skip to main content

Title: THE BOLOCAM GALACTIC PLANE SURVEY. X. A COMPLETE SPECTROSCOPIC CATALOG OF DENSE MOLECULAR GAS OBSERVED TOWARD 1.1 mm DUST CONTINUUM SOURCES WITH 7.°5 ≤ l ≤ 194°

The Bolocam Galactic Plane Survey (BGPS) is a 1.1 mm continuum survey of dense clumps of dust throughout the Galaxy covering 170 deg{sup 2}. We present spectroscopic observations using the Heinrich Hertz Submillimeter Telescope of the dense gas tracers, HCO{sup +} and N{sub 2}H{sup +} 3-2, for all 6194 sources in the BGPS v1.0.1 catalog between 7.°5 ≤ l ≤ 194°. This is the largest targeted spectroscopic survey of dense molecular gas in the Milky Way to date. We find unique velocities for 3126 (50.5%) of the BGPS v1.0.1 sources observed. Strong N{sub 2}H{sup +} 3-2 emission (T {sub mb} > 0.5 K) without HCO{sup +} 3-2 emission does not occur in this catalog. We characterize the properties of the dense molecular gas emission toward the entire sample. HCO{sup +} is very sub-thermally populated and the 3-2 transitions are optically thick toward most BGPS clumps. The median observed line width is 3.3 km s{sup –1} consistent with supersonic turbulence within BGPS clumps. We find strong correlations between dense molecular gas integrated intensities and 1.1 mm peak flux and the gas kinetic temperature derived from previously published NH{sub 3} observations. These intensity correlations are driven by the sensitivity of the 3-2more » transitions to excitation conditions rather than by variations in molecular column density or abundance. We identify a subset of 113 sources with stronger N{sub 2}H{sup +} than HCO{sup +} integrated intensity, but we find no correlations between the N{sub 2}H{sup +}/HCO{sup +} ratio and 1.1 mm continuum flux density, gas kinetic temperature, or line width. Self-absorbed profiles are rare (1.3%)« less
Authors:
;  [1] ; ; ; ; ; ; ;  [2] ;  [3] ;  [4] ;  [5] ;  [6]
  1. Steward Observatory, 933 North Cherry Avenue, Tucson, AZ 85721 (United States)
  2. CASA, University of Colorado, CB 389, Boulder, CO 80309 (United States)
  3. Department of Physics, University of Alberta, 4-181 CCIS Edmonton AB T6G 2E1 (Canada)
  4. Max-Planck-Institut für Astronomie (MPIA), Knigstuhl 17, D-69117 Heidelberg (Germany)
  5. Department of Physics and Astronomy, University of Victoria, P.O. Box 3055, STN CSC, Victoria, BC V8W 3P6 (Canada)
  6. Department of Astronomy, Yale University, P.O. Box 208101, New Haven, CT 06520 (United States)
Publication Date:
OSTI Identifier:
22273289
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal, Supplement Series; Journal Volume: 209; 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; AMMONIA; ASTRONOMY; ASTROPHYSICS; CATALOGS; CORRELATIONS; EXCITATION; FLUX DENSITY; LINE WIDTHS; MILKY WAY; MOLECULAR IONS; SENSITIVITY; STARS; TELESCOPES; TURBULENCE