The Archival Discovery of a Strong Lyα and [C ii] Emitter at z = 7.677

Media type: E-Article
Title: The Archival Discovery of a Strong Lyα and [C ii] Emitter at z = 7.677
Contributor: Valentino, Francesco; Brammer, Gabriel; Fujimoto, Seiji; Heintz, Kasper E.; Weaver, John R.; Strait, Victoria; Gould, Katriona M. L.; Mason, Charlotte; Watson, Darach; Laursen, Peter; Toft, Sune
imprint: American Astronomical Society, 2022
Published in: The Astrophysical Journal Letters
Language: Not determined
DOI: 10.3847/2041-8213/ac62cc
ISSN: 2041-8205; 2041-8213
Keywords: Space and Planetary Science ; Astronomy and Astrophysics
Origination:
Footnote:
Description: <jats:title>Abstract</jats:title> <jats:p>We report the archival discovery of Ly<jats:italic>α</jats:italic> emission from the bright ultraviolet galaxy Y002 at <jats:italic>z</jats:italic> = 7.677, spectroscopically confirmed by its ionized carbon [C <jats:sc>ii</jats:sc>] 158 <jats:italic>μ</jats:italic>m emission line. The Ly<jats:italic>α</jats:italic> line is spatially associated with the rest-frame UV stellar emission (<jats:italic>M</jats:italic> <jats:sub>UV</jats:sub> ∼ −22, 2× brighter than <jats:inline-formula> <jats:tex-math> <?CDATA ${M}_{\mathrm{UV}}^{\star }$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow> <mml:mi>M</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>UV</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>⋆</mml:mo> </mml:mrow> </mml:msubsup> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjlac62ccieqn1.gif" xlink:type="simple" /> </jats:inline-formula>), and it appears offset from the peak of the extended [C <jats:sc>ii</jats:sc>] emission at the current ∼1″ spatial resolution. We derive an estimate of the unobscured SFR<jats:sub>UV</jats:sub> = (22 ± 1) <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub> yr<jats:sup>−1</jats:sup> and set an upper limit of SFR<jats:sub>IR</jats:sub> < 15 <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub> yr<jats:sup>−1</jats:sup> from the far-infrared (FIR) wavelength range, which globally places Y002 on the SFR(UV+IR)–<jats:italic>L</jats:italic> <jats:sub>[C <jats:sc>II</jats:sc>]</jats:sub> correlation observed at lower redshifts. In terms of velocity, the peak of the Ly<jats:italic>α</jats:italic> emission is redshifted by Δ<jats:italic>v</jats:italic> <jats:sub>Ly<jats:italic>α</jats:italic> </jats:sub> ∼ 500 km s<jats:sup>−1</jats:sup> from the systemic redshift set by [C <jats:sc>ii</jats:sc>] and a high-velocity tail extends up to ∼1000 km s<jats:sup>−1</jats:sup>. The velocity offset is up to ∼3.5× higher than the average estimate for similarly UV-bright emitters at <jats:italic>z</jats:italic> ∼ 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<jats:italic>α</jats:italic> light, as indicated by the large equivalent width EW<jats:sub>0</jats:sub>(Ly<jats:italic>α</jats:italic>)<jats:inline-formula> <jats:tex-math> <?CDATA $\,=\,{24}_{-6}^{+5}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mspace width="0.50em" /> <mml:mo>=</mml:mo> <mml:mspace width="0.50em" /> <mml:msubsup> <mml:mrow> <mml:mn>24</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>6</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>5</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjlac62ccieqn2.gif" xlink:type="simple" /> </jats:inline-formula> Å. Assuming that [C <jats:sc>ii</jats:sc>] traces the neutral hydrogen, we estimate a H <jats:sc>i</jats:sc> gas fraction of <jats:italic>M</jats:italic> <jats:sub>H I</jats:sub>/<jats:italic>M</jats:italic> <jats:sub>⋆</jats:sub> ≳ 8 for Y002 as a system and speculate that patches of high H <jats:sc>i</jats:sc> column densities could contribute to explaining the observed spatial offsets between Ly<jats:italic>α-</jats:italic> and [C <jats:sc>ii</jats:sc>]-emitting regions. The low dust content, implied by the nondetection of the FIR continuum emission at rest frame ∼160 <jats:italic>μ</jats:italic>m, would be sufficient to absorb any potential Ly<jats:italic>α</jats:italic> photons produced within the [C <jats:sc>ii</jats:sc>] clump as a result of large H <jats:sc>i</jats:sc> column densities.</jats:p>
Access State: Open Access

Search in field:

Recently searched for: