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

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We report the discovery of a remarkable Ly$\alpha$ emitting galaxy at z = 7.2782, JADES-GS-z7-LA, with EW$_0$(Ly$\alpha$) $= 388.0 \pm 88.8$\AA and UV magnitude -17.0.

• The spectroscopic redshift is confirmed via rest-frame optical lines [O II], H$\beta$ and [O III] in its JWST/NIRSpec Micro-Shutter Assembly (MSA) spectrum.
• The Ly$\alpha$ line is detected in both lower resolution PRISM as well as medium resolution G140M grating spectra.
• The LSF-deconvolved Ly$\alpha$ FWHM in the grating is $383.9 \pm 56.2$ km/s and the Ly$\alpha$ velocity offset compared to the systemic redshift is $113.3 \pm 80.0$ km/s, indicative of very little neutral gas or dust within the galaxy.