ANGULAR MOMENTUM–MASS RELATION FOR DARK MATTER HALOS
| Autor: | Jiayu Tang, Dalong Cheng, Shihong Liao, Ming Chung Chu |
|---|---|
| Rok vydání: | 2015 |
| Předmět: |
Physics
Angular momentum Cosmology and Nongalactic Astrophysics (astro-ph.CO) Mechanical equilibrium Dark matter FOS: Physical sciences Spectral density Astronomy and Astrophysics Astrophysics::Cosmology and Extragalactic Astrophysics Astrophysics Redshift Virial theorem Cosmology law.invention Space and Planetary Science law Halo Astrophysics - Cosmology and Nongalactic Astrophysics |
| Zdroj: | The Astrophysical Journal. 809:64 |
| ISSN: | 1538-4357 |
| DOI: | 10.1088/0004-637x/809/1/64 |
| Popis: | We study the empirical relation between an astronomical object's angular momentum $J$ and mass $M$, $J=\beta M^\alpha$, the $J-M$ relation, using N-body simulations. In particular, we investigate the time evolution of the $J-M$ relation to study how the initial power spectrum and cosmological model affect this relation, and to test two popular models of its origin - mechanical equilibrium and tidal torque theory. We find that in the $\Lambda$CDM model, $\alpha$ starts with a value of $\sim 1.5$ at high redshift $z$, increases monotonically, and finally reaches $5/3$ near $z=0$, whereas $\beta$ evolves linearly with time in the beginning, reaches a maximum and decreases, and stabilizes finally. A three-regime scheme is proposed to understand this newly observed picture. We show that the tidal torque theory accounts for this time evolution behaviour in the linear regime, whereas $\alpha=5/3$ comes from the virial equilibrium of haloes. The $J-M$ relation in the linear regime contains the information of the power spectrum and cosmological model. The $J-M$ relations for haloes in different environments and with different merging histories are also investigated to study the effects of a halo's non-linear evolution. An updated and more complete understanding of the $J-M$ relation is thus obtained. Comment: 16 pages, 17 figures, matches the version published in The Astrophysical Journal |
| Databáze: | OpenAIRE |
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