Disc formation and the origin of clumpy galaxies at high redshift

By O. Agertz, Romain Teyssier, B. Moore. Monthly Notices of the Royal Astronomical Society Letters, 2009

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Observations of high-redshift galaxies have revealed a multitude of large clumpy rapidly star-forming galaxies. Their formation scenario and their link to present-day spirals are still unknown. In this Letter, we perform adaptive mesh refinement simulations of disc formation in a cosmological context that are unrivalled in terms of mass and spatial resolution. We find that the so-called 'chain-galaxies' and 'clump-clusters' are a natural outcome of early epochs of enhanced gas accretion from cold dense streams as well as tidally and ram-pressured stripped material from minor mergers and satellites. Through interaction with the hot halo gas, this freshly accreted cold gas settles into a large disc-like system, not necessarily aligned to an older stellar component, that undergoes fragmentation and subsequent star formation, forming large clumps in the mass range 10 7-10 9 M ⊙. Galaxy formation is a complex process at this important epoch when most of the central baryons are being acquired through a range of different mechanisms - we highlight that a rapid mass loading epoch is required to fuel the fragmentation taking place in the massive arms in the outskirts of extended discs, an accretion mode that occurs naturally in the hierarchical assembly process at early epochs.

Subfields: Astronomy and Astrophysics, Instrumentation

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Citations in the corpus

Accretion-driven turbulence as universal process: galaxies, molecular clouds, and protostellar disks (2009, background): “Roughly three quarters of all star-forming galaxies are fed by smooth streams (see also Agertz et al. 2009).”
ON THE INTERPLAY BETWEEN STAR FORMATION AND FEEDBACK IN GALAXY FORMATION SIMULATIONS (2014, methodology): “…− 100pc, comparable to the scale of massive giant molecular clouds (GMCs), is not uncommon in modern cosmological galaxy formation simulations (e.g. Kravtsov 2003; Gnedin & Kravtsov 2010; Agertz et al. 2009b; Hopkins et al. 2014), the relevant star formation and feedback processes remain “subgrid”.”
Radiative feedback and the low efficiency of galaxy formation in low-mass haloes at high redshift (2013, methodology): “This is better than the 40-pc resolution in Agertz et al. (2009) and much better than the 120-pc of the spline softening length in Eris simulation (Guedes et al. 2011), although the SPH kernel could be much smaller.”
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): “Since clumps are a telltale signature of violent disk instabilities in gas-rich high-redshift galaxies (e.g., Agertz et al. 2009, Ceverino et al. 2010, Förster Schreiber et al. 2011, Swinbank et al. 2011, Wuyts et al. 2012) this observation thus provides independent evidence for increasing gas…”
ISM properties in hydrodynamic galaxy simulations: turbulence cascades, cloud formation, role of gravity and feedback (2010, methodology): “The levels of turbulent speed in these models seem realistic for both nearby and high-redshift galaxies (see Agertz et al. 2009a and Ceverino, Dekel & Bournaud 2010, respectively).”
Misaligned angular momentum in hydrodynamic cosmological simulations: warps, outer discs and thick discs (2010, background): “‘Cold accretion’ discussed here should not be confused with highredshift ‘cold streams’ (e.g. Dekel et al. 2009a; Agertz et al. 2009; Ceverino et al. 2010), which are a result of filaments penetrating the virialized halo directly to the central disc region.”
Lyα blobs as an observational signature of cold accretion streams into galaxies (2009, background): “…which show that baryons assemble into galaxies through a two-phase medium which contains filamentary streams of cold (T ∼ 104 K) gas embedded within a hot gaseous halo (e.g Kereš et al. 2005; Dekel & Birnboim 2006; Ocvirk et al. 2008; Dekel et al. 2009; Kereš et al. 2009; Agertz et al. 2009).”
Small scale problems of the $\Lambda$CDM model: a short review (2016, background): “Galaxies containing baryon mass of 1010–1011M typically form clumps of mass '108–109M (see [320,322,323]).”
Moving mesh cosmology: tracing cosmological gas accretion (2013, methodology): “A common alternate approach is to use the instantaneous gas properties such as mass flux through a surface (e.g. Ocvirk et al. 2008; Dekel et al. 2009) to measure rates, or the low metallicity of gas as an indicator of cosmological origin (Agertz et al. 2009).”
Neutral hydrogen in galaxy haloes at the peak of the cosmic star formation history (2014, background): “…profiles of hot halo gas in PSPH are close to those found in grid-based codes and substantially different than in density-based SPH simulations, resulting in enhanced hot gas accretion rates onto galaxies (as found, e.g., in the mesh-based calculations of Agertz et al. 2009; Nelson et al. 2013).”
A unified model for galactic discs: star formation, turbulence driving, and mass transport (2017, background): “…theories that link the problems of velocity dispersion, marginal stability, and star formation fuelling (e.g. Bournaud, Elmegreen & Elmegreen 2007; Agertz et al. 2009b; Bournaud & Elmegreen 2009; Dekel, Sari & Ceverino 2009; Ceverino, Dekel & Bournaud 2010; Krumholz & Burkert 2010; Vollmer &…”
Physical Processes in the Interstellar Medium (2014, background): “In this case, roughly three quarters of all galaxies forming stars at a given rate are fed by smooth streams (see also Agertz et al., 2009).”
Four phases of angular-momentum buildup in high-z galaxies: from cosmic-web streams through an extended ring to disc and bulge (2014, background): “…of the baryons (28 per cent if the gas of intermediate temperatures slightly above 105 K is included) and 40 per cent (47 per cent) of the gas (see also Kereš et al. 2005, 2009, Dekel & Birnboim 2006, Birnboim, Dekel & Neistein 2007; Ocvirk et al. 2008; Agertz et al. 2009; Ceverino et al. 2010).”
The impact of baryonic physics on the structure of dark matter haloes: the view from the FIRE cosmological simulations (2015, result): “Overall, the resulting halo gas properties are similar to the results from adaptive-mesh and moving-mesh simulations (Agertz et al. 2009; Kereš et al. 2012; Vogelsberger et al. 2012b; Nelson et al. 2013).”
High-redshift clumpy discs and bulges in cosmological simulations (2009, methodology): “This is probably a result of some degree of artificial fragmentation in Agertz et al. (2009b) due to the lower pressure floor adopted in their simulation (Section 6).”