Related papers: The Quasar Mass-Luminosity Plane III: Smaller Erro…

We present the single-epoch black hole mass (M$_{\rm BH}$) calibrations based on the rest-frame UV and optical measurements of Mg II 2798\AA\ and H$\beta$ 4861\AA\ lines and AGN continuum, using a sample of 52 moderate-luminosity AGNs at…

We present the first detection of weak gravitational lensing around spectroscopically confirmed dwarf galaxies, using the large overlap between DESI DR1 spectroscopic data and DECADE/DES weak lensing catalogs. A clean dwarf galaxy sample…

We compiled a catalogue of about 4000 SDSS quasars including individual estimators V for the variability strength, virial black hole masses M, and mass accretion rates dM/dt from the Davis-Laor scaling relation. We confirm significant…

We present observations of SDSSp J104433.04--012502.2, a luminous quasar at z=5.80 discovered from Sloan Digital Sky Survey (SDSS) multicolor imaging data. This object was selected as an i'-band dropout object, with i*=21.8 +/- 0.2, z*=19.2…

We present a new approach to capturing the broad diversity of emission line and continuum properties in quasar spectra. We identify populations of spectrally similar quasars through pixel-level clustering on 12,968 high signal-to-noise…

This paper reports on the extreme ultraviolet (EUV) spectrum of three low redshift ($z \sim 0.6$) radio loud quasars, 3C 95, 3C 57 and PKS 0405-123. The spectra were obtained with the Cosmic Origins Spectrograph (COS) of the Hubble Space…

We test general relativity (GR) at the effective redshift $\bar{z} \sim 1.5$ by estimating the statistic $E_G$, a probe of gravity, on cosmological scales $19 - 190\,h^{-1}{\rm Mpc}$. This is the highest-redshift and largest-scale…

We present an analysis of quasar variability from data collected during a photometric monitoring of 50 objects carried out at CNPq/Laboratorio Nacional de Astrofisica, Brazil, between March 1993 and July 1996. A distinctive feature of this…

The observed lensed fraction of high-redshift quasars $(\sim0.2\%)$ is significantly lower than previous theoretical predictions $(\gtrsim4\%)$. We revisit the lensed fraction of high-redshift quasars predicted by theoretical models, where…

We present a method for obtaining accurate black hole (BH) mass estimates from the MgII emission line in active galactic nuclei (AGNs). Employing the large database of AGN measurements from the Sloan Digital Sky Survey (SDSS) presented by…

This study is focused on the observational measurement of the viewing angle of individual quasars by modeling the broadband quasar spectrum ranging from the infra-red (IR) to the soft X-ray band. Sources are selected from various published…

We present results from analysis of spectra from a sample of ~900 quasars from the Sloan Digital Sky Survey. These objects were selected for their intermediate redshift (1.2<z<1.8), placing MgII and UV FeII in the optical band pass,…

We present the discovery of five new quasars at z>5.7, selected from the multicolor imaging data of the Sloan Digital Sky Survey (SDSS). Three of them, at redshifts 5.93, 6.07, and 6.22, were selected from ~1700 deg^2 of new SDSS Main…

The black hole (BH) mass and luminosity are key factors in determining how a quasar interacts with its environment. In this study, we utilise data from the European Southern Observatory Large Programme XQ-100, a high-quality sample of 100…

We report the discovery of a quasar at z = 7.07, which was selected from the deep multi-band imaging data collected by the Hyper Suprime-Cam (HSC) Subaru Strategic Program survey. This quasar, HSC J124353.93+010038.5, has an order of…

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…

Using Extreme Value Statistics applied to the observed galaxy stellar mass and the UV luminosity functions, we empirically estimate masses and luminosities of the most extreme galaxies in cosmological surveys, including the full sky. We…

We measure quasar variability using the Panoramic Survey Telescope and Rapid Response System 1 Survey (Pan-STARRS1 or PS1) and the Sloan Digital Sky Survey (SDSS) and establish a method of selecting quasars via their variability in 10,000…

In the standard model, a lower bound to the Higgs mass (for a given top quark mass) exists if one requires that the standard model vacuum be stable. This bound is calculated as precisely as possible, including the most recent values of the…

We quantify the variability of faint unresolved optical sources using a catalog based on multiple SDSS imaging observations. The catalog covers SDSS Stripe 82, and contains 58 million photometric observations in the SDSS ugriz system for…