit the Hα line variations very well. We estimate jet mass-loss r…
Recent work on jets and disk winds in low-mass X-ray binaries (LMXBs) suggests that they are to a large extent mutually exclusive, with jets observed in spectrally hard states and disk winds observed in spectrally soft states. In this paper we use existing literature on jets and disk winds in the luminous neutron star (NS) LMXB GX 13+1, in combination with archival Rossi X-ray Timing Explorer data, to show that this source is likely able to produce jets and disk winds simultaneously. We find that jets and disk winds occur in the same location on the source's track in its X-ray color-color diag…
We calculate the expected effects on the spectral energy distributions and light curves in X-ray binary jets from eclipses by the donor stars. Jets will be eclipsed for all inclination angles, with just the height along the jet where the eclipse takes place being set by the orbital parameters. Typically, eclipses will lead to 5-10\% reductions in the jet emission over a range of a factor of few in wavelength with a periodic modulation. In ideal systems with high inclination angles, relatively even mass ratios, and modest jet speeds, the eclipses may be deeper. We discuss how eclipses can be us…
Relationship Between the Kinetic Power and Bolometric Luminosity of Jets: limitation from black hole X-ray binaries, active galactic nuclei, and gamma-ray bursts
Relativistic jets are observed only in the low/hard and intermediate states of X-ray binaries (XRBs), and are switched off in the thermal state, but they appear to be present in both low-luminosity and luminous active galactic nuclei (AGNs). It is widely believed that strong large-scale magnetic fields is a crucial ingredient in jet production; such fields can be attained only through efficient advection from the outer disc. We suggest that geometrically thin accretion discs with magnetic outflows are present in luminous radio-loud AGNs; this is likely because the interstellar medium provides …
The models that seek to explain the reflection spectrum in black hole binaries usually invoke a point-like primary source of hard X-rays. This source illuminates the accretion disk and gives rise to the discrete (lines) and continuum-reflected components. The main goal of this work is to investigate whether the extended, mildly relativistic jet that is present in black hole binaries in the hard and hard-intermediate states is the hard X-ray source that illuminates the accretion disk. We use a Monte Carlo code that simulates the process of inverse Compton scattering in a mildly relativistic jet…
The observed tight radio/X-ray correlation in the low spectral state of some black hole X-ray binaries implies the strong coupling of the accretion and jet. The correlation of $L_{\rm R} \propto L_{\rm X}^{\sim 0.5-0.7}$ was well explained by the coupling of a radiatively inefficient accretion flow and a jet. Recently, however, a growing number of sources show more complicated radio/X-ray correlations, e.g., $L_{\rm R} \propto L_{\rm X}^{\sim 1.4}$ for $L_{\rm X}/L_{\rm Edd} \gtrsim 10^{-3}$, which is suggested to be explained by the coupling of a radiatively efficient accretion flow and a jet…
When the matter from a companion star is accreted towards the central compact accretor, i.e. a black hole (BH) or a neutron star (NS), an accretion disc and a jet outflow will form, providing bight X-ray and radio emission, which is known as X-ray binaries (XRBs). In the low/hard state, there exist disc-jet couplings in XRBs, but it remains uncertain whether the jet power comes from the disc or the central accretor. Moreover, BHXRBs have different properties compared with NSXRBs: quiescent BHXRBs are typically two to three orders of magnitude less luminous than NSXRBs in X-ray, whereas BHXRBs …
The radiative mechanism of the black hole X-ray transients (BHXTs) in their quiescent states (defined as the 2-10 keV X-ray luminosity $\le 10^{34}{\rm \,erg\,s^{-1}}$) remains unclear. In this work, we investigate the quasi-simultaneous quiescent state spectrum (including radio, infrared, optical, ultraviolet and X-ray) of two BHXTs, A0620--00 and XTE J1118+480. We find that, these two sources can be well described by a coupled accretion -- jet model. More specifically, most of the emission (radio up-to infrared, and the X-ray waveband) comes from the collimated relativistic jet. Emission fro…
Compact, continuously launched jets in black hole X-ray binaries (BHXBs) produce radio to optical-infrared synchrotron emission. In most BHXBs, an infrared (IR) excess (above the disc component) is observed when the jet is present in the hard spectral state. We investigate why some BHXBs have prominent IR excesses and some do not, quantified by the amplitude of the IR quenching or recovery over the transition from/to the hard state. We find that the amplitude of the IR excess can be explained by inclination dependent beaming of the jet synchrotron emission, and the projected area of the accret…
