Gas physics, disk fragmentation, and bulge formation in young galaxies

By Andreas Immeli, M. Samland, O. Gerhard, Pieter Westera Astronomisches Institut, U. Basel, Switzerland., Observat'orio do Valongo, R. Janeiro, Brasil.. 2003

231 citations recorded by the source corpus.

We investigate the evolution of star-forming gas-rich disks, using a 3D chemodynamical model including a dark halo, stars, and a two-phase interstellar medium with feedback processes from the stars. We show that galaxy evolution proceeds along very different routes depending on whether it is the gas disk or the stellar disk which first becomes unstable, as measured by the respective Q-parameters. This in turn depends on the uncertain efficiency of energy dissipation of the cold cloud component from which stars form. When the cold gas cools efficiently and drives the instability, the galactic disk fragments and forms a number of massive clumps of stars and gas. The clumps spiral to the center of the galaxy in a few dynamical times and merge there to form a central bulge component in a strong starburst. When the kinetic energy of the cold clouds is dissipated at a lower rate, stars form from the gas in a more quiescent mode, and an instability only sets in at later times, when the surface density of the stellar disk has grown sufficiently high. The system then forms a stellar bar, which channels gas into the center, evolves, and forms a bulge whose stars are the result of a more extended star formation history. We investigate the stability of the gas-stellar disks in both regimes, as well as the star formation rates and element enrichment. We study the morphology of the evolving disks, calculating spatially resolved colours from the distribution of stars in age and metallicity, including dust absorption. We then discuss morphological observations such as clumpy structures and chain galaxies at high redshift as possible signatures of fragmenting, gas-rich disks. Finally, we investigate abundance ratio distributions as a means to distinguish the different scenarios of bulge formation.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/ddf00463a537f54f48a1d6e2cdb056cb21bace3e

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In Astronomy and Astrophysics

