%0 Journal Article %T Lyman Break Galaxies at z~5: Rest-Frame UV Spectra. III %A Hiroki Kajino %A Kouji Ohta %A Ikuru Iwata %A Kiyoto Yabe %A Suraphong Yuma %A Masayuki Akiyama %A Naoyuki Tamura %A Kentaro Aoki %A Marcin Sawicki %J Physics %D 2009 %I arXiv %R 10.1088/0004-637X/704/1/117 %X We present results of optical spectroscopic observations of candidates of Lyman Break Galaxies (LBGs) at $z \sim 5$ in the region including the GOODS-N and the J0053+1234 region by using GMOS-N and GMOS-S, respectively. Among 25 candidates, five objects are identified to be at $z \sim 5$ (two of them were already identified by an earlier study) and one object very close to the color-selection window turned out to be a foreground galaxy. With this spectroscopically identified sample and those from previous studies, we derived the lower limits on the number density of bright ($M_{UV}<-22.0$ mag) LBGs at $z \sim 5$. These lower limits are comparable to or slightly smaller than the number densities of UV luminosity functions (UVLFs) that show the smaller number density among $z \sim 5$ UVLFs in literature. However, by considering that there remain many LBG candidates without spectroscopic observations, the number density of bright LBGs is expected to increase by a factor of two or more. The evidence for the deficiency of UV luminous LBGs with large Ly$\alpha$ equivalent widths was reinforced. We discuss possible causes for the deficiency and prefer the interpretation of dust absorption. %U http://arxiv.org/abs/0908.1646v1