A Semi-analytical Model for Wind-fed Black Hole High-mass X-Ray Binaries: State Transition Triggered by Magnetic Fields from the Companion Star

During my PhD study, I was working on two types of Black Hole (BH) binaries, i.e. coalescing binary BHs and BH High-mass X-ray binaries (HMXBs). Most of the measured spin chi_eff are quite low, while three BH spin measurements in HMXBs show only values near the maximum. My study is focused mainly on the detailed stellar and binary evolution by tracking the evolution of angular momentum of the BH progenitor star in BH binaries. More specifically, we systematically studied the origin of the BH spin in these two different BH binaries systems. Furthermore, I have been working on a project that is related to a detailed comparison of the implementation for chemical mixing and angular momentum transport between two stellar evolution codes, namely, MESA and GENEVA codes. More specifically, we want to understand the minimum rotation that is required for chemically homogeneous evolution to occur.

We show that black-hole High-Mass X-ray Binaries (HMXBs) with O- or B-type donor stars and relatively short orbital periods, of order one week to several months may survive spiral in, to then form Wolf-Rayet (WR) X-ray binaries with orbital periods of order a day to a few days; while in systems where the compact star is a neutron star, HMXBs with these orbital periods never survive spiral-in. We therefore predict that WR X-ray binaries can only harbor black holes. The reason why black-hole HMXBs with these orbital periods may survive spiral in is: the combination of a radiative envelope of the donor star, and a high mass of the compact star. In this case, when the donor begins to overflow its Roche lobe, the systems are able to spiral in slowly with stable Roche-lobe overflow, as is shown by the system SS433. In this case the transferred mass is ejected from the vicinity of the compact star (so-called "isotropic re-emission" mass loss mode, or "SS433-like mass loss"), leading to gradual spiral-in. If the mass ratio of donor and black hole is $>3.5$, these systems will go into CE evolution and are less likely to survive. If they survive, they produce WR X-ray binaries with orbital periods of a few hours to one day. Several of the well-known WR+O binaries in our Galaxy and the Magellanic Clouds, with orbital periods in the range between a week and several months, are expected to evolve into close WR-Black-Hole binaries,which may later produce close double black holes. The galactic formation rate of double black holes resulting from such systems is still uncertain, as it depends on several poorly known factors in this evolutionary picture. It might possibly be as high as $\sim 10^{-5}$ per year.

We conduct binary population synthesis to investigate the formation of wind-fed high-mass X-ray binaries containing black holes (BH-HMXBs). We evolve multiple populations of high-mass binary stars and consider BH-HMXB formation rates, masses, spins, and separations. We find that systems similar to Cygnus X-1 likely form after stable Case A mass transfer (MT) from the main-sequence progenitors of BHs, provided such MT is characterized by low accretion efficiency, β ≲ 0.1, with modest orbital angular momentum losses from the non-accreted material. Additionally, efficient BH-HMXB formation relies on a new simple treatment for Case A MT that allows donors to retain larger core masses compared to traditional rapid population-synthesis assumptions. At solar metallicity, our Preferred model yields $\mathcal {O}(1)$ observable BH-HMXBs in the Galaxy today, consistent with observations. In this simulation, 8 per cent of BH-HMXBs go on to merge as binary black holes or neutron star-black hole binaries within a Hubble time; however, none of the merging binaries have BH-HMXB progenitors with properties similar to Cygnus X-1. With our preferred settings for core mass growth, mass transfer efficiency, and angular momentum loss, accounting for an evolving metallicity, and integrating over the metallicity-specific star formation history of the Universe, we find that BH-HMXBs may have contributed ≈2–5 BBH merger signals to detections reported in the third gravitational-wave transient catalogue of the LIGO–Virgo–KAGRA Collaboration. We also suggest MT efficiency should be higher during stable Case B MT than during Case A MT.

