Properties of galaxies and supermassive black holes in cosmic voids. (arXiv:1912.06662v1 [astro-ph.GA])
<a href="http://arxiv.org/find/astro-ph/1/au:+Habouzit_M/0/1/0/all/0/1">Melanie Habouzit</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Pisani_A/0/1/0/all/0/1">Alice Pisani</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Goulding_A/0/1/0/all/0/1">Andy Goulding</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Dubois_Y/0/1/0/all/0/1">Yohan Dubois</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Somerville_R/0/1/0/all/0/1">Rachel S. Somerville</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Greene_J/0/1/0/all/0/1">Jenny E. Greene</a>
Cosmic voids, the under-dense regions of the cosmic web, are widely used to
extract cosmological information. Voids contain few, isolated galaxies,
presumably expected to be less evolved and preserving memory of the pristine
Universe. We use the cosmological hydrodynamical simulation Horizon-AGN coupled
to the void finder VIDE to investigate properties of galaxies in cosmic voids
at redshift z=0. We find that low-mass galaxies are more common than their
massive counterparts at small void-centric distances. At fixed dark matter halo
mass, they also have smaller stellar masses than in denser regions. While the
star formation rate of void galaxies is lower when approaching the center of
voids, their sSFR increases, suggesting that these void galaxies form stars
more efficiently with respect to their stellar mass. We find that this can not
only be attributed to the prevalence of low-mass galaxies. As a consequence of
the presence of low-mass galaxies in voids, the inner regions of voids also
predominantly host low-mass BHs. However, the ratios of BH mass to galaxy mass
are similar to those of the whole simulation at z=0. Our results suggest that
even if the growth channels in cosmic voids are different than in denser
environments, voids grow their galaxies and BHs in a similar way. While a large
fraction of the BHs have low Eddington ratios, we find that 20% could be
observed as AGN with log10 L=41.5-42.5 erg/s in hard X-ray (2-10 keV). These
results pave the way to future work with larger next-generation hydro
simulations, aiming to confirm our findings and prepare the application on data
from upcoming large surveys such as PFS, Euclid and WFIRST.
Cosmic voids, the under-dense regions of the cosmic web, are widely used to
extract cosmological information. Voids contain few, isolated galaxies,
presumably expected to be less evolved and preserving memory of the pristine
Universe. We use the cosmological hydrodynamical simulation Horizon-AGN coupled
to the void finder VIDE to investigate properties of galaxies in cosmic voids
at redshift z=0. We find that low-mass galaxies are more common than their
massive counterparts at small void-centric distances. At fixed dark matter halo
mass, they also have smaller stellar masses than in denser regions. While the
star formation rate of void galaxies is lower when approaching the center of
voids, their sSFR increases, suggesting that these void galaxies form stars
more efficiently with respect to their stellar mass. We find that this can not
only be attributed to the prevalence of low-mass galaxies. As a consequence of
the presence of low-mass galaxies in voids, the inner regions of voids also
predominantly host low-mass BHs. However, the ratios of BH mass to galaxy mass
are similar to those of the whole simulation at z=0. Our results suggest that
even if the growth channels in cosmic voids are different than in denser
environments, voids grow their galaxies and BHs in a similar way. While a large
fraction of the BHs have low Eddington ratios, we find that 20% could be
observed as AGN with log10 L=41.5-42.5 erg/s in hard X-ray (2-10 keV). These
results pave the way to future work with larger next-generation hydro
simulations, aiming to confirm our findings and prepare the application on data
from upcoming large surveys such as PFS, Euclid and WFIRST.
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