NIR Narrow- and Broad-Band Study of the SSA 22 Field

Abstract

Abstract Deep narrow- and broad-band near-infrared imaging observations of the central $ {2{}^{\mathrm {\prime }}} \times {2{}^{\mathrm {\prime }}}$ region of the SSA 22 field were made with the near-infrared camera (CISCO) attached to the Subaru Telescope. Using a narrow-band filter centered at $2.033\, {\mu \mathrm {m}}$, [O III] $\lambda~5007$ emitters at $z \sim 3.06 \pm 0.02$ were searched to examine star-forming activities in an over-density region where a clustering of Lyman Break Galaxies (LBGs) and Lyman $ \alpha$ emitter candidates around $ z = 3.09$ was reported, though the targeted redshift is slightly different from that of the peak of the over-density region. Although one emitter candidate at $ z = 3.06$ was detected, it is likely to be located at a redshift of between 1 and 2 judged based on multi-band photometry. Another emission-line object was detected in another narrow-band filter (“off band” filter) centered at $ 2.120\, {\mu \mathrm {m}}$, which is identified with a galaxy at $ z = 0.132$ (the emission line is Paschen $\alpha$). The $ K^{\prime}$-band imaging data revealed the presence of 12 Extremely Red Objects (EROs) with $I_{814}-K^{\prime} \geq4$. The distribution of the EROs does not seem to coincide with that of Lyman Break Galaxies or Lyman $\alpha $ emitters at $ z \sim3$. The magnitudes and colors of the EROs are not consistent with those of passively evolving massive elliptical galaxies at $ z \sim3$. Candidates for counterparts of the submm sources detected with SCUBA are found; no EROs around the submm sources are found in our magnitude limit.