Gamma-Ray Absorption By The Cosmic Lyman Continuum From Star-forming Galaxies

Abstract

Motivated by the discovery of the ultra-strong emission line starburst galaxies (EELGs) known as "green pea galaxies", we consider here their contribution to the intergalactic flux of ionizing UV at high redshifts. Most galaxies that have been observed show a precipitous drop in their flux blueward of the Lyman limit. However, recent observations of EELGs have discovered that many more Lyman continuum photons escape from them into intergalactic space than was previously suspected. We calculate their contribution to the extragalactic background light (EBL). We also calculate the effect of these photons on the absorption of high energy $\gamma$-rays. For the more distant $\gamma$-ray sources, particularly at $z\ge 3$, the intergalactic opacity above a few GeV is significantly higher than previous estimates which ignored the Lyman continuum photons. We calculate the results of this increased opacity on observed $\gamma$-ray spectra, which produces a high-energy turnover starting at lower energies than previously thought, and a gradual spectral steepening that may also be observable.

arXiv comment22 pages, 9 figures, published in the Astrophysical Journal

References in corpus (62)

• Constraining the Evolution of the Ionizing Background and the Epoch of Reionization with z ~ 6 Quasars II: A Sample of 19 Quasars
• Binary Population and Spectral Synthesis Version 2.1: construction, observational verification and new results
• Cosmic Reionization and Early Star-Forming Galaxies: A Joint Analysis of New Constraints from Planck and Hubble Space Telescope
• Galaxy Zoo Green Peas: Discovery of A Class of Compact Extremely Star-Forming Galaxies
• Reionization after Planck: The Derived Growth of the Cosmic Ionizing Emissivity now matches the Growth of the Galaxy UV Luminosity Density
• Evidence of patchy hydrogen reionization from an extreme Ly$\alpha$ trough below redshift six
• The End of the Reionization Epoch Probed by Ly-alpha Emitters at z=6.5 in the Subaru Deep Field
• The Birth of a Galaxy - III. Propelling reionisation with the faintest galaxies
• The Fourth Catalog of Active Galactic Nuclei Detected by the Fermi Large Area Telescope
• The observed ionization rate of the intergalactic medium and the ionizing emissivity at z >5: Evidence for a photon starved and extended epoch of reionization
• Low-redshift Lyman continuum leaking galaxies with high [OIII]/[OII] ratios
• The Keck Lyman Continuum Spectroscopic Survey (KLCS): The Emergent Ionizing Spectrum of Galaxies at $z\sim 3$
• Using Lyman-alpha to detect galaxies that leak Lyman continuum
• J1154+2443: a low-redshift compact star-forming galaxy with a 46 per cent leakage of Lyman continuum photons
• Completing the Census of Ly-alpha Emitters at the Reionization Epoch
• A Cosmic UV/X-ray Background Model Update
• On the Stellar Populations and Evolution of Star-Forming Galaxies at 6.3 < z < 8.6
• The Luminosity Function and Star Formation Rate between Redshifts of 0.07 and 1.47 for Narrow-band Emitters in the Subaru Deep Field
• The Giant Gemini GMOS survey of z>4.4 quasars - I. Measuring the mean free path across cosmic time
• A Local Clue to the Reionization of the Universe
• An extreme [OIII] emitter at $z=3.2$: a low metallicity Lyman continuum source
• The changing Lya optical depth in the range 6<z<9 from MOSFIRE spectroscopy of Y-dropouts
• The Lyman Continuum Escape Survey: Ionizing Radiation from [O III]-Strong Sources at a Redshift of 3.1
• Absorption of High Energy Gamma Rays by Interactions With Starlight Photons in Extragalactic Space at High Redshifts and the High Energy Gamma-Ray Background
• Consistent modelling of the meta-galactic UV background and the thermal/ionization history of the intergalactic medium
