ETHOS – an Effective Theory of Structure Formation: detecting dark matter interactions through the Lyman-$alpha$ forest. (arXiv:1811.10630v1 [astro-ph.CO])
<a href="http://arxiv.org/find/astro-ph/1/au:+Bose_S/0/1/0/all/0/1">Sownak Bose</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Vogelsberger_M/0/1/0/all/0/1">Mark Vogelsberger</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Zavala_J/0/1/0/all/0/1">Jesús Zavala</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Pfrommer_C/0/1/0/all/0/1">Christoph Pfrommer</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Cyr_Racine_F/0/1/0/all/0/1">Francis-Yan Cyr-Racine</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bohr_S/0/1/0/all/0/1">Sebastian Bohr</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bringmann_T/0/1/0/all/0/1">Torsten Bringmann</a>
We perform a series of cosmological hydrodynamic simulations to investigate
the effects of non-gravitational dark matter (DM) interactions on the
intergalactic medium (IGM). In particular, we use the ETHOS framework
(Cyr-Racine et al. 2016; Vogelsberger et al. 2016) to compare statistics of the
Lyman-$alpha$ forest in cold dark matter (CDM) with an alternative model in
which the DM couples strongly with a relativistic species in the early
universe. These models are characterised by a cutoff in the linear power
spectrum, followed by a series of ‘dark acoustic oscillations’ (DAOs) on
sub-dwarf scales. While the primordial cutoff delays the formation of the first
galaxies, structure builds-up more rapidly in the interacting DM model compared
to CDM. We show that although DAOs are quickly washed away in the non-linear
clustering of DM at $zlesssim10$, their signature can be imprinted prominently
in the Lyman-$alpha$ flux power spectrum at $z>5$. On scales larger than the
cutoff ($ksim0.08$ s/km for the specific model considered here), the relative
difference to CDM is reminiscent of a warm dark matter (WDM) model with a
similar initial cutoff; however, the redshift evolution on smaller scales is
distinctly different. The appearance and disappearance of DAOs in the
Lyman-$alpha$ flux spectrum provides a powerful way to distinguish interacting
DM models from WDM and, indeed, variations in the thermal history of the IGM
that may also induce a small-scale cutoff.
We perform a series of cosmological hydrodynamic simulations to investigate
the effects of non-gravitational dark matter (DM) interactions on the
intergalactic medium (IGM). In particular, we use the ETHOS framework
(Cyr-Racine et al. 2016; Vogelsberger et al. 2016) to compare statistics of the
Lyman-$alpha$ forest in cold dark matter (CDM) with an alternative model in
which the DM couples strongly with a relativistic species in the early
universe. These models are characterised by a cutoff in the linear power
spectrum, followed by a series of ‘dark acoustic oscillations’ (DAOs) on
sub-dwarf scales. While the primordial cutoff delays the formation of the first
galaxies, structure builds-up more rapidly in the interacting DM model compared
to CDM. We show that although DAOs are quickly washed away in the non-linear
clustering of DM at $zlesssim10$, their signature can be imprinted prominently
in the Lyman-$alpha$ flux power spectrum at $z>5$. On scales larger than the
cutoff ($ksim0.08$ s/km for the specific model considered here), the relative
difference to CDM is reminiscent of a warm dark matter (WDM) model with a
similar initial cutoff; however, the redshift evolution on smaller scales is
distinctly different. The appearance and disappearance of DAOs in the
Lyman-$alpha$ flux spectrum provides a powerful way to distinguish interacting
DM models from WDM and, indeed, variations in the thermal history of the IGM
that may also induce a small-scale cutoff.
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