2019/05/23 by Haibin Zhang, Masami Ouchi, Ryohei Itoh +20 · 1 citation
Physics and Astronomy · #astro-ph.GA
paper · pdf · doi:10.3847/1538-4357/ab7917
Submitted to ApJ
arxiv created 2019/05/23 · arxiv updated 2020/03/25
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\rm Lyα/\rm [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, \sc Nvλ1240 emission, or Lyα line broadening, while z49-1 has a strong \sc 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\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-Lyα luminosity relation of the Lyα 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.