SIMBAD references

The early stage in the formation of a galaxy inevitably involves a spatially extended distribution of infalling, cold gas. If a central luminous quasar turned on during this phase, it would result in significant extended Lyα emission, possibly accompanied by other lines. For halos condensing at redshifts 3≲z≲8 and having virial temperatures 2x10⁵ K≲T_vir≲2x10⁶ K, this emission results in a ``fuzz'' of characteristic angular diameter of a few arcseconds and surface brightness ∼10^–18 to 10^–16 ergs.s^–1.cm^–2 arcsec^–2. The fuzz around bright, high-redshift quasars could be detected in deep narrowband imaging with current telescopes, providing a direct constraint on galaxy formation models. The absence of detectable fuzz might suggest that most of the protogalaxy's gas settles to a self-gravitating disk before a quasar turns on. However, continued gas infall from large radii, or an on-going merger spreading cold gas over a large solid angle, during the luminous quasar phase could also result in extended Lyα emission, and can be constrained by deep narrowband imaging.