The effect of galaxy mass ratio on merger-driven starbursts

By Thomas J. Cox, P. Jonsson, R. Somerville, Joel R. Primack, A. Dekel, HarvardCfA, U. Cruz, Mpia, HU Jerusalem. 2007

399 citations recorded by the source corpus.

We employ numerical simulations of galaxy mergers to explore the effect of galaxy mass ratio on merger-driven starbursts. Our numerical simulations include radiative cooling of gas, star formation, and stellar feedback to follow the interaction and merger of four disc galaxies. The galaxy models span a factor of 23 in total mass and are designed to be representative of typical galaxies in the local universe. We find that the merger-driven star formation is a strong function of merger mass ratio, with very little, if any, induced star formation for large mass ratio mergers. We define a burst efficiency that is useful to characterize the merger-driven star formation and test that it is insensitive to uncertainties in the feedback parametrization. In accord with previous work we find that the burst efficiency depends on the structure of the primary galaxy. In particular, the presence of a massive stellar bulge stabilizes the disc and suppresses merger-driven star formation for large mass ratio mergers. Direct, coplanar merging orbits produce the largest tidal disturbance and yield the most intense burst of star formation. Contrary to naive expectations, a more compact distribution of gas or an increased gas fraction both decrease the burst efficiency. Owing to the efficient feedback model and the newer version of smoothed particle hydrodynamics employed here, the burst efficiencies of the mergers presented here are smaller than in previous studies.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/9581c540fa73abec634d22bb0f52793d0927e75f

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In Astronomy and Astrophysics

1. P. Hopkins
2. L. Hernquist
3. R. Somerville
4. R. Dav'e
5. Volker Springel
6. Thomas J. Cox
7. T. Naab
8. M. Cappellari

In Instrumentation

1. P. Hopkins
2. L. Hernquist
3. R. Somerville
4. M. Cappellari
5. Thomas J. Cox
6. R. Dav'e
7. Volker Springel
8. T. Naab

