Abstract / Description of output
We present the first direct measurements of the rest-frame 10–40 keV
X-ray luminosity function (XLF) of active galactic nuclei (AGNs) based
on a sample of 94 sources at 0.1 < z < 3, selected at 8–24 keV energies from sources in the Nuclear Spectroscopic Telescope Array (NuSTAR)
extragalactic survey program. Our results are consistent with the
strong evolution of the AGN population seen in prior, lower-energy
studies of the XLF. However, different models of the intrinsic
distribution of absorption, which are used to correct for selection
biases, give significantly different predictions for the total number of
sources in our sample, leading to small, systematic differences in our
binned estimates of the XLF. Adopting a model with a lower intrinsic
fraction of Compton-thick sources and a larger population of sources
with column densities cm−2 or a model with stronger Compton reflection component (with a relative normalization of R ~ 2 at all luminosities) can bring extrapolations of the XLF from 2–10 keV into agreement with our NuSTAR sample. Ultimately, X-ray spectral analysis of the NuSTAR
sources is required to break this degeneracy between the distribution
of absorbing column densities and the strength of the Compton reflection
component and thus refine our measurements of the XLF. Furthermore, the
models that successfully describe the high-redshift population seen by NuSTAR
tend to over-predict previous, high-energy measurements of the local
XLF, indicating that there is evolution of the AGN population that is
not fully captured by the current models.
Original language | English |
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Number of pages | 14 |
Journal | Astrophysical Journal |
Volume | 815 |
Issue number | 1 |
DOIs | |
Publication status | Published - 10 Dec 2015 |
Keywords / Materials (for Non-textual outputs)
- astro-ph.HE
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James Aird
- School of Physics and Astronomy - UKRI Future Leader Fellowship
Person: Academic: Research Active