The Small Covering Factor of Cold Accretion Streams

Abstract

Theoretical models of galaxy formation predict that galaxies acquire most of their baryons via cold mode accretion. Observations of high-redshift galaxies, while showing ubiquitous outflows, have so far not revealed convincing traces of the predicted cold streams, which has been interpreted as a challenge for the current models. Using high-resolution, zoom-in smooth particle hydrodynamics simulations of Lyman break galaxy (LBG) halos combined with ionizing radiative transfer, we quantify the covering factor of the cold streams at z=2-4. We focus specifically on Lyman limit systems (LLSs) and damped Ly-alpha absorbers (DLAs), which can be probed by absorption spectroscopy using a background galaxy or quasar sightline, and which are closely related to low-ionization metal absorbers. We show that the covering factor of these systems is relatively small and decreases with time. At z=2, the covering factor of DLAs within the virial radius of the simulated galaxies is ~3% (~1% within twice this projected distance), and arises principally from the galaxy itself. The corresponding values for LLSs are ~10% and ~4%. Because of their small covering factor compared to the order unity covering fraction expected for galactic winds, the cold streams are naturally dominated by outflows in stacked spectra. We conclude that the existing observations are consistent with the predictions of cold mode accretion, and outline promising kinematic and chemical diagnostics to separate out the signatures of galactic accretion and feedback.

5 pages, 2 figures. MNRAS, in press

References in corpus (8)

• Cold streams in early massive hot haloes as the main mode of galaxy formation
• The rapid formation a large rotating disk galaxy three billion years after the Big Bang
• Bimodal gas accretion in the Horizon-MareNostrum galaxy formation simulation
• On the (Non)Evolution of HI Disks over Cosmic Time
• A Population of Faint Extended Line Emitters and the Host Galaxies of Optically Thick QSO Absorption Systems
• Observations of Thick Disks in the Hubble Space Telescope Ultra Deep Field
• Seeding the formation of cold gaseous clouds in Milky Way size halos
• The Subaru Ly-alpha blob survey: A sample of 100 kpc Ly-alpha blobs at z=3

Cited by in corpus (142)

• Galaxies on FIRE (Feedback In Realistic Environments): Stellar Feedback Explains Cosmologically Inefficient Star Formation
• Gusty, gaseous flows of FIRE: galactic winds in cosmological simulations with explicit stellar feedback
• The Origin and Evolution of the Galaxy Mass-Metallicity Relation
• The Cosmic Baryon Cycle and Galaxy Mass Assembly in the FIRE Simulations
• The Impact of Baryonic Physics on the Structure of Dark Matter Halos: the View from the FIRE Cosmological Simulations
• The Gaseous Environment of High-z Galaxies: Precision Measurements of Neutral Hydrogen in the Circumgalactic Medium of z ~ 2-3 Galaxies in the Keck Baryonic Structure Survey
• Demographics and Physical Properties of Gas Out/Inflows at 0.4 < z < 1.4
• Four phases of angular-momentum buildup in high-z galaxies: from cosmic-web streams through an extended ring to disc and bulge
• Absorption line systems in simulated galaxies fed by cold streams
• The Baryonic Assembly of Dark Matter Halos
• The Current Status of Galaxy Formation
• Cosmic evolution of the atomic and molecular gas content of galaxies
• The Bimodal Metallicity Distribution of the Cool Circumgalactic Medium at z<1
• The circumgalactic medium of massive galaxies at z~3: a test for stellar feedback, galactic outflows, and cold streams
• Star formation sustained by gas accretion
• Extended Lyman-alpha emission from cold accretion streams
• The COS-Halos Survey: Origins of the Highly Ionized Circumgalactic Medium of Star-Forming Galaxies
• The Origins of the Circumgalactic Medium in the FIRE Simulations
• The Giant Gemini GMOS survey of z>4.4 quasars - I. Measuring the mean free path across cosmic time
• Detection of Pristine Gas Two Billion Years after the Big Bang
• Orbiting Circum-galactic Gas as a Signature of Cosmological Accretion
• Fuel Efficient Galaxies: Sustaining Star Formation with Stellar Mass Loss
• Tracing Inflows and Outflows with Absorption Lines in Circumgalactic Gas
• Fast, Slow, Early, Late: Quenching Massive Galaxies at z~0.8
• Properties of gas in and around galaxy haloes
• Neutral hydrogen in galaxy halos at the peak of the cosmic star formation history
• Angular Momentum Acquisition in Galaxy Halos
• Cold accretion flows and the nature of high column density HI absorption at redshift 3
• Quasars Probing Quasars VI. Excess HI Absorption Within One Proper Mpc of z~2 Quasars
• The distribution of neutral hydrogen around high-redshift galaxies and quasars in the EAGLE simulation
• Constraints on Hydrodynamical Subgrid Models from Quasar Absorption Line Studies of the Simulated Circumgalactic Medium
• IGM Emission Observations with the Cosmic Web Imager: I. The Circum-QSO Medium of QSO 1549+19, and Evidence for a Filamentary Gas Inflow
• Dwarf galaxy formation with H2-regulated star formation
• Evidence for a Massive, Extended Circumgalactic Medium Around the Andromeda Galaxy
• Inspiraling Halo Accretion Mapped in Lyman-$\alpha$ Emission around a $z\sim 3$ Quasar
• A Stellar Feedback Origin for Neutral Hydrogen in High-Redshift Quasar-Mass Halos
• Dissecting the properties of optically-thick hydrogen at the peak of cosmic star formation history
• The physical properties of z>2 Lyman limit systems: new constraints for feedback and accretion models
• Evidence for Cold Accretion: Primitive Gas Flowing onto a Galaxy at z~0.274
• First Look at z > 1 Bars in the Rest-Frame Near-Infrared with JWST Early CEERS Imaging
• Trident: a universal tool for generating synthetic absorption spectra from astrophysical simulations
• A Substantial Mass of Cool, Metal-Enriched Gas Surrounding the Progenitors of Modern-Day Ellipticals
• Low-Redshift Lyman Limit Systems as Diagnostics of Cosmological Inflows and Outflows
• High Angular Momentum Halo Gas: a Feedback and Code-Independent Prediction of LCDM
• The ESO UVES Advanced Data Products Quasar Sample - VI. Sub-Damped Lyman-$\alpha$ Metallicity Measurements and the Circum-Galactic Medium
• The HST/ACS+WFC3 Survey for Lyman Limit Systems II: Science
• The impact of supernovae driven winds on stream-fed protogalaxies
• Neutral hydrogen optical depth near star-forming galaxies at z~2.4 in the Keck Baryonic Structure Survey
