%0 Generic %1 ciardullo2014emission %A Ciardullo, Robin %A Zeimann, Gregory %A Gronwall, Caryl %A Gebhardt, Henry %A Schneider, Donald P. %A Hagen, Alex %A Malz, A. I. %A Blanc, Guillermo A. %A Hill, Gary J. %A Drory, Niv %A Gawiser, Eric %D 2014 %K escape fraction high-z lya observation %T HST Emission Line Galaxies at z ~ 2: The Ly-alpha Escape Fraction %U http://arxiv.org/abs/1409.8304 %X We compare the H-beta line strengths of 1.90 < z < 2.35 star-forming galaxies observed with the near-IR grism of the Hubble Space Telescope with ground-based measurements of Ly-alpha from the HETDEX Pilot Survey and narrow-band imaging. By examining the line ratios of 73 galaxies, we show that most star-forming systems at this epoch have a Ly-alpha escape fraction below ~6%. We confirm this result by using stellar reddening to estimate the effective logarithmic extinction of the H-beta emission line (c_Hbeta = 0.5) and measuring both the H-beta and Ly-alpha luminosity functions in a ~ 100,000 cubic Mpc volume of space. We show that in our redshift window, the volumetric Ly-alpha escape fraction is at most 4.4+/-2.1(1.2)%, with an additional systematic ~25% uncertainty associated with our estimate of extinction. Finally, we demonstrate that the bulk of the epoch's star-forming galaxies have Ly-alpha emission line optical depths that are significantly greater than that for the underlying UV continuum. In our predominantly O~III 5007-selected sample of galaxies, resonant scattering must be important for the escape of Ly-alpha photons.

@misc{ciardullo2014emission, abstract = {We compare the H-beta line strengths of 1.90 < z < 2.35 star-forming galaxies observed with the near-IR grism of the Hubble Space Telescope with ground-based measurements of Ly-alpha from the HETDEX Pilot Survey and narrow-band imaging. By examining the line ratios of 73 galaxies, we show that most star-forming systems at this epoch have a Ly-alpha escape fraction below ~6%. We confirm this result by using stellar reddening to estimate the effective logarithmic extinction of the H-beta emission line (c_Hbeta = 0.5) and measuring both the H-beta and Ly-alpha luminosity functions in a ~ 100,000 cubic Mpc volume of space. We show that in our redshift window, the volumetric Ly-alpha escape fraction is at most 4.4+/-2.1(1.2)%, with an additional systematic ~25% uncertainty associated with our estimate of extinction. Finally, we demonstrate that the bulk of the epoch's star-forming galaxies have Ly-alpha emission line optical depths that are significantly greater than that for the underlying UV continuum. In our predominantly [O~III] 5007-selected sample of galaxies, resonant scattering must be important for the escape of Ly-alpha photons.}, added-at = {2014-10-01T09:53:23.000+0200}, author = {Ciardullo, Robin and Zeimann, Gregory and Gronwall, Caryl and Gebhardt, Henry and Schneider, Donald P. and Hagen, Alex and Malz, A. I. and Blanc, Guillermo A. and Hill, Gary J. and Drory, Niv and Gawiser, Eric}, biburl = {https://www.bibsonomy.org/bibtex/2758f59c77c469764a4538588da1c3e05/miki}, description = {[1409.8304] HST Emission Line Galaxies at z ~ 2: The Ly-alpha Escape Fraction}, interhash = {24beb746cf4189bd968551cc4765f6f3}, intrahash = {758f59c77c469764a4538588da1c3e05}, keywords = {escape fraction high-z lya observation}, note = {cite arxiv:1409.8304Comment: 14 pages, 3 figures, Accepted to ApJ}, timestamp = {2014-10-01T09:53:23.000+0200}, title = {HST Emission Line Galaxies at z ~ 2: The Ly-alpha Escape Fraction}, url = {http://arxiv.org/abs/1409.8304}, year = 2014 }