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

In Instrumentation

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

Citations in the corpus

• THE IMPACT OF COLD GAS ACCRETION ABOVE A MASS FLOOR ON GALAXY SCALING RELATIONS (2009, background): “This feature indicates wild gravitational instability, which is a likely outcome of a high gas density (Noguchi 1998; Immeli et al. 2004; Bournaud et al. 2007; Elmegreen et al. 2008; Dekel et al. 2009b).”
• Resolved Galaxies in the Hubble Ultra Deep Field: Star Formation in Disks at High Redshift (2007, background): “Bulges could result from clump coalescence (Noguchi 1999; Immeli et al. 2004a, 2004b), or bar dissolution (Hasan &Norman 1990), but then there is no clear way to make nuclear black holes unless they are already inside the disk clumps and merge or they grow in the nuclei over extended periods of…”
• Bars in Disk-dominated and Bulge-dominated Galaxies at z ~ 0: New Insights from ~3600 SDSS Galaxies (2007, background): “It is also conceivable that the bulge does not form in a single event, but is assembled by star-forming clumps, which originate in a protodisk and coalesce in the center of the disk and form a bulge (Noguchi1999; Immeli et al. 2004).”
• The metallicity distribution of bulge clump giants in Baade’s window (2011, methodology): “Immeli et al. (2004) investigated different scenarios of bulge, disc and halo population formation from the evolution of a starforming disc with a chemodynamical 3D model that includes initial conditions from ΛCDM results and a two-phase (gas and stars) interstellar medium.”
• Alpha element abundances and gradients in the Milky Way bulge from FLAMES-GIRAFFE spectra of 650 K giants (2011, background): “Such gas-rich galaxies are prone to disk instabilities that can result in bulge formation over timescales of a few 108 yr, much shorter than those typically ascribed to secular instabilities in local disk galaxies (Immeli et al. 2004; Carollo et al. 2007; Elmegreen et al. 2008).”
• From Rings to Bulges: Evidence for Rapid Secular Galaxy Evolution at z ~ 2 from Integral Field Spectroscopy in the SINS Survey (2008, background): “Exactly which secular process dominates depends on the stellar and gas fraction, whetherQgas is greater or less thanQstars ( Immeli et al. 2004a, 2004b), and whether bar instabilities occur in a turbulent environment.”
• THE KILOPARSEC-SCALE KINEMATICS OF HIGH-REDSHIFT STAR-FORMING GALAXIES (2009, background): “…disperse and sink to the center of the galaxy through dynamical friction, providing a possible mechanism for bulge formation aided by the massive starburst (SFR ∼ 100 M⊙ yr −1) predicted to occur when the remaining clouds merge in the galactic center (e.g., Immeli et al. 2004ab; Elmegreen 2008).”
• FORMATION OF MASSIVE GALAXIES AT HIGH REDSHIFT: COLD STREAMS, CLUMPY DISKS, AND COMPACT SPHEROIDS (2009, background): “…clumps, and the subsequent migration into a central bulge, have been proposed (van den Bergh et al. 1996; Elmegreen & Elmegreen 2005; Genzel et al. 2008; Bournaud et al. 2008) and successfully simulated for idealized disks in isolation (Noguchi 1999; Immeli et al. 2004b,a; Bournaud et al. 2007).”
• EVIDENCE FOR WIDE-SPREAD ACTIVE GALACTIC NUCLEUS-DRIVEN OUTFLOWS IN THE MOST MASSIVE z ∼ 1–2 STAR-FORMING GALAXIES (2014, background): “If there is efficient radial transport of gas from the outer disk to the center, as advocated by many theoretical studies (Noguchi 1999; Immeli et al. 2004a, 2004b; Genzel et al. 2008; Bournaud et al. 2009; Ceverino et al. 2010; Dekel & Burkert T h e A stroph ysical Jou rn al,796:7 (25pp),2014 N…”
• SINFONI Integral Field Spectroscopy of z ~ 2 UV-selected Galaxies: Rotation Curves and Dynamical Evolution (2006, methodology): “In this simulation, Immeli et al. (2004b) start from a gaseous disk with a mass inflow rate of 120M yr 1, growing to a total mass of 1:2 ; 1011 M in 1 Gyr.”
• CONSTRAINTS ON THE ASSEMBLY AND DYNAMICS OF GALAXIES. II. PROPERTIES OF KILOPARSEC-SCALE CLUMPS IN REST-FRAME OPTICAL EMISSION OF z ∼ 2 STAR-FORMING GALAXIES (2011, background): “…migration may provide an important mechanism for growing a stellar bulge and/or inner disk component in highredshift galaxies (e.g. Noguchi 1999; Immeli et al. 2004a,b; Bournaud et al. 2007; Carollo et al. 2007; Elmegreen et al. 2009a; Ceverino et al. 2010), along with other internal mechanisms…”
• The Secular Evolution of Disk Structural Parameters (2005, background): “Immeli et al. (2004) showed that the rate at which clouds dissipate their energy is the main parameter that determines whether the clump instability occurs.”
• High-redshift clumpy discs and bulges in cosmological simulations (2009, background): “These difficulties limited the earlier simulations of disc fragmentation to idealized discs in isolation (Noguchi 1999; Immeli et al. 2004a,b; Bournaud et al. 2007; Elmegreen et al. 2008a; Bournaud & Elmegreen 2009; Bournaud et al. 2009).”
• Wet Disc Contraction to Galactic Blue Nuggets and Quenching to Red Nuggets (2013, background): “…fraction induces VDI, which is characterized by turbulence and perturbations in the form of large transient features and giant clumps (Noguchi 1999; Immeli et al. 2004b,a; Genzel et al. 2006; Bournaud, Elmegreen & Elmegreen 2007; Genzel et al. 2008; Dekel, Sari & Ceverino 2009; Agertz, Teyssier &…”
• Evolution of density profiles in high-z galaxies: compaction and quenching inside-out (2015, background): “…(VDIs), which are characterized by turbulence and perturbations in the form of large transient features and giant clumps (Noguchi 1998; Immeli et al. 2004a,b; Genzel et al. 2006; Bournaud et al. 2007; Genzel et al. 2008; Agertz et al. 2009; Dekel et al. 2009b; Ceverino et al. 2010,…”
• THE SINS SURVEY OF z ∼ 2 GALAXY KINEMATICS: PROPERTIES OF THE GIANT STAR-FORMING CLUMPS (2010, methodology): “The dissolving stellar component of the clump may still continue the in-spiral and contribute to the secular buildup of a central bulge, albeit with smaller efficiency than assumed in the original work of Noguchi (1999) and Immeli et al. (2004a, 2004b).”