2024/01/10 by Christopher Snapp-Kolas, Brian Siana, Snapp-Kolas, Christopher +11 · 1 citation
Engineering · Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics of Galaxies (astro-ph.GA) #FOS: Physical sciences #Galaxies: Formation, Evolution, Phenomena #Semiconductor Lasers and Optical Devices
paper · pdf · doi:10.48550/arxiv.2401.05498
openalex publication_date 2024/01/10 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Rest-UV spectroscopy can constrain properties of the stellar populations, outflows, covering fractions, and can indirectly constrain the Lyman continuum escape fraction of galaxies. Many works have studied the rest-UV spectra of more massive star forming galaxies and low-mass galaxies selected via strong nebular line emission or via Lyα emission. However, studies of rest-UV spectroscopy have yet to be done on an unbiased sample at low mass during the epoch of peak star formation (z∼2). We present a stacked rest-UV spectrum of a complete sample of 16 dwarf galaxies (\rm ⟨ log(M^*/M_\odot)⟩median = 8.2) at z∼2. The rest-UV Keck/LRIS spectroscopy is complemented by rest-optical Keck/MOSFIRE spectroscopy and Hubble photometry. We find generally larger Lyα equivalent widths (\rm EWLyα = 11.2 Å) when compared with higher mass (\rm ⟨ log(M^*/M_\odot)⟩median = 10.3) composites from KBSS (\rm EWLyα = -5 Å). The average low- and high-ionization absorption line EWs (\rm EWLIS and \rm EWHIS, respectively) are weaker (\rm EWLIS=-1.18 Å, \rm EWHIS=-0.99 Å) in dwarf galaxies than in higher mass galaxies (\rm EWLIS=-2.04 Å, \rm EWHIS=-1.42 Å). The LIS absorption lines are optically thick and is thus a good tracer of the neutral hydrogen covering fraction. Both higher \rm EWLyα and lower \rm EWLIS measurements imply that the escape fraction of ionizing radiation is larger in lower-mass galaxies at z∼2.