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      High Eddington accreting quasar spectra as discovery tools: current state and challenges

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          Abstract

          Broad emitting line regions (BLR) in active galaxies are primarily emitted by photoionization processes that are driven by the incident continuum arising from the underlying, complex geometrical structure, i.e. accretion disk and corona around a supermassive black hole. Modelling the broad-band spectral energy distribution (SED) effective in ionizing the gas-rich BLR is key to understanding the various radiative processes at play and their importance that eventually leads to the emission of emission lines from diverse physical conditions. Photoionization codes are a useful tool to investigate two aspects - the importance of the shape of the SED, and the physical conditions in the BLR. In this work, we provide the first results focusing on a long-standing issue pertaining to the anisotropic continuum radiation from the very centres (few 10-100 gravitational radii) of these active galaxies. The anisotropic emission is a direct consequence of the development of a geometrically and optically thick structure at regions very close to the black hole due to a marked increase in the accretion rates. Incorporating the radiation emerging from such a structure in our photoionization modelling, we are successful in replicating the observed emission line intensities, in addition to the remarkable agreement on the location of the BLR with current reverberation mapping estimates. This study took advantage of the look at the diversity of the Type-1 active galactic nuclei (AGNs) provided by the main sequence of quasars. The main sequence permitted to locate of the super Eddington sources in observational parameter space and to constrain the distinctive} physical conditions of their line-emitting BLR. This feat will eventually allow us to use the fascinating super Eddington quasars as probes to understand better the cosmological state of our Universe.

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          Author and article information

          Journal
          26 October 2022
          Article
          2210.15041
          024f0dcc-8052-4539-a968-ee6ff31b2523

          http://arxiv.org/licenses/nonexclusive-distrib/1.0/

          History
          Custom metadata
          29 pages, 5 figures, 2 tables, based on the invited talk presented at the SPIG - 31st Summer School and International Symposium on the Physics of Ionized Gases, held between 05th - 09th September 2022
          astro-ph.GA astro-ph.HE

          Galaxy astrophysics,High energy astrophysical phenomena
          Galaxy astrophysics, High energy astrophysical phenomena

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