Green Pea Galaxies Eat Their Atomic Gas



Deep search observations using data from the Arecibo Observatory and the Green Bank Telescope reveal the atomic gas content of “Green Pea” galaxies for the first time. While Green Pea galaxies have similarities to other star-forming galaxies, they consume their atomic gas on very short timescales to fuel their intense star formation. + Read the GBT Press Release

The Atomic Gas Mass of Green Pea Galaxies

N. Kanekar, T. Ghosh, J. Rhoads, S. Malhotra, S. Harish, J. N. Chengalur, and K. M. Jones

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 MHi ≈ (4–300) × 108 M⊙ for the detections, with a median Hi mass of ≈ 2.6 × 109 M⊙; for the non-detections, the median 3σ upper limit on the Hi mass is ≈ 5.5 × 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 MHi–MB 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.
+ Read the Publication at the Astrophysical Journal

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Keywords: arecibo, observatory, green, pea, galaxy, north, astronomy, atomic, gas, Kanekar, ghosh, rhoads, malhotra, harish, chengalur, jones