• EVLA Observations of Galactic Supernova Remnants: Wide-field Continuum and Spectral-index Imaging
• MUSE searches for galaxies near very metal-poor gas clouds at z~3: new constraints for cold accretion models
• Observing the End of Cold Flow Accretion using Halo Absorption Systems
• The Fates of the Circumgalactic Medium in the FIRE Simulations
• Confronting Simulations of Optically Thick Gas in Massive Halos with Observations at z=2-3
• The Cosmic Ultraviolet Baryon Survey (CUBS) I. Overview and the diverse environments of Lyman limit systems at z<1
• Observational Requirements for Lyman-alpha Forest Tomographic Mapping of Large-Scale Structure at z ~ 2
• Metal-Poor, Cool Gas in the Circumgalactic Medium of a z = 2.4 Star-Forming Galaxy: Direct Evidence for Cold Accretion?
• A Survey of MgII Absorption at 2 < z < 6 with Magellan / FIRE: I: Sample and Evolution of the MgII Frequency
• Probing the Circumgalactic Medium at High-Redshift Using Composite BOSS Spectra of Strong Lyman-alpha Forest Absorbers
• Spatially Resolved Velocity Maps of Halo Gas Around Two Intermediate-redshift Galaxies
• Galaxy disks do not need to survive in the L-CDM paradigm: the galaxy merger rate out to z~1.5 from morpho-kinematic data
• IGM Emission Observations with the Cosmic Web Imager: II. Discovery of Extended, Kinematically-Linked Emission around SSA22 Lyman-alpha Blob 2
• Low-metallicity Absorbers Account for Half of the Dense Circumgalactic Gas at z < 1
• Enriched haloes at redshift $z=2$ with no star-formation: Implications for accretion and wind scenarios
• MUSE Analysis of Gas around Galaxies (MAGG) -- I: Survey design and the environment of a near pristine gas cloud at z~3.5
• Are cold flows detectable with metal absorption lines?
• Moving mesh cosmology: properties of neutral hydrogen in absorption
• Mg II Absorption at 2<z<7 with Magellan/FIRE, III. Full Statistics of Absorption Towards 100 High-Redshift QSOs
• Observational signatures of a warped disk associated with cold-flow accretion
• Slicing the cool circumgalactic medium along the major-axis of a star-forming galaxy at $z=0.7$
• Ultra-strong MgII Absorbers as a Signature of Cool Intragroup Gas
• The Keck+Magellan Survey for Lyman Limit Absorption III: Sample Definition and Column Density Measurements
• Detectability of cold streams into high-redshift galaxies by absorption lines
• MUSE Analysis of Gas around Galaxies (MAGG) -- IV: The gaseous environment of $z\sim$ 3-4 Lyman-alpha emitting galaxies
• The Cosmic Ultraviolet Baryon Survey (CUBS) -- III. Physical properties and elemental abundances of Lyman limit systems at $z<1$
• GMRT observation of neutral atomic hydrogen gas in the COSMOS field at $z\sim 0.37$
• Effect of radiative transfer on damped Lyman-alpha and Lyman limit systems in cosmological SPH simulations
• Warm Gas in the Virgo Cluster: I. Distribution of Lya Absorbers
• Kinematics of Gas in Lyman Alpha Nebulae
• The Properties of Lyman Alpha Nebulae: Gas Kinematics from Non-resonant Lines
• The High-Ion Content and Kinematics of Low-Redshift Lyman Limit Systems
• The Incidence of Low-Metallicity Lyman-Limit Systems at z~3.5: Implications for the Cold-Flow Hypothesis of Baryonic Accretion
• The Role of Cold Flows and Reservoirs in Galaxy Formation With Strong Feedback
• Neutral CGM as damped Lyα absorbers at high redshift
• Properties of the ionized CGM and IGM: a comparison of galaxy formation models via the Sunyaev-Zel'dovich effect
• The Effect Of AGN Heating On The Low-Redshift Lyα Forest
• The Star Formation History of Luminous Red Galaxies Hosting MgII Absorbers
• Thermal Instability in the CGM of $L_{\star }$ Galaxies: Testing "Precipitation" Models with the FIRE Simulations
• Non-Gravitational Contributions to the Clustering of Ly-alpha Selected Galaxies: Implications for Cosmological Surveys
• Flows around galaxies. I. The dependency of galaxy connectivity on cosmic environments and effects on the star-formation rate
• A submillimeter galaxy illuminating its circumgalactic medium: Ly-alpha scattering in a cold, clumpy outflow
• Shattering of Cosmic Sheets due to Thermal Instabilities: a Formation Channel for Metal-Free Lyman Limit Systems
• Virial shocks are suppressed in cosmic ray-dominated galaxy halos
