Based on Data Collected at Subaru Telescope and in Part Obtained from Data Archive at Astronomical Data Analysis Center, Which Are Operated by the National Astronomical Observatory of Japan

We present the results of an intermediate resolution (∼ 2 Å) spectroscopy of a sample of 37 candidate Lyα blobs and emitters at redshift z = 3.1 using the DEIMOS spectrograph on the 10 m Keck telescope. The emission lines are detected for all the 37 objects and have variety in their line profiles. The Lyα velocity widths (FWHM) of the 28 objects with higher quality spectra, measured by fitting a single Gaussian profile, are in the range of 150 − 1700 km s and correlate with the Lyα spatial extents. All the 12 Lyα blobs (≥ 16 arcsec) have large velocity widths of & 500 km s. While there are several possible physical interpretations of the Lyα velocity widths (motion of gravitationallybound gas clouds, inflows, merging of clumps, or outflows from superwinds), the large velocity widths of the Lyα blobs suggest that they are the sites of massive galaxy formation. If we assume gravitationally-bound gas clouds, the dynamical masses of the Lyα blobs are estimated to be ∼ 10−10 M⊙. Even for the case of outflows, the outflow velocities are likely to be the same order of the rotation velocities as inferred from the observational evidence for local starburst galaxies. Subject headings: cosmology: observations — galaxies: evolution — galaxies: formation — galaxies: high-redshift — galaxies: starburst The data presented herein were obtained at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W.M. Keck Foundation. Based on data collected at Subaru Telescope and in part obtained from data archive at Astronomical Data Analysis Center, which are operated by the National Astronomical Observatory of Japan. Department of Astronomy, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan; [email protected] National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588, Japan; [email protected] Research Center for Neutrino Science, Graduate School of Science, Tohoku University, Aramaki, Aoba, Sendai 980-8578, Japan; [email protected]; [email protected]; [email protected]