1. The star formation burstiness and ionizing efficiency of low-mass galaxies
- Author
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Hakim Atek, Lukas J Furtak, Pascal Oesch, Pieter van Dokkum, Naveen Reddy, Thierry Contini, Garth Illingworth, Stephen Wilkins, Institut d'Astrophysique de Paris (IAP), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Institut de recherche en astrophysique et planétologie (IRAP), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), and Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)
- Subjects
dwarf [galaxies] ,FOS: Physical sciences ,Astrophysics::Cosmology and Extragalactic Astrophysics ,galaxies: high-redshift ,LYMAN-CONTINUUM ,SIMILAR-TO 2.5 ,evolution [galaxies] ,Astrophysics::Galaxy Astrophysics ,DUST ATTENUATION ,FORMING GALAXIES ,NEBULAR EMISSION ,Astronomy and Astrophysics ,HUBBLE-SPACE-TELESCOPE ,galaxies: dwarf ,Astrophysics - Astrophysics of Galaxies ,observations [cosmology] ,FORMATION RATES ,Space and Planetary Science ,[SDU]Sciences of the Universe [physics] ,Astrophysics of Galaxies (astro-ph.GA) ,cosmology: observations ,STELLAR MASS ,galaxies: evolution ,high-redshift [galaxies] ,PHOTON PRODUCTION EFFICIENCY ,COSMIC REIONIZATION - Abstract
We investigate the burstiness of star formation and the ionizing efficiency of a large sample of galaxies at $0.7 < z < 1.5$ using HST grism spectroscopy and deep ultraviolet (UV) imaging in the GOODS-N and GOODS-S fields. The star formation history (SFH) in these strong emission line low-mass galaxies indicates an elevated star formation rate (SFR) based on the H$\alpha$ emission line at a given stellar mass when compared to the standard main sequence. Moreover, when comparing the H$\alpha$ and UV SFR indicators, we find that an excess in SFR(H$\alpha$) compared to SFR(UV) is preferentially observed in lower-mass galaxies below $10^{9}$ M$\odot$, which are also the highest-EW galaxies. These findings suggest that the burstiness parameters of these strong emission line galaxies may differ from those inferred from hydrodynamical simulations and previous observations. For instance, a larger burstiness duty cycle would explain the observed SFR(H$\alpha$) excess. We also estimate the ionizing photon production efficiency $\xi_{ion}$, finding a median value of Log($\xi_{ion}$/erg$^{-1}$ Hz)$=24.80 \pm 0.26$ when adopting a Galactic dust correction for H$\alpha$ and an SMC one for the stellar component. We observe an increase of $\xi_{ion}$ with redshift, further confirming similar results at higher redshifts. We also find that $\xi_{ion}$ is strongly correlated with EW(H$\alpha$), which provides an approach for deriving $\xi_{ion}$ in early galaxies. Lower-mass, lower-luminosity galaxies have a higher $\xi_{ion}$. Overall, these results provide further support for faint galaxies playing a major role in the reionization of the Universe., Comment: 17 pages. Accepted for publication in MNRAS
- Published
- 2022