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Published July 10, 2014 | Published + Submitted
Journal Article Open

Hubble Space Telescope Grism Spectroscopy of Extreme Starbursts across Cosmic Time: The Role of Dwarf Galaxies in the Star Formation History of the Universe

Abstract

Near infrared slitless spectroscopy with the Wide Field Camera 3, on board the Hubble Space Telescope, offers a unique opportunity to study low-mass galaxy populations at high redshift (z ~ 1-2). While most high-z surveys are biased toward massive galaxies, we are able to select sources via their emission lines that have very faint continua. We investigate the star formation rate (SFR)-stellar mass (M_★) relation for about 1000 emission line galaxies identified over a wide redshift range of 0.3 ≾ z ≾ 2.3. We use the Hα emission as an accurate SFR indicator and correct the broadband photometry for the strong nebular contribution to derive accurate stellar masses down to M_★ ~10^7 M_☉. We focus here on a subsample of galaxies that show extremely strong emission lines (EELGs) with rest-frame equivalent widths ranging from 200 to 1500 Å. This population consists of outliers to the normal SFR-M_★ sequence with much higher specific SFRs (>10 Gyr^(–1)). While on-sequence galaxies follow continuous star formation processes, EELGs are thought to be caught during an extreme burst of star formation that can double their stellar mass in a period of less than 100 Myr. The contribution of the starburst population to the total star formation density appears to be larger than what has been reported for more massive galaxies in previous studies. In the complete mass range 8.2 < log(M_★/M_☉) <10 and a SFR lower completeness limit of about 2 M_☉ yr^(–1) (10 M_☉ yr^(–1)) at z ~ 1 (z ~ 2), we find that starbursts having EW_(rest)(Hα) > 300, 200, and 100 Å contribute up to ~13%, 18%, and 34%, respectively, to the total SFR of emission-line-selected sample at z ~ 1-2. The comparison with samples of massive galaxies shows an increase in the contribution of starbursts toward lower masses.

Additional Information

© 2014 American Astronomical Society. Received 2014 February 17; accepted 2014 April 8; published 2014 June 19. Based on observations made with the NASA/ESA Hubble Space Telescope, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with programs 11696, 12283, 12568, 12177, and 12328. H.A. and J.P.K. are supported by the European Research Council (ERC) advanced grant "Light on the Dark" (LIDA).C.P. acknowledges support from the KASI-Yonsei Joint Research Program for the Frontiers of Astronomy and Space Science funded by the Korea Astronomy and Space Science Institute. S.C. acknowledges support from the European Research Council via an Advanced Grant under grant agreement No. 321323.

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Published - 0004-637X_789_2_96.pdf

Submitted - 1406.4132v1.pdf

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August 20, 2023
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