Theoretical Galaxy Merger Calculations

• DM simulations, with or without assumptions for gas (which might change criteria for merger)
  • Mamon, ApJL, 401, 1992, "Are cluster ellipticals the products of mergers?", an analytical model for merger rates of galaxies in clusters, agreeing well with Makino & Hut below, astro-ph/9911333, again by Mamon, compares the two.
  • Makino & Hut, http://arxiv.org/abs/astro-ph/9608159
    cross sections and reaction rates for spherical galaxies to merge by looking at 500 galaxy mergers in a simulation. and analytic description.
  • Kolatt et al, http://arxiv.org/abs/astro-ph/0010222, "Interaction rates of dark-matter halos and subhalos",
    BDM subhalos, halo and subhalo merger rates combined and compared. 60 Mpc/h side box, compares to Makino & Hut for subhalo collision rate Fig. 8
  • Springel et al http://arxiv.org/abs/astro-ph/0012055
    "Populating a cluster of galaxies-I. Results at z=0"
    assembly of a cluster, track galaxy merging explicitly within it in DM simulation plus model for gas with history.
  • De Lucia et al, http://arxiv.org/abs/astro-ph/0306205
    11 massive clusters and one region of mean density, dependence on parent halo mass for subhalos, merging histories of substructures.
  • Taylor & Babul, http://arxiv.org/abs/astro-ph/0410049,
    "The Evolution of Substructure in Galaxy, Group and Cluster Haloes III: Comparison with Simulations",
    structure in 6 halos at high resolution, find substructure using SKID.
  • Berrier et al, http://arxiv.org/abs/astro-ph/0604506, "Close Galaxy Counts as a Probe of Hierarchical Structure formation", comparison in simulations of observed close pairs and merger rate. argue number of pairs not good for merger rates but good constraint of halo occupation distribution. 120 Mpc/h side box, 10⁹ particle mass.
  • Guo & White, http://arxiv.org/abs/0708.1814, "Galaxy Growth in the concordance LCDM cosmology"
    In MS, dimensionless mean growth rates for galaxies as a function of redshift for different stellar masses: growth through major mergers, all mergers, star formation. Major merger is 1:3 or more in stellar mass. Fig 1 merger rates, Fig 3 galaxy growth rates.
  • Wang & Kauffmann, | http://arxiv.org/abs/0801.3530, "Why are AGN found in High Mass Galaxies"
    Millennium Simulation. Why major mergers of halos based upon stellar mass don't always lead to major mergers of subhalos with central, merger definition based upon stellar mass.
  • Mateus, http://arxiv.org/abs/0802.2720,
    "Evolution of the galaxy merger rate in model universes"
    2 semi-analytic models using the MS, rate for number of mergers per Gyr from z=0-2. rates equation 2, also fig. 3 for variation with merger definition.
  • Angulo et al 2008, http://arxiv.org/abs/0810.2177, "The Fate of Substructures of Dark Matter Halos"
    Millennium Simulation Subhalo descendant has the majority of the 10% most bound particles from the subhalo. Merger if descendants coincide. Subhalo merger rate figure 5, description of mass ratios, orbits and radial distributions of subhalo-subhalo mergers, merger probability since accretion of satellite subhalo. Rate here is rate satellites disappear (i.e., merge).
    
