Author:
Marziani Paola,Bon Edi,Bon Natasa,del Olmo Ascension,Martínez-Aldama Mary,D’Onofrio Mauro,Dultzin Deborah,Negrete C.,Stirpe Giovanna
Abstract
Quasars accreting matter at very high rates (known as extreme Population A (xA) or super-Eddington accreting massive black holes) provide a new class of distance indicators covering cosmic epochs from the present-day Universe up to less than 1 Gyr from the Big Bang. The very high accretion rate makes it possible that massive black holes hosted in xA quasars can radiate at a stable, extreme luminosity-to-mass ratio. This in turn translates into stable physical and dynamical conditions of the mildly ionized gas in the quasar low-ionization line emitting region. In this contribution, we analyze the main optical and UV spectral properties of extreme Population A quasars that make them easily identifiable in large spectroscopic surveys at low- ( z ≲ 1 ) and intermediate-z (2 ≲ z ≲ 2.6), and the physical conditions that are derived for the formation of their emission lines. Ultimately, the analysis supports the possibility of identifying a virial broadening estimator from low-ionization line widths, and the conceptual validity of the redshift-independent luminosity estimates based on virial broadening for a known luminosity-to-mass ratio.
Subject
Condensed Matter Physics,Nuclear and High Energy Physics,Atomic and Molecular Physics, and Optics
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