Related papers: Sub-parsec supermassive Binary Quasars: expectatio…
The growth of supermassive black holes (SMBHs) through merging has long been predicted but its detection remains elusive. However, a promising target has been discovered in the Seyfert-1 galaxy J1430+2303. If a binary system truly lies at…
Gravitational waves from the inspiral and coalescence of supermassive black-hole (SMBH) binaries with masses ~10^6 Msun are likely to be among the strongest sources for the Laser Interferometer Space Antenna (LISA). We describe a…
This paper presents a technique to search for supermassive black hole binaries (MBHBs) in the Sloan Digital Sky Survey (SDSS). The search is based on the peculiar properties of merging galaxies that are found in a mock galaxy catalog from…
Direct electromagnetic observation of the orbital motion of a sub-parsec, supermassive black hole binary (SMBHB) would provide the first conclusive proof of such systems existing. Widely considered to be the sources of gravitational waves,…
We assess models for the assembly of supermassive black holes (SMBHs) at the center of galaxies that trace their hierarchical build-up far up in the dark halo `merger tree'. We assume that the first `seed' black holes (BHs) formed in…
Extreme mass ratio inspirals (EMRIs) take place when a stellar-mass black hole (BH) merges with a supermassive black hole (SMBH). The gravitational wave emission from such an event is expected to be detectable by the future Laser…
We investigated a sample of 15 luminous high-redshift quasars (3.3 < z < 5.1) to measure the mass of their super-massive black holes (SMBH) and compare, for the first time, results based on CIV, MgII, and Hbeta emission lines at…
We measure host galaxy stellar masses for a sample of five luminous quasars at $z\sim5-7$. Using JWST/NIRCam medium-band images of nearby PSF reference stars, we carefully subtract the contribution from the quasar light to place upper and…
One of the most promising targets for Pulsar Timing Arrays (PTAs) is identifying an individual supermassive black hole binary (SMBHB) out of the population of binaries theorized to produce a gravitational wave background (GWB). In this…
Ultra-luminous quasars ($M_{1450} \leq -29$) provide us with a rare view into the nature of the most massive and most rapidly accreting supermassive black holes (SMBHs). Following the discovery of two of these extreme sources,…
The gravitational waves generated during supermassive black hole (SMBH) coalescence are prime candidates for detection by the satellite LISA. We use the extended Press-Schechter formalism combined with empirically motivated estimates for…
We present deep near-infrared spectroscopy of six quasars at 6.1<z<6.7 with VLT/X-Shooter and Gemini-N/GNIRS. Our objects, originally discovered through a wide-field optical survey with the Hyper Suprime-Cam (HSC) Subaru Strategic Program…
We assess the effects of super-massive black hole (SMBH) environments on the gravitational-wave (GW) signal from binary SMBHs. To date, searches with pulsar timing arrays for GWs from binary SMBHs, in the frequency band $\sim1-100$\,nHz,…
I review the current status of quasar black hole (BH) mass estimations. Spectroscopic methods have been developed to estimate BH mass in broad line quasars to an accuracy of ~0.5 dex. Despite their popularity, significant issues and…
We study the prospect of using TianQin to detect stellar-mass binary black holes (SBBHs). We estimate the expected detection number as well as the precision of parameter estimation on SBBH inspirals, using five different population models.…
In the local universe, the masses of Super-Massive Black-Holes (SMBH) appear to correlate with the physical properties of their hosts, including the mass of the dark-matter halo. Using these clues as a starting point many studies have…
We report the first results of a sub-solar mass compact binary search using the data from the first part of the fourth observing run (O4a) of the Advanced LIGO detectors. Sub-solar mass neutron stars and black holes are not expected to form…
We report on a gravitational wave search for compact binary coalescences involving at least one component with mass between $0.2 M_\odot$ to $1 M_\odot$, and ratio of component masses between 0.1 and 1. The analysis uses data collected by…
The quasar lifetime $t_{\rm\,Q}$ is one of the most fundamental quantities for understanding quasar evolution and the growth of supermassive black holes (SMBHs), but remains uncertain by several orders of magnitude. In a recent study we…
Periodic quasars have been suggested as candidates for hosting binary supermassive black holes (SMBHs), although alternative scenarios remain possible to explain the optical light curve periodicity. To test the alternative hypothesis of…