Median surface-brightness profiles of Lyman-<i>α</i> haloes in the MUSE Extremely Deep Field
Yucheng Guo, Roland Bacon, L. Wisotzki, Thibault Garel, J. Blaizot, Joop Schaye, Johan Richard, Yohana Herrero Alonso, Floriane Leclercq, Leindert Boogaard, Haruka Kusakabe, John Pharo, Eloïse Vitte
Abstract
We present the median surface brightness profiles of diffuse Ly α haloes (LAHs) around star-forming galaxies by stacking 155 spectroscopically confirmed Ly α emitters (LAEs) at 3 < z < 4 in the MUSE Extremely Deep Field (MXDF) with a median Ly α luminosity of L Ly α ≈ 10 41.1 erg s −1 . After correcting for a systematic surface brightness offset we identified in the data cube, we detect extended Ly α emission out to a distance of ≈270 kpc. The median Ly α surface-brightness profile shows a power-law decrease in the inner 20 kpc and a possible flattening trend at a greater distance. This shape is similar for LAEs with different Ly α luminosities, but the normalisation of the surface-brightness profile increases with luminosity. At distances over 50 kpc, we observe a strong overlap of adjacent LAHs, and the Ly α surface brightness is dominated by the LAHs of nearby LAEs. We find no clear evidence of redshift evolution of the observed Ly α profiles when comparing with samples at 4 < z < 5 and 5 < z < 6. Our results are consistent with a scenario in which the inner 20 kpc of the LAH is powered by star formation in the central galaxy, while the LAH beyond a radius of 50 kpc is dominated by photons from surrounding galaxies.