117 research outputs found
The spin alignment of galaxies with the large-scale tidal field in hydrodynamic simulations
The correlation between the spins of dark matter halos and the large-scale
structure (LSS) has been studied in great detail over a large redshift range,
while investigations of galaxies are still incomplete. Motivated by this point,
we use the state-of-the-art hydrodynamic simulation, Illustris-1, to
investigate mainly the spin--LSS correlation of galaxies at redshift of .
We mainly find that the spins of low-mass, blue, oblate galaxies are
preferentially aligned with the slowest collapsing direction () of the
large-scale tidal field, while massive, red, prolate galaxy spins tend to be
perpendicular to . The transition from a parallel to a perpendicular trend
occurs at in the stellar mass, in the g-r
color, and in triaxiality. The transition stellar mass decreases with
increasing redshifts. The alignment was found to be primarily correlated with
the galaxy stellar mass. Our results are consistent with previous studies both
in N-body simulations and observations. Our study also fills the vacancy in the
study of the galaxy spin--LSS correlation at using hydrodynamical
simulations and also provides important insight to understand the formation and
evolution of galaxy angular momentum.Comment: 9 pages, 6 figures, 1 table. Accepted for publication in ApJ, match
the proof versio
A rotating satellite plane around Milky Way-like galaxy from the TNG50 simulation
We study the Satellite Plane Problem of the Milky Way\ (MW) by using the
recently published simulation data of TNG50-1. Here, we only consider the
satellite plane consisting of the brightest 14 MW satellites \ (11 classical
satellites plus Canes Venatici I\ (CVn I), Crater II and Antlia II). One halo\
(haloID=395, at z=0, hereafter halo395 ) of 231 MW like candidates, possesses a
satellite plane as spatially thin and kinematically coherent as the observed
one has been found. Halo395 resembles the MW in a number of intriguing ways: it
hosts a spiral central galaxy and its satellite plane is almost ()perpendicular to the central stellar disk. In addition, halo395 is
embedded in a sheet plane, with a void on the top and bottom, similar to the
local environment of MW. More interestingly, we found that the 11 of 14 of the
satellites on the plane of halo395, arise precisely from the peculiar geometry
of its large-scale environment\ (e.g. sheet and voids). The remaining three
members appeared at the right place with the right velocity by chance at z=0.
Our results support previous studies wherein the Satellite Plane Problem is not
seen as a serious challenge to the CDM model and its formation is
ascribed to the peculiarities of our environment.Comment: Accepted for publication by ApJ. The article title has been changed
since the last version, and some minor corrections have been mad
Filaments from the galaxy distribution and from the velocity field in the local universe
The cosmic web that characterizes the large-scale structure of the Universe
can be quantified by a variety of methods. For example, large redshift surveys
can be used in combination with point process algorithms to extract long
curvilinear filaments in the galaxy distribution. Alternatively, given a full
3D reconstruction of the velocity field, kinematic techniques can be used to
decompose the web into voids, sheets, filaments and knots. In this paper we
look at how two such algorithms - the Bisous model and the velocity shear web -
compare with each other in the local Universe (within 100 Mpc), finding good
agreement. This is both remarkable and comforting, given that the two methods
are radically different in ideology and applied to completely independent and
different data sets. Unsurprisingly, the methods are in better agreement when
applied to unbiased and complete data sets, like cosmological simulations, than
when applied to observational samples. We conclude that more observational data
is needed to improve on these methods, but that both methods are most likely
properly tracing the underlying distribution of matter in the Universe.Comment: 6 Pages, 2 figures, Submitted to MNRAS Letter
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