Probing IGM accretion onto faint Lyα emitters at z~2.8

Abstract

(abridged) Observing the signature of accretion from the intergalactic medium (IGM) onto galaxies at z~3 requires the detection of faint (L<<L*) galaxies embedded in a filamentary matrix of low-density, metal-poor gas coherent over hundreds of kpc. We study the gaseous environment of three Lyman$\alpha$ emitters (LAEs) at z=2.7-2.8, found to be aligned in projection with a background QSO over ~250 kpc along the slit of a long-slit spectrum. The lack of detection of the LAEs in deep continuum images and the low inferred Ly$\alpha$ luminosities show the LAEs to be intrinsically faint, low-mass galaxies (L<0.1 L*, M_star< 0.1 M*). An echelle spectrum of the QSO reveals strong Ly-alpha absorption within $\pm 200$ km/s from the LAEs. Our absorption line analysis leads to HI column densities in the range of log N(HI) =16-18. Associated absorption from ionic metal species CIV and SiIV constrains the gas metallicities to ~0.01 solar if the gas is optically thin, and possibly as low as ~0.001 solar if the gas is optically thick, assuming photoionization equilibrium. While the inferred metallicities are at least a factor of ten lower than expected metallicities in the interstellar medium (ISM) of these LAEs, they are consistent with the observed chemical enrichment level in the IGM at the same epoch. Total metal abundances and kinematic arguments suggest that these faint galaxies have not been able to affect the properties of their surrounding gas. The projected spatial alignment of the LAEs, together with the kinematic quiescence and correspondence between the LAEs and absorbing gas in velocity space suggests that these observations probe a possible filamentary structure. Taken together with the blue-dominant Ly$\alpha$ emission line profile of one of the objects, the evidence suggests that the absorbing gas is part of an accretion stream of low-metallicity gas in the IGM.

arXiv commentAccepted for publication in MNRAS. 13 pages and 6 figures + an Appendix

References in corpus (70)

