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How Are Red and Blue Quasars Different? The Radio Properties

Lookup NU author(s): Dr Vicky FawcettORCiD, Dr David Rosario



This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).


A non-negligible fraction of quasars are red at optical wavelengths, indicating (in the majority of cases) that the accretion disc is obscured by a column of dust which extinguishes the shorter-wavelength blue emission. In this paper, we summarize recent work by our group, where we find fundamental differences in the radio properties of SDSS optically-selected red quasars. We also present new analyses, using a consistent color-selected quasar parent sample matched to four radio surveys (FIRST, VLA Stripe 82, VLA COSMOS 3 GHz, and LoTSS DR1) across a frequency range 144 MHz–3 GHz and four orders of magnitude in radio flux. We show that red quasars have enhanced small-scale radio emission (∼kpc) that peaks around the radio-quiet threshold (defined as the ratio of 1.4 GHz luminosity to 6 micron luminosity) across the four radio samples. Exploring the potential mechanisms behind this enhancement, we rule out star-formation and propose either small-scale synchrotron jets, frustrated jets, or dusty winds interacting with the interstellar medium; the latter two scenarios would provide a more direct connection between opacity (dust; gas) and the production of the radio emission. In our future study, using new multi-band uGMRT data, we aim to robustly distinguish between these scenarios.

Publication metadata

Author(s): Fawcett VA, Alexander DM, Rosario DJ, Klindt L, Fotopoulou S, Lusso E, Morabito LK, Calistro Rivera G

Publication type: Article

Publication status: Published

Journal: MDPI Galaxies

Year: 2021

Volume: 9

Issue: 4

Print publication date: 01/12/2021

Online publication date: 19/11/2021

Acceptance date: 16/11/2021

Date deposited: 18/10/2022

ISSN (electronic): 2075-4434

Publisher: MDPI


DOI: 10.3390/galaxies9040107


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