Feedback in simulations of disc-galaxy major mergers

By Thomas J. Cox, P. Jonsson, Joel R. Primack, R. Cruz, Harvard, Stsci. 2005

261 citations recorded by the source corpus.

Using hydrodynamic simulations of disc-galaxy major mergers, we investigate the star formation history and remnant properties when various parametrizations of a simple stellar feedback model are implemented. The simulations include radiative cooling, a density-dependent star formation recipe and a model for feedback from massive stars. The feedback model stores supernova feedback energy within individual gas particles and dissipates this energy on a time-scale specified by two free parameters; τ fb , which sets the dissipative time-scale, and n, which sets the effective equation of state in star-forming regions. Via this model, feedback energy can provide pressure support to regions of gas that are thermally cold. Using a self-consistent disc galaxy, modelled after a local Sbc spiral, in both isolated and major-merger simulations, we investigate parametrizations of the feedback model that are selected with respect to the quiescent disc stability. These models produce a range of star formation histories for discs evolved in isolation, or during a major merger, yet all are consistent with the star formation relation found by Kennicutt. We suggest that this result is produced by the adopted recipe for star formation and is not a byproduct of the feedback model. All major mergers produce a population of new stars that is highly centrally concentrated, demonstrating a distinct break in the r 1/4 surface density profile, consistent with previous findings. The half-mass radius and one-dimensional velocity dispersion are affected by the feedback model used. In tests with up to an order of magnitude higher resolution, the star formation history is nearly identical, suggesting that we have achieved a numerically converged star formation history. Finally, we compare our results to those of previous simulations of star formation in disc-galaxy major mergers, addressing the effects of star formation normalization, the version of smoothed particle hydrodynamics (SPH) employed and assumptions about the interstellar medium. We conclude by suggesting several methods by which future studies may better constrain feedback models.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/5f441117b3385f2979ab49f8fc32dbd2e22098ad

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In Astronomy and Astrophysics

