A Multimessenger View of Supermassive Black Holes and the Quasar Main Sequence

Dear Colleagues,

The last 30 years has seen a major step forward in the analysis of optical and UV spectroscopic data of large quasar samples. It is an important achievement that the main empirical correlates can now be organized along what has become known as the Eigenvector 1 “main sequence” (MS) of quasars. The current research is oriented toward the definition and the expansion of the MS correlates, as well as to the exploitation of the MS systematic trends as a basic input to physical and dynamical modelling of the quasar structure, including the accretion disk structure. Nowadays, it has become widely accepted that the main physical parameter governing the sequence is Eddington ratio, i.e., the ratio between AGN luminosity and black hole mass or equivalently, between radiation and gravitation forces—a parameter that for AGN takes the role of mass for stars. This means that a number of applications have become possible, among them the estimate of the accretion disk wind properties and of the metal enrichment in large samples of AGN, and, finally, the use of quasars as high-redshift distance indicators. The present Special Issue is aimed to host several contributions (both theoretical and observational) dealing with diverse aspects related to the main sequence at the frontier of research on AGN.

Potential topics include, but are not limited to:

• The quasar Eigenvector 1/main sequence;
• Accretion disk structure and connection with observational multi-frequency properties;
• The broad line emitting region;
• AGN winds at all frequencies and powers;
• The host-galaxy/active nucleus connection: star formation and metal enrichment;
• The radio loud/radio quiet dichotomy;
• The evolution of accreting black holes across cosmic times;
• Intrinsic luminosity effects and quasars as cosmological standard candles. 

Dr. Ascension Del Olmo
Dr. Paola Marziani
Guest Editors

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• quasars
• active galactic nuclei
• supermassive black holes
• quasar main sequence

1. Carolina Andoine

2. Alberto Rodriguez Ardila

3. Erika Benítez 

4. Andjelka Kavacevic

5. Dragana Ilic 

6. Luka Popovic 

7. Ascension Del Olmo

8. Paola Marziani