We report the serendipitous discoveries of companion galaxies to two high-redshift quasars .
SDSS J025617.7+001904 is a z = 4.79 quasar included in our recent survey of faint quasars in the SDSS Stripe 82 region .
The initial MMT slit spectroscopy shows excess Ly \alpha emission extending well beyond the quasar ’ s light profile .
Further imaging and spectroscopy with LBT/MODS1 confirms the presence of a bright galaxy ( i _ { AB } = 23.6 ) located 2″ ( 12 kpc projected ) from the quasar with strong Ly \alpha emission ( EW _ { 0 } \approx 100 Å ) at the redshift of the quasar , as well as faint continuum .
The second quasar , CFHQS J005006.6+344522 ( z = 6.25 ) , is included in our recent HST SNAP survey of z \sim 6 quasars searching for evidence of gravitational lensing .
Deep imaging with ACS and WFC3 confirms an optical dropout \sim 4.5 mag fainter than the quasar ( Y _ { AB } = 25 ) at a separation of 0.9″ .
The red i _ { 775 } - Y _ { 105 } color of the galaxy and its proximity to the quasar ( 5 kpc projected if at the quasar redshift ) strongly favor an association with the quasar .
Although it is much fainter than the quasar it is remarkably bright when compared to field galaxies at this redshift , while showing no evidence for lensing .
Both systems may represent late-stage mergers of two massive galaxies , with the observed light for one dominated by powerful ongoing star formation and for the other by rapid black hole growth .
Observations of close companions are rare ; if major mergers are primarily responsible for high-redshift quasar fueling then the phase when progenitor galaxies can be observed as bright companions is relatively short .