2021ApJ...913L..15K

We have used the Arecibo Telescope and the Green Bank Telescope (GBT) to carry out a deep search for HI 21 cm emission from a large sample of "Green Pea" galaxies, yielding 19 detections, and 21 upper limits on the HI mass. We obtain HI masses of M_HI ≃ (4-300) x 10⁸ M_☉ for the detections, with a median HI mass of ≃ 2.6 x 10⁹ M_☉; for the non-detections, the median 3σ upper limit on the HI mass is ≃ 5.5 x 10⁸ M_☉. These are the first estimates of the atomic gas content of Green Pea galaxies. We find that the HI-to-stellar mass ratio in Green Peas is consistent with trends identified in star-forming galaxies in the local universe. However, the median HI depletion timescale in Green Peas is ≃0.6 Gyr, an order of magnitude lower than that obtained in local star-forming galaxies. This implies that Green Peas consume their atomic gas on very short timescales. A significant fraction of the Green Peas of our sample lie >=0.6 dex (2σ) above the local M_HI-M_B relation, suggesting recent gas accretion. Further, ≃30% of the Green Peas are more than ±2σ deviant from this relation, suggesting possible bimodality in the Green Pea population. We obtain a low HI 21 cm detection rate in the Green Peas with the highest O32 ≡ [O III]λ5007/[O II]λ3727 luminosity ratios, O32 > 10, consistent with the high expected Lyman-continuum leakage from these galaxies.