Lyman alpha Emitting Galaxies in the Nearby Universe

Abstract

The Lya emission line of HI is intrinsically the brightest feature in the spectrum of astrophysical nebulae, making it a very attractive observational tool with which to survey galaxies. Moreover as a UV resonance line, Lya possesses several unique characteristics that make it useful to study the ISM and ionizing stellar population at all cosmic epochs. In this review I present a summary of Lya observations of galaxies in the nearby universe. At UV magnitudes reachable with current facilities, only ~5% of the local galaxy population shows a Lya equivalent width (EW_Lya) that exceeds 20Å. This fraction increases dramatically at higher z, but only in the local universe can we study galaxies in detail and assemble unprecedented multi-wavelength datasets. I discuss many local Lya observations, showing that when galaxies show net Lya emission, they ubiquitously produce large halos of scattered Lya, that dominate the integrated luminosity. We discuss how global EW_Lya and the Lya escape fraction (fescLya) are higher (EW_Lya >~ 20Å and fescLya> 10%) in galaxies that represent the less massive and younger end of the distributions for local objects. This is connected with various properties, such that Lya-emitters have lower metallicities (median value of 12+log(O/H) ~ 8.1) and dust reddening. However, the presence of galactic outflows is also vital to Doppler shift the Lya line out of resonance with the HI, as high EW_Lya is found only among galaxies with winds faster than ~50km/s. The evidence is then assembled into a coherent picture, and the requirement for star formation driven feedback is discussed in the context of an evolutionary sequence where the ISM is accelerated and/or subject to fluid instabilities, which reduce the scattering of Lya. Concluding remarks take the form of perspectives upon the most pressing questions that can be answered by observation.

arXiv commentInvited review article, in press at PASA as part of the series on Lyman alpha emitting galaxies. 27 pages, 12 figures

References in corpus (83)

