The evolving AGN duty cycle in galaxies since z$sim$3 as encoded in the X-ray luminosity function. (arXiv:2002.08965v1 [astro-ph.GA])

The evolving AGN duty cycle in galaxies since z$sim$3 as encoded in the X-ray luminosity function. (arXiv:2002.08965v1 [astro-ph.GA])
<a href="http://arxiv.org/find/astro-ph/1/au:+Delvecchio_I/0/1/0/all/0/1">I. Delvecchio</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Daddi_E/0/1/0/all/0/1">E. Daddi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Aird_J/0/1/0/all/0/1">J. Aird</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Mullaney_J/0/1/0/all/0/1">J. R. Mullaney</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bernhard_E/0/1/0/all/0/1">E. Bernhard</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Grimmett_L/0/1/0/all/0/1">L. P. Grimmett</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Carraro_R/0/1/0/all/0/1">R. Carraro</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Cimatti_A/0/1/0/all/0/1">A. Cimatti</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Zamorani_G/0/1/0/all/0/1">G. Zamorani</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Caplar_N/0/1/0/all/0/1">N. Caplar</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Vito_F/0/1/0/all/0/1">F. Vito</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Elbaz_D/0/1/0/all/0/1">D. Elbaz</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Rodighiero_G/0/1/0/all/0/1">G. Rodighiero</a>

We present a new modeling of the X-ray luminosity function (XLF) of Active
Galactic Nuclei (AGN) out to z$sim$3, dissecting the contribution of
main-sequence (MS) and starburst (SB) galaxies. For each galaxy population, we
convolved the observed galaxy stellar mass (M$_{star}$) function with a grid
of M$_{star}$-independent Eddington ratio ($lambda_{rm EDD}$) distributions,
normalised via empirical black hole accretion rate (BHAR) to star formation
rate (SFR) relations. Our simple approach yields an excellent agreement with
the observed XLF since z$sim$3. We find that the redshift evolution of the
observed XLF can only be reproduced through an intrinsic flattening of the
$lambda_{rm EDD}$ distribution, and with a positive shift of the break
$lambda^{*}$, consistent with an anti-hierarchical behavior. The AGN accretion
history is predominantly made by massive (10$^{10}<$M$_{star}<$10$^{11}$
M$_{odot}$) MS galaxies, while SB-driven BH accretion, possibly associated
with galaxy mergers, becomes dominant only in bright quasars, at $log$(L$_{rm
X}$/erg s$^{-1}$)$>$44.36 + 1.28$cdot$(1+z). We infer that the probability of
finding highly-accreting ($lambda_{rm EDD}>$ 10%) AGN significantly increases
with redshift, from 0.4% (3.0%) at z=0.5 to 6.5% (15.3%) at z=3 for MS (SB)
galaxies, implying a longer AGN duty cycle in the early Universe. Our results
strongly favor a M$_{star}$-dependent ratio between BHAR and SFR, as BHAR/SFR
$propto$ M$_{star}^{0.73[+0.22,-0.29]}$, supporting a non-linear BH buildup
relative to the host. Finally, this framework opens potential questions on
super-Eddington BH accretion and different $lambda_{rm EDD}$ prescriptions
for understanding the cosmic BH mass assembly.

We present a new modeling of the X-ray luminosity function (XLF) of Active
Galactic Nuclei (AGN) out to z$sim$3, dissecting the contribution of
main-sequence (MS) and starburst (SB) galaxies. For each galaxy population, we
convolved the observed galaxy stellar mass (M$_{star}$) function with a grid
of M$_{star}$-independent Eddington ratio ($lambda_{rm EDD}$) distributions,
normalised via empirical black hole accretion rate (BHAR) to star formation
rate (SFR) relations. Our simple approach yields an excellent agreement with
the observed XLF since z$sim$3. We find that the redshift evolution of the
observed XLF can only be reproduced through an intrinsic flattening of the
$lambda_{rm EDD}$ distribution, and with a positive shift of the break
$lambda^{*}$, consistent with an anti-hierarchical behavior. The AGN accretion
history is predominantly made by massive (10$^{10}<$M$_{star}<$10$^{11}$
M$_{odot}$) MS galaxies, while SB-driven BH accretion, possibly associated
with galaxy mergers, becomes dominant only in bright quasars, at $log$(L$_{rm
X}$/erg s$^{-1}$)$>$44.36 + 1.28$cdot$(1+z). We infer that the probability of
finding highly-accreting ($lambda_{rm EDD}>$ 10%) AGN significantly increases
with redshift, from 0.4% (3.0%) at z=0.5 to 6.5% (15.3%) at z=3 for MS (SB)
galaxies, implying a longer AGN duty cycle in the early Universe. Our results
strongly favor a M$_{star}$-dependent ratio between BHAR and SFR, as BHAR/SFR
$propto$ M$_{star}^{0.73[+0.22,-0.29]}$, supporting a non-linear BH buildup
relative to the host. Finally, this framework opens potential questions on
super-Eddington BH accretion and different $lambda_{rm EDD}$ prescriptions
for understanding the cosmic BH mass assembly.

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