Lyman Continuum emission in the youngest galaxies: the role of X-ray binaries and Low Luminosity AGN.

Lyman continuum (LyC) radiation produced in starbursts in the youngest galaxies is thought to be responsible for re-ionizing the universe at high redshift. However, LyC is strongly absorbed by interstellar material leading to the suggestion that mechanical feedback from stellar winds and supernovae must “blow away” the intervening material to allow the LyC to escape. Recent observations of nearby LyC analog galaxies — low metallicity star bursting dwarfs that resemble the first galaxies — suggests that accretion sources are also important sources of feedback. In this talk, I focus on X-ray observations of two nearby LyC analog galaxies. Haro 11 has two bright X-ray clumps that are best modeled as an ensemble of two or more unresolved X-ray sources. All the unresolved sources show evidence for variability on a timescale of years. In contrast, an X-ray source in the LyC galaxy Tol 0440-381 shows dramatic evidence for variability on a timescale of days, suggesting a single source. Taken together, these observations suggest that X-ray binaries and/or Low Luminosity AGN are an important contributor to the mechanical feedback in these galaxies, and by extension the high redshift universe.