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ALMA deep field in SSA22 : blindly detected CO emitters and [C ii] emitter candidates.

Hayatsu, N.H. and Matsuda, Y. and Umehata, H. and Yoshida, N. and Smail, I. and Swinbank, A.M. and Ivison, R. and Kohno, K. and Tamura, Y. and Kubo, M. and Iono, D. and Hatsukade, B. and Nakanishi, K. and Kawabe, R. and Nagao, T. and Inoue, A.K. and Takeuchi, T.T. and Lee, M. and Ao, Y. and Fujimoto, S. and Izumi, T. and Yamaguchi, Y. and Ikarashi, S. and Yamada, T. (2017) 'ALMA deep field in SSA22 : blindly detected CO emitters and [C ii] emitter candidates.', Publications of the Astronomical Society of Japan., 69 (3).


We report the identification of four millimeter line-emitting galaxies with the Atacama Large Milli/submillimeter Array (ALMA) in SSA22 Field (ADF22). We analyze the ALMA 1.1-mm survey data, with an effective survey area of 5 arcmin2, frequency ranges of 253.1–256.8 and 269.1–272.8 GHz, angular resolution of 0 ′′. .′′ 7 and rms noise of 0.8 mJy beam−1 at 36 km s−1 velocity resolution. We detect four line-emitter candidates with significance levels above 6σ. We identify one of the four sources as a CO(9–8) emitter at z = 3.1 in a member of the proto-cluster known in this field. Another line emitter with an optical counterpart is likely a CO(4–3) emitter at z = 0.7. The other two sources without any millimeter continuum or optical/near-infrared counterpart are likely to be [C II] emitter candidates at z = 6.0 and 6.5. The equivalent widths of the [C II] candidates are consistent with those of confirmed high-redshift [C II] emitters and candidates, and are a factor of 10 times larger than that of the CO(9–8) emitter detected in this search. The [C II] luminosity of the candidates are 4–7 × 108 L⊙. The star formation rates (SFRs) of these sources are estimated to be 10–20 M⊙ yr−1 if we adopt an empirical [C II] luminosity–SFR relation. One of them has a relatively low S/N ratio, but shows features characteristic of emission lines. Assuming that at least one of the two candidates is a [C II] emitter, we derive a lower limit of [C II]-based star formation rate density (SFRD) at z ∼ 6. The resulting value of >10−2 M⊙ yr−1 Mpc−3 is consistent with the dust-uncorrected UV-based SFRD. Future millimeter/submillimeter surveys can be used to detect a number of high-redshift line emitters, with which to study the star formation history in the early universe.

Item Type:Article
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Publisher statement:This is a pre-copyedited, author-produced version of an article accepted for publication in Publications of the Astronomical Society of Japan following peer review. The version of record Hayatsu, N.H., Matsuda, Y., Umehata, H., Yoshida, N., Smail, I., Swinbank, A.M., Ivison, R., Kohno, K., Tamura, Y., Kubo, M., Iono, D., Hatsukade, B., Nakanishi, K., Kawabe, R., Nagao, T., Inoue, A.K., Takeuchi, T.T., Lee, M., Ao, Y., Fujimoto, S., Izumi, T., Yamaguchi, Y., Ikarashi, S. & Yamada, T. (2017). ALMA deep field in SSA22: Blindly detected CO emitters and [C ii] emitter candidates. Publications of the Astronomical Society of Japan 69(3): 45 is available online at:
Date accepted:24 February 2017
Date deposited:29 August 2017
Date of first online publication:04 May 2017
Date first made open access:04 May 2018

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