CHORUS. III. Photometric and Spectroscopic Properties of Ly$\alpha$
  Blobs at $z=4.9-7.0$
  We report the Subaru Hyper Suprime-Cam (HSC) discovery of two Ly$\alpha$
blobs (LABs), dubbed z70-1 and z49-1 at $z=6.965$ and $z=4.888$ respectively,
that are Ly$\alpha$ emitters with a bright ($\log L_{\rm Ly\alpha}/{\rm [erg\
s^{-1}]}>43.4$) and spatially-extended Ly$\alpha$ 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 Ly$\alpha$ emission with a scale length of $1.4\pm 0.2$ 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, {\sc Nv}$\lambda$1240 emission, or
Ly$\alpha$ line broadening, while z49-1 has a strong {\sc Civ}$\lambda$1548
emission line indicating an AGN on the basis of the UV-line ratio diagnostics.
We carefully model the point-spread functions of the HSC images, and conduct
two-component exponential profile fitting to the extended Ly$\alpha$ emission
of the LABs. The Ly$\alpha$ scale lengths of the core (star-forming region) and
the halo components are $r_{\rm c}=0.6-1.2$ kpc and $r_{\rm h}=2.0-13.8$ kpc,
respectively. The average $r_{\rm h}$ of the LABs falls on the extrapolation of
the $r_{\rm h}$-Ly$\alpha$ luminosity relation of the Ly$\alpha$ halos around
VLT/MUSE star-forming galaxies at the similar redshifts, suggesting that
typical LABs at $z\gtrsim5$ are not special objects, but star-forming galaxies
at the bright end.
