J. Read, O. Agertz, and M. Collins. (2015)cite arxiv:1508.04143Comment: 17 pages; 7 figures; submitted to MNRAS. Comments welcome!.
Abstract
We use high resolution simulations of isolated dwarf galaxies to study the
physics of dark matter cusp-core transformation at the edge of galaxy formation
(Mvir = 10^7 - 10^9 Msun). We work at a resolution (4 pc) at which the impact
from individual supernovae explosions can be resolved, becoming insensitive to
even large changes in our numerical 'sub-grid' parameters. We find that our
dwarf galaxies give a remarkable match to the stellar light profile; star
formation history; metallicity distribution function; and star/gas kinematics
of isolated dwarf irregular galaxies. Our key result is that dark matter cores
of size comparable to the half light radius r_1/2 always form if star formation
proceeds for long enough. Cores fully form in less than 4 Gyrs for the Mvir
=10^8 Msun and 14 Gyrs for the 10^9 Msun dwarf. We provide a convenient two
parameter 'coreNFW' fitting function that captures this dark matter core growth
as a function of star formation time and the projected half light radius.
Our results have several important implications: (i) we make a strong
prediction that if LambdaCDM is correct, then 'pristine' dark matter cusps will
be found either in systems that have truncated star formation and/or at radii r
> r_1/2; (ii) complete core formation lowers the projected velocity dispersion
at r_1/2 by a factor ~2, which is sufficient to fully explain the 'too big to
fail problem' (though we stress that a full solution likely also involves
unmodelled environmental effects); and (iii) cored dwarfs will be much more
susceptible to tides, leading to a dramatic scouring of the subhalo mass
function inside galaxies and groups. We will explore such environmental effects
in a forthcoming paper.
%0 Generic
%1 read2015matter
%A Read, J. I.
%A Agertz, O.
%A Collins, M. L. M.
%D 2015
%K baryon cores dark feedback matter
%T Dark matter cores all the way down
%U http://arxiv.org/abs/1508.04143
%X We use high resolution simulations of isolated dwarf galaxies to study the
physics of dark matter cusp-core transformation at the edge of galaxy formation
(Mvir = 10^7 - 10^9 Msun). We work at a resolution (4 pc) at which the impact
from individual supernovae explosions can be resolved, becoming insensitive to
even large changes in our numerical 'sub-grid' parameters. We find that our
dwarf galaxies give a remarkable match to the stellar light profile; star
formation history; metallicity distribution function; and star/gas kinematics
of isolated dwarf irregular galaxies. Our key result is that dark matter cores
of size comparable to the half light radius r_1/2 always form if star formation
proceeds for long enough. Cores fully form in less than 4 Gyrs for the Mvir
=10^8 Msun and 14 Gyrs for the 10^9 Msun dwarf. We provide a convenient two
parameter 'coreNFW' fitting function that captures this dark matter core growth
as a function of star formation time and the projected half light radius.
Our results have several important implications: (i) we make a strong
prediction that if LambdaCDM is correct, then 'pristine' dark matter cusps will
be found either in systems that have truncated star formation and/or at radii r
> r_1/2; (ii) complete core formation lowers the projected velocity dispersion
at r_1/2 by a factor ~2, which is sufficient to fully explain the 'too big to
fail problem' (though we stress that a full solution likely also involves
unmodelled environmental effects); and (iii) cored dwarfs will be much more
susceptible to tides, leading to a dramatic scouring of the subhalo mass
function inside galaxies and groups. We will explore such environmental effects
in a forthcoming paper.
@misc{read2015matter,
abstract = {We use high resolution simulations of isolated dwarf galaxies to study the
physics of dark matter cusp-core transformation at the edge of galaxy formation
(Mvir = 10^7 - 10^9 Msun). We work at a resolution (4 pc) at which the impact
from individual supernovae explosions can be resolved, becoming insensitive to
even large changes in our numerical 'sub-grid' parameters. We find that our
dwarf galaxies give a remarkable match to the stellar light profile; star
formation history; metallicity distribution function; and star/gas kinematics
of isolated dwarf irregular galaxies. Our key result is that dark matter cores
of size comparable to the half light radius r_1/2 always form if star formation
proceeds for long enough. Cores fully form in less than 4 Gyrs for the Mvir
=10^8 Msun and 14 Gyrs for the 10^9 Msun dwarf. We provide a convenient two
parameter 'coreNFW' fitting function that captures this dark matter core growth
as a function of star formation time and the projected half light radius.
Our results have several important implications: (i) we make a strong
prediction that if LambdaCDM is correct, then 'pristine' dark matter cusps will
be found either in systems that have truncated star formation and/or at radii r
> r_1/2; (ii) complete core formation lowers the projected velocity dispersion
at r_1/2 by a factor ~2, which is sufficient to fully explain the 'too big to
fail problem' (though we stress that a full solution likely also involves
unmodelled environmental effects); and (iii) cored dwarfs will be much more
susceptible to tides, leading to a dramatic scouring of the subhalo mass
function inside galaxies and groups. We will explore such environmental effects
in a forthcoming paper.},
added-at = {2015-08-19T10:51:28.000+0200},
author = {Read, J. I. and Agertz, O. and Collins, M. L. M.},
biburl = {https://www.bibsonomy.org/bibtex/2d40eb11221b936b1293223889699bb18/miki},
description = {[1508.04143] Dark matter cores all the way down},
interhash = {5a7afc85dd6c9aa9fbd60abdbc4ec795},
intrahash = {d40eb11221b936b1293223889699bb18},
keywords = {baryon cores dark feedback matter},
note = {cite arxiv:1508.04143Comment: 17 pages; 7 figures; submitted to MNRAS. Comments welcome!},
timestamp = {2015-08-19T10:51:28.000+0200},
title = {Dark matter cores all the way down},
url = {http://arxiv.org/abs/1508.04143},
year = 2015
}