The growth of dark matter halos: evidence for significant smooth accretion

Details The growth of dark matter halos: evidence for significant smooth accretion The growth of dark matter halos: evidence for significant smooth accretion

2010-05-21

arxiv.org/abs/1005.4058v2

Astrophysical Journal 719 (2010) 229-239

Astronomy and Astrophysics

Astrophysics

Cosmology and Extragalactic Astrophysics

11 pages, 9 figures. Accepted for publication in the Astrophysical Journal

Scientific paper

10.1088/0004-637X/719/1/229

We study the growth of dark matter halos in the concordance LCDM cosmology using several N-body simulations of large cosmological volumes. We build merger trees from the Millennium and Millennium-II simulations, covering a range 10^9-10^15 Msun in halo mass and 1-10^5 in merger mass ratio. Our algorithm takes special care of halo fragmentation and ensures that the mass contribution of each merger to halo growth is only counted once. This way the integrated merger rate converges and we can consistently determine the contribution of mergers of different mass ratios to halo growth. We find that all resolved mergers, up to mass ratios of 10^5, contribute only ~60% of the total halo mass growth, while major mergers are subdominant, e.g. mergers with mass ratios smaller than 3:1 (10:1) contribute only ~20% (~30%). This is verified with an analysis of two additional simulation boxes, where we follow all particles individually throughout cosmic time. Our results are also robust against using several halo definitions. Under the assumption that the power-law behaviour of the merger rate at large mass ratios can be extrapolated to arbitrarily large mass ratios, it is found that, independently of halo mass, ~40% of the mass in halos comes from genuinely smooth accretion of dark matter that was never bound in smaller halos. We discuss possible implications of our findings for galaxy formation. One implication, assuming as is standard that the pristine intergalactic medium is heated and photoionized by UV photons, is that all halos accrete >40% of their baryons in smooth "cold" T>~10^4K gas, rather than as warm, enriched or clumpy gas or as stars.

Affiliated with

Also associated with

No associations

Rating

The growth of dark matter halos: evidence for significant smooth accretion does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with The growth of dark matter halos: evidence for significant smooth accretion, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The growth of dark matter halos: evidence for significant smooth accretion will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-412414