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Article Dans Une Revue Astronomy and Astrophysics - A&A Année : 2023

JADES: Discovery of extremely high equivalent width Lyman- α emission from a faint galaxy within an ionized bubble at z = 7.3

Aayush Saxena
Brant E Robertson
  • Fonction : Auteur
Andrew J Bunker
  • Fonction : Auteur
Ryan Endsley
  • Fonction : Auteur
Alex J Cameron
Stephane Charlot
Charlotte Simmonds
Sandro Tacchella
Joris Witstok
Chris Willott
  • Fonction : Auteur
Stefano Carniani
Emma Curtis-Lake
  • Fonction : Auteur
Pierre Ferruit
Peter Jakobsen
Santiago Arribas
Jacopo Chevallard
Mirko Curti
Francesco D’eugenio
Anna de Graaff
Gareth C Jones
Tobias J Looser
  • Fonction : Auteur
Michael V Maseda
Tim Rawle
Hans-Walter Rix
Bruno Rodríguez del Pino
Renske Smit
  • Fonction : Auteur
Hannah Übler
Daniel J Eisenstein
Kevin Hainline
  • Fonction : Auteur
Ryan Hausen
Benjamin D Johnson
Marcia Rieke
Christina C Williams
Christopher N A Willmer
William M Baker
Rachana Bhatawdekar
  • Fonction : Auteur
Rebecca Bowler
Kristan Boyett
Zuyi Chen
  • Fonction : Auteur
Eiichi Egami
  • Fonction : Auteur
Zhiyuan Ji
  • Fonction : Auteur
Nimisha Kumari
  • Fonction : Auteur
Erica Nelson
  • Fonction : Auteur
Michele Perna
Lester Sandles
Jan Scholtz
  • Fonction : Auteur
Irene Shivaei
  • Fonction : Auteur

Résumé

We report the discovery of a remarkable Ly α emitting galaxy at z = 7.2782, JADES-GS+53.16746−27.7720 (shortened to JADES-GS-z7-LA), with rest-frame equivalent width, EW 0 (Ly α ) = 388.0 ± 88.8 Å and UV magnitude −17.0. The spectroscopic redshift is confirmed via rest-frame optical lines [O II ], H β and [O III ] in its JWST/NIRSpec Micro-Shutter Assembly (MSA) spectrum. The Ly α line is detected in both lower resolution ( R ∼ 100) PRISM as well as medium resolution ( R ∼ 1000) G 140 M grating spectra. The line spread function-deconvolved Ly α full width at half maximum in the grating is 383.9 ± 56.2 km s −1 and the Ly α velocity offset compared to the systemic redshift is 113.3 ± 80.0 km s −1 , indicative of very little neutral gas or dust within the galaxy. We estimate the Ly α escape fraction to be > 70%. JADES-GS-z7-LA has a [O III ]/[O II ] ratio (O32) of 11.1 ± 2.2 and a ([O III ] + [O II ])/H β ratio (R23) of 11.2 ± 2.6, consistent with low metallicity and high ionization parameters. Deep NIRCam imaging also revealed a close companion source (separated by 0.23″), which exhibits similar photometry to that of JADES-GS-z7-LA, with a photometric excess in the F 410 M NIRCam image consistent with [O III ] + H β emission at the same redshift. The spectral energy distribution of JADES-GS-z7-LA indicates a “bursty” star formation history, with a low stellar mass of ≈10 7 M ⊙ . Assuming that the Ly α transmission through the intergalactic medium is the same as its measured escape fraction, an ionized region of size > 1.5 pMpc is needed to explain the high Ly α EW and low velocity offset compared to systemic seen in JADES-GS-z7-LA. Owing to its UV-faintness, we show that it is incapable of single-handedly ionizing a region large enough to explain its Ly α emission. Therefore, we suggest that JADES-GS-z7-LA (and possibly the companion source) may be a part of a larger overdensity, presenting direct evidence of overlapping ionized bubbles at z > 7.
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Dates et versions

hal-04293562 , version 1 (18-11-2023)

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Citer

Aayush Saxena, Brant E Robertson, Andrew J Bunker, Ryan Endsley, Alex J Cameron, et al.. JADES: Discovery of extremely high equivalent width Lyman- α emission from a faint galaxy within an ionized bubble at z = 7.3. Astronomy and Astrophysics - A&A, 2023, 678, pp.A68. ⟨10.1051/0004-6361/202346245⟩. ⟨hal-04293562⟩
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