  • Wetzel, Cohn & White http://arxiv.org/abs/0810.2537
    Dark matter: major merger if ratio of infall masses is 1:3 or bigger for subhalos.
    Rates as a function of redshift from ~1-5. Comparison to halo merger rates. Eqn. 7 is fit to subhalo merger rates (+table 1), Halo Merger and subhalo merger rates as function of redshift in Fig. 4
  • Yang, Mo, van den Bosch http://arxiv.org/abs/0808.2526 The subhalo-satellite connection and the fate of disrupted satellite galaxies.
  • Tweed et al, http://arxiv.org/abs/0902.0679, "Building Merger Trees from Cosmological N-body Simulations", AdaptaHOP vs. FoF for halo and subhalo trees.
  • Hester & Tasitsiomi, arxiv.org/abs/0902.4489, Dark Matter Halo Mergers I: Dependence on Environment & Redshift Evolution
    Mergers in halos with more satellites (similar to Wetzel et al http://arxiv.org/abs/0810.3650) Fig. 1 Halo merger rate with redshift, Fig. 1, subhalo merger rates. Fig. 5 how subhalo number changes merger rate., Fig. 6 Merger rates.
  • (merger definition issues) Wetzel and White, http://arxiv.org/abs/0907.0702, "What determines satellite galaxy disruption?", uses observations to say when a dark matter subhalo should be considered as merged with the central halo, but matching counts/clustering at redshift ~0 and 1. Also gives a corresponding dynamical friction model calibration.
  • (merger definition issues) Hopkins et al 2010, http://arxiv.org/abs/1004.2708, Mergers in Lambda-CDM: Uncertainties in Theoretical Predictions and Interpretations of the Merger Rate: comparing different defintions of mergers (stellar mass, baryons, cold gas) in different approaches, and some corrections needed in some approaches for convergence with data.
• Mergers, simulations with gas included, mostly same group over time.
  • Murali et al, http://arxiv.org/abs/astro-ph/0106282
    "The growth of galaxies in cosmological simulations of structure formation,"
    mergers and smooth accretion contributions for ~L* systems. redshift 2 to 0. boxes 50-11 Mpc/h sides.
  • Maller http://arxiv.org/abs/astro-ph/0509474
    cosmological hydro simulation. merger rates for galaxies. [22 mpc/h box], figure 7.
  • Simha et al http://arxiv.org/abs/0809.2999, "Assembly histores of central and satellite galaxies"
    mergers broken down into parent populations/sources
  • Keres et al http://arxiv.org/abs/0809.1430, "Galaxies in a simulated LCDM Universe I: cold mode and hot cores", satellites keep gaining mass after infall, at high redshift, relative to centrals.
  • Keres et al http://arxiv.org/abs/0901.1880, "Galaxies in a simulated LCDM Universe II: Observable Properties and Constraints on Feedback"

Subhalos + infall prescription

• Hopkins et al, http://arxiv.org/abs/0906.5357, "Mergers and Bulge Formation in Lambda-CDM: Which Mergers Matter?", semi-empirical models, predicts galaxy merger rates and contributions to bulge growth as functions of merger mass, redshift, and mass ratio. uses empirical halo occupation constraints to identify mergers, together with high-resolution simulations to quantify how mergers with different properties contribute to the bulge population. compares to observational constraints, gives fitting functions for merger rates and contributions to bulge growth.
• Hopkins et al, "A Cosmological Framework for the Co-Evolution of Quasars, Supermassive Black Holes, and Elliptical Galaxies: I. Galaxy Mergers & Quasar Activity " http://arxiv.org/abs/0706.1243
  know subhalos are there, calculate how long it takes for them to hit the center, use range of methods and range of subhalo distributions people have. Efficiency of major mergers, fig. 2, as fn of Mhalo, merger fraction as function of host halo mass, fig 6, merger efficiency for sat-sat, cen-sat etc., fig 4.

Halo (not subhalo) mergers plus dynamical infall model

• Wetzel & White, http://arxiv.org/abs/0907.0702, What determines satellite galaxy disruption?
  calibration of dynamical infall time from cosmological simulations
• Stewart, Bullock, Barton, Wechsler http://arxiv.org/abs/0811.1218, "Galaxy and Dark Matter Halo mergers"
  Dark matter simulations. Merger if subhalo loses >90% of mass. Take halos, get halo merger rates, associate halos with galaxies to get galaxy merger rate. Galaxy major merger fraction assuming halo mergers give galaxy mergers in 1-1??
• Khochfar & Silk, http://xxx.uni-augsburg.de/abs/0809.1734,
  "Dry Mergers: A Crucial Test for Galaxy Formation,"
  The dry merger rate and the consequences of feedback on it. Especially the mass ratio of merging galaxies.
• Khochfar & Burkert, http://xxx.uni-augsburg.de/abs/astro-ph/0105383,
  "Redshift Evolution of the Merger Fraction of Galaxies in CDM Cosmologies"
  Galaxy merger rates in LCDM SAM from EPS merger trees + dynamical friction. Shows the dependency of the power-law slope as a function of environment, mass resolution and mass ratio
• Kitzbichler & White?
• Benson et al, arXiv:astro-ph/0108217,
  ""The effects of photoionization on galaxy formation - I. Model and results at z=0"
  The evolution of the galaxies is calculated using a semi-analytical model, including a detailed treatment of the effects of tidal stripping and dynamical friction on satellite galaxies orbiting inside larger dark matter haloes
• Dynamical friction simulation measurements
  • http://arxiv.org/abs/0902.3734 Jiang, Jing & Lin,
    "Influence of baryonic physics on the merger time-scale of galaxies in N-body/hydrodynamical simulations"
    Merger time-scale little affected by the star formation recipes, except for the satellites in nearly radial orbits (22 percent higher time-scale in the lower stellar mass case). Radial orbits only a small part of the satellites' orbits.
  • Boylan-Kolchin, Ma, Quataert, http://arxiv.org/abs/0707.2960 "Dynamical Friction and Merging Galaxy Timescales"
    collide DM halos to get merging timescales, dynam friction predictions for merging timescales, systematically shorter than those found in simulations, give fitting function.
  • Jiang++08, http://arxiv.org/abs/0707.2628, "A fitting formula for the merger timescale of galaxies in hierarchical clustering",
    Galaxy mergers in hydro/N-body simulation with star formation, compare measured merger timescales with theoretical predictions based on the Chandrasekhar formula. Based on these findings, we present an accurate and convenient fitting formula for the merger timescale of galaxies in cold dark matter models.
  • Taylor & Babul, arXiv:astro-ph/0012305
    "The Dynamics of Sinking Satellites around Disk Galaxies: A Poor Man's Alternative to High-Resolution Numerical Simulations"
    Dynamical friction calculations for satellites and orbital parameters etc.
  • Metcalf & Madau??

