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We search for extended Ly-alpha emission around two z>6 quasars, SDSSJ1030+0524 (z=6.309) and SDSS J1148+5251 (z=6.419) using WFC3 narrow-bandfilters on board the Hubble Space Telescope. For each quasar, we collected twodeep, narrow-band images, one sampling the Ly-alpha line+continuum at thequasar redshifts and one of the continuum emission redwards of the line. Aftercarefully modeling the Point Spread Function, we find no evidence for extendedLy-alpha emission. These observations set 2-sigma limits of L(Ly-alpha,extended) < 3.2 x 10^{44} erg/s for J1030+0524 and L(Ly-alpha, extended) < 2.5x 10^{44} erg/s for J1148+5251. Given the star formation rates typicallyinferred from (rest-frame) far-infrared measurements of z~6 quasars, theselimits are well below the intrinsic bright Ly-alpha emission expected from therecombination of gas photoionized by the quasars or by the star formation inthe host galaxies, and point towards significant Ly-alpha suppression or dustattenuation. However, small extinction values have been observed along the lineof sight to the nuclei, thus reddening has to be coupled with other mechanismsfor Ly-alpha suppression (e.g., resonance scattering). No Ly-alpha emittingcompanions are found, down to a 5-sigma sensitivity of ~ 1 x 10^{-17}erg/s/cm^2/arcsec^2 (surface brightness) and ~ 5 x 10^{-17} erg/s/cm^2(assuming point sources).

HST narrow-band search for extended Ly-alpha emission around two z>6 quasars