Programme by Session

I will present deep MUSE observations of five quasars within the first Gyr of the Universe, four of which display extended Lya halos. Until recently, the cool gas that fuels the growth of the first quasars and galaxies has evaded direct detection, however this picture is beginning to change. With large-area IFUs such as MUSE facilitating the detection of diffuse Lya emission, we can now directly probe the CGM in emission. After careful PSF-subtraction, we reveal halos surrounding two z~6 quasars for the first time, and confirm two more nebulae for which tentative halo detections exist in long-slit spectroscopy and narrow-band imaging. The four Lya nebulae presented here are diverse in morphology and size, they each display spatial asymmetry, and none are centred on the position of the quasar. Spectra of the diffuse emission regions demonstrate that none are dramatically offset in velocity from the systemic redshift of the quasars (∆v 200 kms-1), however each nebula shows a broad Lya line, with a velocity width 1000 kms-1, indicating that the quasar is effecting some fraction of the Lyα emission. Total Lyα luminosities range between ~2x10^43 erg s-1 and ~2x10^44 erg s-1, reaching maximum extents of 27 - 60 pkpc from the quasar positions. As we enter the regime where IFU data circumvent filter- and slit-losses, we find larger sizes and higher Lya luminosities than previous results, and reconsider our understanding of the evolution of halo properties over cosmic time.