• Wang & Kauffmann http://arxiv.org/abs/0801.3530,
• Wetzel, Cohn & White http://arxiv.org/abs/0810.2537, Fig. 4 compares halo and subhalo merger rates as a function of redshift.
• Stewart, http://arxiv.org/abs/0902.2214,
  "Invisible Major Mergers: Why the Definition of a Galaxy Merger Ratio Matters",
  Defns of major mergers differing using halo masses, galaxy stellar masses, galaxy baryonic masses

Halo (not subhalo) merger rates/trees in simulations

• Fakhouri, Ma, Boylan-Kolchin, https://arxiv.org/abs/1001.2304, The Merger Rates and Mass Assembly Histories of Dark Matter Haloes in the Two Millennium Simulations, updated for a large and small box joined together.
• Neistein & Maccio http://arxiv.org/abs/0903.1640, Universal Merging Histories of Dark-Matter Haloes, Statistical properties such as merger-rates and main-progenitor histories, global fit can be used to transform merger-trees extracted from a given N-body simulation into a different cosmology or mass resolution.
• Genel et al, http://arxiv.org/abs/0812.3154
  The halo merger rate in the Millennium Simulation and implications for observed galaxy merger fractions
  Halo Merger rate formulae, section 3
• Fakhouri & Ma, http://arxiv.org/abs/0808.2471,
  "Environmental Dependence of Dark Matter Halo Growth I: Halo Merger Rates"
  Dependence of the merger rate of haloes on their surrounding environment, using different definitions of environment.
• Stewart et alhttp://arxiv.org/abs/0711.5027,
  "Merger Histories of Galaxy Halos and Implications for Disk Survival",
  halo merger fractions for 10^11-10^13 Msun halos in the past t=0-12 Gyrs. Emphasis on disk survival. Uses 2 different definitions of merger mass ratio to compare and contrast. Main results: Fig 5 and Fig 8 (Fig 8 in appendix) have fraction of halos (not subhalos) having a major merger since a given time
• Fakhouri & Ma, http://arxiv.org/abs/0710.4567, "The Nearly Universal Merger Rate of Dark Matter Haloes in Lambda-CDM Cosmology",
  Millennium simulation, descendant halo mass (1e12 < M0 < 1e15 Msun), progenitor mass ratio (1e-3 < xi < 1), and redshift (0 < z < 6). (section 4 has results). Equation 12 is fitting function to Halo merger rates.
• Neistein, Dekel http://arxiv.org/abs/0708.1599, Constructing Merger Trees that Mimic N-Body Simulations,
  Accurate analytic time-invariant approximations for the main progenitor accretion history and for halo merger rates.
• Wetzel, Schulz, Holz & Warren http://arxiv.org/abs/0706.0518 Close Pairs as Proxies for Galaxy Cluster Mergers,
  DM simulations, merger timescales, merger rates from z ~ 0-1, environmental dependence (cluster sized halos).
• Cohn & White, http://arxiv.org/abs/0706.0208,
  "Dark matter halo abundances, clustering and assembly histories at high redshift"
  includes comparison with EPS predictions for progenitor masses at z=10.
• Li et al, http://arxiv.org/abs/astro-ph/0510372,
  "On The Assembly History of Dark Matter Haloes",
  mass assembly history of dark matter halos using eps, simulations and pinocchio. slow and fast mass accretion rates.
• Gottloeber, Klypin, Kravtsov http://arxiv.org/abs/astro-ph/0004132,
  "Merging history as a function of halo environment",
  scaling laws for merger rates, comparison of different environments.
• [ lots in here]
• Tormen, http://arxiv.org/abs/astro-ph/9802290,
  "The Assembly of Matter in Galaxy Clusters"
  Merging history of dm halos that end up in rich clusters. Scale free sims.
• Lacey & Cole, http://arxiv.org/abs/astro-ph/9402069
  "Merger rates in hierarchical models of galaxy formation. II: Comparison with N-body simulations"
  Classic EPS derivation, compare to simulations.
• Kauffmann & White, MNRAS 1993, 261, 921
  "The merging history of dark matter haloes in a hierarchical universe". algorithm for merging history trees, comparison to simulations.

