超輕波色暗物質之宇宙大尺度結構數值模擬

High Resolution Simulation on Structure Formation with Extremely Light Bosonic Dark Matter

胡德邦(Tak-Pong Woo)

指導教授 ： 闕志鴻

國立臺灣大學/理學院/物理研究所/博士(2008年)

https://doi.org/10.6342/NTU.2008.02826

摘要

在本篇論文中，我們假設暗物質為質量超輕的波色子，並利用薛丁格-泊松方程式解此問體。並分析暗物質暈的質量分佈及能量分佈。

關鍵字

暗物質 ； 宇宙學

並列摘要

An alternative bosonic dark matter model is examined in detail via high-resolution simulations. These bosons have particle mass of order 10¡22eV and are non-interacting.
If they do exist and can account for structure formation, these bosons must be condensed into the Bose-Einstein state and described by a coherent wave function.
This matter, also known as Fuzzy Dark Matter (Hu, Barkana & Gruzinov, 2000),
is speculated to be able, ‾rst, to eliminate the sub-galactic halos to solve the prob-
lem of over-abundance of dwarf galaxies, and, second, to produce °at halo cores
in galaxies suggested by some observations. Due to the limited dynamical range,
our 10243 simulation literarily addresses cluster-size halos in an 100 h¡1Mpc box,
rather than galaxy-size halos in an 1 h¡1Mpc box, by adopting 10¡26eV boson mass.
However, since the SchrÄodinger-Poisson model studied in this work is a scale-free
system, our results can be rescaled to a simulation box 100 times smaller. The sim-
ulation results show that although this extremely light bosonic dark matter indeed
suppresses low-mass halos, it can, to the contrary of expectation, yield singular halo
cores. The density pro‾le of the singular halo is almost identical to the halo pro‾le
of Navarro, Frenk & White (1997). Such a pro‾le seems to be independent of the
formation processes via accretion or merger. We shall stress a caveat for rescaling
from 100 h¡1Mpc to 1 h¡1Mpc box. The background density averaged over 100 h¡1Mpc is usually considered to represent the true background, but that averaged
over 1 h¡1Mpc can be subject to large sample variance. Though our simulation,
after rescaling, correspond to one of the many background densities, or e®ectively one of the many background cosmologies, we believe that the general trend obtained in this work remains valid in di®erent cosmologies.

並列關鍵字

Dark Matter

參考文獻

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