THE CIRCUMGALACTIC MEDIUM OF MASSIVE GALAXIES AT z {approx} 3: A TEST FOR STELLAR FEEDBACK, GALACTIC OUTFLOWS, AND COLD STREAMS
- Department of Astronomy and Astrophysics, University of California, 1156 High Street, Santa Cruz, CA 95064 (United States)
- Institute for Astronomy, ETH Zurich, Wolgang-Pauli-Strasse 27, CH-8093 Zurich (Switzerland)
- Institute of Theoretical Physics, University of Zurich, Winterthurerstrasse 190, CH-9057 Zurich (Switzerland)
- Department of Physics and Astronomy, McMaster University, Hamilton, ON L8S 4M1 (Canada)
We present new results on the kinematics, thermal and ionization state, and spatial distribution of metal-enriched gas in the circumgalactic medium (CGM) of massive galaxies at redshift {approx}3, using the Eris suite of cosmological hydrodynamic ''zoom-in'' simulations. The reference run adopts a blastwave scheme for supernova feedback that produces large-scale galactic outflows, a star formation recipe based on a high gas density threshold, metal-dependent radiative cooling, and a model for the diffusion of metals and thermal energy. The effect of the local UV radiation field is added in post-processing. The CGM (defined as all gas at R > 0.2 R{sub vir} = 10 kpc, where R{sub vir} is the virial radius) contains multiple phases having a wide range of physical conditions, with more than half of its heavy elements locked in a warm-hot component at T > 10{sup 5} K. Synthetic spectra, generated by drawing sightlines through the CGM, produce interstellar absorption-line strengths of Ly{alpha}, C II, C IV, Si II, and Si IV as a function of the galactocentric impact parameter (scaled to the virial radius) that are in broad agreement with those observed at high redshift by Steidel et al. The covering factor of absorbing material declines less rapidly with impact parameter for Ly{alpha} and C IV compared to C II, Si IV, and Si II, with Ly{alpha} remaining strong (W{sub Ly{alpha}} > 300 mA) to {approx}> 5 R{sub vir} = 250 kpc. Only about one third of all the gas within R{sub vir} is outflowing. The fraction of sightlines within one virial radius that intercept optically thick, N{sub H{sub I}}>10{sup 17.2} cm{sup -2} material is 27%, in agreement with recent observations by Rudie et al. Such optically thick absorption is shown to trace inflowing ''cold'' streams that penetrate deep inside the virial radius. The streams, enriched to metallicities above 0.01 solar by previous episodes of star formation in the main host and in nearby dwarfs, are the origin of strong (N{sub C{sub II}}>10{sup 13} cm{sup -2}) C II absorption with a covering factor of 22% within R{sub vir} and 10% within 2 R{sub vir}. Galactic outflows do not cause any substantial suppression of the cold accretion mode. The central galaxy is surrounded by a large O VI halo, with a typical column density N{sub O{sub VI}} {approx}> 10{sup 14} cm{sup -2} and a near unity covering factor maintained all the way out to 150 kpc. This matches the trends recently observed in star-forming galaxies at low redshift by Tumlinson et al. Our zoom-in simulations of this single system appear then to reproduce quantitatively the complex baryonic processes that determine the exchange of matter, energy, and metals between galaxies and their surroundings.
- OSTI ID:
- 22127020
- Journal Information:
- Astrophysical Journal, Vol. 765, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
COSMOLOGY AND ASTRONOMY
ABSORPTION SPECTRA
ASTRONOMY
ASTROPHYSICS
BARYONS
CARBON
COMPARATIVE EVALUATIONS
DIFFUSION
EMISSION SPECTRA
GALACTIC EVOLUTION
GALAXIES
IMPACT PARAMETER
LYMAN LINES
METALS
RADIATIVE COOLING
RED SHIFT
SILICON
SPATIAL DISTRIBUTION
STAR EVOLUTION
STARS
ULTRAVIOLET RADIATION