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Title: HST/WFC3 near-infrared spectroscopy of quenched galaxies at z ∼ 1.5 from the WISP survey: Stellar population properties

We combine Hubble Space Telescope (HST) G102 and G141 near-IR (NIR) grism spectroscopy with HST/WFC3-UVIS, HST/WFC3-IR, and Spitzer/IRAC [3.6 μm] photometry to assemble a sample of massive (log (M {sub star}/M {sub ☉}) ∼ 11.0) and quenched (specific star formation rate <0.01 Gyr{sup –1}) galaxies at z ∼ 1.5. Our sample of 41 galaxies is the largest with G102+G141 NIR spectroscopy for quenched sources at these redshifts. In contrast to the local universe, z ∼ 1.5 quenched galaxies in the high-mass range have a wide range of stellar population properties. We find that their spectral energy distributions (SEDs) are well fitted with exponentially decreasing star formation histories and short star formation timescales (τ ≤ 100 Myr). Quenched galaxies also show a wide distribution in ages, between 1 and 4 Gyr. In the (u – r){sub 0}-versus-mass space quenched galaxies have a large spread in rest-frame color at a given mass. Most quenched galaxies populate the z ∼ 1.5 red sequence (RS), but an important fraction of them (32%) have substantially bluer colors. Although with a large spread, we find that the quenched galaxies on the RS have older median ages (3.1 Gyr) than the quenched galaxies off the RS (1.5more » Gyr). We also show that a rejuvenated SED cannot reproduce the observed stacked spectra of (the bluer) quenched galaxies off the RS. We derive the upper limit on the fraction of massive galaxies on the RS at z ∼ 1.5 to be <43%. We speculate that the young quenched galaxies off the RS are in a transition phase between vigorous star formation at z > 2 and the z ∼ 1.5 RS. According to their estimated ages, the time required for quenched galaxies off the RS to join their counterparts on the z ∼ 1.5 RS is of the order of ∼1 Gyr.« less
Authors:
; ;  [1] ; ;  [2] ; ;  [3] ; ;  [4] ; ; ;  [5] ; ;  [6] ; ;  [7] ; ;  [8]
  1. Minnesota Institute for Astrophysics, University of Minnesota, Minneapolis, MN 55455 (United States)
  2. Department of Physics, University of California, Santa Barbara, CA 93106 (United States)
  3. Spitzer Science Center, Caltech, Pasadena, CA 91125 (United States)
  4. Infrared Processing and Analysis Center, Caltech, Pasadena, CA 91125 (United States)
  5. Department of Physics and Astronomy, University of California Riverside, Riverside, CA 92521 (United States)
  6. Department of Physics and Astronomy, University of California Los Angeles, Los Angeles, CA 90095 (United States)
  7. Department of Astronomy, Caltech, Pasadena, CA 91125 (United States)
  8. Observatories of the Carnegie Institution for Science, Pasadena, CA 91101 (United States)
Publication Date:
OSTI Identifier:
22341918
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 778; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABSORPTION SPECTROSCOPY; COLOR; DISTRIBUTION; ENERGY SPECTRA; EVOLUTION; GALAXIES; INFRARED SPECTRA; MASS; NEAR INFRARED RADIATION; PHASE TRANSFORMATIONS; PHOTOMETRY; RED SHIFT; SPACE; STARS; TELESCOPES; UNIVERSE