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Title: THE SURVEY OF LINES IN M31 (SLIM): INVESTIGATING THE ORIGINS OF [C II] EMISSION

The [C II] 158 μm line is one of the strongest emission lines observed in star-forming galaxies and has been empirically measured to correlate with the star-formation rate (SFR) globally and on kiloparsec scales. However, because of the multiphase origins of [C II], one might expect this relation to break down at small scales. We investigate the origins of [C II] emission by examining high spatial resolution observations of [C II] in M31 with the Survey of Lines in M31. We present five ∼700 × 700 pc (3' × 3') fields mapping the [C II] emission, Hα emission, and the ancillary infrared (IR) data. We spatially separate star-forming regions from diffuse gas and dust emission on ∼50 pc scales. We find that the [C II]-SFR correlation holds even at these scales, although the relation typically has a flatter slope than found at larger (kiloparsec) scales. While the Hα emission in M31 is concentrated in the SFR regions, we find that a significant amount (∼20%-90%) of the [C II] emission comes from outside star-forming regions and that the total IR emission (TIR) has the highest diffuse fraction of all SFR tracers. We find a weak correlation of the [C II]/TIR tomore » dust color in each field and find a large-scale trend of increasing [C II]/TIR with galactocentric radius. The differences in the relative diffuse fractions of [C II], Hα, and IR tracers are likely caused by a combination of energetic photon leakage from H II regions and heating by the diffuse radiation field arising from older (B-star) stellar populations. However, we find that by averaging our measurements over kiloparsec scales, these effects are minimized, and the relation between [C II] and SFR found in other nearby galaxy studies is retrieved.« less
Authors:
; ; ; ; ; ;  [1] ;  [2] ;  [3] ;  [4]
  1. Max Planck Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg (Germany)
  2. Department of Astronomy, The Ohio State University, 140 West 18th Avenue, Columbus, OH 43210 (United States)
  3. Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195 (United States)
  4. National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903 (United States)
Publication Date:
OSTI Identifier:
22364763
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 798; 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; COLOR; CORRELATIONS; EMISSION SPECTRA; GALAXIES; MAPPING; PHOTON EMISSION; SPATIAL RESOLUTION; STAR EVOLUTION; STARS