Related papers: A Compact Supermassive Binary Black Hole System
Little is known about the properties of the accretion flows and jets of the lowest-luminosity quiescent black holes. We report new, strictly simultaneous radio and X-ray observations of the nearby stellar-mass black hole X-ray binary GS…
By probing the population of binary black hole (BBH) mergers detected by LIGO-Virgo, we can infer properties about the underlying black hole formation channels. A mechanism known as pair-instability (PI) supernova is expected to prevent the…
We report Very Long Baseline Array (VLBA) observations of the 1.5 GHz radio continuum emission of the {\it z=6.326} quasar SDSS J010013.02+280225.8 (hereafter J0100+2802). J0100+2802 is, by far the most optically luminous, and radio-quiet…
Stellar evolution predicts the existence of a mass gap for black hole remnants produced by pair-instability supernova dynamics, whose lower and upper edges are very uncertain. We study the possibility of constraining the location of the…
Merging compact black-hole (BH) binaries are likely to exist in the nuclear star clusters around supermassive BHs (SMBHs), such as Sgr A$^\ast$. They may also form in the accretion disks of active galactic nuclei. Such compact binaries can…
We report the serendipitous multiwavelength discovery of a candidate dual black hole system with a separation of ~100 pc, in the gas-rich luminous infrared galaxy MCG-03-34-64 (z=0.016). Hubble Space Telescope/ACS observations show three…
We characterize the stellar mass of J2239+0207, a z~6.25 sub-Eddington quasar (M_1450=-24.6), using dedicated JWST/NIRCam medium-band observations of a nearby PSF star to remove the central point source and reveal the underlying galaxy…
A new solution of four-dimensional vacuum General Relativity is presented. It describes the near horizon region of the extreme (maximally spinning) binary black hole system with two identical extreme Kerr black holes held in equilibrium by…
Stellar-mass black hole binaries (BHBs) near supermassive black holes (SMBH) in galactic nuclei undergo eccentricity oscillations due to gravitational perturbations from the SMBH. Previous works have shown that this channel can contribute…
We report the discovery of a quasar close to SDSS J0927+2943 (z = 0.713), which is a massive binary / recoiling black hole candidate. The companion quasar is at a projected distance of 125 h_70^{-1} kpc and exhibits a radial velocity…
We report the discovery of two quasars at a redshift of $z$ = 6.05, in the process of merging. They were serendipitously discovered from the deep multi-band imaging data collected by the Hyper Suprime-Cam (HSC) Subaru Strategic Program…
We simulate an equal-mass merger of two Milky Way-size galaxy discs with moderate gas fractions at parsec-scale resolution including a new model for radiative cooling and heating in a multi-phase medium, as well as star formation and…
The realm of strong classical gravity and perhaps even quantum gravity are waiting to be explored. In this letter we consider the recently detected triple system composed of two stars and a non-accreting black hole. Using published…
Our discovery of 1SWASP J093010.78+533859.5 as a probable doubly eclipsing quadruple system containing a contact binary with P~0.23 d and a detached binary with P~1.31 d was announced in 2013. Subsequently Koo et al. confirmed the detached…
We have studied the nuclear region of the previously detected dual AGN system in the galaxy pair IRAS 05589+2828 and 2MASX J06021107+2828382 through new optical spectroscopy observations, along with radio and X-ray archival data. Our…
The existence of binary supermassive black holes (SBHs) is predicted by models of hierarchical galaxy formation. To date, only a single binary SBH has been imaged, at a projected separation of 7.3 parsecs. Here we report the detection of a…
IRAS~04158+2805 has long been thought to be a very low mass T-Tauri star (VLMS) surrounded by a nearly edge-on, extremely large disc. Recent observations revealed that this source hosts a binary surrounded by an extended circumbinary disc…
On August 14, 2019, the LIGO and Virgo detectors observed GW190814, a gravitational-wave signal originating from the merger of a $\simeq 23 M_\odot$ black hole with a $\simeq 2.6 M_\odot$ compact object. GW190814's compact-binary source is…
[ABRIDGED] We study supermassive black hole binary mergers driven by angular momentum loss to small-scale gas discs. Such binaries form after major galaxy mergers, but their fate is unclear since hardening through stellar scattering becomes…
Motivated by observational searches for sub-parsec supermassive black hole binaries (SBHBs) we develop a modular analytic model to determine the likelihood for detection of SBHBs by ongoing spectroscopic surveys. The model combines the…