• The Dust Content and Opacity of Actively Star-Forming Galaxies
• Starburst99: Synthesis Models for Galaxies with Active Star Formation
• Cosmic Star Formation History
• The Origin of the Mass--Metallicity Relation: Insights from 53,000 Star-Forming Galaxies in the SDSS
• How Do Galaxies Get Their Gas?
• Cold streams in early massive hot haloes as the main mode of galaxy formation
• THINGS: The HI Nearby Galaxy Survey
• Rest-Frame Ultraviolet Spectra of z~3 Lyman Break Galaxies
• Keck Spectroscopy of Faint 3<z<7 Lyman Break Galaxies: - I. New constraints on cosmic reionisation from the luminosity and redshift-dependent fraction of Lyman-alpha emission
• New Observations of the Interstellar Medium in the Lyman Break Galaxy MS 1512-cB58
• The COS-Halos Survey: Rationale, Design, and A Census of Circumgalactic Neutral Hydrogen
• Diffuse Lyman Alpha Emitting Halos: A Generic Property of High Redshift Star Forming Galaxies
• The Density of Lyman-alpha Emitters at Very High Redshift
• Lyman Alpha Emitting Galaxies as a Probe of Reionization
• Extreme Feedback and the Epoch of Reionization: Clues in the Local Universe
• New observations of z~7 galaxies: evidence for a patchy reionization
• On the redshift-evolution of the Lyman-alpha escape fraction and the dust content of galaxies
• A high spatial resolution X-ray and H-alpha study of hot gas in the halos of star-forming disk galaxies. II. Quantifying supernova feedback
• The Origin and Optical Depth of Ionizing Radiation in the "Green Pea" Galaxies
• A Population of Faint Extended Line Emitters and the Host Galaxies of Optically Thick QSO Absorption Systems
• The Ha Luminosity Function and Star Formation Rate at z\sim 0.2
• Very Strong Emission-Line Galaxies in the WISP Survey and Implications for High-Redshift Galaxies
• A Local Clue to the Reionization of the Universe
• Lyman-Alpha-Emitting Galaxies at z = 2.1 in ECDF-S: Building Blocks of Typical Present-day Galaxies?
• The Optical Depth of H II Regions in the Magellanic Clouds
• Escape of about five per cent of Lyman-alpha photons from high-redshift star-forming galaxies
• The HETDEX Pilot Survey. II. The Evolution of the Ly-alpha Escape Fraction from the UV Slope and Luminosity Function of 1.9<z<3.8 LAEs
• The Properties of Ultraviolet-Luminous Galaxies at the Current Epoch
• A Universal Neutral Gas Profile for Nearby Disk Galaxies
• Lyman alpha Radiative Transfer with Dust: Escape Fractions from Simulated High-Redshift Galaxies
• Simple Models of Metal-Line Absorption and Emission from Cool Gas Outflows
• The Lyman alpha Reference Sample: II. HST imaging results, integrated properties and trends
• Detection of dark galaxies and circum-galactic filaments fluorescently illuminated by a quasar at z=2.4
• The evolution of superbubbles and the detection of Lyman alpha in star-forming galaxies
• The Complex Kinematics of the Neutral Hydrogen Associated with IZw18
• The Lyman alpha morphology of local starburst galaxies: release of calibrated images
• The Lyman alpha Reference Sample: Extended Lyman alpha Halos Produced at Low Dust Content
• Keck Spectroscopy of Gravitationally Lensed z=4 Galaxies: Improved Constraints on the Escape Fraction of Ionizing Photons
• Lyman alpha emission in starbursts: implications for galaxies at high redshift
• The Lyman-alpha Reference Sample: I. Survey outline and first results for Markarian 259
• The Diverse Properties of the Most Ultraviolet Luminous Galaxies Discovered by the Galaxy Evolution Explorer
• A remarkably high fraction of strong Ly_alpha emitters amongst luminous redshift 6.0<z<6.5 Lyman break galaxies in the UKIDSS Ultra-Deep Survey
