JADES. The diverse population of infant Black Holes at 4<z<11: merging, tiny, poor, but mighty

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 the Balmer emission lines. 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. 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 BH, 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. However, we find that these early BH 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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