The Lyman $\alpha$ Reference Sample XIV: Lyman $\alpha$ imaging of 45 low redshift star-forming galaxies and inferences on global emission
| Autor: | Melinder, Jens, Östlin, Göran, Hayes, Matthew, Rasekh, Armin, Mas-Hesse, J. Miguel, Cannon, John M., Kunth, Daniel, Laursen, Peter, Runnholm, Axel, Herenz, E. Christian, Messa, Matteo, Schaerer, Daniel, Verhamme, Anne, Rivera-Thorsen, T. Emil, Guaita, Lucia, Marquart, Thomas, Puschnig, Johannes, Reste, Alexandra Le, Sandberg, Andreas, Freeland, Emily, Bridge, Joanna |
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| Rok vydání: | 2023 |
| Předmět: | |
| Druh dokumentu: | Working Paper |
| DOI: | 10.3847/1538-4365/acc2b8 |
| Popis: | We present Ly $\alpha$ 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 far-ultraviolet (FUV) luminosity and \ha equivalent width criteria, but no constraints on Ly $\alpha$ luminosity. We employ a pixel stellar continuum fitting code to obtain accurate continuum subtracted Ly $\alpha$, H $\alpha$ and H $\beta$ maps. We find that Ly $\alpha$ is less concentrated than FUV and optical line emission in almost all galaxies with significant Ly $\alpha$ emission. We present global measurements of Ly $\alpha$ and other quantities measured in apertures designed to capture all of the Ly $\alpha$ emission. We then show how the escape fraction of Ly $\alpha$ relates to a number of other measured quantities (mass, metallicity, star formation, ionisation parameter, and extinction). We find that the escape fraction is strongly anti-correlated with nebular and stellar extinction, weakly anti-correlated with stellar mass, but no conclusive evidence for correlations with other quantities. We show that Ly $\alpha$ 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 Ly $\alpha$ luminosity, where the equivalent width of Ly $\alpha$ is used to correct for non-unity escape fraction, and show that this relation provides a reasonably accurate SFR estimate. We also show stacked growth curves of Ly $\alpha$ for the galaxies that can be used to find aperture loss fractions at a given physical radius. Comment: 48 pages, 21 figures, accepted for publication in The Astrophysical Journal Supplement Series. Multipanel figures for all 45 galaxies will be available in the online version of the published paper (and here: https://stockholmuniversity.box.com/s/ghvnvjyhxts64hpbqh90uwcj5dlczlhm ). Data products will be available as a MAST HLSP soon (placeholder DOI: 10.17909/pbe1-m743) |
| Databáze: | arXiv |
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