Detection of HI in Emission in the Lyman Alpha Emitting Galaxy Haro 11

TL;DR

This paper reports the first detection of HI 21 cm emission in the galaxy Haro 11, revealing its gas properties, starburst activity, and how it compares to other galaxies in terms of gas content and star formation efficiency.

Contribution

First robust detection of HI emission in Haro 11, providing detailed measurements of its gas content and insights into its starburst activity and gas depletion timescale.

Findings

Haro 11 contains approximately 5.1 x 10^8 solar masses of HI gas.

Haro 11 has a very low gas fraction and is HI deficient compared to similar galaxies.

Haro 11's starburst will deplete its gas supply in less than 0.2 Gyr.

Abstract

We present the first robust detection of HI 21 cm emission in the blue compact galaxy Haro 11 using the 100m Robert C. Byrd Green Bank Telescope (GBT). Haro 11 is a luminous blue compact galaxy with emission in both Lyman Alpha and the Lyman continuum. We detect (5.1 $\pm$ 0.7 $\times$10$^8$) M$_{\odot}$ of HI gas at an assumed distance of 88 Mpc, making this galaxy HI deficient compared to other local galaxies with similar optical properties. Given this small HI mass, Haro 11 has an elevated M$_{H2}$/M$_{HI}$ ratio and a very low gas fraction compared to most local galaxies, and contains twice as much mass in ionized hydrogen as in neutral hydrogen. The HI emission has a linewidth of 71 kms$^{-1}$ and is offset 60 kms$^{-1}$ redward of the optical line center. It is undergoing a starburst after a recent merger which has elevated the star formation rate, and will deplete the gas supply in $<$ 0.2 Gyr. Although this starburst has elevated the SFR compared to galaxies with similar HI masses and linewidths, Haro 11 matches a trend of lower gas fractions toward higher star formation rates and is below the general trend of increasing HI mass with increasing luminosity. Taken together, our results paint Haro 11 as a standard low-mass galaxy that is undergoing an unusually efficient star formation episode.