Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Luminosity-Dependent Quasar Lifetimes: Reconciling the Optical and X-ray
  Quasar Luminosity Functions   We consider implications of our new model of quasar lifetimes and light
curves for the quasar luminosity function (LF) at different frequencies and
redshifts. In our picture, quasars evolve rapidly and the lifetime depends on
both their instantaneous and peak luminosities. The bright end of the LF traces
the peak intrinsic quasar activity, but the faint end consists of quasars which
are either undergoing exponential growth to much larger masses and
luminosities, or are in sub-Eddington quiescent states going into or coming out
of a period of peak activity. The 'break' in the observed LF corresponds
directly to the maximum in the intrinsic distribution of peak luminosities,
which falls off at both brighter and fainter luminosities. We study this model
using simulations of galaxy mergers which successfully reproduce a wide range
of observed quasar phenomena, including the observed column density
distribution. By combining quasar lifetimes and the distribution of maximum
quasar luminosities determined from the observed hard X-ray LF with the
corresponding luminosity and host-system dependent column densities, we produce
the expected soft X-ray and B-band LFs. Our predictions agree exceptionally
well with the observed LFs at all observed luminosities, over the redshift
range considered (z < 1), without invoking any ad hoc assumptions about an
obscured population of sources. Our results also suggest that observed
correlations in hard X-ray samples between the obscured fraction of quasars and
luminosity can be explained in the context of our model by the expulsion of
surrounding gas due to heating from accretion feedback energy as a quasar nears
its peak luminosity and final black hole mass.

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The categories of this paper are: supr-con
17
The categories of this paper are: q-fin
21
The categories of this paper are: adap-org
7
The categories of this paper are: hep-th
10
The categories of this paper are: q-bio
12
The categories of this paper are: nucl-th
15
The categories of this paper are: nucl-ex
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The categories of this paper are: bayes-an
9
The categories of this paper are: nlin
8
The categories of this paper are: hep-ex
23
The categories of this paper are: solv-int
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The categories of this paper are: mtrl-th
22
The categories of this paper are: chao-dyn
20
The categories of this paper are: acc-phys
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The categories of this paper are: atom-ph
4
The categories of this paper are: cond-mat