Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Formation of black holes in the pair-instability mass gap: evolution of
  a post-collision star   The detection of GW190521 by the LIGO-Virgo collaboration revealed the
existence of black holes (BHs) in the pair-instability (PI) mass gap. Here, we
investigate the formation of BHs in the PI mass gap via star -- star collisions
in young stellar clusters. To avoid PI, the stellar-collision product must have
a relatively small core and a massive envelope. We generate our initial
conditions from the outputs of a hydro-dynamical simulation of the collision
between a core helium burning star ($\sim 58$ M$_\odot$) and a main-sequence
star ($\sim 42$ M$_\odot$). The hydro-dynamical simulation allows us to take
into account the mass lost during the collision ($\sim 12$ M$_\odot$) and to
build the chemical composition profile of the post-collision star. We then
evolve the collision product with the stellar evolution codes PARSEC and MESA.
We find that the post-collision star evolves through all the stellar burning
phases until core collapse, avoiding PI. At the onset of core collapse, the
post-collision product is a blue super-giant star. We estimate a total mass
loss of about 1 M$_\odot$ during the post-collision evolution, due to stellar
winds and shocks induced by neutrino emission in a failed supernova. The final
BH mass is $\approx{87}$ M$_\odot$. Therefore, we confirm that the collision
scenario is a suitable formation channel to populate the PI mass gap.

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The categories of this paper are: solv-int
9
The categories of this paper are: nlin
34
The categories of this paper are: chem-ph
12
The categories of this paper are: nucl-th
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The categories of this paper are: dg-ga
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The categories of this paper are: eess
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The categories of this paper are: acc-phys
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The categories of this paper are: econ
4
The categories of this paper are: cond-mat
35
The categories of this paper are: mtrl-th
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The categories of this paper are: cmp-lg
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The categories of this paper are: hep-th
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The categories of this paper are: math-ph
5
The categories of this paper are: gr-qc
3
The categories of this paper are: physics
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The categories of this paper are: comp-gas