Browsing by Author "Cheng, Cheng"

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    CO (7-6), [C I] 370 mu m, and [N II] 205 mu m Line Emission of the QSO BRI1335-0417 at Redshift 4.407
    (2018) Lu, Nanyao; Cao, Tianwen; Diaz-Santos, Tanio; Zhao, Yinghe; Privon, George C.; Cheng, Cheng; Gao, Yu; Xu, C. Kevin; Charmandaris, Vassilis; Rigopoulou, Dimitra; Van der Werf, Paul P.; Huang, Jiasheng; Wang, Zhong; Evans, Aaron S.; Sanders, David B.
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    Ionized and Cold Gas Components in Low Surface Brightness Galaxy AGC 102004
    (2024) Cao, Tian-Wen; Li, Zi-Jian; Chen, Pei-Bin; Zhang, Chun-Yi; Galaz, Gaspar; Cheng, Cheng; Yu, Qingzheng; Kalari, Venu M.; Wang, Junfeng; Wu, Hong
    We present the integral field spectroscopic observations of ionized gas (H alpha and [N II]) using the PCWI, along with deep CO(2-1) observations by the '(U) over bar'(u) over bar receiver on JCMT for AGC 102004. The velocity field of H alpha shows an anomalous distribution in the northwestern (NW) disk. The H alpha spectrum is well-fitted by two Gaussian components, and the weak Gaussian component is dominated by the anomalous H alpha in the NW disk. The Gaussian fit center of H alpha emission is offset by +24.2 km s(-1) from the systemic velocity obtained from the H i emission. We derive the gas-phase metallicity, 12+log(O/H), using [N II]lambda 6583/H alpha ratio as a proxy. The mean value of 12+log(O/H) is 8.30 +/- 0.19 over the whole galaxy. The metallicity in the outer disk is lower than the detection limit of 7.72, indicating the metallicity gradient exists in AGC 102004. We speculate a minor/mini-merger event could have happened to the NW disk. CO(2-1) emission has nondetection in AGC 102004, reaching a noise level of 0.33 mK smoothed to 30 km s(-1). The upper limit of molecular gas mass in AGC 102004 is 2.1 x 107 M-circle dot with X-CO = 3.02 x 1020 cm(-2) (K km s(-1))(-1). The MH2 /M-HI(corr) of AGC 102004 is lower than 0.0037 and lower than that of normal galaxies.