Kavli Affiliate: Roberto Maiolino
| First 5 Authors: Roberto Maiolino, Jan Scholtz, Emma Curtis-Lake, Stefano Carniani, William Baker
| Summary:
We present 12 new AGN at 4<z<7 in the JADES survey (in addition to the
previously identified AGN in GN-z11 at z=10.6) revealed through the detection
of a Broad Line Region as seen in Halpha. The depth of JADES, together with the
use of three different spectral resolutions, enables us to probe a lower mass
regime relative to previous studies. In a few cases we find evidence for two
broad components of Halpha which suggests that these could be candidate merging
black holes (BHs). The inferred BH masses range between 8 x 10^7 Msun down to 4
x 10^5 Msun, interestingly probing the regime expected for Direct Collapse
Black Holes (DCBHs). The inferred AGN bolometric luminosities (~10^44-10^45
erg/s) imply accretion rates that are < 0.5 times the Eddington rate in most
cases. However, small BHs, with M_BH ~ 10^6 Msun, tend to accrete at Eddington
or super-Eddington rates. These BH at z~4-11 are over-massive relative to their
host galaxies stellar masses when compared to the local M_BH-Mstar relation,
and even approaching M_BH~Mstar, as expected for DCBHs and super-Eddington
scenarios. However, we find that these early BHs tend to be more consistent
with the local relation between M_BH and velocity dispersion, as well as
between M_BH and dynamical mass, suggesting that these are more fundamental and
universal relations. On the BPT excitation-diagnostic diagram these AGN are
located in the region that is that is locally occupied by star-forming
galaxies, implying that they would be missed by the standard classification
techniques if they did not display broad lines. Their location on the diagram
is consistent with what expected for AGN hosted in metal poor galaxies (Z ~
0.1-0.2 Zsun). The fraction of broad line AGN with L_AGN > 10^44 erg/s, among
galaxies in the redshift range 4<z<6, is about 10%, suggesting that the
contribution of AGN and their hosts to the reionization of the Universe is >
10%.
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