Gas Motion Study of Lya Emitters at z~2 Using UV and Optical Spectral Lines

Abstract

We present the results of Magellan/MMIRS and Keck/NIRSPEC spectroscopy for five Lya emitters (LAEs) at z=2.2 for which high-resolution FUV spectra from Magellan/MagE are available. We detect nebular emission lines including Ha on the individual basis and low-ionization interstellar (LIS) absorption lines in a stacked FUV spectrum, and measure average offset velocities of the Lya line, Delta_v_Lya, and LIS absorption lines, Delta_v_abs, with respect to the systemic velocity defined by the nebular lines. For a sample of eight z~2-3 LAEs without AGN from our study and the literature, we obtain Delta_v_Lya = 175+/-35 km s^{-1}, which is significantly smaller than that of Lyman-break Galaxies (LBGs), Delta_v_Lya=400 km s^{-1}. The stacked FUV spectrum gives Delta_v_abs = -179 +/- 73 km s^{-1}, comparable to that of LBGs. These positive Delta_v_Lya and negative Delta_v_abs suggest that LAEs also have outflows. In contrast to LBGs, however, the LAEs' Delta_v_Lya is as small as |Delta_v_abs|, suggesting low neutral hydrogen column densities. Such a low column density with a small number of resonant scattering may cause the observed strong Lya emission of LAEs. We find an anti-correlation between Lya equivalent width (EW) and Delta_v_Lya in a compilation of LAE and LBG samples. Although its physical origin is not clear, this anti-correlation result appears to challenge the hypothesis that a strong outflow, by means of a reduced number of resonant scattering, produces a large EW. If LAEs at z>6 have similarly small Delta_v_Lya values, constraints on the reionization history derived from the Lya transmissivity may need to be revised.

15 pages, 13 figures, 7 tables. Accepted for publication in ApJ

References in corpus (17)

• Cold streams in early massive hot haloes as the main mode of galaxy formation
• Five-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Likelihoods and Parameters from the WMAP data
• The Mass-Metallicity Relation at z~2
• The Stellar, Gas and Dynamical Masses of Star-Forming Galaxies at z~2
• 3D Lyman-alpha radiation transfer. I. Understanding Lyman-alpha line profile morphologies
• The Chandra COSMOS Survey, I: Overview and Point Source Catalog
• 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
• The End of the Reionization Epoch Probed by Ly-alpha Emitters at z=6.5 in the Subaru Deep Field
• The Multiwavelength Survey by Yale-Chile (MUSYC): Deep Medium-Band optical imaging and high quality 32-band photometric redshifts in the ECDF-S
• A Population of Faint Extended Line Emitters and the Host Galaxies of Optically Thick QSO Absorption Systems
• 3D Lyman-alpha radiation transfer. III. Constraints on gas and stellar properties of z~3 Lyman break galaxies (LBG) and implications for high-z LBGs and Lyman-alpha emitters(LAEs)
• The Properties and Prevalence of Galactic Outflows at z = 1 in the Extended Groth Strip
• On the Detectability of Lyman-alpha Emission in Star-forming Galaxies: The Role of Dust
• Effects of Dust Geometry in Lyman Alpha Galaxies at z = 4.4
• Turning Back the Clock: Inferring the History of the Eight O'clock Arc
• The Optically Unbiased GRB Host (TOUGH) survey. IV. Lyman-alpha emitters
• Intrinsic Shape of Star-Forming BzK Galaxies II: Rest-Frame UV and Optical Structures in GOODS-South and SXDS

Cited by in corpus (100)

