TY - JOUR
T1 - JADES
T2 - Discovery of extremely high equivalent width Lyman- α emission from a faint galaxy within an ionized bubble at z = 7.3
AU - Saxena, Aayush
AU - Robertson, Brant E.
AU - Bunker, Andrew J.
AU - Endsley, Ryan
AU - Cameron, Alex J.
AU - Charlot, Stephane
AU - Simmonds, Charlotte
AU - Tacchella, Sandro
AU - Witstok, Joris
AU - Willott, Chris
AU - Carniani, Stefano
AU - Curtis-Lake, Emma
AU - Ferruit, Pierre
AU - Jakobsen, Peter
AU - Arribas, Santiago
AU - Chevallard, Jacopo
AU - Curti, Mirko
AU - D'Eugenio, Francesco
AU - De Graaff, Anna
AU - Jones, Gareth C.
AU - Looser, Tobias J.
AU - Maseda, Michael V.
AU - Rawle, Tim
AU - Rix, Hans Walter
AU - Del Pino, Bruno Rodríguez
AU - Smit, Renske
AU - Ubler, Hannah
AU - Eisenstein, Daniel J.
AU - Hainline, Kevin
AU - Hausen, Ryan
AU - Johnson, Benjamin D.
AU - Rieke, Marcia
AU - Williams, Christina C.
AU - Willmer, Christopher N.A.
AU - Baker, William M.
AU - Bhatawdekar, Rachana
AU - Bowler, Rebecca
AU - Boyett, Kristan
AU - Chen, Zuyi
AU - Egami, Eiichi
AU - Ji, Zhiyuan
AU - Kumari, Nimisha
AU - Nelson, Erica
AU - Perna, Michele
AU - Sandles, Lester
AU - Scholtz, Jan
AU - Shivaei, Irene
N1 - Publisher Copyright:
© 2023 The Authors.
PY - 2023/10/1
Y1 - 2023/10/1
N2 - We report the discovery of a remarkable Lyα emitting galaxy at z = 7.2782, JADES-GS+53.16746-27.7720 (shortened to JADES-GS-z7-LA), with rest-frame equivalent width, EW0(Lyα) = 388.0 ± 88.8 Å and UV magnitude -17.0. The spectroscopic redshift is confirmed via rest-frame optical lines [O- ¯II], Hβ and [O- ¯III] in its JWST/NIRSpec Micro-Shutter Assembly (MSA) spectrum. The Lyα line is detected in both lower resolution (R ∼ 100) PRISM as well as medium resolution (R ∼ 1000) G140M grating spectra. The line spread function-deconvolved Lyα full width at half maximum in the grating is 383.9 ± 56.2 km s-1 and the Lyα 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 Lyα 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])/Hβ 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- ³), which exhibits similar photometry to that of JADES-GS-z7-LA, with a photometric excess in the F410M NIRCam image consistent with [O- ¯III] + Hβ 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 107† M·. Assuming that the Lyα 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 Lyα 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 Lyα 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.
AB - We report the discovery of a remarkable Lyα emitting galaxy at z = 7.2782, JADES-GS+53.16746-27.7720 (shortened to JADES-GS-z7-LA), with rest-frame equivalent width, EW0(Lyα) = 388.0 ± 88.8 Å and UV magnitude -17.0. The spectroscopic redshift is confirmed via rest-frame optical lines [O- ¯II], Hβ and [O- ¯III] in its JWST/NIRSpec Micro-Shutter Assembly (MSA) spectrum. The Lyα line is detected in both lower resolution (R ∼ 100) PRISM as well as medium resolution (R ∼ 1000) G140M grating spectra. The line spread function-deconvolved Lyα full width at half maximum in the grating is 383.9 ± 56.2 km s-1 and the Lyα 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 Lyα 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])/Hβ 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- ³), which exhibits similar photometry to that of JADES-GS-z7-LA, with a photometric excess in the F410M NIRCam image consistent with [O- ¯III] + Hβ 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 107† M·. Assuming that the Lyα 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 Lyα 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 Lyα 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.
KW - Dark ages
KW - First stars
KW - Galaxies: evolution
KW - Galaxies: high-redshift
KW - Galaxies: star formation
KW - Reionization
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U2 - 10.1051/0004-6361/202346245
DO - 10.1051/0004-6361/202346245
M3 - Article
AN - SCOPUS:85172403744
SN - 0004-6361
VL - 678
JO - Astronomy and astrophysics
JF - Astronomy and astrophysics
M1 - A68
ER -