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

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 (f _{H I} ≡ M _{H I}/M _⋆) of Green Pea galaxies follows the existing scaling relations between the f _{H 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 M _{H I}/M _⋆ of 38 Green Pea galaxies, including 17 detections and 21 non-detections. The H I to stellar mass ratios (f _{H 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 $-0.34(\mathrm{NUV}-r)-0.64\mathrm{log}({\mu }_{\star ,z})$ +5.9 and $-0.77\mathrm{log}{\mu }_{\star ,i}+0.26\mathrm{logSFR}/{M}_{\star }+8.53$ , 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.