Double-peaked Lyman α emission at z = 6.803: a reionization-era galaxy self-ionizing its local H ii bubble. Issue 1 (22nd October 2020)

• Record Type: Journal Article
• Authors: Meyer, Romain A; Laporte, Nicolas; Ellis, Richard S; Verhamme, Anne; Garel, Thibault
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 500:Issue 1(2021)
• Page Start: 558
• Page End: 564
• Publication Date: 2020-10-22
• Subjects: galaxies: high-redshift -- dark ages, reionization, first stars; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/staa3216
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: We report the discovery of a double-peaked Lyman α 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 α profile ($\Delta v=101_{-19}^{+38} (\pm 48)\, \rm km\, \rm s^{-1}$ ) suggests an extremely high escape fraction of ionizing photons $\gt 59(51){{\ \rm per\ cent}} (2\sigma)$ . The spectral energy distribution indicates a young (50 Myr), star-forming ($12\pm 6 \, \rm {M}_\odot \rm {yr}^{-1}$ ) galaxy with an IRAC excess implying strong [O iii ] + H β emission. On the basis of the high escape fraction measured, we demonstrate that A370p_z1 was solely capable of creating an ionized bubble sufficiently large to account for the blue component of its Lyman α profile. We discuss whether A370p_z1 may be representative of a larger population of luminous z ≃ 7 double-peaked Lyman α emitting sources with high escape fractions that self-ionized their surroundings without contributions from associated ultraviolet-fainter sources.