Early black-hole seeds in the first billion years. (arXiv:1908.04823v1 [astro-ph.GA])

Early black-hole seeds in the first billion years. (arXiv:1908.04823v1 [astro-ph.GA])
<a href="http://arxiv.org/find/astro-ph/1/au:+Maio_U/0/1/0/all/0/1">Umberto Maio</a>

Supermassive black holes with billion solar masses are in place already
within the first Gyr, however, their origin and growth in such a short lapse of
time is extremely challenging to understand. Here, we discuss the formation
paths of early black-hole seeds, showing the limits of light black-hole seeds
from stellar origin and the features of heavy/massive black-hole seeds
originated by gas direct collapse in peculiar primordial conditions. To draw
conclusions on the possible candidates and the role of the environment, we use
results from N-body hydrodynamic simulations including atomic and molecular
non-equilibrium abundance calculations, cooling, star formation, feedback
mechanisms, stellar evolution, metal spreading of several heavy elements from
SNII, AGB and SNIa, and multifrequency radiative transfer over 150 frequencies
coupled to chemistry and SED emission for popII-I and popIII stellar sources.
Standard stellar-origin light black holes are unlikely to be reliable seeds of
early supermassive black holes, because, under realistic assumptions, they
cannot grow significantly in less than a billion years. Alternatively, massive
black-hole seeds might originate from direct collapse of pristine gas in
primordial quiescent mini-haloes that are exposed to stellar radiation from
nearby star forming regions. However, the necessary conditions required to form
these heavy seeds must be complemented with information on the complex features
of the local environment and a very fine balance between chemistry evolution
and radiative transfer.

Supermassive black holes with billion solar masses are in place already
within the first Gyr, however, their origin and growth in such a short lapse of
time is extremely challenging to understand. Here, we discuss the formation
paths of early black-hole seeds, showing the limits of light black-hole seeds
from stellar origin and the features of heavy/massive black-hole seeds
originated by gas direct collapse in peculiar primordial conditions. To draw
conclusions on the possible candidates and the role of the environment, we use
results from N-body hydrodynamic simulations including atomic and molecular
non-equilibrium abundance calculations, cooling, star formation, feedback
mechanisms, stellar evolution, metal spreading of several heavy elements from
SNII, AGB and SNIa, and multifrequency radiative transfer over 150 frequencies
coupled to chemistry and SED emission for popII-I and popIII stellar sources.
Standard stellar-origin light black holes are unlikely to be reliable seeds of
early supermassive black holes, because, under realistic assumptions, they
cannot grow significantly in less than a billion years. Alternatively, massive
black-hole seeds might originate from direct collapse of pristine gas in
primordial quiescent mini-haloes that are exposed to stellar radiation from
nearby star forming regions. However, the necessary conditions required to form
these heavy seeds must be complemented with information on the complex features
of the local environment and a very fine balance between chemistry evolution
and radiative transfer.

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