TY - JOUR
T1 - Bringing faint active galactic nuclei (AGNs) to light: a view from large-scale cosmological simulations
AU - Schirra, Adrian P.
AU - Habouzit, Melanie
AU - Klessen, Ralf S.
AU - Fornasini, Francesca
AU - Nelson, Dylan
AU - Pillepich, Annalisa
AU - Anglés-Alcázar, Daniel
AU - Davé, Romeel
AU - Civano, Francesca
N1 - Published version - MNRAS
PY - 2021/12/1
Y1 - 2021/12/1
N2 - The sensitivity of X-ray facilities and our ability to detect fainter
active galactic nuclei (AGNs) will increase with the upcoming Athena
mission and the AXIS and Lynx concept missions, thus improving our
understanding of supermassive black holes (BHs) in a luminosity regime
that can be dominated by X-ray binaries. We analyse the population of
faint AGNs (Lx,2−10keV⩽1042ergs−1)
in the Illustris, TNG100, EAGLE, and SIMBA cosmological simulations,
and find that the properties of their host galaxies vary from one
simulation to another. In Illustris and EAGLE, faint AGNs are powered by
low-mass BHs located in low-mass star-forming galaxies. In TNG100 and
SIMBA, they are mostly associated with more massive BHs in quenched
massive galaxies. We model the X-ray binary (XRB) populations of the
simulated galaxies, and find that AGNs often dominate the galaxy AGN +
XRB hard X-ray luminosity at z > 2, while XRBs dominate in some simulations at z
< 2. Whether the AGN or XRB emission dominates in star-forming and
quenched galaxies depends on the simulations. These differences in
simulations can be used to discriminate between galaxy formation models
with future high-resolution X-ray observations. We compare the
luminosity of simulated faint AGN host galaxies to observations of
stacked galaxies from Chandra. Our comparison indicates that
the simulations post-processed with our X-ray modelling tend to
overestimate the AGN + XRB X-ray luminosity; luminosity that can be
strongly affected by AGN obscuration. Some simulations reveal clear AGN
trends as a function of stellar mass (e.g. galaxy luminosity drop in
massive galaxies), which are not apparent in the observations.
AB - The sensitivity of X-ray facilities and our ability to detect fainter
active galactic nuclei (AGNs) will increase with the upcoming Athena
mission and the AXIS and Lynx concept missions, thus improving our
understanding of supermassive black holes (BHs) in a luminosity regime
that can be dominated by X-ray binaries. We analyse the population of
faint AGNs (Lx,2−10keV⩽1042ergs−1)
in the Illustris, TNG100, EAGLE, and SIMBA cosmological simulations,
and find that the properties of their host galaxies vary from one
simulation to another. In Illustris and EAGLE, faint AGNs are powered by
low-mass BHs located in low-mass star-forming galaxies. In TNG100 and
SIMBA, they are mostly associated with more massive BHs in quenched
massive galaxies. We model the X-ray binary (XRB) populations of the
simulated galaxies, and find that AGNs often dominate the galaxy AGN +
XRB hard X-ray luminosity at z > 2, while XRBs dominate in some simulations at z
< 2. Whether the AGN or XRB emission dominates in star-forming and
quenched galaxies depends on the simulations. These differences in
simulations can be used to discriminate between galaxy formation models
with future high-resolution X-ray observations. We compare the
luminosity of simulated faint AGN host galaxies to observations of
stacked galaxies from Chandra. Our comparison indicates that
the simulations post-processed with our X-ray modelling tend to
overestimate the AGN + XRB X-ray luminosity; luminosity that can be
strongly affected by AGN obscuration. Some simulations reveal clear AGN
trends as a function of stellar mass (e.g. galaxy luminosity drop in
massive galaxies), which are not apparent in the observations.
KW - astro-ph.GA
U2 - 10.1093/mnras/stab2863
DO - 10.1093/mnras/stab2863
M3 - Article
VL - 508
SP - 4816
EP - 4843
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
SN - 0035-8711
IS - 4
ER -