THE DRIVING MECHANISM OF STARBURSTS IN GALAXY MERGERS

By Romain Teyssier, Damien Chapon, Frédéric Bournaud. 2010

198 citations recorded by the source corpus.

We present hydrodynamic simulations of a major merger of disk galaxies, and study the interstellar medium (ISM) dynamics and star formation (SF) properties. High spatial and mass resolutions of 12 pc and 4 × 104 M☉ allow us to resolve cold and turbulent gas clouds embedded in a warmer diffuse phase. We compare lower-resolution models, where the multiphase ISM is not resolved and is modeled as a relatively homogeneous and stable medium. While merger-driven bursts of SF are generally attributed to large-scale gas inflows toward the nuclear regions, we show that once a realistic ISM is resolved, the dominant process is actually gas fragmentation into massive and dense clouds and rapid SF therein. As a consequence, SF is more efficient by a factor of up to ∼10 and is also somewhat more extended, while the gas density probability distribution function rapidly evolves toward very high densities. We thus propose that the actual mechanism of starburst triggering in galaxy collisions can only be captured at high spatial resolution and when the cooling of gas is modeled down to less than 103 K. Not only does our model reproduce the properties of the Antennae system, but it also explains the “starburst mode” recently revealed in high-redshift mergers compared to quiescent disks.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/bb7dc47f6ee3c98052026939b716bca9040c239e

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In Astronomy and Astrophysics

1. P. Hopkins
2. L. Hernquist
3. A. Dekel
4. E. Quataert
5. D. Narayanan
6. R. Somerville
7. R. Dav'e
8. Thomas J. Cox

In Instrumentation

1. P. Hopkins
2. L. Hernquist
3. A. Dekel
4. Thomas J. Cox
5. R. Somerville
6. E. Quataert
7. R. Dav'e
8. D. Narayanan

Citations in the corpus

• Rotational support of giant clumps in high-z disc galaxies (2011, methodology): “The technique relies on a quasi-Lagrangian refinement of the AMR grid and a barotropic equation of state for the heterogeneous ISM (Teyssier et al. 2010; Bournaud et al. 2010).”
• ISM properties in hydrodynamic galaxy simulations: turbulence cascades, cloud formation, role of gravity and feedback (2010, background): “1 and Teyssier et al. 2010).”
• Self-regulated star formation in galaxies via momentum input from massive stars (2011, methodology): “This is a standard approach in high-resolution simulations (see e.g. Teyssier et al. 2010).”
• A UNIVERSAL, LOCAL STAR FORMATION LAW IN GALACTIC CLOUDS, NEARBY GALAXIES, HIGH-REDSHIFT DISKS, AND STARBURSTS (2011, unknown): “…formation on galactic or cosmological scales (e.g. Springel & Hernquist 2003; Robertson & Kravtsov 2008; Gnedin et al. 2009; Bournaud et al. 2010; Teyssier et al. 2010; Ceverino et al. 2010; Agertz et al. 2011; Kuhlen et al. 2011), and suggests that there is no need to modify these laws to…”
• An analytic model of angular momentum transport by gravitational torques: from galaxies to massive black holes (2010, methodology): “This is qualitatively consistent with the results from galaxy merger simulations, but needs to be studied in more detail (for comparison, see e.g. Agertz et al. 2009; Teyssier et al. 2010).”
• Star formation in galaxy mergers with realistic models of stellar feedback and the interstellar medium (2012, methodology): “Like the qeos = 0 models, the Teyssier et al. (2010) models adopt an effective EOS, but one in which the ‘median’ ISM temperature is much colder than the subgrid sound speeds used in the EOS models here, which makes catastrophic fragmentation possible.”
• 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, unknown): “However, a dichotomy in the distribution of SFEs could still occur if the timescales for such variations were short (e.g., Teyssier et al. 2010, Bournaud et al. 2011a).”
• A sub-parsec resolution simulation of the Milky Way: global structure of the interstellar medium and properties of molecular clouds (2013, methodology): “On the one hand, cosmological aspects like accretion of gas (e.g. Dekel & Birnboim 2006) or galaxy interaction/mergers (Di Matteo et al. 2007; Karl et al. 2010; Teyssier et al. 2010) are known to affect the behaviour of the gas reservoir of the galaxy, and thus the formation of stars.”
• THE LONG LIVES OF GIANT CLUMPS AND THE BIRTH OF OUTFLOWS IN GAS-RICH GALAXIES AT HIGH REDSHIFT (2013, methodology): “We also impose a pressure floor to keep the Jeans length greater than four times the smallest cell size and avoid spurious instabilities (Truelove et al. 1997, see Section 2.1 in Teyssier et al. 2010).”
• Dusty Star Forming Galaxies at High Redshift (2014, background): “Significant theoretical progress towards this picture has beenmade by Hopkins et al. (2005a,b, 2006), Kim et al. (2009), Younger et al. (2009a), Teyssier et al. (2010), Hayward et al. (2013c) and others.”
• Radiative feedback and the low efficiency of galaxy formation in low-mass haloes at high redshift (2013, background): “Some of these subgrid models encapsulate the effect of feedback and unresolved multiphase structure as an effective equation of state (Springel & Hernquist 2003; Teyssier et al. 2010).”
• HYDRODYNAMICS OF HIGH-REDSHIFT GALAXY COLLISIONS: FROM GAS-RICH DISKS TO DISPERSION-DOMINATED MERGERS AND COMPACT SPHEROIDS (2010, methodology): “…effect in mergers of present-day spirals with just a few percent of gas, with significant differences both in the star-formation history during the interaction (Teyssier et al. 2010; Saitoh et al. 2009) and the prop- 3 erties of the relaxed post-merger ETG (Bournaud et al. 2008; Bois et al. 2010).”
• Hierarchical formation of bulgeless galaxies: why outflows have low angular momentum (2010, result): “The importance of resolving star forming regions was also demonstrated by the results from a constrained merger simulation done by Teyssier et al. (2010).”
• The current status of galaxy formation (2012, background): “Sharp increases of the SF density threshold result in moving the SF regions outside of the nucleus (Teyssier et al., 2010).”
• Ionized gas outflows and global kinematics of low-z luminous star-forming galaxies (2014, background): “Recent hydrodynamical simulations of major mergers of disc galaxies (Teyssier et al. 2010) are able to reproduce the starburst mode with hig star formation rates soon after the first pericentre, and reaching its maximum at the final coalescence.”
• The properties of the interstellar medium within a star-forming galaxy at z= 2.3 (2010, background): “Interestingly, Teyssier et al. (2010) have c© 0000 RAS, MNRAS 000, 000–000 recently used hydrodynamic simulations of major mergers of disk galaxies to show that the density of gas at which a majority of the star formation in these systems occurs is n∼ 104 cm−3, as we find here.”
• The CO-H2 Conversion Factor in Disc Galaxies and Mergers (2011, result): “We note, however, that our work, like that of Teyssier et al. (2010), is consistent with the idea that e observed behaviour in the star formation rates andXCO can be explained without the need to invoke a volumetric star formation law that is different in discs and mergers.”