Lyman alpha escape from 45 star forming galaxies– the Lyα Reference Sample XIV

• We present Lyα imaging of 45 low redshift star-forming galaxies observed with the Hubble space telescope. The galaxies have been selected to have moderate to high star formation rates using FUVluminosity and Hα equivalent width criteria, but no constraints on Lyα luminosity have been applied. We employ a pixel SED fitting code to obtain accurate continuum subtracted Lyα, Hα and Hβ maps. We find that Lyα is less concentrated than FUV and optical line emission in almost all galaxies with significant Lyα emission. We present global measurements of Lyα and other quantities measured in apertures designed to capture all of the Lyα emission. We then show how the escape fraction ofLyα relates to a number of other measured quantities (mass, metallicity, star formation, ionization parameter, and extinction). We find that the escape fraction is strongly anti-correlated with both nebular and stellar extinction, weakly anti-correlated with stellar mass, but no conclusive evidence for correlations to other quantities. We show that Lyα escape fractions are inconsistent with common dust extinction laws and discuss how a combination of radiative transfer effects and clumpy dust models can help resolve the discrepancies. We present a star formation rate calibration based on Lyαluminosity, where the equivalent width of Lyα is used to correct for non-unity escape fraction, and show that this relation provides a reasonably accurate calibration but with a large scatter. We also show stacked growth curves of Lyα for the galaxies that can be used to find aperture loss fractions at a given physical radius

Ämnesord

NATURVETENSKAP  -- Fysik -- Astronomi, astrofysik och kosmologi (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Astronomy, Astrophysics and Cosmology (hsv//eng)

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