Related papers: The central engine of the highest redshift blazar

Observations of the most luminous quasars at high redshifts ($z > 6$) have revealed that the largest supermassive black holes (SMBHs) at those epochs tend to be substantially overmassive relative to their host galaxies compared to the local…

We have selected SDSS J222032.50+002537.5 and SDSS J142048.01+120545.9 as best blazar candidates out of a complete sample of extremely radio-loud quasars at z>4, with highly massive black holes. We observed them and a third serendipitous…

Successful observations of the seven predicted bremsstrahlung flares from the unique bright blazar OJ 287 firmly point to the presence of a nanohertz gravitational wave (GW) emitting supermassive black hole (SMBH) binary central engine. We…

Massive Black Hole (MBH) seeds at redshift $z \gtrsim 10$ are now thought to be key ingredients to explain the presence of the super-massive ($10^{9-10} \, \mathrm{M_{\odot}}$) black holes in place $ < 1 \, \mathrm{Gyr}$ after the Big Bang.…

Luminous quasars powered by accreting supermassive black holes (SMBHs) have been found in the early Universe at $z \gtrsim 7.5$, which set a strong constraint on both the seed black hole mass and the rapid growth of the SMBHs. In this work,…

From near-infrared spectroscopic measurements of the MgII emission line doublet, we estimate the black hole (BH) mass of the quasar, SMSS J215728.21-360215.1, as being (3.4 +/- 0.6) x 10^10 M_sun and refine the redshift of the quasar to be…

We intend to use the impact of microlensing on the Fe III emission line blend along with a measure of its gravitational redshift to estimate the mass of the quasar's central supermassive black hole (SMBH). We fit the Fe III feature in…

Starting from the ~50000 quasars of the Sloan Digital Sky Survey for which MgII line width and 3000 A monochromatic flux are available, we aim to study the dependence of the mass of active black holes on redshift. We focus on the observed…

Observations of $z \sim 6$ quasars powered by supermassive black holes (SMBHs; $M_{\rm BH} \sim 10^{8-10}\, M_\odot$) challenge our current understanding of early black hole (BH) formation and evolution. The advent of the James Webb Space…

SMSS J0521-4351 is reportedly the most luminous quasar known to date, and assuming a mean radiative efficiency of 0.1, it is inferred to be the fastest-growing black hole, accreting approximately one solar mass per day. Assessing the…

Observations of luminous quasars at $z\gtrsim7$ reveal supermassive black holes (SMBHs) with inferred masses $M_{\rm BH}\sim10^9 \, M_\odot$ formed within the first $\sim700$~Myr of cosmic history. Standard growth channels \textrm{ -- }…

The search for extremely massive high redshift blazars is essential to put strong constraints on the supermassive black holes formation theories. Up to now, the few blazars known to have a redshift larger than 4 have been discovered…

We report on Gemini, NuSTAR and 8-year Fermi observations of the most distant blazar QSO~J0906$+$6930 ($z=5.48$). We construct a broadband spectral energy distribution (SED) and model the SED using a synchro-Compton model. The measurements…

JWST is unveiling for the first time accreting black holes (BHs) with masses of 10^6 - 10^7 Msun at z > 4, with the most distant residing in GNz11 at z = 10.6. Are we really surprised to find them in the nuclei of z = 5 - 11 galaxies? Here…

We present a study of the central engine in the broad-line radio galaxy 3C 109. To investigate the immediate surrounding of this accreting, supermassive black hole, we perform a multi-epoch broad-band spectral analysis of a joint NuSTAR/XMM…

A super-massive black hole (SMBH) binary in the core of the blazar OJ 287 has been invoked in previous works to explain its observed optical flare quasi-periodicity. Following this picture, we investigate a hadronic origin for the X-ray and…

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,…

So far, roughly 40 quasars with redshifts greater than z=6 have been discovered. Each quasar contains a black hole with a mass of about one billion solar masses ($10^9 M_\odot$). The existence of such black holes when the Universe was less…

The recent discoveries of luminous quasars at high redshifts imply that black holes more massive than a few billion solar masses have been assembled already when the universe was less than a billion years old. We show that the existence of…

Given a large-scale mixture of self-interacting dark matter (SIDM) particles and baryon matter distributed in the early Universe, we advance here a two-phase accretion scenario for forming supermassive black holes (SMBHs) with masses around…