Magnetic, radiation pressure, and thermal driving are the three mechanisms capable of launching accretion disk winds. In X-ray binaries, radiation pressure is often not significant, as in many systems the luminosity is too low for driving due to continuum transitions yet too high for driving due to line transitions. This leaves thermal and magnetic driving as the contender launching mechanisms in these systems. Using Athena++, we perform axisymmetric ideal MHD simulations that include radiative heating and cooling processes appropriate for Compton heated winds to show that the inclusion of mag…
Interacting binaries are of general interest as laboratories for investigating the physics of accretion, which gives rise to the bulk of high-energy radiation in the Galaxy. They allow us to probe stellar evolution processes that cannot be studied in single stars. Understanding the orbital evolution of binaries is essential in order to model the formation of compact binaries. Here we focus our attention on studying orbital evolution driven by angular momentum loss through stellar winds in massive binaries. We run a suite of hydrodynamical simulations of binary stars hosting one mass losing sta…
High-mass microquasar jets propagate under the effect of the wind from the companion star, and the orbital motion of the binary system. The stellar wind and the orbit may be dominant factors determining the jet properties beyond the binary scales.} An analytical study is performed to characterize the effects of the stellar wind and the orbital motion on the jet properties. Accounting for the wind thrust transferred to the jet, we derive analytical estimates to characterize the jet evolution under the impact of the stellar wind. We include the Coriolis force effect, induced by orbital motion an…
Context. Particle-accelerating colliding-wind binaries (PACWBs) are systems that are formed by two massive and hot stars and produce nonthermal (NT) radiation. The key elements of these systems are fast winds and the shocks that they create when they collide. Binaries with nonaccreting young pulsars have also been detected as NT emitters, again as a consequence of the wind-wind interaction. Black holes (BHs) might produce NT radiation by this mechanism if they accrete at super-Eddington rates. In such cases, the disk is expected to launch a radiation-driven wind, and if this wind has an equato…
Infrared interferometry is a new frontier for precision ground based observing, with new instrumentation achieving milliarcsecond (mas) spatial resolutions for faint sources, along with astrometry on the order of 10 microarcseconds. This technique has already led to breakthroughs in the observations of the supermassive black hole at the Galactic centre and its orbiting stars, AGN, and exo-planets, and can be employed for studying X-ray binaries (XRBs), microquasars in particular. Beyond constraining the orbital parameters of the system using the centroid wobble and spatially resolving jet disc…
Strong winds from massive stars are a topic of interest to a wide range of astrophysical fields. In High-Mass X-ray Binaries the presence of an accreting compact object on the one side allows to infer wind parameters from studies of the varying properties of the emitted X-rays; but on the other side the accretor's gravity and ionizing radiation can strongly influence the wind flow. Based on a collaborative effort of astronomers both from the stellar wind and the X-ray community, this presentation attempts to review our current state of knowledge and indicate avenues for future progress.
Binary systems formed by early-type stars with strong winds are known to display variable non-thermal radio emission, thermal X-rays, and, at least in one case (Eta Carina), $γ$ rays. Some of these systems are quite eccentric and the conditions for efficient particle acceleration and $γ$-ray production might manifest only occasionally. In this paper I briefly review the physics of colliding wind binaries with emphasis on the observational signatures of non-thermal particle acceleration. I discuss, in particular, the case of the system HD 93129A which is made up by an O2 If* star (the primary) …
Recently, evidence for synchrotron emission in both black hole and neutron star X-ray binaries has been mounting, from optical/infrared spectral, polarimetric, and fast timing signatures. The synchrotron emission of jets can be highly linearly polarised, depending on the configuration of the magnetic field. Optical and infrared (OIR) polarimetric observations of X-ray binaries are presented in this brief review. The OIR polarimetric signature of relativistic jets is detected at levels of ~ 1-10 %, similar to AGN cores. This reveals that the magnetic geometry in the compact jets may be similar …
We present a new model of the population of symbiotic X-ray binaries (SyXBs) that takes into account non-stationary character of quasi-spherical sub-sonic accretion of the red giant's stellar wind onto slowly rotating neutron stars. Updates of the earlier models are given, which include more strict criteria of slow NS rotation for plasma entry into the NS magnetosphere via Rayleigh-Taylor instability, as well as more strict conditions for settling accretion for slow stellar winds, with an account of variations in the specific angular momentum of captured stellar wind in eccentric binaries. The…
