TY - JOUR

T1 - The Archival Discovery of a Strong Ly alpha and [C II] Emitter at z=7.677

AU - Valentino, Francesco

AU - Brammer, Gabriel

AU - Fujimoto, Seiji

AU - Heintz, Kasper E.

AU - Weaver, John R.

AU - Strait, Victoria

AU - Gould, Katriona M. L.

AU - Mason, Charlotte

AU - Watson, Darach

AU - Laursen, Peter

AU - Toft, Sune

PY - 2022/4/1

Y1 - 2022/4/1

N2 - We report the archival discovery of Ly alpha emission from the bright ultraviolet galaxy Y002 at z = 7.677, spectroscopically confirmed by its ionized carbon [C II] 158 mu m emission line. The Ly alpha line is spatially associated with the rest-frame UV stellar emission (M-UV similar to-22, 2x brighter than M-UV*), and it appears offset from the peak of the extended [C II] emission at the current similar to 1 '' spatial resolution. We derive an estimate of the unobscured SFRUV = (22 +/- 1) M-circle dot yr(-1) and set an upper limit of SFRIR < 15 M-circle dot yr(-1) from the far-infrared (FIR) wavelength range, which globally places Y002 on the SFR(UV-FIR)-L-[C II] correlation observed at lower redshifts. In terms of velocity, the peak of the Ly alpha emission is redshifted by Delta nu(Ly alpha) similar to 500 km s(-1) from the systemic redshift set by [C II] and a high-velocity tail extends up to similar to 1000 km s(-1). The velocity offset is up to similar to 3.5x higher than the average estimate for similarly UV-bright emitters at z similar to 6-7, which might suggest that we are witnessing the merging of two clumps. A combination of strong outflows and the possible presence of an extended ionized bubble surrounding Y002 would likely facilitate the escape of copious Ly alpha light, as indicated by the large equivalent width EW0(Ly alpha) = 24(-6)(+5) angstrom. Assuming that [C II] traces the neutral hydrogen, we estimate a H I gas fraction of M-H I/M* greater than or similar to 8 for Y002 as a system and speculate that patches of high H I column densities could contribute to explaining the observed spatial offsets between Ly alpha- and [C II]-emitting regions. The low dust content, implied by the nondetection of the FIR continuum emission at rest frame similar to 160 mu m, would be sufficient to absorb any potential Ly alpha photons produced within the [C II] clump as a result of large H I column densities.

AB - We report the archival discovery of Ly alpha emission from the bright ultraviolet galaxy Y002 at z = 7.677, spectroscopically confirmed by its ionized carbon [C II] 158 mu m emission line. The Ly alpha line is spatially associated with the rest-frame UV stellar emission (M-UV similar to-22, 2x brighter than M-UV*), and it appears offset from the peak of the extended [C II] emission at the current similar to 1 '' spatial resolution. We derive an estimate of the unobscured SFRUV = (22 +/- 1) M-circle dot yr(-1) and set an upper limit of SFRIR < 15 M-circle dot yr(-1) from the far-infrared (FIR) wavelength range, which globally places Y002 on the SFR(UV-FIR)-L-[C II] correlation observed at lower redshifts. In terms of velocity, the peak of the Ly alpha emission is redshifted by Delta nu(Ly alpha) similar to 500 km s(-1) from the systemic redshift set by [C II] and a high-velocity tail extends up to similar to 1000 km s(-1). The velocity offset is up to similar to 3.5x higher than the average estimate for similarly UV-bright emitters at z similar to 6-7, which might suggest that we are witnessing the merging of two clumps. A combination of strong outflows and the possible presence of an extended ionized bubble surrounding Y002 would likely facilitate the escape of copious Ly alpha light, as indicated by the large equivalent width EW0(Ly alpha) = 24(-6)(+5) angstrom. Assuming that [C II] traces the neutral hydrogen, we estimate a H I gas fraction of M-H I/M* greater than or similar to 8 for Y002 as a system and speculate that patches of high H I column densities could contribute to explaining the observed spatial offsets between Ly alpha- and [C II]-emitting regions. The low dust content, implied by the nondetection of the FIR continuum emission at rest frame similar to 160 mu m, would be sufficient to absorb any potential Ly alpha photons produced within the [C II] clump as a result of large H I column densities.

KW - STAR-FORMATION

KW - DUST CONTENT

KW - GALAXIES

KW - REIONIZATION

KW - EMISSION

KW - STELLAR

KW - KINEMATICS

KW - RADIATION

KW - UNIVERSE

KW - EPOCH

U2 - 10.3847/2041-8213/ac62cc

DO - 10.3847/2041-8213/ac62cc

M3 - Letter

VL - 929

JO - The Astrophysical Journal Letters

JF - The Astrophysical Journal Letters

SN - 2041-8205

IS - 1

M1 - 9

ER -