• The Universe is Reionizing at z~7: Bayesian Inference of the IGM Neutral Fraction Using Ly$\alpha$ Emission from Galaxies
• Lyman-alpha and CIII] Emission in z=7-9 Galaxies: Accelerated Reionization Around Luminous Star Forming Systems?
• Ionization State of Inter-Stellar Medium in Galaxies: Evolution, SFR-M_star-Z Dependence, and Ionizing Photon Escape
• Lyman Alpha Emitting Galaxies as a Probe of Reionization
• Line Emitting Galaxies Beyond a Redshift of 7: An Improved Method for Estimating the Evolving Neutrality of the Intergalactic Medium
• Spectroscopic detection of CIV in a galaxy at z=7.045: Implications for the ionizing spectra of reionization-era galaxies
• Ly$\alpha$ emission from Green Peas: the role of circumgalactic gas density, covering, and kinematics
• "Big Three Dragons": a z = 7.15 Lyman BreakGalaxy Detected in [OIII] 88 $\mu$m, [CII] 158 $\mu$m, and Dust Continuum with ALMA
• Detection of an oxygen emission line from a high redshift galaxy in the reionization epoch
• Ultraviolet Emission Lines in Young Low Mass Galaxies at z~2: Physical Properties and Implications for Studies at z>7
• Observations of the Lyman-$\alpha$ Universe
• Spectroscopic detections of CIII]1909 at z~6-7: A new probe of early star forming galaxies and cosmic reionisation
• Ly$\alpha$ profile, dust, and prediction of Ly$\alpha$ escape fraction in Green Pea Galaxies
• An Intensely Star-Forming Galaxy at z~7 with Low Dust and Metal Content Revealed by Deep ALMA and HST Observations
• Large Population of ALMA Galaxies at z>6 with Very High [OIII]88um to [CII]158um Flux Ratios: Evidence of Extremely High Ionization Parameter or PDR Deficit?
• The MUSE Hubble Ultra Deep Field Survey: II. Spectroscopic redshifts and comparisons to color selections of high-redshift galaxies
• The Ly-alpha Properties of Faint Galaxies at z2-3 with Systemic Redshifts and Velocity Dispersions from Keck-MOSFIRE
• Accelerated Evolution of Ly$\alpha$ Luminosity Function at $\text{z}\gtrsim 7$ Revealed by the Subaru Ultra-Deep Survey for Ly$\alpha$ Emitters at $\text{z}=7.3$
• The Spectroscopic Properties of Lyα-Emitters at z $\approx$ 2.7: Escaping Gas and Photons from Faint Galaxies
• Diffuse Lyman-alpha Halos around Galaxies at z=2.2-6.6: Implications for Galaxy Formation and Cosmic Reionization
• What is the physical origin of strong Lya emission? II. Gas Kinematics and Distribution of Lya Emitters
• Observational Searches for Galaxies at z > 6
• ISM excitation and metallicity of star-forming galaxies at z~3.3 from near-IR spectroscopy
• The Lyman-alpha Reference Sample: I. Survey outline and first results for Markarian 259
• Recovering the systemic redshift of galaxies from their Lyman-alpha line profile
• Metal-enriched, sub-kiloparsec gas clumps in the circumgalactic medium of a faint z = 2.5 galaxy
• First Spectroscopic Evidence for High Ionization State and Low Oxygen Abundance in Lya Emitters
• 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
• A Review of Recent Observations of Galactic Winds Driven by Star Formation
• Green Pea Galaxies Reveal Secrets of Ly$\alpha$ Escape
• The CALYMHA survey: Lya luminosity function and global escape fraction of Lya photons at z=2.23
• On the (non-)enhancement of the Lyman α equivalent width by a multiphase interstellar medium
• A Close Comparison between Observed and Modeled Lyα Lines for z ~ 2.2 Lyman Alpha Emitters
