Starlight from galaxies plays a pivotal role throughout the process of cosmic
reionisation. We present the statistics of dwarf galaxy properties at z > 7 in
haloes with masses up to 10^9 solar masses, using a cosmological radiation
hydrodynamics simulation that follows their buildup starting with their
Population III progenitors. We find that metal-enriched star formation is not
restricted to atomic cooling (T_vir > 10^4 K) haloes, but can occur in haloes
down to masses ~10^6 solar masses, especially in neutral regions. Even though
these smallest galaxies only host up to 10^4 solar masses of stars, they
provide a significant fraction of the ionising photon budget because of their
high number densities. We find that the galaxy luminosity function flattens
above M_UV ~ -12 with a number density that is unchanged during reionisation.
The fraction of ionising radiation escaping into the intergalactic medium is
inversely dependent on halo mass, decreasing from 50 to 5 per cent in the mass
range $M/M_= 7.0-8.5$. We find that low-mass galaxies are just as
efficient at producing ionising photons per unit mass as atomic cooling haloes.
However, they are gradually photo-suppressed as they are engulfed in ionised
regions, giving way for larger galaxies to dominate the latter half of
reionisation. Using our galaxy statistics in a semi-analytic reionisation
model, we find a Thomson scattering optical depth consistent with the latest
Planck results, while still being consistent with the UV emissivity constraints
provided by Ly-alpha forest observations at z = 4-6. We find that haloes less
massive than the atomic cooling limit provide nearly 30 per cent to the total
ionising photon budget. Our work suggests that a yet-to-be observed population
of low-mass galaxies was responsible for starting reionisation at very high
redshifts.
Description
[1403.6123] The Birth of a Galaxy - III. Propelling reionisation with the faintest galaxies
%0 Generic
%1 wise2014birth
%A Wise, John H.
%A Demchenko, Vasiliy G.
%A Halicek, Martin T.
%A Norman, Michael L.
%A Turk, Matthew J.
%A Abel, Tom
%A Smith, Britton D.
%D 2014
%K dwarf galaxy reionization
%T The Birth of a Galaxy - III. Propelling reionisation with the faintest
galaxies
%U http://arxiv.org/abs/1403.6123
%X Starlight from galaxies plays a pivotal role throughout the process of cosmic
reionisation. We present the statistics of dwarf galaxy properties at z > 7 in
haloes with masses up to 10^9 solar masses, using a cosmological radiation
hydrodynamics simulation that follows their buildup starting with their
Population III progenitors. We find that metal-enriched star formation is not
restricted to atomic cooling (T_vir > 10^4 K) haloes, but can occur in haloes
down to masses ~10^6 solar masses, especially in neutral regions. Even though
these smallest galaxies only host up to 10^4 solar masses of stars, they
provide a significant fraction of the ionising photon budget because of their
high number densities. We find that the galaxy luminosity function flattens
above M_UV ~ -12 with a number density that is unchanged during reionisation.
The fraction of ionising radiation escaping into the intergalactic medium is
inversely dependent on halo mass, decreasing from 50 to 5 per cent in the mass
range $M/M_= 7.0-8.5$. We find that low-mass galaxies are just as
efficient at producing ionising photons per unit mass as atomic cooling haloes.
However, they are gradually photo-suppressed as they are engulfed in ionised
regions, giving way for larger galaxies to dominate the latter half of
reionisation. Using our galaxy statistics in a semi-analytic reionisation
model, we find a Thomson scattering optical depth consistent with the latest
Planck results, while still being consistent with the UV emissivity constraints
provided by Ly-alpha forest observations at z = 4-6. We find that haloes less
massive than the atomic cooling limit provide nearly 30 per cent to the total
ionising photon budget. Our work suggests that a yet-to-be observed population
of low-mass galaxies was responsible for starting reionisation at very high
redshifts.
@misc{wise2014birth,
abstract = {Starlight from galaxies plays a pivotal role throughout the process of cosmic
reionisation. We present the statistics of dwarf galaxy properties at z > 7 in
haloes with masses up to 10^9 solar masses, using a cosmological radiation
hydrodynamics simulation that follows their buildup starting with their
Population III progenitors. We find that metal-enriched star formation is not
restricted to atomic cooling (T_vir > 10^4 K) haloes, but can occur in haloes
down to masses ~10^6 solar masses, especially in neutral regions. Even though
these smallest galaxies only host up to 10^4 solar masses of stars, they
provide a significant fraction of the ionising photon budget because of their
high number densities. We find that the galaxy luminosity function flattens
above M_UV ~ -12 with a number density that is unchanged during reionisation.
The fraction of ionising radiation escaping into the intergalactic medium is
inversely dependent on halo mass, decreasing from 50 to 5 per cent in the mass
range $\log M/M_\odot = 7.0-8.5$. We find that low-mass galaxies are just as
efficient at producing ionising photons per unit mass as atomic cooling haloes.
However, they are gradually photo-suppressed as they are engulfed in ionised
regions, giving way for larger galaxies to dominate the latter half of
reionisation. Using our galaxy statistics in a semi-analytic reionisation
model, we find a Thomson scattering optical depth consistent with the latest
Planck results, while still being consistent with the UV emissivity constraints
provided by Ly-alpha forest observations at z = 4-6. We find that haloes less
massive than the atomic cooling limit provide nearly 30 per cent to the total
ionising photon budget. Our work suggests that a yet-to-be observed population
of low-mass galaxies was responsible for starting reionisation at very high
redshifts.},
added-at = {2014-03-26T09:53:25.000+0100},
author = {Wise, John H. and Demchenko, Vasiliy G. and Halicek, Martin T. and Norman, Michael L. and Turk, Matthew J. and Abel, Tom and Smith, Britton D.},
biburl = {https://www.bibsonomy.org/bibtex/27c286e04d72b260b264144c39aca9fc6/miki},
description = {[1403.6123] The Birth of a Galaxy - III. Propelling reionisation with the faintest galaxies},
interhash = {83e1263eeba5027cedc62be569a58aee},
intrahash = {7c286e04d72b260b264144c39aca9fc6},
keywords = {dwarf galaxy reionization},
note = {cite arxiv:1403.6123Comment: 21 pages, 15 figures, 4 tables. Submitted to MNRAS. Comments welcome},
timestamp = {2014-03-26T09:53:25.000+0100},
title = {The Birth of a Galaxy - III. Propelling reionisation with the faintest
galaxies},
url = {http://arxiv.org/abs/1403.6123},
year = 2014
}