Related papers: The Large-Scale Distribution of Quasars
We use the first data release of the 2-degree Field Quasar survey to investigate the effect of gravitational magnification by foreground absorbing systems on background quasars. We select two populations of quasars from this sample: one…
Based on the SDSS catalog, we have found new close quasar-galaxy pairs. Quasars projected onto the halos of nearer galaxies are encountered among the multitude of quasars observed at various distances from us. Among them there are quasars…
The distribution on the sky of clusters of galaxies shows significant association with relatively nearby, large, active galaxies. The pattern is that of clusters paired equidistant across a central galaxy with the apparent magnitudes and…
By virtue of their high galaxy space densities and their large spatial separations, clusters are efficient and accurate tracers of the large-scale density and velocity fields. Substantial progress has been made over the past decade in the…
A fundamental prediction of relativistic cosmologies is that, due to the expansion of space, observations of the distant cosmos should be time dilated and appear to run slower than events in the local universe. Whilst observations of…
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…
The 2dF Galaxy Redshift Survey is the first to observe more than 100,000 redshifts, making possible precise measurements of many aspects of galaxy clustering. The spatial distribution of galaxies can be studied as a function of galaxy…
We introduce a statistical quantity, known as the $K$ function, related to the integral of the two--point correlation function. It gives us straightforward information about the scale where clustering dominates and the scale at which…
We demonstrate that gravitationally lensed quasars are easily recognized using image subtraction methods as time variable sources that are spatially extended. For Galactic latitudes |b|>20 deg, lensed quasars dominate the population of…
The objective of the XMM-LSS Survey is to map the large scale structure of the universe, as highlighted by clusters and groups of galaxies, out to a redshift of about 1, over a single 8x8 sq.deg. area. For the first time, this will reveal…
Quasar pairs, a special subclass of galaxy pairs, are valuable in the investigation of quasar interaction, clustering, co-evolution between the two quasars' host galaxies, the growth of supermassive black holes, as well as the formation and…
The observation of redshift-dependent coherent orientations of quasar polarisation vectors over cosmological distances in some regions of the sky is reviewed. Based on a good-quality sample of 355 measured quasars, this observation seems to…
The Clowes & Campusano (1991) Large Quasar Group (LQG) at <z> = 1.28 has been re-examined using the quasar data from the DR7QSO catalogue of the Sloan Digital Sky Survey. In the 1991 discovery, the LQG impinged on the northern, southern and…
Understanding the formation and evolution of the cosmic web of galaxies is a fundamental goal of cosmology, using various tracers of the cosmic large-scale structure at an ever wider range of redshifts. Our principal aim is to advance the…
Hot big bang cosmology says nothing about the topology of the Universe. A topology-independent algorithm is presented which is complementary to that of Lehoucq et al. 1996 and which searches for evidence of multi-connectedness using…
The statistics of galactic-scale quasar pairs can elucidate our understanding of the dynamical evolution of supermassive black hole (SMBH) pairs, the duty cycles of quasar activity in mergers, or even the nature of dark matter, but have…
We examine the dependence of the spatial two-point correlation function of quasars $\xi_{qq}(r,z)$ at different redshifts on the initial power spectrum in flat cosmological models. Quasars and other elements of the large-scale structure of…
In this paper, we study gravitational lensing by groups of galaxies. Since groups are abundant and therefore have a large covering fraction on the sky, lensing by groups is likely to be very important observationally. Besides, it has…
One of the main problems of observational cosmology is to determine the range in which a reliable measurement of galaxy correlations is possible. This corresponds to determine the shape of the correlation function, its possible evolution…
We present photometric and spectroscopic observations of two close quasar-quasar pairs found in the Large Bright Quasar Survey (LBQS) (Hewett et al. 1995, AJ, 109, 1498). The two components of the 2153-2056 pair ($z=1.845$,…