• VLA-ANGST: A high-resolution HI Survey of Nearby Dwarf Galaxies
• Gas Motion Study of Lya Emitters at z~2 Using UV and Optical Spectral Lines
• The Lyman Alpha Reference Sample: V. The impact of neutral ISM kinematics and geometry on Lyman Alpha escape
• The Evolution of Ly-alpha Emitting Galaxies Between z = 2.1 and z = 3.1
• Low-Redshift Ly-alpha Selected Galaxies from GALEX Spectroscopy: A Comparison with Both UV-Continuum Selected Galaxies and High-Redshift Ly-alpha Emitters
• Feedback in the local LBG Analog Haro 11 as probed by far-UV and X-ray observations
• Low-ionization Line Emission from Starburst Galaxies: A New Probe of Galactic-Scale Outflows
• Ly-alpha Emitting Galaxies at z = 2.1: Stellar Masses, Dust and Star Formation Histories from Spectral Energy Distribution Fitting
• On the (non-)enhancement of the Lyman α equivalent width by a multiphase interstellar medium
• The effect of dust geometry on the Lyman-alpha output of galaxies
• A Chandra X-ray survey of nearby dwarf starburst galaxies: II. Starburst properties and outflows
• The First Deep ACS Lyman alpha Images of Local Starburst Galaxies
• Lyman alpha emitting galaxies at 0.2 < z < 0.35 from GALEX spectroscopy
• The escape of Lyman photons from a young starburst: the case of Haro 11
• Identification of Galactic Wind Candidates using Excitation Maps: Tunable-Filter Discovery of a Shock-Excited Wind in the Galaxy NGC 1482
• Linking Ly-alpha and Low-Ionization Transitions at Low Optical Depth
• Empirical Estimate of Lyman-alpha Escape Fraction in a Statistical Sample of Lyman-alpha Emitters
• Sizing up Lyman-alpha and Lyman Break Galaxies
• Lya escape from z~0.03 star-forming galaxies: the dominant role of outflows
• Ly alpha emitting galaxies as early stages in galaxy formation
• A Semi-Analytical Line Transfer (SALT) model to interpret the spectra of galaxy outflows
• Escape of Lyman-alpha and continuum photons from star-forming galaxies
• The LyAlpha Line Profiles of Ultraluminous Infrared Galaxies: Fast Winds and Lyman Continuum Leakage
• Confirmation of a Steep Luminosity Function for Lyman-alpha Emitters at z = 5.7: A Major Component of Reionization
• Investigating Nearby Star-Forming Galaxies in the Ultraviolet with HST/COS Spectroscopy. I: Spectral Analysis and Interstellar Abundance Determinations
• On the Lyman-alpha Emission of Starburst Galaxies
• Modelling high redshift Lyman-alpha Emitters
• New Constraints on the Escape of Ionizing Photons From Starburst Galaxies Using Ionization-Parameter Mapping
• An Ionization Cone in the Dwarf Starburst Galaxy NGC 5253
• Dust Extinction and Metallicities of Star-Forming Lyman Alpha Emitting Galaxies at Low Redshift
• The Lyman Alpha Reference Sample: III. Properties of the Neutral ISM from GBT and VLA Observations
• Deep Spectroscopy of Ultra-Strong Emission Line Galaxies
• Studying reionization with the next generation of Ly-alpha emitter surveys
• z~1 Lya Emitters I. The Luminosity Function
• Evolution of Lyman Alpha Galaxies: Stellar Populations at z ~ 0.3
• Far-Ultraviolet Observations of Outflows from IR-Luminous Galaxies
• Extended Tidal Structure In Two Lyman Alpha-Emitting Starburst Galaxies
• Empirical Constraints on the Star Formation & Redshift Dependence of the Lyman Alpha `Effective' Escape Fraction
• A Flux-Limited Sample of z~1 Ly-alpha Emitting Galaxies in the CDFS
• On The Origin of Lyman-alpha Absorption in Nearby Starbursts and Implications for Other Galaxies
• HI Lyman-alpha equivalent widths of stellar populations

