Journal Article

Dark matter halo merger and accretion probabilities in the excursion set formalism

Esfandiar Alizadeh and Benjamin Wandelt

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 409, issue 2, pages 694-700
Published in print December 2010 | ISSN: 0035-8711
Published online November 2010 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2010.17332.x
Dark matter halo merger and accretion probabilities in the excursion set formalism

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The merger and accretion probabilities of dark matter haloes have so far only been calculated for an infinitesimal time interval. This means that a Monte Carlo simulation with very small time-steps is necessary to find the merger history of a parent halo. In this paper, we use the random walk formalism to find the merger and accretion probabilities of haloes for a finite time interval. Specifically, we find the number density of haloes at an early redshift that will become part of a halo with a specified final mass at a later redshift, given that they underwent n major mergers, n= 0, 1, 2, … . We reduce the problem into an integral equation which we then solve numerically. To ensure the consistency of our formalism, we compare the results with Monte Carlo simulations and find very good agreement. Though we have done our calculation assuming a flat barrier, the more general case can easily be handled using our method. This derivation of finite time merger and accretion probabilities can be used to make more efficient merger trees or implemented directly into analytical models of structure formation and evolution.

Keywords: galaxies: evolution; galaxies: haloes; cosmology: theory; dark matter

Journal Article.  5257 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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