1. P. Hopkins
2. L. Hernquist
3. R. Somerville
4. R. Dav'e
5. Thomas J. Cox
6. A. Dekel
7. T. Naab
8. P. V. van Dokkum

Citations in the corpus

• Interaction-induced star formation in a complete sample of 105 nearby star-forming galaxies (2007, background): “…& White 1983; Barnes & Hernquist 1992; Mihos & Hernquist 1996; Springel 2000; Tissera et al. 2002; Meza et al. 2003; Kapferer et al. 2005; Cox et al. 2006) have demonstrated that interactions between galaxies can bring gas from the disc to the central regions of the galaxy, leading to…”
• Galaxy pairs in the Sloan Digital Sky Survey – V. Tracing changes in star formation rate and metallicity out to separations of 80 kpc (2012, background): “This gas then falls towards the nucleus of the galaxy, efficiently funnelled by the bar instabilities (Barnes & Hernquist 1996; Mihos & Hernquist 1996; Cox et al. 2006; Di Matteo et al. 2007; Montuori et al. 2010; Rupke et al. 2010a; Torrey et al. 2012).”
• THE METALLICITY EVOLUTION OF INTERACTING GALAXIES (2011, methodology): “We adopt a value t∗ = 4.5 Gyrs so that our simulations are consistent with the Kennicutt-Schmidt relation (Schmidt 1959; Kennicutt 1998; Cox et al. 2006b).”
• Galaxy merger morphologies and time-scales from simulations of equal-mass gas-rich disc mergers (2008, methodology): “…mass distribution of star particles follow r1/4 laws with steep central cusps consistent with or more concentrated than the light profiles of elliptical galaxies (e.g. Cox et al. 2006, 2008; Naab et al. 2006; Bournaud, Jog, & Combes 2005) and lie on the fundamental plane (Robertson et al. 2006b).”
• Minor Galaxy Interactions: Star Formation Rates and Galaxy Properties (2007, methodology): “The simulations of Cox et al. (2006) model colliding disk galaxies with feedback from massive stars and radiative cooling and use a density-dependent star formation prescription; they produce a centrally concentrated burst of star formation for simulations with a range of star formation histories.”
• Galaxy pairs in the Sloan Digital Sky Survey – VIII. The observational properties of post-merger galaxies (2013, background): “Moreover, the detection of enhanced SFRs at wide separations is consistent with the much longer timescales (up to a Gyr or more) for interaction-induced star formation predicted by contemporary hydrodynamical simulations (e.g. Cox et al 2006, 2008; Torrey et al 2012).”
• Star Formation in AEGIS Field Galaxies since z = 1.1: The Dominance of Gradually Declining Star Formation, and the Main Sequence of Star-forming Galaxies (2007, background): “The amplitude of thesez p 1 variations ( #4) is consistent with gas-poor or minor mergers, rather than the peak SFR of gas-rich major mergers (Springel2000; Cox et al. 2006).”
• Submillimetre galaxies in a hierarchical universe: number counts, redshift distribution, and implications for the IMF (2012, methodology): “The division of mass, energy and entropy between the two phases is affected by star formation, radiative heating and cooling, and supernova feedback, which heats the diffuse phase and evaporates the cold clouds (Cox et al. 2006b).”
• THE ROLE OF STELLAR FEEDBACK IN THE FORMATION OF GALAXIES (2007, methodology): “Moreover, instead of using a subresolution model of a multiphase medium (Springel & Hernquist 2003; Cox et al. 2006), we resolve that (A color version of this figure is available in the online journal.) multiphase medium.”
• Energy, momentum and mass outflows and feedback from thick accretion discs around rotating black holes (2013, unknown): “…2008) and (iii) modelled via simple prescriptions in gas dynamical computer simulations of galaxy/cluster formation in the universe (Di Matteo, Springel & Hernquist 2005; Springel et al. 2005; Cox et al. 2006; Ciotti, Ostriker & Proga 2010; Novak, Ostriker & Ciotti 2011; Scannapieco et al. 2012).”
• The CO-H2 Conversion Factor in Disc Galaxies and Mergers (2011, methodology): “The normalisation of this relation is set in order to match the localΣSFR −Σgas relation (Kennicutt 1998a,b; Springel 2000; Cox et al. 2006b).”
• The DEEP2 Galaxy Redshift Survey: the role of galaxy environment in the cosmic star formation history (2007, background): “Similarly, galaxy groups are the preferred location for galaxy mergers (Cavaliere et al. 1992) and interactions which may induce bursts of star formation and/or expulsion of gas (e.g., Mihos & Hernquist 1996; Cox et al. 2006; Lin et al. 2007).”
• 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 effect of gas fraction on the morphology and time-scales of disc galaxy mergers (2009, methodology): “Low density gas shocked by mergers can linger as hot X-ray emitting gaseous haloes (e.g. Cox et al. 2004, 2006a; Sinha & Holley-Bockelmann 2009).”
• Simulations of the grand design galaxy M51: a case study for analysing tidally induced spiral structure (2009, methodology): “Unlike GADGET (Springel, Yoshida & White 2001; Springel 2005), which has previously been applied to simulations of interacting galaxies (e.g. Cox et al. 2006; Jáchym et al. 2007), our code has predominantly been used for simulations of star formation (e.g. Bate, Bonnell & Bromm 2003; Price & Bate…”
• MERGERS AND BULGE FORMATION IN ΛCDM: WHICH MERGERS MATTER? (2009, methodology): “…L∗ ellipticals (in terms of their profile shapes, effective radii and fundamental plane correlations, rotation and higher-order kinematics, isophotal shapes, triaxiality, and other prope ties; see e.g. Naab et al. 2006; Cox et al. 2006a; Jesseit et al. 2007, 2009; Hopkins et al. 2008c,a, 2009c)23.”
• Physical properties and environments of nearby galaxies (2009, background): “Theory suggests that major gas-rich mergers would create such starbursts — a consequence of the large amount of gas that is driven to the center of the merging system (e.g., Mihos, Richstone & Bothun 1992; Cox et al. 2006).”