MID-INFRARED PROPERTIES OF OH MEGAMASER HOST GALAXIES. I. SPITZER IRS LOW- AND HIGH-RESOLUTION SPECTROSCOPY

Journal Article · Tue Mar 15 04:00:00 EDT 2011 · Astrophysical Journal, Supplement Series

DOI:https://doi.org/10.1088/0067-0049/193/1/18· OSTI ID:21557052

Willett, Kyle W; Darling, Jeremy ^[1]; Spoon, Henrik W. W. ^[2]; Charmandaris, Vassilis ^[3]; Armus, Lee ^[4]

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1. Center for Astrophysics and Space Astronomy, Department of Astrophysical and Planetary Sciences, UCB 391, University of Colorado, Boulder, CO 80309-0391 (United States)
2. Astronomy Department, Cornell University, Ithaca, NY 14853 (United States)
3. Department of Physics and Institute of Theoretical and Computational Physics, University of Crete, GR-71003 Heraklion (Greece)
4. Spitzer Science Center, California Institute of Technology, Pasadena, CA 91125 (United States)

We present mid-infrared spectra and photometry from the Infrared Spectrograph on the Spitzer Space Telescope for 51 OH megamasers (OHMs), along with 15 galaxies confirmed to have no megamaser emission above L {sub OH} = 10{sup 2.3} L {sub sun}. The majority of galaxies display moderate-to-deep 9.7 {mu}m amorphous silicate absorption, with OHM galaxies showing stronger average absorption and steeper 20-30 {mu}m continuum emission than non-masing galaxies. Emission from multiple polycyclic aromatic hydrocarbons (PAHs), especially at 6.2, 7.7, and 11.3 {mu}m, is detected in almost all systems. Fine-structure atomic emission (including [Ne II], [Ne III], [S III], and [S IV]) and multiple H{sub 2} rotational transitions are observed in more than 90% of the sample. A subset of galaxies show emission from rarer atomic lines, such as [Ne V], [O IV], and [Fe II]. Fifty percent of the OHMs show absorption from water ice and hydrogenated amorphous carbon grains, while absorption features from CO{sub 2}, HCN, C{sub 2}H{sub 2}, and crystalline silicates are also seen in several OHMs. Column densities of OH derived from 34.6 {mu}m OH absorption are similar to those derived from 1667 MHz OH absorption in non-masing galaxies, indicating that the abundance of masing molecules is similar for both samples. This data paper presents full mid-infrared spectra for each galaxy, along with measurements of line fluxes and equivalent widths, absorption feature depths, and spectral indices.

• OSTI ID: 21557052
• Journal Information: Astrophysical Journal, Supplement Series, Journal Name: Astrophysical Journal, Supplement Series Journal Issue: 1 Vol. 193; ISSN 0067-0049; ISSN APJSA2
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ABSORPTION
AMPLIFIERS
AROMATICS
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON OXIDES
CHALCOGENIDES
ELECTRONIC EQUIPMENT
ELEMENTS
EMISSION
EQUIPMENT
GALAXIES
HYDROCARBONS
HYDROCYANIC ACID
HYDROGEN
HYDROGEN COMPOUNDS
INFRARED SPECTRA
INORGANIC ACIDS
INORGANIC COMPOUNDS
MASERS
MICROWAVE AMPLIFIERS
MICROWAVE EQUIPMENT
NONMETALS
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PHOTOMETRY
POLYCYCLIC AROMATIC HYDROCARBONS
SILICATES
SILICON COMPOUNDS
SORPTION
SPECTRA
TELESCOPES