Citations in the corpus

• HOW DO DISKS SURVIVE MERGERS? (2008, background): “…is also ruled out observationally, both for the arguments above (starbursts exist, and the winds seen are not so enormous; see the discussion in Cox et al. 2008b; Hopkins et al. 2005a,b,c,d, 2006), and because such a prescription yields black hole masses orders-of-magnitude discrepant from the…”
• The effects of gas on morphological transformation in mergers: implications for bulge and disc demographics (2009, result): “…because the efficiency of bulge formation as calibrated in simulations is nearly linear in mass ratio, they give indistinguishable results for our purposes here, so long as they all occur within a short time-scale (see e.g. Naab & Burkert 2003; Bournaud, Jog & Combes 2005; Cox et al. 2008; H09).”
• Galaxy formation theory (2010, methodology): “18The equation in Cox et al. (2008) is missing the coefficient ofe1:1 (Cox, private communication).”
• Galaxy pairs in the Sloan Digital Sky Survey – IX. Merger-induced AGN activity as traced by the Wide-field Infrared Survey Explorer (2014, background): “These numerical simulations show that multiple gas inflow epochs along the merger sequence occur, with enhanced nuclear accretion in the mostadvanced mergers, just prior to coalescence (e.g., Mihos & Hernquist 1996; Cox et al. 2006; Barnes & Hernquist 1996; Cox et al. 2008).”
• The star formation main sequence and stellar mass assembly of galaxies in the Illustris simulation (2014, methodology): “However, in higher-resolution idealised merger simulations that employed the same ISM model, SFR elevations of an order of magnitude or more have been found (e.g. Cox et al. 2008; Hayward et al. 2011, 2014; Torrey et al. 2012).”
• Dusty Star Forming Galaxies at High Redshift (2014, background): “First, the majority of stars formed in galaxy mergers are done during early quiescent phases, rather than bursts (e.g. Cox et al., 2008).”
• WHAT DOES A SUBMILLIMETER GALAXY SELECTION ACTUALLY SELECT? THE DEPENDENCE OF SUBMILLIMETER FLUX DENSITY ON STAR FORMATION RATE AND DUST MASS (2010, background): “…infalling disks (normal galaxies that are not yet interacting strongly) blended into one submm source (“galaxy-pair SMGs”).12 Note also that not only major mergers but also favorably oriented minor mergers (see, e.g., Cox et al. 2008; Hopkins et al. 2009b) can contribute to the SMG population.”
• Galaxy pairs in the Sloan Digital Sky Survey – V. Tracing changes in star formation rate and metallicity out to separations of 80 kpc (2012, methodology): “Cox et al. (2008) find that high mass galaxies in unequal mass mergers are less likely to be tidally perturbed and drive strong SFR enhancements when interacting with a low mass companion, whereas the low mass companion will be strongly perturbed by a massive companion.”
• High-resolution panchromatic spectral models of galaxies including photoionization and dust (2009, methodology): “The galaxy simulations used in this work have been described in detail in earlier papers (Cox 2004; Jonsson 2004; Cox et al. 2006; Jonsson et al. 2006; Cox et al. 2008; Rocha et al. 2008; Lotz et al. 2008), but a brief overview will be given here for context.”
• Galaxy pairs in the Sloan Digital Sky Survey – VIII. The observational properties of post-merger galaxies (2013, background): “Simulations of galaxy interactions generally conclude that intense bursts of star formation should occur at, or shortly before, coalescence (e.g. Di Matteo et al. 2007, 2008; Cox et al. 2008; Torrey et al. 2012).”
• REGULARITY UNDERLYING COMPLEXITY: A REDSHIFT-INDEPENDENT DESCRIPTION OF THE CONTINUOUS VARIATION OF GALAXY-SCALE MOLECULAR GAS PROPERTIES IN THE MASS-STAR FORMATION RATE PLANE (2013, neutral): “If SFR enhancements in merger-driven SBs depend on the mass ratio of the galaxies involved (e.g., Cox et al. 2008), then the boost distribution including minor mergers should be broader.”
• The impact of gas inflows on star formation rates and metallicities in barred galaxies (2011, background): “Simulations have also predicted that the triggered star formation should be more effective in interactions between approximately equal mass galaxies (Cox et al. 2008).”
• GALAXY PAIRS IN THE SLOAN DIGITAL SKY SURVEY. I. STAR FORMATION, ACTIVE GALACTIC NUCLEUS FRACTION, AND THE LUMINOSITY/MASS–METALLICITY RELATION (2008, methodology): “We expect (e.g., Lambas et al. 2003; Woods et al. 2006; Bekki et al. 2006; Cox et al. 2008; Woods & Geller 2007) that pairs with almost equal masses (“major mergers/interactions”) will exhibit more pronounced interaction-induced effects than unequal (“minor”) mass encounters.”
• Gravitational waves from resolvable massive black hole binary systems and observations with Pulsar Timing Arrays (2008, background): “The ”SA” and the ”DA” modes are to be expected in gaspoor mergers, especially in non-equal-mass mergers, where the dynamical evolution of the binary is much slower (e.g., Yu 2002) than the infall timescale of the gas (e.g., Cox et al. 2008).”
• A semi-analytic model for the co-evolution of galaxies, black holes and active galactic nuclei (2008, methodology): “(7) This functional form has been shown to describe well the scaling of burst efficiency with merger mass ratio in hydrodynamic simulations of galaxy mergers (Cox et al. 2008, hereafter C08).”
• GALAXY STRUCTURE AND MODE OF STAR FORMATION IN THE SFR–MASS PLANE FROM z ∼ 2.5 TO z ∼ 0.1 (2011, neutral): “Overall, the timescales obtained are not inconsistent with those expected from merger-induced star formation on the basis of hydrodynamical simulations (Mihos & Hernquist 1996; Cox et al. 2008), although there may be room 11 for other evolutionary paths to reach the quiescent phase as well.”
• Simulations of binary galaxy mergers and the link with fast rotators, slow rotators, and kinematically distinct cores (2011, background): “…with observed properties of ETGs (Naab & Burkert 2003; Bournaud, Combes & Jog 2004; Bournaud, Jog & Combes 2005; Naab, Jesseit & Burkert 2006a; Cox et al. 2006a, 2008; Rothberg & Joseph 2006; Di Matteo et al. 2007; Burkert et al. 2008; Jesseit et al. 2009; Hoffman et al. 2010; Chilingarian et…”
• THE DEPENDENCE OF QUENCHING UPON THE INNER STRUCTURE OF GALAXIES AT 0.5 ⩽ z < 0.8 IN THE DEEP2/AEGIS SURVEY (2012, background): “They act to heat the surrounding gas and/or drive winds out of the galaxy (e.g., Sanders et al. 1988; Springel et al. 2005; Murray et al. 2005; Cox et al. 2008; Ciotti et al. 2009; Alexander et al. 2010).”