TY - JOUR
T1 - Clocking the Evolution of Post-starburst Galaxies
T2 - Methods and First Results
AU - French, K. Decker
AU - Yang, Yujin
AU - Zabludoff, Ann I.
AU - Tremonti, Christy A.
N1 - Funding Information:
We thank the referee for detailed feedback and suggestions that have improved this paper. We thank C. Conroy for his help regarding the FSPS models. We thank Stephen Shectman for providing the LCRS spectra. We thank Dennis Zaritsky, Zhihui Li, and Adam Smercina for useful discussions. KDF is supported by Hubble Fellowship grant HST-HF2-51391.001-A, provided by NASA through a grant from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. KDF acknowledges support from NSF grant DGE-1143953, P.E.O., and the ARCS Phoenix Chapter and Burton Family. YY is supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT & Future Planning (NRF-2016R1C1B2007782). AIZ acknowledges funding from NASA grant ADP-NNX10AE88G. Funding for SDSS-III has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Science Foundation, and the U.S. Department of Energy Office of Science. The SDSS-III website is http://www.sdss3.org/.
Publisher Copyright:
© 2018. The American Astronomical Society. All rights reserved.
PY - 2018/7/20
Y1 - 2018/7/20
N2 - Detailed modeling of the recent star formation histories (SFHs) of post-starburst (or "E+A") galaxies is impeded by the degeneracy between the time elapsed since the starburst ended (post-burst age), the fraction of stellar mass produced in the burst (burst strength), and the burst duration. To resolve this issue, we combine GALEX ultraviolet photometry, SDSS photometry and spectra, and new stellar population synthesis models to fit the SFHs of 532 post-starburst galaxies. In addition to an old stellar population and a recent starburst, 48% of the galaxies are best fit with a second recent burst. Lower stellar mass galaxies (log M < 10.5) are more likely to experience two recent bursts, and the fraction of their young stellar mass is more strongly anticorrelated with their total stellar mass. Applying our methodology to other, younger post-starburst samples, we identify likely progenitors to our sample and examine the evolutionary trends of molecular gas and dust content with post-burst age. We discover a significant (4σ) decline, with a 117-230 Myr characteristic depletion time, in the molecular gas to stellar mass fraction with the post-burst age. The implied rapid gas depletion rate of 2-150 M yr-1 cannot be due to current star formation, given the upper limits on the current star formation rates in these post-starbursts. Nor are stellar winds or supernova feedback likely to explain this decline. Instead, the decline points to the expulsion or destruction of molecular gas in outflows, a possible smoking gun for active galactic nucleus feedback.
AB - Detailed modeling of the recent star formation histories (SFHs) of post-starburst (or "E+A") galaxies is impeded by the degeneracy between the time elapsed since the starburst ended (post-burst age), the fraction of stellar mass produced in the burst (burst strength), and the burst duration. To resolve this issue, we combine GALEX ultraviolet photometry, SDSS photometry and spectra, and new stellar population synthesis models to fit the SFHs of 532 post-starburst galaxies. In addition to an old stellar population and a recent starburst, 48% of the galaxies are best fit with a second recent burst. Lower stellar mass galaxies (log M < 10.5) are more likely to experience two recent bursts, and the fraction of their young stellar mass is more strongly anticorrelated with their total stellar mass. Applying our methodology to other, younger post-starburst samples, we identify likely progenitors to our sample and examine the evolutionary trends of molecular gas and dust content with post-burst age. We discover a significant (4σ) decline, with a 117-230 Myr characteristic depletion time, in the molecular gas to stellar mass fraction with the post-burst age. The implied rapid gas depletion rate of 2-150 M yr-1 cannot be due to current star formation, given the upper limits on the current star formation rates in these post-starbursts. Nor are stellar winds or supernova feedback likely to explain this decline. Instead, the decline points to the expulsion or destruction of molecular gas in outflows, a possible smoking gun for active galactic nucleus feedback.
KW - catalogs
KW - galaxies: evolution
KW - galaxies: starburst
KW - galaxies: stellar content
KW - methods: data analysis
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U2 - 10.3847/1538-4357/aacb2d
DO - 10.3847/1538-4357/aacb2d
M3 - Article
AN - SCOPUS:85050773131
SN - 0004-637X
VL - 862
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 1
M1 - 2
ER -