Related papers: Quasar Pairs as Large--Scale Structure tracers
Based on a new sample of 355 quasars with significant optical polarization and using complementary statistical methods, we confirm that quasar polarization vectors are not randomly oriented over the sky with a probability often in excess of…
We cross-correlate a cosmic microwave background (CMB) lensing map with the projected space densities of quasars to measure the bias and halo masses of a quasar sample split into obscured and unobscured populations, the first application of…
Quasars with a high redshift (z) are important to understand the evolution processes of galaxies in the early universe. However only a few of these distant objects are known to this date. The costs of building and operating a 10-metre class…
Models and observations suggest that luminous quasar activity is triggered by mergers, so it should preferentially occur in the most massive primordial dark matter haloes, where the frequency of mergers is expected to be the highest. Since…
We present detailed clustering measurements for a flux limited sample of 14,000 quasars extracted from the 2dF QSO Redshift Survey (2QZ) in the redshift range 0.8<z<2.1. After splitting the sample into three redshift bins and each of them…
We have obtained deep, multi-band imaging observations around three of the most distant known quasars at redshifts z>6. Standard accretion theory predicts that the supermassive black holes present in these quasars were formed at a very…
Galaxy cluster merger statistics are an important component in understanding the formation of large-scale structure. Unfortunately, it is difficult to study merger properties and evolution directly because the identification of cluster…
The comparison of the orientations of the optical-polarization vectors of quasars that are separated by billions of light-years has led to the discovery that they are aligned instead of pointing in random directions as expected. This…
Dual and lensed quasars are valuable astrophysical targets in many aspects. Dual quasars, considered as the precursors of supermassive black hole binaries, can provide crucial insights into how black hole mergers drive the growth of…
We present the clustering of DEEP2 galaxies at 0.7<z<1.4 around quasars identified using both the SDSS and DEEP2 surveys. We measure the two-point cross-correlation of a sample of 36 optically-selected, spectroscopically-identified quasars…
The majority of bright distant quasars $(z {}^{>}_{\sim} 1)$ may form in massive mergers appearing in compact galaxy groups in/and young clusters. The expected tests are (i) large correlation signal for medium-$z$ QSOs $(1 < z < 2)$ and…
Groups and clusters of galaxies hosting a quasar can be found through the detection of Lyman-alpha absorption lines beyond the quasar redshift. The effect occurs whenever the distortion to the redshift distribution of Lyman-alpha clouds…
Motivated by the significant overdensity of background bright quasars recently detected behind the foreground clusters of galaxies on scale of $10$ arcminutes, we have investigated the possibility of attributing the quasar-cluster…
We have investigated the spatial distribution of quasars and its relationship with redshift by using the two-point correlation function, the variance of cell counts and the conditional density as a function of redshift. By comparing our…
A survey measuring quasar polarization vectors has been started in two regions towards the North and South Galactic Poles. Here, We review the discovery of significant correlations of orientations of polarization vectors over huge angular…
Recent observations from the EIGER JWST program have measured for the first time the quasar-galaxy cross-correlation function at $z\approx6$. The auto-correlation function of faint $z\approx6$ quasars was also recently estimated. These…
The Clowes-Campusano Large Quasar Group (LQG) is the largest known structure at high redshifts, with at least 18 quasars at z~1.3 forming a structure ~200 Mpc across. We are conducting an ultra-deep optical and deep NIR study to examine the…
We use the large catalogues of haloes available for the Millennium Simulation to test whether recently merged haloes exhibit stronger large-scale clustering than other haloes of the same mass. This effect could help to understand the very…
Using ~300,000 photometrically classified quasars, by far the largest quasar sample ever used for such analyses, we study the redshift and luminosity evolution of quasar clustering on scales of ~50 kpc/h to ~20 Mpc/h from redshifts of…
We investigate the environments of quasars such as number distribution of galaxies using a semi-analytic model which includes both galaxy and quasar formations based on the hierarchical clustering scenario. We assume that a supermassive…