Résumé / Abstract Journal-club_Galaxies

Journal-club Galaxies

« Toward the first sample of radio powerful AGN in the epoch of reionization with the Murchison Widefield Array (MWA), a Square Kilometer Array precursor »

Guillaume Drouart
International Centre for Radio Astronomy Research, Curtin University (Perth, Australie)

With the very recent discovery of radio luminous AGN at z>6, a new window of opportunity is finally opening in the study of the galaxy evolution at the end of the Epoch of Reionization. The nature of radio selection presents the advantage of being insensitive to orientation-dependent obscuration and it allows us (i) to study simultaneously the co-evolution of the supermassive black hole and host galaxy, (ii) to enable the study of the IGM through the HI absorption line and, (iii) to complete our view on AGN evolution with the existing z>6 quasar samples.

Our pilot programme in the 60 deg^2 GAMA-09 field uses a new selection technique taking advantage of the large frequency coverage of GLEAM, an all-sky 70-230MHz survey performed by the MWA (a SKA-precursor). By selecting compact, steep and curved sources, we were able to confirm one new powerful radio galaxy, 0856+0224 at z=5.55, finally overtaking the z=5.2 twenty year-old record for distant radio galaxies (albeit just falling short of the new recent z=5.7 record). Interestingly, 0856+0224 presents similarities with existing z<5 redshift samples, giving confidence in the success of our selection technique. Our recent progress on a second source, 0917-0012, thanks to the extensive multi-wavelength coverage from follow-up observations with ALMA and JVLA, supplemented with publicly available data, place this source at a likely promising z>7.

I will discuss the refinement of our selection technique over the full 1200 deg^2 sky area covered by the ESO VIKING near-infrared survey, leading to 55 new high-redshift candidates. This sample aims to provide us with the first statistically significant radio luminous active galactic nuclei sample at z > 6.5 during the Epoch of Reionization.
jeudi 24 juin 2021 - 11:30
Webinaire, Institut d'Astrophysique
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