Vol 23, No 6

The H i Gas Fraction Scaling Relation of the Green Pea Galaxies

Siqi Liu (刘思琦), A-Li Luo (罗阿理), Wei Zhang (张伟), Yan-Xia Zhang (张彦霞), Xiao Kong (孔啸) and Yong-Heng Zhao (赵永恒)

Abstract

Green Pea galaxies are compact galaxies with high star formation rates. However, limited samples of Green Pea galaxies have H i 21 cm measurements. Whether the H i gas fraction (fH I ≡ MH I/M) of Green Pea galaxies follows the existing scaling relations between the fH I and NUV-r color or linear combinations of color and other physical quantities needs checking. Using archival data of H i 21 cm observations, we investigate the scaling relation of the NUV-r color with the MH I/M of 38 Green Pea galaxies, including 17 detections and 21 non-detections. The H i to stellar mass ratios (fH I) of Green Pea galaxies deviate from the polynomial form, where a higher H i gas fraction is predicted given the current NUV-r color, even with the emission lines removed. The blue sources (NUV-r < 1) from the comparison sample (ALFALFA-SDSS) follow a similar trend. The H i gas fraction scaling relations with linear combination forms of \(-0.34({\rm NUV}-r)-0.64\log(\mu_{\star,z})\)+5.9 and \(-0.77\log\mu_{\star,i}_0.26\log{\rm SFR}/M_{\star}+8.53\), better predict the H i gas fraction of the Green Pea galaxies. In order to obtain accurate linear combined forms, higher-resolution photometry from space-based telescopes is needed.

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