Updated Measurements of [O iii] 88 μm, [C ii] 158 μm, and Dust Continuum Emission from a z = 7.2 Galaxy
Yi W. Ren, Yoshinobu Fudamoto, Akio Inoue, Yuma Sugahara, Tsuyoshi Tokuoka, Yoichi Tamura, Hiroshi Matsuo, Kotaro Kohno, Hideki Umehata, Takuya Hashimoto, R. J. Bouwens, Renske Smit, Nobunari Kashikawa, Takashi Okamoto, Takatoshi Shibuya, Ikkoh Shimizu
Abstract
Abstract We present updated measurements of the [O iii ] 88 μ m, [C ii ] 158 μ m, and dust continuum emission from a star-forming galaxy at z = 7.212, SXDF-NB1006-2, by utilizing Atacama Large Millimeter/submillimeter Array (ALMA) archival data sets analysed in previous studies and data sets that have not been analysed before. The follow-up ALMA observations with higher angular resolution and sensitivity reveal a clumpy structure of the [O iii ] emission on a scale of 0.32–0.85 kpc. We also combined all the ALMA [O iii ] ([C ii ]) data sets and updated the [O iii ] ([C ii ]) detection to 5.9 σ (3.6 σ –4.5 σ ). The non-detection of [C ii ] with data from the REBELS large program implies the incompleteness of spectral-scan surveys using [C ii ] to detect galaxies with high star formation rates (SFRs) but marginal [C ii ] emission at high- z . The dust continuum at 90 and 160 μ m remains undetected, indicating little dust content of <3.9 × 10 6 M ⊙ (3 σ ), and we obtained a more stringent constraint on the total infrared luminosity. We updated the [O iii ]/[C ii ] luminosity ratios to 10.2 ± 4.7 (6.1 ± 3.5) and 20 ± 12 (9.6 ± 6.1) for the 4.5 σ and 3.6 σ [C ii ] detections, respectively, where the ratios in the parentheses are corrected for the surface brightness dimming effect on the extended [C ii ] emission. We also found a strong [C ii ] deficit (0.6–1.3 dex) between SXDF-NB1006-2 and the mean L [C II ] −SFR relation of galaxies at 0 < z < 9.