Ammonia Thermometry of Star Forming Galaxies

Abstract

With a goal toward deriving the physical conditions in external galaxies, we present a study of the ammonia (NH${}_3$) emission and absorption in a sample of star forming systems. Using the unique sensitivities to kinetic temperature afforded by the excitation characteristics of several inversion transitions of NH${}_3$, we have continued our characterization of the dense gas in star forming galaxies by measuring the kinetic temperature in a sample of 23 galaxies and one galaxy offset position selected for their high infrared luminosity. We derive kinetic temperatures toward 13 galaxies, 9 of which possess multiple kinetic temperature and/or velocity components. Eight of these galaxies exhibit kinetic temperatures $>100$ K, which are in many cases at least a factor of two larger than kinetic temperatures derived previously. Furthermore, the derived kinetic temperatures in our galaxy sample, which are in many cases at least a factor of two larger than derived dust temperatures, point to a problem with the common assumption that dust and gas kinetic temperatures are equivalent. As previously suggested, the use of dust emission at wavelengths greater than 160 $\mu$m to derive dust temperatures, or dust heating from older stellar populations, may be skewing derived dust temperatures in these galaxies to lower values. We confirm the detection of high-excitation OH ${}^2{\Pi }_{3/2}$ J=9/2 absorption toward Arp220 (Ott et. al. 2011). We also report the first detections of non-metastable NH${}_3$ inversion transitions toward external galaxies in the (2,1) (NGC253, NGC660, IC342, and IC860), (3,1), (3,2), (4,3), (5,4) (all in NGC660) and (10,9) (Arp220) transitions.

29 pages, 22 figures, final version following proof corrections accepted for publication in ApJ

References in corpus (7)

• Molecular gas in extreme star-forming environments: the starbursts Arp220 and NGC6240 as case studies
• The thermal state of molecular clouds in the Galactic Center: evidence for non-photon-driven heating
• Mechanical feedback in the molecular ISM of luminous IR galaxies
• The Arecibo Arp 220 Spectral Census I: Discovery of the Pre-Biotic Molecule Methanimine and New Cm-wavelength Transitions of Other Molecules
• Formaldehyde Densitometry of Starburst Galaxies
• Formaldehyde Densitometry of Starburst Galaxies: Density-Independent Global Star Formation
• Hot Molecular Gas in the Nuclear Region of IC 342

Cited by in corpus (36)

• Cool Outflows in Galaxies and their Implications
• ALMA Reveals the Molecular Medium Fueling the Nearest Nuclear Starburst
• New Constraints on the ${}^{12}$CO(2-1)/(1-0) Line Ratio Across Nearby Disc Galaxies
• Low-J CO Line Ratios From Single Dish CO Mapping Surveys and PHANGS-ALMA
• Forming Super Star Clusters in the Central Starburst of NGC 253
• The Survey of Water and Ammonia in the Galactic Center (SWAG): Molecular Cloud Evolution in the Central Molecular Zone
• A Survey of the Molecular ISM Properties of Nearby Galaxies using the Herschel FTS
• ATLASGAL-selected massive clumps in the inner Galaxy: VI. Kinetic temperature and spatial density measured with formaldehyde
• Chemically Distinct Nuclei and Outflowing Shocked Molecular Gas in Arp 220
• Survey of Water and Ammonia in Nearby galaxies (SWAN): Resolved Ammonia Thermometry, Water and Methanol Masers in the Nuclear Starburst of NGC 253
• Herschel spectroscopic observations of the compact obscured nucleus in Zw 049.057
• Fire in the Heart: A Characterization of the High Kinetic Temperatures and Heating Sources in the Nucleus of NGC253
• Kinetic temperature of massive star forming molecular clumps measured with formaldehyde
• Kinetic temperature of massive star-forming molecular clumps measured with formaldehyde. III. The Orion Molecular Cloud 1
• First extragalactic detection of a phosphorus-bearing molecule with ALCHEMI: phosphorus nitride (PN)
• Kinetic temperature of massive star forming molecular clumps measured with formaldehyde. II. The Large Magellanic Cloud
• Spatially resolved carbon and oxygen isotopic ratios in NGC 253 using optically thin tracers
• The Morpho-Kinematic Architecture of Super Star Clusters in the Center of NGC253
• A 2-3 mm high-resolution molecular line survey towards the centre of the nearby spiral galaxy NGC 6946
• Survey of Water and Ammonia in Nearby galaxies (SWAN): Resolved Ammonia Thermometry, and Water and Methanol Masers in IC 342, NGC 6946 and NGC 2146
• Widespread Rotationally-Hot Hydronium Ion in the Galactic Interstellar Medium
• The Molecular ISM in the Super Star Clusters of the Starburst NGC 253
• A new period of activity in the core of NGC660
• Comparing Models for IMF Variation Across Cosmological Time in Milky Way-like Galaxies
• The galaxy-wide stellar initial mass function in the presence of cluster-to-cluster IMF variations
• High Resolution Observations of Molecular Lines in Arp 220: Kinematics, Morphology, and Limits on the Applicability of the Ammonia Thermometer
• Hot Ammonia in the Center of the Seyfert 2 galaxy NGC 3079
• Molecular Gas and Star Formation Properties in the Central and Bar Regions of NGC 6946
• Kinetic temperature of massive star-forming molecular clumps measured with formaldehyde V. The massive filament DR21
• Cold Molecular Gas in Merger Remnants. II. The properties of dense molecular gas
• Water Masers in the Andromeda Galaxy: I. A Survey for Water Masers, Ammonia, and Hydrogen Recombination Lines
• Secondary Radio and X-ray Emissions from Galaxy Mergers
• Gas infall via accretion disk feeding Cepheus A HW2
• High-Temperature Chemistry in External Galaxies
• A Spectral Analysis of the Centimeter Regime of Nearby Galaxies: RRLs, Excited OH, and NH${}_3$
• An Imaging and Spectroscopic Exploration of the Dusty Compact Obscured Nucleus Galaxy Zw~049.057