相关论文: The High-z Quasar Hubble Diagram

We aim to evaluate the behaviour of our 22 high-redshift (2.2 < z < 3.7) and high-luminosity (47.39 < Lbol < 48.36) quasars in the context of the 4-Dimensional Eigenvector 1. Our approach involves studying quasar physics through…

The ultraviolet (UV) spectra of 16 blazars (<z> ~1) from the archives of the Hubble Space Telescope Faint Object Spectrograph have been analyzed in order to study in a systematic way the properties oftheir broad UV emission lines. We find…

We present the initial results from our search for high redshift, z > 6, quasars using near infrared data from the UKIRT Infrared Deep Sky Survey (UKIDSS) Large Area Survey (LAS). Our analysis of 106 deg^2 of sky from Data Release 1 (DR1)…

We present a simple model for the relationship between quasars, galaxies, and dark matter halos from 0.5<z<6. In the model, black hole (BH) mass is linearly related to galaxy mass, and galaxies are connected to dark matter halos via…

For many years some astronomers have continued to argue, using redshift periodicities and quasar-galaxy associations, that quasars may be closer than their redshifts imply. Here, for the first time using raw radio data, I re-examine this…

We present new near-infrared (IR) observations of the H$\beta\ \lambda4861$ and MgII $\lambda2798$ lines for 32 luminous quasars with $3.2<z<3.9$ using the Palomar Hale 200 inch telescope and the Large Binocular Telescope. We find that the…

We report the discovery of four quasars with $M_{1450} \gtrsim -25.0$ mag at $z\sim5$ and supermassive black hole mass measurement for one of the quasars. They were selected as promising high-redshift quasar candidates via deep learning and…

We present high S/N UV spectra for eight quasars at z $\sim$ 3 obtained with VLT/FORS. The spectra enable us to analyze in detail the strong and weak emission features in the rest-frame range 1300-2000 A of each source (Ciii]$\lambda$1909,…

We present the first results of a survey for high redshift, z $\ge$ 6, quasars using izY multi-colour photometric observations from the Dark Energy Survey (DES). Here we report the discovery and spectroscopic confirmation of the $\rm…

We investigate the relationship between the mass of the central supermassive black hole, M_bh, and the host galaxy luminosity, L_gal, in a sample of quasars from the Sloan Digital Sky Survey (SDSS) Data Release 7 (DR7). We use composite…

We studied the spectra of six $z \sim 2.2$ quasars obtained with the X-shooter spectrograph at the Very Large Telescope. The redshift of these sources and X-shooter's spectral coverage allow us to cover the rest spectral range $\sim1200 -…

Distant luminous quasars provide important information on the growth of the first supermassive black holes, their host galaxies and the epoch of reionization. The identification of quasars is usually performed through detection of their…

Recently, two classes of quasar samples were identified, which are promising as new cosmological probes extending to higher redshifts. The first sample uses the nonlinear relation between the ultraviolet and X-ray luminosities of quasars to…

Luminous distant quasars are unique probes of the high redshift intergalactic medium (IGM) and of the growth of massive galaxies and black holes in the early universe. Absorption due to neutral Hydrogen in the IGM makes quasars beyond a…

In this paper, based on a 2.29 GHz VLBI all-sky survey of 613 milliarcsecond ultra-compact radio sources with $0.0035<z<3.787$, we describe a method of identifying the sub-sample which can serve as individual standard rulers in cosmology.…

We use a recently proposed luminosity distance measure for relatively nearby active galactic nuclei (AGNs) to test the predicted expansion of the Universe in the R_h=ct and LCDM cosmologies. This comparative study is particularly relevant…

High-redshift quasars are currently the only probes of the growth of supermassive black holes and potential tracers of structure evolution at early cosmic time. Here we present our candidate selection criteria from the Panoramic Survey…

Although Type Ia supernova cosmology has now reached a mature state, it is important to develop as many independent methods as possible to understand the true nature of dark energy. Recent studies have shown that Type II supernovae (SNe II)…

The proposal to use HII galaxies (HIIGx) and giant extragalactic HII regions (GEHR) as standard candles to construct the Hubble diagram at redshifts beyond the current reach of Type Ia supernovae has gained considerable support recently…

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…