Related papers: Pending problems in QSOs
We evaluate with numerical simulations the hypothesis that BL Lacertae objects are the remnants of Quasi Stellar Objects. This hypothesis is based on their highly peculiar redshift evolution. They have a comoving space density that…
Observed magnitudes of many quasars with redshifts exceeding $z=5$ correspond to luminosities $L_{\rm bol} > 10^{14}\,L_\odot$. The standard mechanism of quasar energy release by accretion suggests that masses of superluminous quasars…
It was previously shown from the redshifts and positions of the compact, high-redshift objects near the Seyfert galaxy NGC 1068 that they appear to have been ejected from the center of the galaxy in at least four similarly structured…
Together with the CMB, the three sources of information that astronomers have at high redshift as probes of the formation and evolution of the LSS are QSOs, galaxies and absorbers observed in the spectrum of distant background objects. In…
The uncertain origin of the recently-discovered `changing-looking' quasar phenomenon -- in which a luminous quasar dims significantly to a quiescent state in repeat spectroscopy over ~10 year timescales -- may present unexpected challenges…
We present an analysis of the submillimetre/X-ray properties of 19 X-ray absorbed, Compton-thin quasi-stellar objects (QSOs) selected to have luminosities and redshifts which represent the peak of cosmic QSO activity. i.e. ~L* objects at…
Objects that are on the verge of being extremal black holes but actually are distinct in many ways are called quasi-black holes. Quasi-black holes are defined here and treated in a unified way through the displaying of their properties. The…
The theoretically expected amplitude of the associations of background quasars with foreground galaxies as a result of gravitational lensing has been updated in this paper. Since the galactic matter alone yields an amplitude of quasar…
Accounting for ~20% of the total QSO population, Broad Absorption Line QSOs are still an unsolved problem in the AGN context. They present wide troughs in the UV spectrum, due to material with velocities up to 0.2 c toward the observer. The…
We present a model for the cosmological evolution of quasars (QSOs) under the assumption that they are powered by massive accreting black holes. Accretion flows around massive black holes make a transition from high radiative efficiency…
Obscuration in high-redshift quasi-stellar objects (QSO) has a profound impact on our understanding of the evolution of supermassive black holes across the cosmic time. An accurate quantification of its relevance is therefore mandatory. We…
Astronomers occasionally detect an object having unexpected shape, unexplainable photometry, or unprecedented spectra that are inconsistent with our contemporary knowledge of the universe. Upon careful assessment, many of these anomalies…
This paper considers the hypothesis that BL Lacertae objects (BLLs) are the beamed remnants of Quasi Stellar Objects. The hypothesis explains why BLLs do not undergo the strong evolution seen in other active galactic nuclei since it…
We test the hypothesis whether high redshift QSOs would preferentially appear in small groups or pairs, and if they are associated with massive, young clusters. We carried out a photometric search for \Ly emitters on scales $\lesssim 10…
Quasars, the brightly glowing disks of material that can form around the super-massive black holes at the centres of large galaxies, are amongst the most luminous astronomical objects known and so can be seen at great distances. The most…
Last year (2013) was more or less the 50th anniversary of the discovery of quasars. It is an interesting time to review what we know (and don't know) about them both empirically and theoretically. These compact sources involving line…
Three high-redshift (z=2) and high luminosity (M_B < -28 mag for Ho = 50, qo=0.5) QSOs, two radio-quiet one radio-loud, were imaged in R, I and K bands. The luminosities, colours and sizes of the hosts overlap with those of actively…
Exceptionally bright quasars with redshifts up to z=6.28 have recently been discovered. Quasars are thought to be powered by the accretion of gas onto supermassive black holes at the centres of galaxies. Their maximum (Eddington) luminosity…
A picture has emerged connecting QSOs with Sub-Millimetre Galaxies (SMGs) through an evolutionary sequence in which forming galaxies are initially FIR-luminous but X-ray weak, similar to known SMGs. As the black hole and spheroid grow with…
Quasars are the most luminous non-transient sources in the epoch of cosmological reionization (i.e., which ended a billion years after the Big Bang, corresponding to a redshift of z ~ 5), and are powerful probes of the inter-galactic medium…