On the origin of Lyα blobs at high redshift:: Submillimetric evidence for a hyperwind galaxy at z=3.1

The most remarkable class of high-redshift objects observed so far is made up of extended Ly alpha emission-line blobs found in an overdensity region at a redshift of 3.1. They may be either a dust-enshrouded extreme starburst galaxy with a large-scale galactic outflow (superwind) or cooling radiation from dark matter halos. Recently one of these Ly alpha blobs has been detected at submillimeter wavelengths (450 and 850 mum). Here we show that its rest-frame spectral energy distribution between optical and far-infrared is quite similar to that of Arp 220, which is a typical ultraluminous starburst/superwind galaxy in the local universe. This suggests strongly that the superwind model proposed by Taniguchi & Shioya is applicable to this Ly alpha blob. Since the blob is more luminous in the infrared by a factor of 30 than Arp 220, it comprises a new population of hyperwind galaxies at high redshift.