Lyman alpha emission from the first galaxies: Signatures of accretion and infall in the presence of line trapping

Abstract

The formation of the first galaxies is accompanied by large accretion flows and virialization shocks, during which the gas is shock-heated to temperatures of $\sim 10^4$ K, leading to potentially strong fluxes in the Lyman alpha line. Indeed, a number of Lyman alpha blobs has been detected at high redshift. In this letter, we explore the origin of such Lyman alpha emission using cosmological hydrodynamical simulations that include a detailed model of atomic hydrogen as a multi-level atom and the effects of line trapping with the adaptive mesh refinement code FLASH. We see that baryons fall into the center of a halo through cold streams of gas, giving rise to a Lyman alpha luminosity of at least $10^{44}\mathrm{erg}{\mathrm{s}}^{-1}$ at $\mathrm{z}=4.7$, similar to observed Lyman alpha blobs. We find that a Lyman alpha flux of $5.0\times 10^{-17}\mathrm{ergc}{\mathrm{m}}^{-2}{\mathrm{s}}^{-1}$ emerges from the envelope of the halo rather than its center, where the photons are efficiently trapped. Such emission can be probed in detail with the upcoming James Webb Space Telescope (JWST) and will constitute an important probe of gas infall and accretion.

5 pages, 3 figures, Accepted for publication in MNRAS LETTERS

References in corpus (12)

• Cold streams in early massive hot haloes as the main mode of galaxy formation
• Fluctuations in the High-Redshift Lyman-Werner Background: Close Halo Pairs as the Origin of Supermassive Black Holes
• Resolving the Formation of Protogalaxies. II. Central Gravitational Collapse
• Spectroscopic confirmation of a galaxy at redshift z=8.6
• Evidence for Cold Accretion onto a Massive Galaxy at High Redshift?
• HD and H2 formation in low-metallicity dusty gas clouds at high redshift
• A Keck/DEIMOS Spectroscopy of Lyman Alpha Blobs at Redshift z=3.1
• Effects of primordial chemistry on the cosmic microwave background
• On the Detection of High Redshift Black Holes with ALMA through CO and H2 Emission
• Heating of the Intergalactic Medium by Primordial Miniquasars
• Deep Spectroscopy of Systematically Surveyed Extended Lyman-alpha Sources at z~3-5
• The Impact of Lyman alpha Trapping on the Formation of Primordial Objects

Cited by in corpus (14)

• Star formation sustained by gas accretion
• The Epoch of Reionization
• Intensity Mapping of Lyman-alpha Emission During the Epoch of Reionization
• The Formation of the First Massive Black Holes
• The Lyman-alpha signature of the first galaxies
• 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?
• Exploring the nature of the Lyman-$\alpha$ emitter CR7
• The Properties of Lyman Alpha Nebulae: Gas Kinematics from Non-resonant Lines
• Gas infall into atomic cooling haloes: on the formation of protogalactic disks and supermassive black holes at z > 10
• Star formation near an obscured AGN: Variations in the initial mass function
• Rivers of Gas I.: Unveiling The Properties of High Redshift Filaments
• The implications of dust for high-redshift protogalaxies and the formation of binary disks
• Extended Lyman-alpha emission from a high-z DLA at z=3.115
• Effect of Dust on Lyman-alpha Photon Transfer in Optically Thick Halo