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Title: TIMESCALES ON WHICH STAR FORMATION AFFECTS THE NEUTRAL INTERSTELLAR MEDIUM

Turbulent neutral hydrogen (H I) line widths are often thought to be driven primarily by star formation (SF), but the timescale for converting SF energy to H I kinetic energy is unclear. As a complication, studies on the connection between H I line widths and SF in external galaxies often use broadband tracers for the SF rate, which must implicitly assume that SF histories (SFHs) have been constant over the timescale of the tracer. In this paper, we compare measures of H I energy to time-resolved SFHs in a number of nearby dwarf galaxies. We find that H I energy surface density is strongly correlated only with SF that occurred 30-40 Myr ago. This timescale corresponds to the approximate lifetime of the lowest mass supernova progenitors ({approx}8 M{sub Sun }). This analysis suggests that the coupling between SF and the neutral interstellar medium is strongest on this timescale, due either to an intrinsic delay between the release of the peak energy from SF or to the coherent effects of many supernova explosions during this interval. At {Sigma}{sub SFR} > 10{sup -3} M{sub Sun} yr{sup -1} kpc{sup -2}, we find a mean coupling efficiency between SF energy and H I energymore » of {epsilon} = 0.11 {+-} 0.04 using the 30-40 Myr timescale. However, unphysical efficiencies are required in lower {Sigma}{sub SFR} systems, implying that SF is not the primary driver of H I kinematics at {Sigma}{sub SFR} < 10{sup -3} M{sub Sun} yr{sup -1} kpc{sup -2}.« less
Authors:
; ; ;  [1] ;  [2] ;  [3] ;  [4] ;  [5]
  1. Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195 (United States)
  2. Department of Astronomy, University of Maryland, CSS Building, Room 1024, Stadium Drive, College Park, MD 20742-2421 (United States)
  3. Minnesota Institute for Astrophysics, University of Minnesota, 116 Church Street SE, Minneapolis, MN 55455 (United States)
  4. National Radio Astronomy Observatory, P.O. Box O, 1003 Lopezville Road, Socorro, NM 87801 (United States)
  5. Raytheon Company, 1151 East Hermans Road, Tucson, AZ 85756 (United States)
Publication Date:
OSTI Identifier:
22121793
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 772; 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; DENSITY; DWARF STARS; GALAXIES; HYDROGEN; INTERSTELLAR SPACE; KINETIC ENERGY; LINE WIDTHS; MASS; SUPERNOVAE; TIME DEPENDENCE; TIME RESOLUTION