在拉姆達冷暗物質宇宙模擬中銀河系暈的分佈及其演化

Distribution of Galactic Halos and their Evolution in Lambda CDM Cosmology

簡鴻裕(Hung-Yu Jian)

指導教授 ： 闕志鴻

國立臺灣大學/理學院/物理研究所/博士(2010年)

https://doi.org/10.6342/NTU.2010.02690

摘要

我們提出在宇宙摸擬中新的尋找星系暈的方法,再配合一星系形成的模型,我們可建立一星系樣本,經過一系列的與觀測數劇的比對,皆出現吻合的結果,因此我們相信,我們找到的樣本能正確的反應出真實宇宙中星系的分佈與演化,這些樣本將可進一步的被利用來研究星系未被探所的一些性質

關鍵字

宇宙模擬 ； 星系形成 ； 星系演化

並列摘要

Galaxies can form in a sufficiently deep gravitational potential so that
efficient gas cooling occurs. We estimate that such potential is provided
by a halo of mass $M gtsim M_{c} approx 7.0 imes 10^{12} ~
(Delta_{c}(z) (1+z)^{3})^{-1/2} Msun$, where $Delta_{c}(z)$ is
the mean overdensity of spherically virialized objects formed at
redshift $z$, and $M_{c} approx 4.0 imes 10^{11} Msun$ at $z =
0$. Based on this criterion, our galaxy samples are constructed from cosmology simulation data by using HiFOF to select subhalos in those FOF halos that are more massive than $M_{c}$. There are far more dark subhalos than galaxy-hosting subhalos. Several tests against observations have been performed to examine our galaxy samples, including: (1) The differential galaxy
mass functions of this sample are found to be close to the
observation derived from the combination of the luminosity function
of the DEEP2 galaxies as well as the mass-to-light ratio from
Red-Sequence Cluster Survey at $z = 0.3$. (2) The galaxy
space density is analyzed as a function of redshift to examine the density
evolution, which is found to be roughly consistent with the
observational result based on the luminosity functions in
cite{fab07}. (3) The projected two point correlation functions (CF) of
our galaxy sample at $z$ = 0 and $z$ = 1 are in good agreement with those of the SDSS and DEEP2 galaxies,
respectively. (4) The HODs of our galaxy
samples show good agreement with the SDSS and DEEP2 data. (5) Finally,
the kinematic pair fractions for $r_{max}$ = 50 and 100 $kpc$ are
computed, and the evolution is parameterized as $(1+z)^{m}$.
Comparing with the results, m = $0.41pm0.14$ ($r_{max}$ = 50) and m
= $0.29pm0.05$ ($r_{max}$ = 100), in cite{lin08}, we found m
$approx$ 0.96 and m $approx$ 0.48 respectively from one of our
simulations.
Based on the consistency with observations, our galaxy
sample is believed to correctly represent galaxies in real universe,
and can be used to study other unexplored galaxy properties.

並列關鍵字

cosmology: theory ； galaxies: formation ； galaxies: evolution ； halos: large-scale-structure ； methods: numerical

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