A Merger Tree with Microsolar Mass Resolution: Application to $\gamma$-ray Emission from Subhalo Population

Abstract

The hierarchical growth of dark matter haloes, in which galaxies are hosted, has been studied and modeled using various approaches. In this paper we use a modified version the Sheth & Lemson algorithm for a $\mathrm{\Lambda }$ cold dark matter power spectrum, and model the growth of a Milky-Way sized halo with microsolar mass resolution, corresponding to the typical Jeans mass for a dark matter Weakly Interacting Massive Particle with mass of 100 GeV. We then compute the \emph{unevolved} subhalo mass function and build-up a Milky-Way halo placing and evolving its satellites. This subhalo population is used to study the $\gamma$-ray emission from dark matter annihilation. In this case, the subhaloes which populate the host halo have been computed considering only progenitor haloes accreted by the main branch of the tree, so as to correctly treat the embedding of sub-subhaloes inside subhaloes. Each subhalo will indeed host atthe present-time sub-subhaloes accreted when it was an isolated system. In order to compute the sub-subhalo population of a Milky-Way dwarf galaxy, like Draco, and to study its $\gamma$-ray emission, we first estimate the Draco virial mass at merging redshift $z_m$ and then we run the merger tree from $z_m$ following the halo down to the dark matter Jeans mass. We then study the effect on the Fermi-LAT (GLAST) detectability for both subhaloes in the Milky-Way and in Draco, and we show how subhaloes cannot be responsible for the boost factor needed for detection.

Accepted for publication by MNRAS - 12 pages, 7 figures. Text improved and comments added. Name of a author fixed

References in corpus (46)

• A Universal Density Profile from Hierarchical Clustering
• Wilkinson Microwave Anisotropy Probe (WMAP) Three Year Results: Implications for Cosmology
• Simulating the joint evolution of quasars, galaxies and their large-scale distribution
• Dark Matter Substructure in Galactic Halos
• Large scale bias and the peak background split
• Populating a cluster of galaxies - I. Results at z=0
• Profiles of dark haloes: evolution, scatter, and environment
• The Aquarius Project: the subhalos of galactic halos
• Ellipsoidal collapse and an improved model for the number and spatial distribution of dark matter haloes
• GADGET: A code for collisionless and gasdynamical cosmological simulations
• Using the Evolution of Clusters to Constrain Omega
• An excursion set model of hierarchical clustering: Ellipsoidal collapse and the moving barrier
• The Dark Side of the Halo Occupation Distribution
• Reionization and the abundance of galactic satellites
• Merger rates in hierarchical models of galaxy formation. II: Comparison with N-body simulations
• The subhalo populations of LCDM dark haloes
• Formation and evolution of galaxy dark matter halos and their substructure
• Dark matter substructure and gamma-ray annihilation in the Milky Way halo
• Can Photoionization Squelching Resolve the Sub-structure Crisis?
• Earth-mass dark-matter haloes as the first structures in the early Universe
• The Structural Evolution of Substructure
• How to Plant a Merger Tree
• The Physics of Galaxy Clustering I: A Model for Subhalo Populations
• The first WIMPy halos
• The Non-Parametric Model for Linking Galaxy Luminosity with Halo/Subhalo Mass
• The power spectrum of SUSY-CDM on sub-galactic scales
• What mass are the smallest protohalos?
• The distribution and kinematics of early high-sigma peaks in present-day haloes: implications for rare objects and old stellar populations
• The Population of Dark Matter Subhaloes: Mass Functions and Average Mass Loss Rates
• Kinematically Cold Populations at Large Radii in the Draco and Ursa Minor Dwarf Spheroidals
• Pre-launch estimates for GLAST sensitivity to Dark Matter annihilation signals
• An excursion set model for the distribution of dark matter and dark matter haloes
• Neutralino annihilation into gamma-rays in the Milky Way and in external galaxies
• New insights on the Draco dwarf spheroidal galaxy from SDSS: a larger radius and no tidal tails
• Merger Rates of Dark-Matter Haloes
• Dark Matter Annihilation in Substructures Revised
• Properties of cluster satellites in hydrodynamical simulations
• Dark matter distribution in the Draco dwarf from velocity moments
• An improved model for the formation times of dark matter haloes
• Evaluating Semi-Analytic Halo Merging Histories
• The forest of merger history trees associated with the formation of dark matter halos
• Formation times and masses of dark matter haloes
• Cosmological Evolution & Hierarchical Galaxy Formation
• Substructure in dark matter halos: Towards a model of the abundance and spatial distribution of subclumps
• Galton--Watson branching processes and the growth of gravitational clustering
• An analytic model for the epoch of halo creation

Cited by in corpus (11)

• Characterization of subhalo structural properties and implications for dark matter annihilation signals
• Hierarchical Formation of Dark Matter Halos and the Free Streaming Scale
• The Substructure Hierarchy in Dark Matter Haloes
• Density Profiles of CDM Microhalos and their Implications for Annihilation Boost Factors
• Formation times, mass growth histories and concentrations of dark matter haloes
• Small-scale clumps of dark matter
• A Cosmic Coincidence: The Power-Law Galaxy Correlation Function
• Constraints on small-scale primordial power by annihilation signals from extragalactic dark matter minihalos
• Constraining Satellite Galaxy Stellar Mass Loss and Predicting Intrahalo Light I: Framework and Results at Low Redshift
• Constraining the Sommerfeld enhancement with Cherenkov telescope observations of dwarf galaxies
• Dark Matter annihilation energy output and its effects on the high-z IGM