期刊
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
卷 444, 期 2, 页码 1260-1281出版社
OXFORD UNIV PRESS
DOI: 10.1093/mnras/stu1418
关键词
galaxies: evolution; galaxies: haloes; intergalactic medium; galaxies: kinematics and dynamics; quasars: absorption lines; cosmology: theory
资金
- NASA ATP [NNX10AJ95G, NNX12AH86G]
- HST [HST-GO-11598, HST-GO-12248]
- NASA ADP [NNX08AJ44G]
- NSF [AST-0847667, AST-0907998, AST-0908334, AST-133514]
- South African National Research Chairs programme
- Ahmanson foundation
- National Science Foundation [DMS-0619881]
- NASA [NNX10AJ95G, 19766, 131405, NNX12AH86G] Funding Source: Federal RePORTER
- Direct For Mathematical & Physical Scien
- Division Of Astronomical Sciences [0847667] Funding Source: National Science Foundation
We examine how HI and metal absorption lines within low-redshift galaxy haloes trace the dynamical state of circumgalactic gas, using cosmological hydrodynamic simulations that include a well-vetted heuristic model for galactic outflows. We categorize inflowing, outflowing, and ambient gas based on its history and fate as tracked in our simulation. Following our earlier work, showing that the ionization level of absorbers was a primary factor in determining the physical conditions of absorbing gas, we show here that it is also a governing factor for its dynamical state. Low-ionization metal absorbers (e. g. MgII) tend to arise in gas that will fall on to galaxies within several Gyr, while high-ionization metal absorbers (e.g. OVI) generally trace material that was deposited by outflows many Gyr ago. Inflowing gas is dominated by enriched material that was previously ejected in an outflow; hence, accretion at low redshifts is typically substantially enriched. Recycling wind material is preferentially found closer to galaxies, and is more dominant in lower mass haloes since high-mass haloes have more hot gas that is able to support itself against infall. Low-mass haloes also tend to re-eject more of their accreted material, owing to our outflow prescription that employs higher mass loading factors for lower mass galaxies. Typical HI absorbers trace unenriched ambient material that is not participating in the baryon cycle, but stronger HI absorbers arise in cool, enriched inflowing gas. Instantaneous radial velocity measures of absorbers are generally poor at distinguishing between inflowing and outflowing gas, except in the case of very recent outflows. These results suggest that probing halo gas using a range of absorbers can provide detailed information about the amount and physical conditions of material that is participating in the baryon cycle.
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