On the sizes of ionized bubbles around the highest redshift galaxies. Spectral shapes of the Lyman-alpha emission from galaxies

Understand

We develop a new method to determine the distance between a high-redshift galaxy and a foreground screen of atomic hydrogen.

• In a partially neutral universe, and assuming spherical symmetry, this equates to the radius of a ionized 'bubble' (R_B) surrounding the galaxy.
• The method requires an observed Lya equivalent width, its velocity offset from systemic, and an input Lya profile for which we adopt scaled versions of the profiles observed in low-z galaxies.
• We demonstrate the technique in a sample of 23 galaxies at z > 6, including eight at z = 7.2 - 10.6 recently observed with JWST.