Kavli Affiliate: Kohei Inayoshi
| First 5 Authors: Anthony J. Taylor, Steven L. Finkelstein, Dale D. Kocevski, Junehyoung Jeon, Volker Bromm
| Summary:
We present a sample of 50 H-alpha detected broad-line active galactic nuclei
(BLAGN) at redshifts 3.5<z<6.8 using data from the CEERS and RUBIES surveys. We
select these sources directly from JWST/NIRSpec G395M/F290LP spectra. We use a
multi-step pre-selection and a Bayesian fitting procedure to ensure a
high-quality sample of sources with broad Balmer lines and narrow forbidden
lines. We compute rest-frame ultraviolet and optical spectral slopes for these
objects, and determine that 10 BLAGN in our sample are also little red dots
(LRDs). These LRD BLAGN, when examined in aggregate, show broader H-alpha line
profiles and a higher fraction of broad-to-narrow component H-alpha emission
than non-LRD BLAGN. Moreover, we find that ~66% of these objects are
intrinsically reddened (beta (optical)>0), independent of the contributions of
emission lines to the broadband photometry. We construct the black hole (BH)
mass function at 3.5<z<6 after computing robust observational and line
detection completeness corrections. This BH mass function shows broad agreement
with both recent JWST/NIRSpec and JWST/NIRCam WFSS based BH mass functions,
though we extend these earlier results to log(M(BH)/M(sun)) < 7. The derived BH
mass function is consistent with a variety of theoretical models, indicating
that the observed abundance of black holes in the early universe is not
discrepant with physically-motivated predictions. The BH mass function shape
resembles a largely featureless power-law, suggesting that any signature from
black-hole seeding has been lost by redshift z~5-6. Finally, we compute the
BLAGN UV luminosity function and find good agreement with JWST-detected BLAGN
samples from recent works, finding that BLAGN hosts constitute <10% of the
total observed UV luminosity at all but the brightest luminosities.
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