The quantity of dark matter in early-type galaxies and its relation to the environment. (arXiv:1906.11161v1 [astro-ph.GA])

The quantity of dark matter in early-type galaxies and its relation to the environment. (arXiv:1906.11161v1 [astro-ph.GA])
<a href="http://arxiv.org/find/astro-ph/1/au:+Nigoche_Netro_A/0/1/0/all/0/1">A. Nigoche-Netro</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ramos_Larios_G/0/1/0/all/0/1">G. Ramos-Larios</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lagos_P/0/1/0/all/0/1">P. Lagos</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Fuente_E/0/1/0/all/0/1">E. de la Fuente</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ruelas_Mayorga_A/0/1/0/all/0/1">A. Ruelas-Mayorga</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Mendez_Abreu_J/0/1/0/all/0/1">J. Mendez-Abreu</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kemp_S/0/1/0/all/0/1">S. N. Kemp</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Diaz_R/0/1/0/all/0/1">R. J. Diaz</a>

We study the behavior of the dynamical and stellar mass inside the effective
radius of early-type galaxies (ETGs) as a function of environment considering
Newtonian dynamics, different surface–brightness profiles, different initial
mass functions (IMF) and different redshift ranges. We use several samples of
ETGs –ranging from 19,000 to 98,000 objects– from the ninth data release of
the Sloan Digital Sky Survey. We assume that any difference between the
dynamical and stellar mass is due to dark matter and/or a non-universal IMF.
The main results, considering samples in the redshift range 0.0024
$leq;z;leq$ 0.35 are: (i) the amount of dark matter inside ETGs depends on
the environment; (ii) ETGs in low density environments span a wider dark matter
range than ETGs in dense environments; (iii) the amount of dark matter inside
ETGs in the most dense environments will be less than approximately 55%–75%
of the dynamical mass; (iv) the accurate value of this upper limit depends on
the impact of the IMF on the stellar mass estimation; (v) in the case of an
ETGs sample which is approximately complete for log$({bf M_{Virial}}/{bf
M_{Sun}}) > 10.5$ and in the redshift range 0.04 $leq;z;leq$ 0.08 we find
that the amount of dark matter in the most dense environments will be less than
approximately 60%–65% of the dynamical mass.

We study the behavior of the dynamical and stellar mass inside the effective
radius of early-type galaxies (ETGs) as a function of environment considering
Newtonian dynamics, different surface–brightness profiles, different initial
mass functions (IMF) and different redshift ranges. We use several samples of
ETGs –ranging from 19,000 to 98,000 objects– from the ninth data release of
the Sloan Digital Sky Survey. We assume that any difference between the
dynamical and stellar mass is due to dark matter and/or a non-universal IMF.
The main results, considering samples in the redshift range 0.0024
$leq;z;leq$ 0.35 are: (i) the amount of dark matter inside ETGs depends on
the environment; (ii) ETGs in low density environments span a wider dark matter
range than ETGs in dense environments; (iii) the amount of dark matter inside
ETGs in the most dense environments will be less than approximately 55%–75%
of the dynamical mass; (iv) the accurate value of this upper limit depends on
the impact of the IMF on the stellar mass estimation; (v) in the case of an
ETGs sample which is approximately complete for log$({bf M_{Virial}}/{bf
M_{Sun}}) > 10.5$ and in the redshift range 0.04 $leq;z;leq$ 0.08 we find
that the amount of dark matter in the most dense environments will be less than
approximately 60%–65% of the dynamical mass.

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