hide
Free keywords:
Astrophysics, Galaxy Astrophysics, astro-ph.GA,Astrophysics, Cosmology and Extragalactic Astrophysics, astro-ph.CO
Abstract:
One of the most challenging and exciting subjects in modern astrophysics is
that of galaxy formation at the epoch of reionisation. The SKA, with its
revolutionary capabilities in terms of frequency range, resolution and
sensitivity, will allow to explore the first Gyr of structure formation in the
Universe, in particular, with the detection and study of the earliest
manifestations of the AGN phenomenon. The tens of QSOs that are currently known
out to the highest redshifts (z~7), many of them exhibiting powerful radio
emission, imply that super-massive black holes can be grown on a very short
timescale and support the existence of very high redshift (z > 7) radio loud
sources - sources that have so far escaped detection. Not only would such
detections be paramount to the understanding of the earliest stages of galaxy
evolution, they are necessary for the direct study of neutral hydrogen in the
Epoch of Reionisation, through observations of the HI 21cm forest against such
background sources. In order to understand how SKA and SKA1 observations can be
optimised to reveal these earliest AGN, we have examined the effect of a hot
CMB on the emission of powerful and young radio galaxies. By looking at the
SKA1 capabilities, in particular in terms of wavelength coverage and
resolution, we determine how the effects of "CMB-muting" of a radio loud source
can be observationally minimised and how to identify the best highest-redshift
radio candidates. Considering different predictions for the space density of
radio loud AGN at such redshifts, we identify the survey characteristics
necessary to optimize the detection and identification of the very first
generation of radio loud AGN in the Universe.
