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Abstract:
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. 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 by selecting
compact, steep and curved sources at low-frequency (70-230MHz). Out of
four candidates, one new powerful radio galaxy, 0856+0224, is
confirmed at z=5.55, finally overtaking the z=5.2 20 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 promising z>5. I will also
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. The nature of radio selection presents the advantage of
being insensitive to orientation-dependent obscuration, it allows us
(i) to study simultaneously the co-evolution of the supermassive black
hole and host galaxy and (ii) to enable the study of the IGM through
the HI absorption line.
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