THE CIRCUMGALACTIC MEDIUM OF MASSIVE GALAXIES AT z ∼ 3: A TEST FOR STELLAR FEEDBACK, GALACTIC OUTFLOWS, AND COLD STREAMS

By S. Shen, P. Madau, J. Guedes, Lucio Mayer, J. Xavier Prochaska, James Wadsley. 2012

155 citations recorded by the source corpus.

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 ∼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 Rvir = 10 kpc, where Rvir 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 > 105 K. Synthetic spectra, generated by drawing sightlines through the CGM, produce interstellar absorption-line strengths of Lyα, 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 Lyα and C iv compared to C ii, Si iv, and Si ii, with Lyα remaining strong (WLyα > 300 mÅ) to ≳ 5 Rvir = 250 kpc. Only about one third of all the gas within Rvir is outflowing. The fraction of sightlines within one virial radius that intercept optically thick, NH I>1017.2  cm-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 (NC II>1013 cm-2) C ii absorption with a covering factor of 22% within Rvir and 10% within 2 Rvir. 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 NO VI ≳ 1014  cm-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.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/a9cd7e17282e226707f0647212e08d4a35896200

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In Astronomy and Astrophysics

1. P. Hopkins
2. C. Faucher-Giguére
3. E. Quataert
4. L. Hernquist
5. Volker Springel
6. D. Keres̆
7. A. Dekel
8. R. Dav'e

In Instrumentation

1. P. Hopkins
2. L. Hernquist
3. C. Faucher-Giguére
4. A. Dekel
5. E. Quataert
6. R. Somerville
7. R. Dav'e
8. D. Keres̆

Citations in the corpus

• THE UNIVERSAL STELLAR MASS–STELLAR METALLICITY RELATION FOR DWARF GALAXIES (2013, background): “Our present measurements do not inform us whether the missing iron has left the galaxy or has been incorporated into a hot gas halo (Shen et al. 2012, 2013).”
• Radiative feedback and the low efficiency of galaxy formation in low-mass haloes at high redshift (2013, methodology): “For example, the Eris2 simulation (Shen et al. 2013) forms too many stars at high redshifts (SFR= 20M⊙ yr −1 at z = 2.8).”
• THE BIMODAL METALLICITY DISTRIBUTION OF THE COOL CIRCUMGALACTIC MEDIUM AT z ≲ 1 (2013, background): “Thus they may instead trace cold streams of ionized, metal-poor gas falling onto galaxies with properties consistent with those predicted in cosmological simulations (e.g., Fumagalli et al. 2011b; Shen et al. 2013, see below).”
• THE COS-HALOS SURVEY: ORIGINS OF THE HIGHLY IONIZED CIRCUMGALACTIC MEDIUM OF STAR-FORMING GALAXIES (2016, background): “…both star-formation and AGN) give rise to significant Ovi absorption in the CGM of both cosmological zoom-in and hydrodynamical simulations (e.g. Shen et al. 2013; Hummels et al. 2013; Cen 2013; Suresh et al. 2015; Liang et al. 2016; Ford et al. 2016; Oppenheimer et al. 2016; Rahmati et al.…”
• The Circumgalactic Medium (2017, background): “…simulations, which exhibit a mixture of cool (104 K) and warm-hot (105.5–106 K) gas within a galaxy virial radius with a density profile that drops with increased distance from the central host galaxy (e.g., Shen et al. 2013; Stinson et al. 2012; Ford et al. 2013; Suresh et al. 2017, Figure 3).”
• The impact of star formation feedback on the circumgalactic medium (2016, background): “These topics are, of course, also addressed by fully cosmological simulations focused on the CGM that incorporate stellar feedback (e.g., van de Voort & Schaye 2012; Shen et al. 2013; Ford et al. 2013; Faucher-Giguère et al. 2015, 2016; van de Voort et al. 2016).”
• Gusty, gaseous flows of FIRE: Galactic winds in cosmological simulations with explicit stellar feedback (2015, background): “…Rudie et al. 2012) and provides important constraints for theoretical models which seek to determine the origin of gas in present-day galaxies (Kereš et al. 2005; FaucherGiguère et al. 2010, 2015; Faucher-Giguère, Kereš & Ma 2011; van de Voort et al. 2011; Shen et al. 2013; Ford et al. 2014).”
• Neutral hydrogen in galaxy haloes at the peak of the cosmic star formation history (2014, methodology): “Shen et al. (2013) presented a comprehensive analysis of the Eris2 simulation at z ∼ 3.”
• THE SYSTEMATIC PROPERTIES OF THE WARM PHASE OF STARBURST-DRIVEN GALACTIC WINDS (2015, background): “…et al. 2015; Henriques et al. 2015; Mitra et al. 2015), high-resolution simulations of individual galaxies that are able to calculate ab initio more of the relevant physical processes are clearly needed (e.g. Cooper et al. 2008, 2009; Shen et al. 2013; Hopkins et al. 2013; Muratov et al. 2015).”
• The COS-Halos Survey: Metallicities in the Low-redshift Circumgalactic Medium (2017, background): “This indicates that the halo was primarily enriched by stars at an earlier time, when the galaxy itself had lower metallicity, or that metal-rich ejecta were diluted by more metal-poor gas within the halo, and/or lower metallicity gas from accreting satellite dwarf galaxies (e.g. Shen et al. 2013).”
• THE HISTORY OF R-PROCESS ENRICHMENT IN THE MILKY WAY (2014, methodology): “While improved runs within the Eris suite include turbulent mixing (Shen et al. 2013), for this study we have used a simulation without mixing so that our r-process injection method is consistent with the O and Fe enrichment in the simulation.”