We have obtained a 63 ks Chandra ACIS-I observation of the Wolf–Rayet + black hole binary NGC 300 X-1. We measure rapid low-amplitude variability in the 0.35–8 keV light curve. The power density spectrum has a power-law index γ = 1.02 ± 0.15 consistent with an accreting black hole in a steep power-law state. When compared to previous studies of NGC 300 X-1 performed with XMM-Newton, we find the source at the low end of the previously measured 0.3–10 keV luminosity. The spectrum of NGC 300 X-1 is dominated by a power law (Γ = 2.0 ± 0.3) with a contribution at low energies by a thermal component. We estimate the 0.3–10 keV luminosity to be 2.6+0.8−1.0 × 1038 erg s−1. The timing and spectroscopic properties of NGC 300 X-1 are consistent with being in a steep power-law state, similar to earlier observations performed with XMM-Newton. We additionally compare our observations to known high-mass X-ray binaries and ultraluminous X-ray sources, and find the properties of NGC 300 X-1 are most consistent with black hole high-mass X-ray binaries.

The three dynamically confirmed wind-fed black hole high-mass X-ray binaries (BH-HMXBs) are suggested to all contain a highly spinning black hole (BH). However, based on the theories of efficient angular momentum transport inside the stars, we expect that the first-born BHs in binary systems should have low spins, which is consistent with gravitational-wave observations. As a result, the origin of the high BH spins measured in wind-fed BH-HMXBs remains a mystery. In this paper, we conduct a binary population synthesis study on wind-fed BH-HMXBs at solar metallicity with the use of the newly developed code POSYDON, considering three scenarios for BH accretion: Eddington-limited, moderately super-Eddington, and fully conservative accretion. Taking into account the conditions for accretion-disk formation, we find that regardless of the accretion model, these systems are more likely to have already experienced a phase of Roche-lobe overflow after the BH formation. To account for the extreme BH spins, highly conservative accretion onto BHs is required, when assuming the accreted material carries the specific angular momentum at the innermost stable orbit. Besides, in our simulations we found that the systems with donor stars within the mass range of 10 − 20 M⊙ are prevalent, posing a challenge in explaining simultaneously all observed properties of the BH-HMXB in our Galaxy, Cygnus X-1, and potentially hinting that the accretion efficiency onto non-degenerate stars, before the formation of the BH, is also more conservative than assumed in our simulations.

We compiled a catalogue of high mass X-ray binaries (HMXBs) and low mass X-ray binaries (LMXBs) which contain 78 HMXBs and 138 LMXBs known up to date. Among these HMXBs and LMXBs 65 and 134 of them belong to the Galaxy, respectively. In this investigation our main goal was to study the differences between the Galactic binaries which contain X-ray pulsars, neutron stars (NSs) and black-holes (BHs). These HMXBs contain 34 X-ray pulsars and 4 BHs, whereas among the 134 LMXBs there are 8 pulsars and 17 BHs. None of the HMXBs demonstrated burster phenomena. 44 LMXBs show burster properties.

Significant historic cosmic evolution for the formation rate of stellar black holes is inferred from current theoretical models of the evolution of massive stars, the multiple observations of compact stellar remnants in the near and distant universe, and the cosmic chemical evolution. The mean mass of stellar black holes, the fraction of black holes/neutron stars, and the fraction of black hole high mass X-ray binaries (BH-HMXBs)/solitary black holes increase with redshift. The energetic feedback from large populations of BH-HMXBs form in the first generations of star burst galaxies has been overlooked in most cosmological models of the reionization epoch of the universe. The powerful radiation, jets, and winds from BH-HMXBs heat the intergalactic medium over large volumes of space and keep it ionized until AGN take over. It is concluded that stellar black holes constrained the properties of the faintest galaxies at high redshifts. I present here the theoretical and observational grounds for the historic cosmic evolution of stellar black holes. Detailed calculations on their cosmic impact are presented elsewhere (Mirabel, Dijkstra, Laurent, Loeb, & Pritchard 2011).

We explore the effect of anisotropic wind driving on the properties of accretion onto black holes (BHs) in close binaries. We specifically focus on line-driven winds, which are common in high-mass X-ray binaries (HMXBs). In close binary systems, the tidal force from the companion star can modify the wind structure in two different ways. One is the reduction of wind terminal velocity due to the weaker effective surface gravity. The other is the reduction in mass flux due to gravity darkening (GD). We incorporate these effects into the so-called CAK theory in a simple way and investigate the wind flow around the accretor on the orbital scale. We find that a focused accretion stream is naturally formed when the Roche lobe filling factor is ${\gtrsim}0.8$ –0.9, analogous to that of wind Roche lobe overflow, but only when the velocity reduction is taken into account. The formation of a stream is necessary to bring in sufficient angular momentum to form an accretion disc around the BH. GD effects reduce the amount of accreted angular momentum, but not enough to prevent the formation of a disc. Based on these results, we expect there to be a discrete step in the observability of HMXBs depending on whether the donor Roche lobe filling factor is below or above ${\sim}$ 0.8–0.9.

