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About the ELUCID Project
A method we developed recently for the reconstruction
of the initial density field in the nearby universe is
applied to the Sloan Digital Sky Survey Data Release 7.
A high-resolution N-body constrained simulation (CS) of
the reconstructed initial conditions, with 30723 particles
evolved in a box, is carried out and analyzed in terms of
the statistical properties of the final density field and
its relation with the distribution of Sloan Digital Sky
Survey galaxies. We find that the statistical properties
of the cosmic web and the halo populations are accurately
reproduced in the CS. The galaxy density field is strongly
correlated with the CS density field, with a bias that
depends on both galaxy luminosity and color. Our further
investigations show that the CS provides robust quantities
describing the environments within which the observed
galaxies and galaxy systems reside. Cosmic variance is
greatly reduced in the CS so that the statistical
uncertainties can be controlled effectively, even for
samples of small volumes.
We examine the quenched fraction of central and satellite galaxies as a
function of galaxy stellar mass, halo mass, and the matter density of their
large-scale environment. Matter densities are inferred from our ELUCID simulation,
a constrained simulation of the local universe sampled by SDSS, while halo masses
and central/satellite classification are taken from the galaxy group catalog of
Yang et al. The quenched fraction for the total population increases systematically
with the three quantities. We find that the “environmental quenching efficiency,”
which quantifies the quenched fraction as a function of halo mass, is independent
of stellar mass. And this independence is the origin of the stellar mass independence
of density-based quenching efficiency found in previous studies. Considering centrals
and satellites separately, we find that the two populations follow similar correlations
of quenching efficiency with halo mass and stellar mass, suggesting that they
have experienced similar quenching processes in their host halo.
We demonstrate
that satellite quenching alone cannot account for the environmental quenching efficiency
of the total galaxy population, and that the difference between the two populations
found previously arises mainly from the fact that centrals and satellites of the same
stellar mass reside, on average, in halos of different mass. After removing these effects
of halo mass and stellar mass, there remains a weak, but significant, residual dependence
on environmental density, which is eliminated when halo assembly bias is taken into account.
Our results therefore indicate that halo mass is the prime environmental parameter that
regulates the quenching of both centrals and satellites.
!!! Has to be filled with a brief intro to ELUCID.
News
Collaboration Workshop on Cosmology and Galaxy Formation
is held in SJTU and Suzhou Bay.
Jun 19, 2023
www.elucid-project.com is online.
Mar 28, 2023
ELUCID. VII (constrained gas simulation) is published.
Jun 16, 2022
ELUCID. VI (cosmic variance of SDSS) is published.
Sep 3, 2018
ELUCID. V (lighting halos with galaxies) is published.
Dec 4, 2017
ELUCID. IV (galaxy quenching) is published.
Jul 27, 2017
ELUCID. II (test of reconstruction diagnostics) is published.
Apr 12, 2017
ELUCID. III (constrained DMO simulation) is published.
Aug 5, 2016
ELUCID. I (HMCMC method) is published.
Jul 13, 2014
People
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Acknowledgements
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