This paper is based on the assumption that the observational evidence to date does point to the possibility that high-redshift quasars are physically associated with low-redshift galaxies. It is first argued that the excess ...

Static, spherically symmetric configurations of core and envelope type have been considered in General Relativity as central gravitational redshift models for the quasi-stellar objects (QSOs) and an attempt has been made ...

New high-resolution images of the field of the quasar MR 2251-178 obtained in the forbidden O III lambda-5007 and O II lambda-3727 lines with an ESA photon counting detector. The data are interpreted as a further evidence ...

The study of narrow-line Seyfert 1 galaxies (NLS1s) is now mostly limited to low redshift (z < 0.8) because their definition requires the presence of the Hβ emission line, which is redshifted out of the spectral coverage ...

We have used optical V and R band observations from the Massive Compact Halo Object (MACHO) project on a sample of 59 quasars behind the Magellan ic clouds to study their long term optical flux and colour ...

We have taken K, R, V, and B band images of Q 2345+007, which has been claimed to be the gravitationally lensed quasar with the widest separation between the two images (approximately equal 7 arcsec), although the lens ...

It is argued that accreting supermassive black holes ejected from centers of galaxies are the likely models for the quasars observed in association with galaxies. Also pointed out are the implications of a recent suggestion ...

Quasar absorption lines are an important tool to probe the universe at high redshifts, as they enable us to observe galaxies and intergalactic clouds at large distances, which are virtually inaccessible otherwise. This ...

The coherent plasma process, parametric decay instability (PDI), has been applied to a homogeneous and unmagnetized plasma. These instabilities cause anomalous absorption of strong electromagnetic radiation under specific ...