The origin of the observed Ly α EW distribution of dwarf galaxies at z 2

November 2023 • 2023MNRAS.525.5500S

Authors • Snapp-Kolas, Christopher • Siana, Brian • Gburek, Timothy • Alavi, Anahita • Emami, Najmeh • Richard, Johan • Stark, Daniel P. • Scarlata, Claudia • Lemaux, Brian C. • Zamorani, Giovanni • Bardelli, Sandro • Hathi, Nimish • Cassata, Paolo

Abstract • We present a rest-UV-selected sample of 32 lensed galaxies at z ~ 2 observed with joint Keck/LRIS rest-UV and Keck/MOSFIRE rest-optical spectra behind the clusters Abell 1689, MACS J0717, and MACS J1149. The sample pushes towards the faintest UV luminosities observed ($-19 \le {M_{\rm UV}} \le -17$) at this redshift. The fraction of dwarf galaxies identified as Ly α emitters ($\rm EW \ge 20$ Å) is ${X_{\rm LAE}}=33^{+17}_{-12}\,{\rm per\, cent}$. We use the Balmer lines and UV continuum to estimate both the intrinsic EW and the Ly α escape fraction to determine their relative importance in dictating the observed EW distribution. Fainter galaxies (M_UV > -19) show larger intrinsic EWs and escape fractions than brighter galaxies. Only galaxies with intrinsic EWs greater than 40 Å have escape fractions larger than 5 per cent. We find little to no anticorrelation between the escape fraction and dust in dwarf galaxies. The volumetric escape fraction of our sample is $f_{\rm esc}^{\rm Ly\alpha } = 4.6^{+2.0}_{-1.4}\,{\rm per\, cent}$ in agreement with measurements found elsewhere in the literature. 60 per cent of the total integrated Ly α luminosity density comes from galaxies with EW_obs > 20 Å.

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• SIMBAD http://simbad.u-strasbg.fr/simbo.pl?bibcode=2023MNRAS.525.5500S
• PDF https://academic.oup.com/mnras/pdf-lookup/doi/10.1093/mnras/stad2412
• PREPRINT http://arxiv.org/abs/2211.00041
• DATA https://archive.stsci.edu/mastbibref.php?bibcode=2023MNRAS.525.5500S
• DATA https://hst.esac.esa.int/ehst/#/pages/search;bibcode=2023MNRAS.525.5500S
• ELECTR https://doi.org/10.1093%2Fmnras%2Fstad2412