• From EMBER to FIRE: predicting high resolution baryon fields from dark matter simulations with Deep Learning
• Investigating The Growing Population of Massive Quiescent Galaxies at Cosmic Noon
• Where is the fuzz? Undetected Lyman alpha nebulae around QSOs at z~2.3
• Exploring the origins of a new, apparently metal-free gas cloud at z = 4.4
• Characterizing circumgalactic gas around massive ellipticals at z~0.4 III. The galactic environment of a chemically-pristine Lyman limit absorber
• Resolving 3D Disk Orientation using High-Resolution Images: New Constraints on Circumgalactic Gas Inflows
• Project AMIGA: A Minimal Covering Factor for Optically Thick Circumgalactic Gas Around the Andromeda Galaxy
• A Lyman alpha halo around a quasar at redshift z=6.4
• A Dusty Locale: Evolution of Galactic Dust Populations from Milky Way to Dwarf-Mass Galaxies
• Outskirts of Distant Galaxies In Absorption
• Starburst and post-starburst high-redshift protogalaxies: The feedback impact of high energy cosmic rays
• Observations of Mg II Absorption Near z ~ 1 Galaxies Selected From The DEEP2 Redshift Survey
• The metallicity distribution of HI systems in the EAGLE cosmological simulation
• Into the Lyα jungle: exploring the circumgalactic medium of galaxies at z ~ 4-5 with MUSE
• A Complex Multiphase DLA Associated with a Compact Group at z=2.431 Traces Accretion, Outflows, and Tidal Streams
• The Gaseous Environments of Quasars: Associate Absorption Lines with Density and Distance Constraints
• Connecting cosmological accretion to strong Lyman-alpha absorbers
• Gas around galaxy haloes - II: hydrogen absorption signatures from the environments of galaxies at redshifts 2 < z < 3
• Imprints of the first billion years: Lyman limit systems at $z\sim 5$
• Gas Accretion in Star-Forming Galaxies
• The gas inflow and outflow rate in star-forming galaxies at $z\sim 1.4$
• Eclipsing damped Ly$\alpha$ systems in the Sloan Digital Sky Survey Data Release 12
• Strongly Time-Variable Ultra-Violet Metal Line Emission from the Circum-Galactic Medium of High-Redshift Galaxies
• Hunting for Metals Using XQ-100 Legacy Survey Composite Spectra
• Evidence for galaxy quenching in the green valley caused by a lack of a circumgalactic medium
• MUSE-ALMA Halos XI: Gas flows in the circumgalactic medium
• Feedback in Galaxy Formation
• Modeling Photoionized Turbulent Material in the Circumgalactic Medium
• Modeling Photoionized Turbulent Material in the Circumgalactic Medium II: Effect of Turbulence within a Stratified Medium
• VLT/UVES observations of peculiar alpha abundances in a sub-DLA at z ~ 1.8 towards the quasar B1101-26
• Gas Accretion and Angular Momentum
• Probing IGM accretion onto faint Lyα emitters at z~2.8
• The MOSDEF-LRIS Survey: Detection of Inflowing Gas Towards Three Star-forming Galaxies at z ~ 2
• The Circumgalactic Medium in Massive Halos
• Ghostly Damped Ly$\alpha$ Systems: Tracers of Gas Flows in the Close Vicinity of Quasars ?
• Detecting neutral hydrogen at z > 3 in large spectroscopic surveys of quasars
• Nature and Origins of Rich Complexes of C IV Associated Absorption Lines
• Triple-ionised carbon associated with the low-density neutral hydrogen gas at 1.7 < z < 3.3: the integrated N(HI)-N(CIV) relation
• Observational Diagnostics of Gas Flows: Insights from Cosmological Simulations
• Cold stream stability during minor mergers
• Stability and Ly$\alpha$ emission of Cold Stream in the Circumgalactic Medium: impact of magnetic fields and thermal conduction
• Observations of Ly$\alpha$ Emitters at High Redshift
• Angular momentum loss of primordial gas in Lyman-alpha radiation field
• Evolution of cold streams in hot gaseous halos
• Ultra-strong MgII absorbers trace both inflowing and outflowing gas: insights from dual down-the-barrel and quasar sightlines
• Dissecting Cosmological Filaments at High Redshifts: Emergence of Spaghetti-type Flow Inside DM Haloes
• Discovery of three new near-pristine absorption clouds at $z=2.6$-4.4
• The multiple coherence scales of C IV at cosmic noon
• Intergalactic Medium Tomography with the Sunburst Arc
• Cold vs. Hot Gas Accretion and Angular Momentum in FIRE Simulations: From Halo to Galaxy Scales