Related papers: A Be-type star with a black hole companion
We present a sample of hard X-ray selected candidate black holes (BHs) in 19 dwarf galaxies. BH candidates are identified by cross-matching a parent sample of ~44,000 local dwarf galaxies (M_stellar < 3 x 10^9 Msun, z<0.055) with the…
Galactic binary systems that contain a black hole candidate emit hard X-rays in their low luminosity mode. We show that this emission can be understood as due to the Compton scattering of photons from the companion star and/or the accretion…
One possible scenario for the formation of massive black holes (BHs) in the early Universe is from the direct collapse of primordial gas in atomic-cooling dark matter haloes in which the gas is unable to cool efficiently via molecular…
Mass distribution of black holes identified through X-ray emission suggests a paucity of black holes in the mass range of 3 to 5 solar masses. Modified theories have been devised to explain this mass gap, and it is suggested that natal…
Detectability of isolated black holes (IBHs) without a companion star but emitting X-rays by accretion from dense interstellar medium (ISM) or molecular cloud gas is investigated. We calculate orbits of IBHs in the Galaxy to derive a…
We use dynamical mass measurements of 16 black holes in transient low-mass X-ray binaries to infer the stellar black hole mass distribution in the parent population. We find that the observations are best described by a narrow mass…
We discuss new observations of X-ray novae which provide strong evidence that black holes have event horizons. Optical observations of 13 X-ray novae indicate that these binary stars contain collapsed objects too heavy to be stable neutron…
In standard stellar evolution, stars with masses ranging from approximately $150$ to $240 M_\odot$ are expected to evolve to a pair instability supernova with no black hole (BH) remnant. This evolutionary behavior leads to a predicted gap…
We have studied the X-ray nuclear activity of 187 nearby (distance < 15 Mpc) galaxies observed with Chandra/ACIS. We found that 86 of them have a point-like X-ray core, consistent with an accreting black hole (BH). We argue that the…
Be X-ray binaries (Be XRBs) are high-mass X-ray binaries, with a neutron star or black hole orbiting and accreting material from a non-supergiant B-star that is rotating at a near critical rate. These objects are prime targets to understand…
Context. Direct imaging provides a steady flow of newly discovered giant planets and brown dwarf companions. These multi-object systems can provide information about the formation of low-mass companions in wide orbits and/or help us to…
At about 70 solar masses, the recently-discovered dark object orbited by a B-type star in the system LB-1 is difficult to understand as the end point of standard stellar evolution, except as a binary black hole (BBH). LB-1 shows a strong,…
We have found compact X-ray sources in the center of 21 (54%) of 39 nearby face-on spiral and elliptical galaxies with available ROSAT HRI data. ROSAT X-ray luminosities (0.2 - 2.4 keV) of these compact X-ray sources are ~ 1e37 - 1e40 erg/s…
We analyze the dynamical evolution of binary stars that interact with a static background of single stars in the environment of a massive black hole (MBH). All stars are considered to be single mass, Newtonian point particles. We follow the…
In X-ray binary star systems consisting of a compact object that accretes material from an orbiting secondary star, there is no straightforward means to decide if the compact object is a black hole or a neutron star. To assist this…
Astrophysical models of binary-black hole mergers in the Universe require a significant fraction of stellar-mass black holes (BHs) to receive negligible natal kicks to explain the gravitational wave detections. This implies that BHs should…
We test the physical model of the relativistic jets in the galactic X-ray binary SS 433 proposed in our previous paper using additional observations from the Chandra High Energy Transmission Grating Spectrometer. These observations sample…
Stellar-mass black holes (BHs) above $30 M_\odot$ are predicted to form from low-metallicity progenitors, but direct detections of such systems in the Milky Way remain scarce. Motivated by the recent discovery of Gaia BH3, a $33 M_\odot$ BH…
We investigate the stellar mass - black hole mass ($\mathcal{M}_*-\mathcal{M}_\mathrm{BH}$) relation with type 1 AGN down to $\mathcal{M}_\mathrm{BH}=10^7 M_\odot$, corresponding to a $\simeq -21$ absolute magnitude in rest-frame…
Binary black holes (BBHs) are one of the endpoints of isolated binary evolution, and their mergers a leading channel for gravitational wave events. Here, using the evolutionary code \textsc{StarTrack}, we study the statistical properties of…