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Extremely Red Quasars in DESI: strong link between dust and radio emission

Speaker

Victoria Fawcett
Durham University, Newcastle University (UK)

Abstract

An important fraction of quasars are red at optical wavelengths, indicating (in the vast majority of cases) that the accretion disc is obscured by a column of dust which extinguishes the shorter-wavelength blue emission. In recent work by our group, we have shown fundamental differences in the properties of SDSS optically selected red quasars, which suggest they could be an important phase in the evolution of galaxies (e.g., Klindt et al. 2019, Rosario et al. 2020, 2021, Fawcett et al. 2020, 2021, 2022). Using DESI spectra, we can now push to more extinguished, lower luminosity systems, which will test whether these results extend to more extreme reddened systems. We have a DESI secondary target program which selects reddened quasars that might have otherwise been missed by the nominal QSO selection. Within the Early Data Release, 3038 candidates have been observed through this program; by visually inspecting the sample, we find ~75% are high quality quasars, of which 76% are red quasars and 38% are the rare "Extremely Red Quasars" (ERQs). We find red quasars with up to ~4 mags of dust extinction, compared to ~1 mags in SDSS. Utilising the LoTSS DR2 radio dataset, we identify a striking relationship between the line-of-sight dust extinction towards a quasar and the radio detection fraction that is not driven by redshift or luminosity.

Date and Time

November 3 2022
4pm KST (= 7am UTC)

Zoom link (active once the seminar starts)

Recording

Link to the recording on YouTube