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|Title:||The Interstellar Medium and Feedback in the Progenitors of the Compact Passive Galaxies at z ~ 2||Authors:||Williams, Christina C.
Ferguson, Henry C.
Trump, Jonathan R.
Bell, Eric F.
Finkelstein, Steven L.
Koo, David C.
Lucas, Ray A.
Weiner, Benjamin J.
|Issue Date:||2015||Journal:||THE ASTROPHYSICAL JOURNAL||Number:||800||Issue:||1||First Page:||21||Abstract:||Quenched galaxies at z > 2 are nearly all very compact relative to z ~ 0, suggesting a physical connection between high stellar density and efficient, rapid cessation of star-formation. We present rest-frame UV spectra of Lyman-break galaxies (LBGs) at z ~ 3 selected to be candidate progenitors of the quenched galaxies at z ~ 2 based on their compact rest-frame-optical sizes and high Σ<SUB>SFR</SUB>. We compare their UV properties to those of more extended LBGs of similar mass and star-formation rate (non-candidates). We find that candidate progenitors have faster bulk interstellar medium (ISM) gas velocities and higher equivalent widths of interstellar absorption lines, implying larger velocity spread among absorbing clouds. Candidates deviate from the relationship between equivalent widths of Lyα and interstellar absorption lines in that their Lyα emission remains strong despite high interstellar absorption, possibly indicating that the neutral H I fraction is patchy, such that Lyα photons can escape. We detect stronger C IV P-Cygni features (emission and absorption) and He II emission in candidates, indicative of larger populations of metal-rich Wolf-Rayet stars compared to non-candidates. The faster bulk motions, broader spread of gas velocity, and Lyα properties of candidates are consistent with their ISM being subject to more energetic feedback than non-candidates. Together with their larger metallicity (implying more evolved star-formation activity) this leads us to propose, if speculatively, that they are likely to quench sooner than non-candidates, supporting the validity of selection criteria used to identify them as progenitors of z ~ 2 passive galaxies. We propose that massive, compact galaxies undergo more rapid growth of their stellar mass content, perhaps because the gas accretion mechanisms are different, and quench sooner than normally sized LBGs at these (early) epochs.||Acknowledgments:||We thank the anonymous referee whose valuable suggestions have improved the paper significantly. The authors thank Naveen Reddy and Charles Steidel for graciously providing the HIRES spectrum of D6. We also thank Alvio Renzini for reading this document and providing his valuable and insightful comments. C.C.W. thanks Shawn Roberts, Joseph Burchett, Todd Tripp, Joseph Meiring, Claudia Scarlata, Eric Gawiser, Nadia Zakamska, Sanchayeeta Borthakur, and Brandon Bozek for enlightening discussions. This work is based on observations taken by the CANDELS Multi-Cycle Treasury Program with the NASA/ESA HST . We acknowledge support from grant program NSF AST 08-8133, and support for HST Program GO 12060.10-A was provided by NASA through grants from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555.||URI:||http://hdl.handle.net/20.500.12386/23264||URL:||https://iopscience.iop.org/article/10.1088/0004-637X/800/1/21||ISSN:||0004-637X||DOI:||10.1088/0004-637X/800/1/21||Bibcode ADS:||2015ApJ...800...21W||Fulltext:||open|
|Appears in Collections:||1.01 Articoli in rivista|
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