Related papers: Building the high-redshift Hubble Diagram with qua…
We examine the clustering of quasars over a wide luminosity range, by utilizing 901 quasars at $\overline{z}_{\rm phot}\sim3.8$ with $-24.73<M_{\rm 1450}<-22.23$ photometrically selected from the Hyper Suprime-Cam Subaru Strategic Program…
The Hubble diagram is one of the cornerstones of observational cosmology. It is usually analysed assuming that, on average, the underlying relation between magnitude and redshift matches the prediction of a…
A number of deep, wide-field, near-infrared surveys employing new infrared cameras on 4m-class telescopes are about to commence. These surveys have the potential to determine the fraction of luminous dust-obscured quasars that may have…
We perform a cosmographic analysis using several cosmological observables such as the luminosity distance moduli, the volume distance, the angular diameter distance and the Hubble parameter. These quantities are determined using different…
Optically bright, wide separation double (gravitationally lensed) quasars can be easily monitored, leading to light curves of great importance in determining the Hubble constant and other cosmological parameters, as well as the structure of…
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…
A hypothesis of curvature pressure is used to derive a static and stable cosmology with a tired-light redshift. The idea is that the high energy particles in the inter-galactic medium do not travel along geodesics because of the strong…
In this letter, the old issue of whether redshifts of quasars are of cosmological origin is investigated. We make a plot of absorption redshifts versus emission redshifts for quasars with large amounts of data. Our study shows that, almost…
Immensely bright quasars and radio-loud active galactic nuclei (AGNs) provide an enticing opportunity to construct standard candles detectable up to the very early universe. An analytic theory is proposed to measure the distance to powerful…
The desire to extend the Hubble Diagram to higher redshifts than the range of current Type Ia Supernovae observations has prompted investigation into spectral correlations in Gamma Ray Bursts, in the hope that standard candle-like…
We test the isotropy of the Hubble diagram. At small redshifts, this is possible without assumptions on the cosmic inventory and provides a fundamental test of the cosmological principle. At higher redshift we check for the self-consistency…
Some proposals to account for the highest energy cosmic rays predict that they should point to their sources. We study the five highest energy events (E>10^20 eV) and find they are all aligned with compact, radio-loud quasars. The…
The clustering of quasars on small scales yields fundamental constraints on models of quasar evolution and the buildup of supermassive black holes. This paper describes the first systematic survey to discover high redshift binary quasars.…
An important part of cosmological model fitting relies on correlating distance indicators of objects (for example type Ia supernovae) with their redshift, often illustrated on a Hubble diagram. Comparing the observed correlation with a…
We investigate the distribution of companion galaxies around quasars using {\em Hubble Space Telescope} ({\em HST}) Advanced Camera for Surveys Wide Field Camera (ACS/WFC) archival images. Our master sample contains 532 quasars which have…
Quasars are among the most luminous objects in the universe, and they can be studied in detail up to the highest known redshift. Assuming that the gas associated with quasars is closely related to the interstellar medium of the host galaxy,…
The current expansion rate of the Universe, the Hubble constant $H_0$, is an important cosmological quantity. However, two different ways to measure its value do not agree -- building a low-redshift distance ladder leads to a higher value…
Quasars at high redshift provide direct information on the mass growth of supermassive black holes and, in turn, yield important clues about how the Universe evolved since the first (Pop III) stars started forming. Yet even basic questions…
We construct a parametric SED model which is able to reproduce the average observed SDSS-UKIDSS-WISE quasar colours to within one tenth of a magnitude across a wide range of redshift $(0<z<5)$ and luminosity $(-22>M_i>-29)$. This model is…
We present low-resolution ultraviolet spectra of 14 low redshift (z<0.8) quasars observed with HST/STIS as part of a Snap project to understand the relationship between quasar outflows and luminosity. By design, all observations cover the…