• Beamed Lyman Alpha Emission through Outflow-Driven Cavities
• The CALYMHA survey: Ly$\alpha$ escape fraction and its dependence on galaxy properties at $z=2.23$
• The HETDEX Pilot Survey V: The Physical Origin of Lyman-alpha Emitters Probed by Near-infrared Spectroscopy
• Lyman alpha Emitting Galaxies in the Nearby Universe
• A connection between extremely strong Damped Lyman-alpha Systems and Lyman-alpha Emitting Galaxies at small impact parameters
• Linking Ly-alpha and Low-Ionization Transitions at Low Optical Depth
• MUSE integral-field spectroscopy towards the Frontier Fields Cluster Abell S1063: I. Data products and redshift identifications
• Statistical Properties of Diffuse Lyman-alpha Halos around Star-forming Galaxies at z~2
• The Mean Ultraviolet Spectrum of a Representative Sample of Faint z~3 Lyman Alpha Emitters
• The MUSE Hubble Ultra Deep Field Survey. IX. Evolution of galaxy merger fraction since z~6
• The MUSE Hubble Ultra Deep Field Survey X. Ly$\alpha$ Equivalent Widths at $2.9<z<6.6$
• The Impact of Scatter in the Galaxy UV Luminosity to Halo Mass Relation on Ly$\alpha$ Visibility During the Epoch of Reionization
• A New Constraint on Reionization from Evolution of the Ly$\alpha$ Luminosity Function at $z\sim 6-7$ Probed by a Deep Census of $z=7.0$ Ly$\alpha$ Emitter Candidates to 0.3 $L^{\ast }$
• SILVERRUSH. VI. A simulation of Ly$\alpha$ emitters in the reionization epoch and a comparison with Subaru Hyper Suprime-Cam survey early data
• Feedback in low-mass galaxies in the early Universe
• Contamination of Broad-Band Photometry by Nebular Emission in High Redshift Galaxies: Investigations with Keck's MOSFIRE Near-Infrared Spectrograph
• No overdensity of Lyman Alpha Emitting Galaxies around a quasar at z~5.7
• A High Fraction of Ly-alpha-Emitters Among Galaxies with Extreme Emission Line Ratios at z ~ 2
• Mapping the Lyman-Alpha Emission Around a z~6.6 QSO with MUSE: Extended Emission and a Companion at Close Separation
• CHORUS II. Subaru/HSC Determination of the Ly$\alpha$ Luminosity Function at $z=7.0$: Constraints on Cosmic Reionization Model Parameter
• A Ly-alpha Emitter with an Extremely Large Rest-frame Equivalent Width of ~900A at z=6.5: A Candidate of Population III-dominated Galaxy?
• What is the Physical Origin of Strong Lya Emission? I. Demographics of Lya Emitter Structures
• Searching for Neutral Hydrogen Halos around z ~ 2.1 and z ~ 3.1 Ly-alpha Emitting Galaxies
• Anisotropic Lyman-alpha Emission
• Spatially Resolved Gas Kinematics within a Ly$\alpha$ Nebula: Evidence for Large-scale Rotation
• The ALMA REBELS Survey: Efficient Ly$\alpha$ Transmission of UV-Bright z$\simeq$7 Galaxies from Large Velocity Offsets and Broad Line Widths
• SILVERRUSH. II. First Catalogs and Properties of ~2,000 Lya Emitters and Blobs at z~6-7 Identified over the 14-21 deg2 Sky
• The Spectrally Resolved Lyman-alpha Emission of Three Lyman-alpha Selected Field Galaxies at z~2.4 from the HETDEX Pilot Survey
• Lyman-alpha spectroscopy of extreme [OIII] emitting galaxies at $z\simeq 2-3$: Implications for Ly$\alpha$ visibility and LyC leakage at $z>6$
• The Stellar Mass, Star Formation Rate and Dark Matter Halo Properties of LAEs at $z\sim 2$
• The Properties of Lyman Alpha Nebulae: Gas Kinematics from Non-resonant Lines
• On the sizes of ionized bubbles around the highest redshift galaxies. Spectral shapes of the Lyman-alpha emission from galaxies
