Chorus. III. Photometric and spectroscopic properties of Lyα blobs at z = 4.9 − 7.0

We report the Subaru Hyper Suprime-Cam (HSC) discovery of two Lyα blobs (LABs), dubbed z70-1 and z49-1 at z = 6.965 and z = 4.888 respectively, that are Lyα emitters with a bright (log L_Lyα/[erg s⁻¹] > 43.4) and spatially-extended Lyα emission, and present the photometric and spectroscopic properties of a total of seven LABs; the two new LABs and five previously-known LABs at z = 5.7 − 6.6. The z70-1 LAB shows the extended Lyα emission with a scale length of 1.4 ± 0.2 kpc, about three times larger than the UV continuum emission, making z70-1 the most distant LAB identified to date. All of the 7 LABs, except z49-1, exhibit no AGN signatures such as X-ray emission, Nvλ1240 emission, or Lyα line broadening, while z49-1 has a strong Civλ1548 emission line indicating an AGN on the basis of the UV-line ratio diagnostics. We carefully model the point-spread functions of the HSC images, and conduct two-component exponential profile fitting to the extended Lyα emission of the LABs. The Lyα scale lengths of the core (star-forming region) and the halo components are r_c = 0.6 − 1.2 kpc and r_h = 2.0 − 13.8 kpc, respectively. The average r_h of the LABs falls on the extrapolation of the r_h-Lyα luminosity relation of the Lyα halos around VLT/MUSE star-forming galaxies at the similar redshifts, suggesting that typical LABs at z ≳ 5 are not special objects, but star-forming galaxies at the bright end.