Relative baryon-dark matter velocities in cosmological zoom simulations

Kavli Affiliate: George Efstathiou

| First 5 Authors: Luke Conaboy, Ilian T. Iliev, Anastasia Fialkov, Keri L. Dixon, David Sullivan

| Summary:

Supersonic relative motion between baryons and dark matter due to the
decoupling of baryons from the primordial plasma after recombination affects
the growth of the first small-scale structures. Large box sizes (greater than a
few hundred Mpc) are required to sample the full range of scales pertinent to
the relative velocity, while the effect of the relative velocity is strongest
on small scales (less than a few hundred kpc). This separation of scales
naturally lends itself to the use of `zoom’ simulations, and here we present
our methodology to self-consistently incorporate the relative velocity at the
start time of the simulation as well as its cumulative effect from
recombination through to the start time of the simulation. We also apply our
methodology to a large-scale cosmological zoom simulation. In qualitative
agreement with previous works, we find that the halo mass function and halo
baryon fraction is suppressed when the relative velocity is included compared
to when it is not. We also find a small delay, of the order of the lifetime of
a $sim$9 M$_odot$ Population III star, in the onset of star formation in the
case where the relative velocity is included.

| Search Query: ArXiv Query: search_query=au:”Anastasia Fialkov”&id_list=&start=0&max_results=10

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