Lyman-alpha Blobs Like Company : The Discovery of A Candidate 100 kpc
  Lyman-alpha Blob Near to A Radio Galaxy with A Giant Lyman-alpha halo, B3
  J2330+3927 at z=3.1
  We present the discovery of a candidate of giant radio-quiet Lyman-alpha
(Lya) blob (RQLAB) in a large-scale structure around a high-redshift radio
galaxy (HzRG) lying in a giant Lya halo, B3 J2330+3927 at redshift z=3.087. We
obtained Lya imaging around B3 J2330+3927 with Subaru/Suprime-Cam to search for
Lya emitters (LAEs) and absorbers (LAAs) at redshift z=3.09+-0.03. We detected
candidate 127 LAEs and 26 LAAs in the field of view of 31' x 24'. We found that
B3 J2330+3927 is surrounded by a 130 kpc Lya halo and a large-scale (60 x 20
comoving Mpc) filamentary structure. The large-scale structure contains one
prominent local density peak with an overdensity of greater than 5, which is 8'
(15 comoving Mpc) away from B3 J2330+3927. In this peak, we discovered a
candidate 100 kpc RQLAB. The existence of both types of Lya nebulae in the same
large-scale structure suggests that giant Lya nebulae need special large-scale
environments to form. On smaller scales, however, the location of B3 J2330+3927
is not a significant local density peak in this structure, in contrast to the
RQLAB. There are two possible interpretations of the difference of the local
environments of these two Lya nebulae. Firstly, RQLAB may need a prominent
(delta ~ 5) density peak of galaxies to form through intense star-bursts due to
frequent galaxy interactions/mergers and/or continuous gas accretion in an
overdense environment. On the other hand, Lya halo around HzRG may not always
need a prominent density peak to form if the surrounding Lya halo is mainly
powered by its radio and AGN activities. Alternatively, both RQLAB and Lya halo
around HzRG may need prominent density peaks to form but we could not
completely trace the density of galaxies because we missed evolved and dusty
galaxies in this survey.