• The Sloan Digital Sky Survey: Technical Summary
• The chemical composition of the Sun
• Star Formation in the Milky Way and Nearby Galaxies
• How Do Galaxies Get Their Gas?
• The Structure and Kinematics of the Circum-Galactic Medium from Far-UV Spectra of z~2-3 Galaxies
• Strong Nebular Line Ratios in the Spectra of z~2-3 Star-forming Galaxies: First Results from KBSS-MOSFIRE
• The Evolution of the Stellar Mass Function of Galaxies from z=4.0 and the First Comprehensive Analysis of its Uncertainties: Evidence for Mass-dependent Evolution
• Galaxies and Intergalactic Matter at Redshift z~3: Overview
• 3D Lyman-alpha radiation transfer. I. Understanding Lyman-alpha line profile morphologies
• The 2013 Release of Cloudy
• Multi-Wavelength Constraints on the Cosmic Star Formation History from Spectroscopy: the Rest-Frame UV, H-alpha, and Infrared Luminosity Functions at Redshifts 1.9<z<3.4
• New Observations of the Interstellar Medium in the Lyman Break Galaxy MS 1512-cB58
• Metallicity of the intergalactic medium using pixel statistics. II. The distribution of metals as traced by C IV
• 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
• A Budget and Accounting of Metals at z~0: Results from the COS-Halos Survey
• Absorption line systems in simulated galaxies fed by cold streams
• The Characteristic Star Formation Histories of Galaxies at Redshifts z~2-7
• The MOSDEF Survey: Mass, Metallicity, and Star-formation Rate at z~2.3
• The COS-Dwarfs Survey: The Carbon Reservoir Around sub-L* Galaxies
• The Minimum Universal Metal Density Between Redshifts of 1.5 and 5.5
• A Population of Faint Extended Line Emitters and the Host Galaxies of Optically Thick QSO Absorption Systems
• The Distribution of Metallicity in the IGM at z~2.5: OVI and CIV Absorption in the Spectra of 7 QSOs
• The circumgalactic medium of massive galaxies at z~3: a test for stellar feedback, galactic outflows, and cold streams
• Extended Lyman-alpha emission from cold accretion streams
• Feedback and metal enrichment in cosmological SPH simulations I. A model for chemical enrichment
• The Ly-alpha Properties of Faint Galaxies at z2-3 with Systemic Redshifts and Velocity Dispersions from Keck-MOSFIRE
• The Small Covering Factor of Cold Accretion Streams
• QSO Metal Absorption Systems at High Redshift and the Signature of Hierarchical Galaxy Formation
• Gravity-driven Lyman-alpha blobs from cold streams into galaxies
• Neutral hydrogen in galaxy halos at the peak of the cosmic star formation history
• The Spectroscopic Properties of Lyα-Emitters at z $\approx$ 2.7: Escaping Gas and Photons from Faint Galaxies
• What is the physical origin of strong Lya emission? II. Gas Kinematics and Distribution of Lya Emitters
• Cold accretion flows and the nature of high column density HI absorption at redshift 3
• Observations of Chemically Enriched QSO Absorbers near z ~ 2.3 Galaxies: Galaxy-Formation Feedback Signatures in the IGM
• Mining Circumgalactic Baryons in the Low-Redshift Universe
• A downturn in intergalactic CIV as redshift 6 is approached
• Measuring the Physical Conditions in High-Redshift Star-Forming Galaxies: Insights from KBSS-MOSFIRE
• Metal-enriched, sub-kiloparsec gas clumps in the circumgalactic medium of a faint z = 2.5 galaxy
• Gas Motion Study of Lya Emitters at z~2 Using UV and Optical Spectral Lines
• Bright and Faint Ends of Ly$\alpha$ Luminosity Functions at $\text{z}=2$ Determined by the Subaru Survey: Implications for AGN, Magnification Bias, and ISM HI Evolution
• The VIMOS VLT Deep Survey: Star Formation Rate Density of Lya emitters from a sample of 217 galaxies with spectroscopic redshifts 2<z<6.6
• Small Scale Structure at High Redshift: II. Physical Properties of the CIV Absorbing Clouds
• Narrow associated QSO absorbers: clustering, outflows and the line-of-sight proximity effect
• A Close Comparison between Observed and Modeled Lyα Lines for z ~ 2.2 Lyman Alpha Emitters
• The physical properties of z>2 Lyman limit systems: new constraints for feedback and accretion models
• Constraints on the Universal CIV Mass Density at z~6 from Early IR Spectra Obtained with the Magellan FIRE Spectrograph
• The Rest-Frame Optical Spectroscopic Properties of Ly$\alpha$-Emitters at $z\sim 2.5$: The Physical Origins of Strong Ly$\alpha$ Emission
• Low-Redshift Lyman Limit Systems as Diagnostics of Cosmological Inflows and Outflows
• Rest-frame ultraviolet spectrum of the gravitationally lensed galaxy `the 8 o'clock arc': stellar and interstellar medium properties
• The Impact of Starbursts on the Circumgalactic Medium
• High-Redshift Metals. II. Probing Reionization Galaxies with Low-Ionization Absorption Lines at Redshift Six
• MUSE searches for galaxies near very metal-poor gas clouds at z~3: new constraints for cold accretion models
• The Cosmic Evolution of the Metallicity Distribution of Ionized Gas Traced by Lyman Limit Systems
• An Extreme Metallicity, Large-Scale Outflow from a Star-Forming Galaxy at z ~ 0.4
• A comparison of observed and simulated absorption from HI, CIV, and SiIV around $z\approx 2$ star-forming galaxies suggests redshift-space distortions are due to inflows
• Metal-Poor, Cool Gas in the Circumgalactic Medium of a z = 2.4 Star-Forming Galaxy: Direct Evidence for Cold Accretion?
• Filamentary Infall of Cold Gas and Escape of Lyman Alpha and Hydrogen Ionizing Radiation from an Interacting High-Redshift Galaxy
• CIV Absorption From Galaxies in the Process of Formation
• Mg II Absorption at 2<z<7 with Magellan/FIRE, III. Full Statistics of Absorption Towards 100 High-Redshift QSOs
• The enrichment history of cosmic metals
• MUSE Deep-Fields: The Lya Luminosity Function in the Hubble Deep Field South at 2.91 < z < 6.64
• Small Scale Structure at High Redshift: III. The Clumpiness of the Intergalactic Medium on Sub-kpc Scales
• The VLT LBG Redshift Survey - V. Characterising the z = 3.1 Lyman Alpha Emitter Population
• The Incidence of Low-Metallicity Lyman-Limit Systems at z~3.5: Implications for the Cold-Flow Hypothesis of Baryonic Accretion
• Galactic Wind Signatures around High Redshift Galaxies
• The origin of intergalactic metals around Lyman-break galaxies
• Dust in the Wind: Composition and Kinematics of Galaxy Outflows at the Peak Epoch of Star Formation
• Empirical Constraints of Super-Galactic Winds at z >= 0.5
• Observational Aspects of Galactic Accretion at Redshift 3.3
• The FourStar Infrared Camera

Cited by in corpus (7)

• MUSEQuBES: Calibrating the redshifts of Ly α emitters using stacked circumgalactic medium absorption profiles
• The Cosmic Ultraviolet Baryon Survey (CUBS) -- III. Physical properties and elemental abundances of Lyman limit systems at $z<1$
• MUSEQuBES: Characterizing the circumgalactic medium of redshift $\approx 3.3$ Ly$\alpha$ emitters
• The CGM at Cosmic Noon with KCWI: Outflows from a Star-forming Galaxy at z=2.071
• A Complex Multiphase DLA Associated with a Compact Group at z=2.431 Traces Accretion, Outflows, and Tidal Streams
• The hot gas distribution, X-ray luminosity and baryon budget in the L-Galaxies semi-analytic model of galaxy formation
• The Halo21 Absorption Modeling Challenge: Lessons From "Observing" Synthetic Circumgalactic Absorption Spectra