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Title: CONNECTING TRANSITIONS IN GALAXY PROPERTIES TO REFUELING

We relate transitions in galaxy structure and gas content to refueling, here defined to include both the external gas accretion and the internal gas processing needed to renew reservoirs for star formation. We analyze two z = 0 data sets: a high-quality ∼200 galaxy sample (the Nearby Field Galaxy Survey, data release herein) and a volume-limited ∼3000 galaxy sample with reprocessed archival data. Both reach down to baryonic masses ∼10{sup 9} M{sub ☉} and span void-to-cluster environments. Two mass-dependent transitions are evident: (1) below the 'gas-richness threshold' scale (V ∼ 125 km s{sup –1}), gas-dominated quasi-bulgeless Sd-Im galaxies become numerically dominant; while (2) above the 'bimodality' scale (V ∼ 200 km s{sup –1}), gas-starved E/S0s become the norm. Notwithstanding these transitions, galaxy mass (or V as its proxy) is a poor predictor of gas-to-stellar mass ratio M{sub gas}/M{sub *}. Instead, M{sub gas}/M{sub *} correlates well with the ratio of a galaxy's stellar mass formed in the last Gyr to its preexisting stellar mass, such that the two ratios have numerically similar values. This striking correspondence between past-averaged star formation and current gas richness implies routine refueling of star-forming galaxies on Gyr timescales. We argue that this refueling underlies the tightmore » M{sub gas}/M{sub *} versus color correlations often used to measure 'photometric gas fractions'. Furthermore, the threshold and bimodality scale transitions reflect mass-dependent demographic shifts between three refueling regimes—accretion-dominated, processing-dominated, and quenched. In this picture, gas-dominated dwarfs are explained not by inefficient star formation but by overwhelming gas accretion, which fuels stellar mass doubling in ∼<1 Gyr. Moreover, moderately gas-rich bulged disks such as the Milky Way are transitional, becoming abundant only in the narrow range between the threshold and bimodality scales.« less
Authors:
; ; ; ; ;  [1] ; ;  [2] ;  [3] ;  [4] ;  [5] ;  [6] ;  [7] ;  [8] ;  [9]
  1. Department of Physics and Astronomy, University of North Carolina, 290 Phillips Hall CB 3255, Chapel Hill, NC 27599 (United States)
  2. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street MS-20, Cambridge, MA 02138 (United States)
  3. Department of Physics, West Virginia University, P.O. Box 6315, Morgantown, WV 26506 (United States)
  4. Department of Physics and Astronomy, Rutgers, the State University of New Jersey, 136 Frelinghuysen Road, Piscataway, NJ 08854-8019 (United States)
  5. Department of Astronomy, University of Maryland, College Park, MD 20742-2421 (United States)
  6. Spitzer Science Center, Caltech, MS 220-6, Pasadena, CA 91125 (United States)
  7. Department of Astronomy, University of Texas at Austin, Austin, TX 78712 (United States)
  8. Department of Radiology, University of Southern California and Children's Hospital Los Angeles, 4650 W Sunset Boulevard, MS 81, Los Angeles, CA 90027 (United States)
  9. Department of Physics, University of Colorado at Boulder, Boulder, CO 80309-0390 (United States)
Publication Date:
OSTI Identifier:
22270660
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 777; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASTRONOMY; ASTROPHYSICS; COLOR; CORRELATIONS; DWARF STARS; MASS; MILKY WAY; PHOTOMETRY; STAR ACCRETION; STAR EVOLUTION