129 research outputs found
The AGORA high-resolution galaxy simulations comparison project. III. Cosmological zoom-in simulation of a Milky Way-mass Halo
ArtÃculo escrito por un elevado número de autores, solo se referencian el que aparece en primer lugar, el nombre del grupo de colaboración, si le hubiere, y los autores pertenecientes a la UA
FirstLight III: Rest-frame UV-optical spectral energy distributions of simulated galaxies at cosmic dawn
Using the FirstLight database of 300 zoom-in cosmological simulations we
provide rest-frame UV-optical spectral energy distributions of galaxies with
complex star-formation histories that are coupled to the non-uniform gas
accretion history of galactic halos during cosmic dawn. The population at any
redshift is very diverse ranging from starbursts to quiescent galaxies even at
a fixed stellar mass. This drives a redshift-dependent relation between UV
luminosity and stellar mass with a large scatter, driven by the specific star
formation rate. The UV slope and the production efficiency of Lyman continuum
photons have high values, consistent with dust-corrected observations. This
indicates young stellar populations with low metallicities. The FirstLight
simulations make predictions on the rest-frame UV-optical absolute magnitudes,
colors and optical emission lines of galaxies at z=6-12 that will be observed
for the first time with JWST and the next generation of telescopes in the
coming decade.Comment: 10 pages+appendix , 11 figures. Accepted at MNRAS. The FirstLight
database is available at
http://www.ita.uni-heidelberg.de/~ceverino/FirstLight/index.htm
Formation of elongated galaxies with low masses at high redshift
We report the identification of elongated (triaxial or prolate) galaxies in
cosmological simulations at . These are preferentially low-mass
galaxies (), residing in dark-matter (DM) haloes
with strongly elongated inner parts, a common feature of high-redshift DM
haloes in the CDM cosmology. Feedback slows formation of stars at the
centres of these halos, so that a dominant and prolate DM distribution gives
rise to galaxies elongated along the DM major axis. As galaxies grow in stellar
mass, stars dominate the total mass within the galaxy half-mass radius, making
stars and DM rounder and more oblate. A large population of elongated galaxies
produces a very asymmetric distribution of projected axis ratios, as observed
in high-z galaxy surveys. This indicates that the majority of the galaxies at
high redshifts are not discs or spheroids but rather galaxies with elongated
morphologies.Comment: 7 pages, 3 figures, accepted version. Minor changes with respect to
the first versio
Early formation of massive, compact, spheroidal galaxies with classical profiles by violent disc instability or mergers
We address the formation of massive stellar spheroids between redshifts
and 1 using a suite of AMR hydro-cosmological simulations. The spheroids form
as bulges, and the spheroid mass growth is partly driven by violent disc
instability (VDI) and partly by mergers. A kinematic decomposition to disc and
spheroid yields that the mass fraction in the spheroid is between 50\% and 90\%
and is roughly constant in time, consistent with a cosmological steady state of
VDI discs that are continuously fed from the cosmic web. The density profile of
the spheroid is typically "classical", with a Sersic index ,
independent of whether it grew by mergers or VDI and independent of the
feedback strength. The disc is characterized by , and the whole
galaxy by . The high-redshift spheroids are compact due to the
dissipative inflow of gas and the high universal density. The stellar surface
density within the effective radius of each galaxy as it evolves remains
roughly constant in time after its first growth. For galaxies of a fixed
stellar mass, the surface density is higher at higher redshifts.Comment: 22 pages, 15 figures, accepted in MNRA
Distribution of streaming rates into high-redshift galaxies
We study the accretion along streams from the cosmic web into high-redshift
massive galaxies using three sets of AMR hydro-cosmological simulations. We
find that the streams keep a roughly constant accretion rate as they penetrate
into the halo centre. The mean accretion rate follows the mass and redshift
dependence predicted for haloes by the EPS approximation, dM / dt is
proportional to Mvir^{1.25} (1 + z)^{2.5}. The distribution of the accretion
rates can well be described by a sum of two Gaussians, the primary
corresponding to "smooth inflow" and the secondary to "mergers". The same
functional form was already found for the distributions of specific star
formation rates in observations. The mass fraction in the smooth component is
60 - 90 %, insensitive to redshift or halo mass. The simulations with strong
feedback show clear signs of reaccretion due to recycling of galactic winds.
The mean accretion rate for the mergers is a factor 2 - 3 larger than that of
the smooth component. The standard deviation of the accretion rate is 0.2 - 0.3
dex, showing no trend with mass or redshift. For the smooth component it is
0.12 - 0.24 dex.Comment: 13 pages, 6 figures, 2 tables, final version accepted for publication
in MNRA
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