Double-peaked Lyman-$\alpha$ emission at z=6.803: a reionisation-era galaxy self-ionising its local HII bubble

Abstract

We report the discovery of a double-peaked Lyman-alpha profile in a galaxy at $z=6.803$, A370p\_z1, in the parallel Frontier Field of Abell 370. The velocity separation between the blue and red peaks of the Lyman-$\alpha$ profile ($\Delta v=101_{-19}^{+38}(\pm 48){\text{km s}}^{-1}$) suggests an extremely high escape fraction of ionising photons $>59(51)\%(2\sigma )$. The spectral energy distribution indicates a young ($50$ Myr), star-forming ($12\pm 6{\mathrm{M}}_{\odot }{\mathrm{yr}}^{-1}$) galaxy with an IRAC excess implying strong [OIII]+H$\beta$ emission. On the basis of the high escape fraction measured, we demonstrate that A370p\_z1 was solely capable of creating an ionised bubble sufficiently large to account for the blue component of its Lyman-alpha profile. We discuss whether A370p\_z1 may be representative of a larger population of luminous $z\simeq 7$ double-peaked Lyman-alpha emitting sources with high escape fractions that self-ionised their surroundings without contributions from associated UV-fainter sources.

Accepted for publication in MNRAS. 7 pages, 4 figures, 3 tables

References in corpus (18)

• UV Luminosity Functions at redshifts z~4 to z~10: 10000 Galaxies from HST Legacy Fields
• Cosmic Reionization and Early Star-Forming Galaxies: A Joint Analysis of New Constraints from Planck and Hubble Space Telescope
• 3D Lyman-alpha radiation transfer. I. Understanding Lyman-alpha line profile morphologies
• 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
• Conditions for Reionizing the Universe with A Low Galaxy Ionizing Photon Escape Fraction
• Dust in the reionization era: ALMA observations of a $z$=8.38 Galaxy
• Using Lyman-alpha to detect galaxies that leak Lyman continuum
• Lyman Alpha Emitting Galaxies as a Probe of Reionization
• Lyman-alpha spectral properties of five newly discovered Lyman continuum emitters
• 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)
• A spectroscopic search for AGN activity in the reionization era
• The origin of the escape of Lyman alpha and ionizing photons in Lyman Continuum Emitters
• Measuring the properties of reionised bubbles with resolved Lyman alpha spectra
• RASCAS: RAdiation SCattering in Astrophysical Simulations
• The Absence of [CII] 158$\mu$m Emission in Spectroscopically-Confirmed Galaxies at $z>8$
• Modeling $237$ Lyman-$\alpha$ spectra of the MUSE-Wide survey
• The Ultraluminous Lyman Alpha Luminosity Function at z=6.6

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