Quasars: From the Physics of Line Formation to Cosmology

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 make...

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Veröffentlicht in:Atoms 2019-02, Vol.7 (1), p.18
Hauptverfasser: Marziani, Paola, Bon, Edi, Bon, Natasa, del Olmo, Ascension, Martínez-Aldama, Mary Loli, D’Onofrio, Mauro, Dultzin, Deborah, Negrete, C. Alenka, Stirpe, Giovanna M.
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Sprache:eng
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Zusammenfassung: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.
ISSN:2218-2004
2218-2004
DOI:10.3390/atoms7010018