• Escape of Lyman continuum radiation from local galaxies - Detection of leakage from the young starburst Tol 1247-232
• High-precision Photometric Redshifts from Spitzer/IRAC: Extreme [3.6]-[4.5] Colors Identify Galaxies in the Redshift Range z~6.6-6.9
• A $\gamma$-ray determination of the Universe's star-formation history
• Extragalactic Background Light from Hierarchical Galaxy Formation: Gamma-ray Attenuation up to the Epoch of Cosmic Reionization and the First Stars
• No evidence for a significant AGN contribution to cosmic hydrogen reionization
• New synthesis models of consistent extragalactic background light over cosmic time
• Direct Detection of Lyman Continuum Escape from Local Starburst Galaxies with the Cosmic Origins Spectrograph
• A Direct Measurement of the IGM Opacity to HI Ionizing Photons
• Gravitational lensing reveals ionizing ultraviolet photons escaping from a distant galaxy
• Fermi Large Area Telescope Constraints on the Gamma-ray Opacity of the Universe
• The redshift evolution of escape fraction of hydrogen ionizing photons from galaxies
• Ionising the Intergalactic Medium by Star Clusters: The first empirical evidence
• The origin of the escape of Lyman alpha and ionizing photons in Lyman Continuum Emitters
• Peering through the holes: the far UV color of star-forming galaxies at z~3-4 and the escaping fraction of ionizing radiation
• Escape fraction of ionizing photons from galaxies at z=0--6
• The properties of He II 1640 emitters at z ~ 2.5-5 from the VANDELS survey
• An Empirical Determination of the Intergalactic Background Light from UV to FIR Wavelengths Using FIR Deep Galaxy Surveys and the Gamma-ray Opacity of the Universe
• Ly$\alpha$-Lyman Continuum connection in 3.5 < z < 4.3 star-forming galaxies from the VUDS survey
• The Lyman Continuum Escape Fraction of Low-Mass Star-Forming Galaxies at z~1
• Gamma-ray Blazars Within the First 2 Billion Years
• An HST Search for Lyman Continuum Emission From Galaxies at z=1.1--1.4
• Hubble Space Telescope Grism Spectroscopy of Extreme Starbursts Across Cosmic Time: The Role of Dwarf Galaxies in the Star Formation History of the Universe
• A GeV-TeV Measurement of the Extragalactic Background Light
• Reconstructing the γ-ray Photon Optical Depth of the Universe to z~4 from Multiwavelength Galaxy Survey Data
• The bursting nature of star formation in compact star-forming galaxies from the Sloan Digital Sky Survey
• The Signature of Patchy Reionization in the Polarization Anisotropy of the CMB
• The Number Density Evolution of Extreme Emission Line Galaxies in 3D-HST: Results from a Novel Automated Line Search Technique for Slitless Spectroscopy
• The Lyman Continuum Escape Fraction of Galaxies and AGN in the GOODS Fields
• The Spectrum of 1ES0229 + 200 and the Cosmic Infrared Background
• The Lyman continuum escape fraction and the Mean Free Path of hydrogen ionizing photons for bright z~4 QSOs from SDSS DR14
• A Simple Analytic Treatment of the Intergalactic Absorption Effect in Blazar Gamma-ray Spectra
• Properties of the KISS Green Pea Galaxies
• An Empirical Determination of the Intergalactic Background Light Using NIR Deep Galaxy Survey Data out to 5 microns and the Gamma-ray Opacity of the Universe
• Lyman-Break Galaxies at $z\sim 3$ in the Subaru Deep Field: Luminosity Function, Clustering and [OIII] Emission
• Detection of a gamma-ray flare from the high-redshift blazar DA 193
• Lyman continuum leakage in faint star-forming galaxies at redshift z=3-3.5 probed by gamma-ray bursts
• Extreme [OIII] Emitters at z $\sim$ 0.5

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• An observational determination of the evolving extragalactic background light from the multiwavelength HST/CANDELS survey in the Fermi and CTA era
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