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

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

Research output: Contribution to journalArticlepeer-review


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 () at this redshift. The fraction of dwarf galaxies identified as Ly α emitters (Å) is. 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 (MUV > -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 in agreement with measurements found elsewhere in the literature. 60 per cent of the total integrated Ly α luminosity density comes from galaxies with EWobs > 20 Å.

Original languageEnglish (US)
Pages (from-to)5500-5511
Number of pages12
JournalMonthly Notices of the Royal Astronomical Society
Issue number4
StatePublished - Nov 1 2023


  • galaxies: evolution
  • galaxies: high-redshift

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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