1308.4131
The baryon cycle of dwarf galaxies: dark, bursty, gas-rich polluters
Shen, Madau, Conroy, Governato, Mayer
Results from a cosmo hi-res LCDM "zoom-in" simulation of a group of 7 field dwarf galaxies with present-day virial masses in the range M_vir = 4.4e8-3.6e10 Msun. The simulation includes a blastwave scheme for SN feedback, a SF recipe based on a high gas density threshold, metal-dependent radiative cooling a scheme for the turbulent diffusion of metals and thermal energy, and a uniform UV background that modifies the ionization and excitation state of the gas. The properties of the simulated dwarfs are strongly modulated by the depth of the gravitational potential well. All 3 haloes with M_vir < 1e9 Msun are devoid of stars, as they never reach the density threshold for SF of 100 atoms/cc. The other 4, M_vir > 1e9 Msun dwarfs have blue colors, low SF efficiencies, high cold gas to stellar mass ratios, and low stellar metallicities. Their bursty SFHs are characterized by peak sSFRs in excess of 40-100 1/Gyr [units?], far outside the realm of normal, more massive galaxies, and in agreement with observations of extreme emission-line star bursting dwarfs by the Cosmic Assembly Near-IR Deep Extragalactic Legacy Survey (CANDELS). Metal-enriched galactic outflows produce sub-solar effective yields and pollute with heavy elements a Mpc-size region of the intergalactic medium, but are not sufficient to completely quench SF activity and are not ubiquitous in the dwarfs. Within the limited size of the sample, simulations appear to simultaneously reproduce the observed stellar mass and cold gas content, resolved SFHs, stellar kinematics, and metallicities of field dwarfs in the Local Volume.
The baryon cycle of dwarf galaxies: dark, bursty, gas-rich polluters
Shen, Madau, Conroy, Governato, Mayer
Results from a cosmo hi-res LCDM "zoom-in" simulation of a group of 7 field dwarf galaxies with present-day virial masses in the range M_vir = 4.4e8-3.6e10 Msun. The simulation includes a blastwave scheme for SN feedback, a SF recipe based on a high gas density threshold, metal-dependent radiative cooling a scheme for the turbulent diffusion of metals and thermal energy, and a uniform UV background that modifies the ionization and excitation state of the gas. The properties of the simulated dwarfs are strongly modulated by the depth of the gravitational potential well. All 3 haloes with M_vir < 1e9 Msun are devoid of stars, as they never reach the density threshold for SF of 100 atoms/cc. The other 4, M_vir > 1e9 Msun dwarfs have blue colors, low SF efficiencies, high cold gas to stellar mass ratios, and low stellar metallicities. Their bursty SFHs are characterized by peak sSFRs in excess of 40-100 1/Gyr [units?], far outside the realm of normal, more massive galaxies, and in agreement with observations of extreme emission-line star bursting dwarfs by the Cosmic Assembly Near-IR Deep Extragalactic Legacy Survey (CANDELS). Metal-enriched galactic outflows produce sub-solar effective yields and pollute with heavy elements a Mpc-size region of the intergalactic medium, but are not sufficient to completely quench SF activity and are not ubiquitous in the dwarfs. Within the limited size of the sample, simulations appear to simultaneously reproduce the observed stellar mass and cold gas content, resolved SFHs, stellar kinematics, and metallicities of field dwarfs in the Local Volume.
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