Original language | English |
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Pages (from-to) | 4209-4217 |
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Journal | Monthly Notices of the Royal Astronomical Society |
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Volume | 459 |
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Issue number | 4 |
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DOIs | |
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Publication status | Published - 21 Apr 2016 |
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Direct collapse black holes (DCBH) have been proposed as a solution to
the challenge of assembling supermassive black holes by z > 6 to
explain the bright quasars observed at this epoch. The formation of a
DCBH seed with MBH ˜ 104-5 M⊙
requires a pristine atomic-cooling halo to be illuminated by an external
radiation field that is sufficiently strong to entirely suppress
H2 cooling in the halo. Many previous studies have attempted
to constrain the critical specific intensity that is likely required to
suppress H2 cooling, denoted as Jcrit. However,
these studies have typically assumed that the incident external
radiation field can be modelled with a blackbody spectrum. Under this
assumption, it is possible to derive a unique value for Jcrit
that depends only on the temperature of the blackbody. In this study we
consider a more realistic spectral energy distribution (SED) for the
external source of radiation that depends entirely on its star formation
history and age. The rate of destruction of the species responsible for
suppressing molecular hydrogen cooling depends on the detailed shape of
the SED. Therefore the value of Jcrit is tied to the shape of
the incident SED of the neighbouring galaxy. We fit a parametric form to
the rates of destruction of H2 and H- that permit
direct collapse. Owing to this, we find that Jcrit is not a
fixed threshold but can lie anywhere in the range Jcrit
˜ 0.5-103, depending on the details of the source
stellar population.
- galaxies: high-redshift, quasars: general, dark ages, reionization, first stars
ID: 42809831