The temporal and spectral properties of ultraluminous X-ray sources (ULXs, LX > 2 × 1039 ergs s-1) and bright X-ray sources (LX > 3 × 1038 ergs s-1) are examined and compared in two extremely different host environments: the old elliptical galaxy NGC 1399 and the young, star-forming Antennae galaxies (NGC 4038/4039). ULXs in NGC 1399 show little variability on either long or short timescales. Only 1 of 8 ULXs and 10 of 63 bright sources in NGC 1399 are variable at a confidence level of 90%. On long timescales, the NGC 1399 sources are steadier than most Galactic black hole X-ray binaries, but are similar to GRS 1915+105. The outburst duration of the NGC 1399 sources is about 20 yr, again, similar to that of GRS 1915+105. The bright X-ray sources in NGC 1399 may be black hole X-ray binaries with giant-star companions similar to GRS 1915+105. The brightest ULX (PSX-1) in NGC 1399 is coincident with a globular cluster, shows a hard spectrum with a photon index around 1.5, and has a nearly constant luminosity around 5 × 1039 ergs s-1. It may be an intermediate-mass black hole (IMBH) in a hard spectral state. In contrast to NGC 1399, the ULXs in the Antennae are all variable, and a large fraction of the bright sources (9 of 15) are also variable. The variability and luminosity of ULXs in the Antennae suggest that they are black hole high-mass X-ray binaries accreting via Roche lobe overflow. A flare with a duration of about 5 ks is found from Antennae X-42. The most luminous ULX, X-16, with a very hard spectrum (Γ = 1.0-1.3) and a luminosity that varies by a factor of 10, could be an IMBH candidate.

We present multiwavelength characterization of 65 high-mass X-ray binary (HMXB) candidates in M33. We use the Chandra ACIS survey of M33 (ChASeM33) catalog to select hard X-ray point sources that are spatially coincident with UV-bright point-source optical counterparts in the Panchromatic Hubble Andromeda Treasury: Triangulum Extended Region catalog, which covers the inner disk of M33 at near-IR, optical, and near-UV wavelengths. We perform spectral energy distribution fitting on multiband photometry for each point-source optical counterpart to measure its physical properties including mass, temperature, luminosity, and radius. We find that the majority of the HMXB companion star candidates are likely B-type main-sequence stars, suggesting that the HMXB population of M33 is dominated by Be X-ray binaries (Be-XRBs), as is seen in other Local Group galaxies. We use spatially resolved recent star formation history maps of M33 to measure the age distribution of the HMXB candidate sample and the HMXB production rate for M33. We find a bimodal distribution for the HMXB production rate over the last 80 Myr, with a peak at ∼10 and ∼40 Myr, which match theoretical formation timescales for the most massive HMXBs and Be-XRBs, respectively. We measure an HMXB production rate of 107–136 HMXBs/(M ⊙ yr−1) over the last 50 Myr and 150–199 HMXBs/(M ⊙ yr−1) over the last 80 Myr. For sources with compact object classifications from overlapping NuSTAR observations, we find a preference for giant/supergiant companion stars in black hole HMXBs and main-sequence companion stars in neutron star HMXBs.

Radiatively inefficient accretion flows onto black holes are unstable due to both an outwardly decreasing entropy (`convection') and an outwardly decreasing rotation rate (the `magnetorotational instability'; MRI). Using a linear magnetohydrodynamic stability analysis, we show that long-wavelength modes are primarily destabilized by the entropy gradient and that such `convective' modes transport angular momentum inwards. Moreover, the stability criteria for the convective modes are the standard Hoiland criteria of hydrodynamics. By contrast, shorter wavelength modes are primarily destabilized by magnetic tension and differential rotation. These `MRI' modes transport angular momentum outwards. The convection-dominated accretion flow (CDAF) model, which has been proposed for radiatively inefficient accretion onto a black hole, posits that inward angular momentum transport and outward energy transport by long-wavelength convective fluctuations are crucial for determining the structure of the accretion flow. Our analysis suggests that the CDAF model is applicable to a magnetohydrodynamic accretion flow provided the magnetic field saturates at a sufficiently sub-equipartition value (plasma beta >> 1), so that long-wavelength convective fluctuations can fit inside the accretion disk. Numerical magnetohydrodynamic simulations are required to determine whether such a sub-equipartition field is in fact obtained.