Analytic Halo Merger Rates

• Alizadeh and Wandelt, https://arxiv.org/abs/0810.2301,
  "Dark matter halo merger and accretion probabilities in the excursion set formalism,"
  EPS merger trees, separating out accretion and mergers, agreement with Monte Carlo method
• Neistein & Dekel, http://arxiv.org/abs/0802.0198
  "Merger rates of Dark-Matter halos"
  EPS analytic merger rates. new way to do trees.
• Zhang, Ma, Fakhouri, http://arxiv.org/abs/0801.3459,
  "Conditional Mass Functions and Merger Rates of Dark Matter Halos in the Ellipsoidal Collapse Model ",
  Analytic merger rates, generalizing EPS
• Benson, 2008,MNRAS 388, 1361,
  "Constraining cold dark matter halo merger rates using the coagulation equations",
• Neistein and Dekel, http://arxiv.org/abs/0708.1599,
  Constructing Merger Trees that Mimic N-Body Simulations,
  Accurate analytic time-invariant approximations for the main progenitor accretion history and for halo merger rates. equation 9 is halo mass growth rate, eqn. 12 is merger rate
• Giocoli et al, 2007, http://arxiv.org/abs/astro-ph/0611221,
  "An improved model for the formation times of dark matter haloes",
  estimates of halo formation based on ellipsoidal collapse model.
• Benson, Kamionkowsi,Hassani, http://arxiv.org/abs/astro-ph/0407136,
  "Self-Consistent Theory of Halo Mergers,"
  for power law spectra can reproduce halo abundance, general considerations.
• Miller?
• Percival & Miller, http://arxiv.org/abs/astro-ph/9906204, "Cosmological Evoultion & Hierarchical Galaxy Formation"
  rates at which DM halos merge to form higher mass systems, compare to N-body and Monte Carlo
• Sheth and Lemson http://arxiv.org/abs/astro-ph/9805322,
  
• [ lots in here]
• Kitayama & Suto,
• Lacey & Cole, http://arxiv.org/abs/astro-ph/9402069
  "Merger rates in hierarchical models of galaxy formation. II: Comparison with N-body simulations"
  Classic EPS derivation.
• Bond & Myers 1991
• Bower 1991

Subhalo merger clustering

• Thacker, Scannapieco & Couchman, http://arxiv.org/abs/0706.0518 cross correlation of mergers (mergers = mass gain of >30%), enhanced clustering for mergers at short distances compared to other objects above some luminosity.
  Also see http://arxiv.org/abs/0706.0518, (Thacker, Scannapieco, Couchman, Richardson). Redshift, Luminosity and Selection Dependence for QSO's, again with merger enhancement.
• Wetzel, Cohn & White http://arxiv.org/abs/0810.3650, Clustering and Hosts of Galaxy Mergers at High Redshift
  DM simulations, Mergers 1:3 in infall mass, HOD for mergers (recently merged subhalos tend to be in halos with more satellites)
• Bonoli,Shankar, White,Springel,Wyithe http://arxiv.org/abs/0909.0003, On merger bias and the clustering of quasars
  Millennium simulations, mergers 1:4 of stellar mass, recent mergers have different clustering, for z ~2-5, bounded by 20-30%.