Vol. 587
In section 4. Extragalactic astronomy

Extended Lyman alpha haloes around individual high-redshift galaxies revealed by MUSE

The new integrated field spectrograph MUSE on the ESO-VLT has produced an ultradeep exposure of the Hubble Deep Field South with an order of magnitude improvement over previous narrowband imaging. On a sample of 26 Ly alpha-emitting objects at redshifts z = 3-6, 21 show an extended halo of Ly alpha emission around the central star-forming region. The Ly alpha halo has an exponential shape with a few kpc in scale length, and it extends farther than the UV continuum light. The z=1-3 Ly alpha halo size is about 5 times larger than analogs at z=0, and they correspond to 40% to 90% of the total observed Ly alpha flux.