90 datasets found

Mass accretion rates in dimensionless and physical units, and efficiency factors describing the total radiant luminosity of the disc and the beam power of the outflow are...

We investigate the responsiveness of the 2798{AA} MgII broad emission line in active galactic nuclei (AGNs) on time-scales of several years. Our study is based on a sample of...

Radio-loud quasars (RLQs) are more X-ray luminous than predicted by the X-ray-optical/UV relation (i.e. L_x_{prop.to}L_uv_^{gamma}^) for radio-quiet quasars (RQQs). The excess...

The mechanisms responsible for the production of relativistic jets from supermassive black holes (SMBHs) accreting at near-Eddington rates are not well understood. Simple...

We present the Global Rapid Advanced Network Devoted to the Multi-messenger Addicts (GRANDMA). The network consists of 21 telescopes with both photometric and spectroscopic...

The gigahertz peaked spectrum (GPS) sources, compact steep spectrum (CSS) radio sources, and high-frequency peaker (HFP) radio sources are thought to be young radio active...

We present the results of a systematic search for quasars in the Catalina Real-time Transient Survey exhibiting both strong photometric variability and spectroscopic variability...

Narrow-line regions excited by active galactic nuclei (AGNs) are important for studying AGN photoionization and feedback. Their strong [OIII] lines can be detected with...

It is well known that environment affects galaxy evolution, which is broadly related to supermassive black hole (SMBH) growth. We investigate whether SMBH evolution also depends...

We present ground-based and Swift photometric and spectroscopic observations of the candidate tidal disruption event (TDE) ASASSN-14li, found at the centre of PGC 043234 (d~90...

We present a systematic study of the orbital inclination effects on black hole transients fast time-variability properties. We have considered all the black hole binaries that...

We analyze a sample of 21 "bare" Seyfert 1 active galactic nuclei, a subclass of Seyfert 1 galaxies, with intrinsic absorption N_H_~10^20^cm^-2^, in the local Universe...

We study the general physical properties of Fermi blazars using the Fermi fourth source catalog data (4FGL-DR2). The quasi-simultaneous multiwavelength data of Fermi blazars are...

This paper provides the compilations of properties of the quasars newly obtained by the Sloan Digital Sky Survey (SDSS) during the fourth stage (SDSS-IV). The catalog is...

We present measurements of broad emission lines and virial estimates of supermassive black hole masses (M_BH_) for a large sample of ultrahard X-ray-selected active galactic...

Quasars behind the Galactic plane (GPQs) are important astrometric references and valuable probes of Galactic gas, yet the search for GPQs is difficult due to severe extinction...

Despite their importance for astrometry and navigation, the active galactic nuclei (AGNs) that comprise the International Celestial Reference Frame (ICRF) are relatively poorly...

We present a catalog of central engine properties, i.e., black hole mass (M_BH_) and accretion luminosity (L_disk_), for a sample of 1077 blazars detected with the Fermi Large...

In this work, we present the first results of the long-term high-cadence spectroscopic monitoring of 15 PG quasars with relatively strong FeII emission, as a part of a broader...

Optical time-domain astronomy has grown rapidly in the past decade, but the dynamic infrared sky is rarely explored. Aiming to construct a sample of mid-infrared outbursts in...