Gespeichert in:
| Hauptverfasser: | , , , , , , |
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| Format: | Preprint |
| Veröffentlicht: |
2024
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| Schlagworte: | |
| Online-Zugang: | https://arxiv.org/abs/2401.05498 |
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Inhaltsangabe:
- 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 Ly$α$ 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 ($z\sim2$). We present a stacked rest-UV spectrum of a complete sample of 16 dwarf galaxies ($\rm \langle log(M^*/M_\odot)\rangle_{median} = 8.2$) at $z\sim2$. The rest-UV Keck/LRIS spectroscopy is complemented by rest-optical Keck/MOSFIRE spectroscopy and Hubble photometry. We find generally larger Ly$α$ equivalent widths ($\rm EW_{Lyα} = 11.2\;$Å) when compared with higher mass ($\rm \langle log(M^*/M_\odot)\rangle_{median} = 10.3$) composites from KBSS ($\rm EW_{Lyα} = -5\;$Å). The average low- and high-ionization absorption line EWs ($\rm EW_{LIS}$ and $\rm EW_{HIS}$, respectively) are weaker ($\rm EW_{LIS}$=-1.18 Å, $\rm EW_{HIS}=$-0.99 Å) in dwarf galaxies than in higher mass galaxies ($\rm EW_{LIS}$=-2.04 Å, $\rm EW_{HIS}=$-1.42 Å). The LIS absorption lines are optically thick and is thus a good tracer of the neutral hydrogen covering fraction. Both higher $\rm EW_{Lyα}$ and lower $\rm EW_{LIS}$ measurements imply that the escape fraction of ionizing radiation is larger in lower-mass galaxies at $z\sim2$.