The Role of Cold Flows and Reservoirs in Galaxy Formation With Strong Feedback

Abstract

We examine gas accretion and subsequent star formation in representative galaxies from the McMaster Unbiased Galaxy Simulations (Stinson et al. 2010). Accreted gas is bimodal with a natural temperature division at $10^5$ K, near the peak of the cooling curve. Cold-mode accretion dominates inflows at early times, creating a peak in total accretion at redshift z=2-4 and declining exponentially below z$\sim$2. Hot-mode accretion peaks near z=1-2 and declines gradually. Hot-mode exceeds cold-mode accretion at z$\sim$1.8 for all four galaxies rather than when the galaxy reaches a characteristic mass. Cold-mode accretion can fuel immediate star formation, while hot-mode accretion preferentially builds a large, hot gas reservoir in the halo. Late-time star formation relies on reservoir gas accreted 2-8 Gyr prior. Thus, the reservoir allows the star formation rate to surpass the current overall gas accretion rate. Stellar feedback cycles gas from the interstellar medium back into the hot reservoir. Stronger feedback results in more gas cycling, gas removal in a galactic outflow and less star formation overall, enabling simulations to match the observed star formation history. For lower mass galaxies in particular, strong feedback can delay the star formation peak to z=1-2 from the accretion peak at z=2-4.

10 pages, 7 figures. Accepted for publication in MNRAS

References in corpus (9)

• Wilkinson Microwave Anisotropy Probe (WMAP) Three Year Results: Implications for Cosmology
• Cold streams in early massive hot haloes as the main mode of galaxy formation
• Star Formation and Feedback in Smoothed Particle Hydrodynamic Simulations--I. Isolated Galaxies
• Moving mesh cosmology: tracing cosmological gas accretion
• Bimodal gas accretion in the Horizon-MareNostrum galaxy formation simulation
• Observing the End of Cold Flow Accretion using Halo Absorption Systems
• EVLA Observations of Galactic Supernova Remnants: Wide-field Continuum and Spectral-index Imaging
• Intergalactic baryon-rich regions at high redshift
• Disk Galaxy Evolution Along the Hubble Sequence

Cited by in corpus (3)

• Building Late-Type Spiral Galaxies by In-Situ and Ex-Situ Star Formation
• The impact of feedback on cosmological gas accretion
• Revisiting long-standing puzzles of the Milky Way: the Sun and its vicinity as typical outer disk chemical evolution