• Lyα Equivalent Width Distribution of Lyα Emitting Galaxies at Redshift z $\sim$ 4.5
• The MUSE Hubble Ultra Deep Field Survey. XV. The mean rest-UV spectra of Ly-alpha emitters at z>3
• Lyman-Alpha Emitter Galaxies at z ~ 2.8 in the Extended Chandra Deep Field-South: I. Tracing the Large-Scale Structure via Lyman-Alpha Imaging
• Environmental Dependence of Galactic Properties Traced by Ly$\alpha$ Forest Absorption: Diversity among Galaxy Populations
• A new quadruple gravitational lens from the Hyper Suprime-Cam Survey: the puzzle of HSC~J115252+004733
• Ly$\alpha$ Emitters with Very Large Ly$\alpha$ Equivalent Widths, EW${}_0$(Ly$\alpha$) $\simeq 200-400$ Å, at $z\sim 2$
• Lyman Alpha and MgII as Probes of Galaxies and their Environments
• Deep rest-frame far-UV spectroscopy of the giant Lyman-alpha emitter 'Himiko'
• Magellan/MMIRS near-infrared multi-object spectroscopy of nebular emission from star forming galaxies at 2<z<3
• ZFIRE: Using H$\alpha$ equivalent widths to investigate the in situ initial mass function at z~2
• The VIMOS Ultra Deep Survey: The role of HI kinematics and HI column density on the escape of Lyalpha photons in star-forming galaxies at 2<z<4
• The ALMA-CRISTAL Survey: Spatial extent of [CII] line emission in star-forming galaxies at $z=4-6$
• Rest-frame UV Properties of Luminous Strong Gravitationally Lensed Ly$\alpha$ Emitters from the BELLS GALLERY Survey
• Extended and Filamentary Lyman Alpha Emission from the Formation of a Protogalactic Halo at z=2.63
• Pinpointing the Molecular Gas within a Lyman Alpha Blob at z ~ 2.7
• The dominant origin of diffuse Ly$\alpha$ halos around LAEs explored by SED fitting and clustering analysis
• The HETDEX Survey: The Ly$\alpha$ Escape Fraction from 3D-HST Emission Line Galaxies at $z\sim 2$
• Similarities and uniqueness of Ly$\alpha$ emitters among star-forming galaxies at z=2.5
• The Active Galactic Nuclei in the Hobby-Eberly Telescope Dark Energy Experiment Survey (HETDEX) I. Sample selection
• The Dynamical Masses, Densities, and Star Formation Scaling Relations of Lyman Alpha Galaxies
• [OIII] Emission and Gas Kinematics in a Lyman-alpha Blob at z ~ 3.1
• Early Results from GLASS-JWST XXIII: The transmission of Lyman-alpha from UV-faint z ~ 3-6 galaxies
• The MOSDEF-LRIS Survey: Connection between Galactic-scale Outflows and the Properties of $z$~2 star-forming Galaxies
• Catch Me if You Can: Biased Distribution of Ly$\alpha$-emitting Galaxies according to the Viewing Direction
• The Lyman Alpha Spectral Database (LASD)
• Cosmological 3D HI Gas Map with HETDEX Ly$\alpha$ Emitters and eBOSS QSOs at $z=2$: IGM-Galaxy/QSO Connection and a $\sim$ 40-Mpc Scale Giant HII Bubble Candidate
• MOSFIRE and LDSS3 Spectroscopy for an [OII] Blob at z=1.18: Gas Outflow and Energy Source
• Probing IGM accretion onto faint Lyα emitters at z~2.8
• SIMPLE: Simple Intensity Map Producer for Line Emission
• Lyman Alpha line properties at $z\simeq 3.78$ and their environmental dependence: a case study around a massive proto-cluster
• Observations of Ly$\alpha$ Emitters at High Redshift
• Effects of photon trapping on the Lyman-alpha properties of star-forming galaxies
• A z ~ 5.7 Lyα Emission Line with an Ultra Broad Red Wing
• The Lyman-$\alpha$ Forest from LBGs: First 3D Correlation Measurement with DESI and Prospects for Cosmology
• Direct Collapse Pre-supermassive Black Hole Objects as Ly$\alpha$ Emitters