Cited by in corpus (68)

• Detection of high Lyman continuum leakage from four low-redshift compact star-forming galaxies
• Spectroscopic Confirmation of CEERS NIRCam-selected Galaxies at $\mathbf{z}\simeq 8-10$
• The Lyman Continuum Escape Survey: Ionizing Radiation from [O III]-Strong Sources at a Redshift of 3.1
• The LyA-LyC Connection: Evidence for an Enhanced Contribution of UV-faint Galaxies to Cosmic Reionization
• The physics of Lyman-alpha escape from high-redshift galaxies
• The CALYMHA survey: Lya luminosity function and global escape fraction of Lya photons at z=2.23
• The CALYMHA survey: Ly$\alpha$ escape fraction and its dependence on galaxy properties at $z=2.23$
• Ly$\alpha$ Spectra from Multiphase Outflows, and their Connection to Shell Models
• Spectroscopic properties of luminous Lyman-α emitters at $z\approx 6-7$ and comparison to the Lyman-break population
• Puzzling Lyman-alpha line profiles in green pea galaxies
• The X-SHOOTER Lyman-$\alpha$ survey at z=2 (XLS-z2) I: What makes a galaxy a Lyman-$\alpha$ emitter?
• Near-Infrared Spectroscopy of Galaxies During Reionization: Measuring CIII] in a Galaxy at $\mathbf{z}=7.5$
• From Mirrors to Windows: Lyman-Alpha Radiative Transfer in a Very Clumpy Medium
• MUSEQuBES: Calibrating the redshifts of Ly α emitters using stacked circumgalactic medium absorption profiles
• Haro 11: Where is the Lyman continuum source?
• Resonant line transfer in a fog: Using Lyman-alpha to probe tiny structures in atomic gas
• Three Lyman-alpha emitting galaxies within a quasar proximity zone at z=5.8
• On the contribution of fluorescence to Ly$\alpha$ halos (LAHs) around star forming galaxies
• The physics of Lyman-alpha escape from disc-like galaxies
• The Diversity of Diffuse Ly$\alpha$ Nebulae around Star-Forming Galaxies at High Redshift
• Boötes-HiZELS: an optical to near-infrared survey of emission-line galaxies at $\mathbf{z}=0.4-4.7$
• Lyman Alpha Signatures from Direct Collapse Black Holes
• O VI Emission Imaging of a Galaxy with the Hubble Space Telescope: a Warm Gas Halo Surrounding the Intense Starburst SDSS J115630.63+500822.1
• Spectral shapes of the Lyman-alpha emission from galaxies: I. blueshifted emission and intrinsic invariance with redshift
• The ALPINE-ALMA [CII] survey: Small Lya-[CII] velocity offsets in main-sequence galaxies at 4.4 < z < 6
• Broadband Intensity Tomography: Spectral Tagging of the Cosmic UV Background
• Cross-correlating Carbon Monoxide Line-intensity Maps with Spectroscopic and Photometric Galaxy Surveys
• Neutral ISM, Lyman-Alpha and Lyman-continuum in the nearby starburst Haro 11
• Ionized gas kinematics and chemical abundances of low-mass star-forming galaxies at $z\sim 3$
• Lyman Alpha Reference Sample: X. Predicting Lyman alpha output from starforming galaxies using multivariate regression
• The Circumgalactic Medium of Extreme Emission Line Galaxies at z ~ 2: Resolved Spectroscopy and Radiative Transfer Modeling of Spatially Extended Lyman-alpha Emission in the KBSS-KCWI Survey
• MUSE Illuminates Channels for Lyman Continuum Escape in the Halo of SBS 0335-52E
• The Lyman alpha Reference Sample VI: Lyman alpha escape from the edge-on disk galaxy Mrk1486
• Spectral Shapes of the Lya Emission from Galaxies. II. the influence of stellar properties and nebular conditions on the emergent Lya profiles
• Nature and chemical abundances of a sample of Lyman-$\alpha$ emitter objects at high redshift
• Variations of Observed Lyman-α Spectra Shapes due to the Intergalactic Absorption
• Unlocking the Full Potential of Extragalactic Ly$\alpha$ through Its Polarization Properties
• Deep submillimeter and radio observations in the SSA22 field. I. Powering sources and Lyα escape fraction of Lyα blobs
• The Detection of Intergalactic Halpha Emission from the Slug Nebula at z~2.3
• Giant Lyman-Alpha Nebulae in the Illustris Simulation
• Effects of Spatial Discretization in Lyman-alpha Line Radiation Transfer Simulations
• The HETDEX Survey: The Ly$\alpha$ Escape Fraction from 3D-HST Emission Line Galaxies at $z\sim 2$
• A $1.4$ deg${}^2$ blind survey for CII], CIII] and CIV at $\mathbf{z}\sim 0.7-1.5$. I: nature, morphologies and equivalent widths
• An investigation of the circumgalactic medium around z~2.2 AGN with ACA and ALMA
• The Lyman Alpha Spectral Database (LASD)
• Detection of HI in Emission in the Lyman Alpha Emitting Galaxy Haro 11
• The Lyman Alpha Reference Sample XI: Efficient Turbulence Driven Lyα Escape and the Analysis of IR, CO and [C II]158 μm
• The Lyman Alpha Reference Sample. VIII. Characterizing Lyman-Alpha Scattering in Nearby Galaxies
• Characterizing the Circumgalactic Medium of Quasars at z $\sim$ 2.2 through H$\alpha$ and Ly$\alpha$ Emission
• Deciphering stellar metallicities in the early Universe: Case study of a young galaxy at z = 4.77 in the MUSE eXtremely Deep Field
• Stellar Populations of Lyman-alpha Emitting Galaxies in the HETDEX Survey I: An Analysis of LAEs in the GOODS-N Field
• A $1.4$ deg${}^2$ blind survey for CII], CIII] and CIV at $\mathbf{z}\sim 0.7-1.5$. II: luminosity functions and cosmic average line ratios
• Lyman-$\alpha$ photons through rotating outflows
• The Lyman $\alpha$ Reference Sample XIV: Lyman $\alpha$ imaging of 45 low redshift star-forming galaxies and inferences on global emission
• Resolved galactic superwinds reconstructed around their host galaxies at z>3
• Radio properties of Green Pea galaxies
• Lyman alpha Properties of Simulated Galaxies in Overdense Regions: Effects of Galactic Winds at z > 6
• A search for Ly-alpha emitters around a concentrated-region of strong Ly-alpha absorbers at z=2.3
• SDSS-IV MaNGA: an observational evidence of density bounded region in a Lyman-$\alpha$ emitter
• Lyman-alpha at Cosmic Noon I: Ly-alpha Spectral Type Selection of z ~ 2-3 Lyman Break Galaxies with Broadband Imaging
• Modelling LAEs in the Epoch of Reionization with OBELISK
• Impact of Cosmic Variance on the Galaxy-Halo Connection for Lyman-$\alpha$ Emitters
• Absorption line abundances in the SMC-like galaxy UGC 5282: evidence for ISM dilution from inflows on kiloparsec scales
• Modelling the gas kinematics of an atypical Lyman-alpha emitting compact dwarf galaxy
• Influence of turbulence on Lyman-alpha scattering
• Lyman-alpha at Cosmic Noon II: The relationship between kinematics and Lyman-alpha in z~2-3 Lyman Break Galaxies
• Uncertainty-Aware Neural Networks for Fuzzy Dark Matter Model Selection from \texorpdfstring{$x_{\mathrm{HI}}$}{x_HI} Measurements
• Extreme equivalent width-selected low-mass starbursts at $z=4-9$: insights into their role in cosmic reionization