Low Luminosity Active Galactic Nuclei (LLAGNs) possess the characteristic features of more luminous Active Galactic Nuclei (AGNs) but exhibit a much lower nuclear Halpha luminosity than their more luminous counterparts. M87 (NGC 4486) and Centaurus A (NGC 5128, CenA) are well-studied nearby LLAGNs. As an additional feature they show gamma-radiation up to TeV (10^{12}eV) energies, but the origin of this radiation is not resolved. The coincident observation of a radio and TeV flare in M87 suggests that the TeV radiation is produced within around 50-100 gravitational radii of the central supermassive black hole, depending on the assumed value of the mass of the black hole. Strong radiation fields can be produced in the central region of an (LL)AGN, e.g., by the accretion flow around the black hole, the jet plasma, or stars closely orbiting the black hole. These radiation fields can lead to the absorption of emitted TeV photons, and in fact high optical depths of such fields can make TeV detection from inner regions impossible. In this paper we consider the accretion flow around the black hole as the most prominent source for such a radiation field and we accordingly calculate the probability for absorption of TeV photons produced near the black holes in M87 and CenA assuming a low luminosity Shakura-Sunyaev Disk (SSD). We find that the results are very different for between the two LLAGNs. While the inner region of M87 is transparent for TeV radiation up to 15TeV, the optical depth in CenA is >> 1, leading to an absorption of TeV photons that might be produced near the central black hole. These results imply either that the TeV gamma production sites and processes are different for both sources, or that LLAGN black holes do not accrete (at least only) in form of a low luminosity SSD.

Black-hole (BH) high-mass X-ray binary (HMXB) systems are likely to be the progenitors of BH-BH mergers detected in gravitational waves by LIGO/Virgo/KAGRA (LVK). Yet merging BHs reach higher masses (∼100 M⊙) than BHs in HMXBs (∼20 M⊙) and typically exhibit lower spins (aBH ≲ 0.25 with a larger values tail) than what is often claimed for BHs in HMXBs (aBH ≳ 0.9). This could suggest that these two classes of systems belong to different populations, but here we show that this may not necessarily be the case. The difference in masses is easily explained as the known HMXB-BHs are in galaxies with relatively high metallicity, so their progenitor stars are subject to strong mass loss from winds, leading to relatively low-mass BH at core collapse. Conversely, LVK is also able to detect BHs from low-metallicity galaxies that are known to naturally produce more massive stellar-origin BHs. However, the difference in spin is more difficult to explain. Models with efficient angular momentum transport in stellar interiors produce slowly spinning progenitors for both LVK and HMXB BHs. Known HMXBs have orbital periods that are too long for efficient tidal spin-up and are also unlikely to have undergone significant accretion spin-up. Instead, we show that the derived value of the BH spin depends strongly on how the HMXB accretion disc emission is modelled. We argue that since Cyg X-1 is never observed to be in a soft spectral state, the appropriate spectral models must take into account the Comptonisation of the disc photosphere. We show that such models are consistent with low spin values, namely: aBH ∼ 0.1. This was recently confirmed by other teams for both Cyg X-1 and LMC X-1 and here we show this is also the case for M33 X-7. We conclude that all known HMXB BHs can exhibit a low spin, in accordance with the results of stellar evolution models. Hence, the observations presented in this work are consistent with LVK BHs and HMXB BHs belonging to the same population.

Limits on the spin up of stellar-mass black holes through a spiral stationary accretion shock instability

885. Kinetic theory of motion of a gas between two parallel planes at all Knudsen numbers: P E Suetin and B T Porodnov,Zh Tekh Fiz, 37 (1), Jan 1967, 171–178 ( in Russian)