Marble, A. R. and Engelbracht, C. W. and van Zee, L. and Dale, D. A. and Smith, J. D. T. and Gordon, K. D. and Wu, Y. and Lee, J. C. and Kennicutt, R. C. and Skillman, E. D. and Johnson, L. C. and Block, M. and Calzetti, D. and Cohen, S. A. and Lee, H. and Schuster, M. D. (2010) An Aromatic Inventory of the Local Volume. Astrophysical Journal, 715 (1). pp. 506-540. ISSN 0004-637X http://resolver.caltech.edu/CaltechAUTHORS:20100611-143523005
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Using infrared photometry from the Spitzer Space Telescope, we perform the first inventory of aromatic feature emission (also commonly referred to as polycyclic aromatic hydrocarbon emission) for a statistically complete sample of star-forming galaxies in the local volume. The photometric methodology involved is calibrated and demonstrated to recover the aromatic fraction of the Infrared Array Camera 8 μm flux with a standard deviation of 6% for a training set of 40 SINGS galaxies (ranging from stellar to dust dominated) with both suitable mid-infrared Spitzer Infrared Spectrograph spectra and equivalent photometry. A potential factor of 2 improvement could be realized with suitable 5.5 μm and 10 μm photometry, such as what may be provided in the future by the James Webb Space Telescope. The resulting technique is then applied to mid-infrared photometry for the 258 galaxies from the Local Volume Legacy (LVL) survey, a large sample dominated in number by low-luminosity dwarf galaxies for which obtaining comparable mid-infrared spectroscopy is not feasible. We find the total LVL luminosity due to five strong aromatic features in the 8 μm complex to be 2.47 × 10^(10) L_☉ with a mean volume density of 8.8 × 10^6 L_☉ Mpc^(–3). Twenty-four of the LVL galaxies, corresponding to a luminosity cut at M_B = –18.22, account for 90% of the aromatic luminosity. Using oxygen abundances compiled from the literature for 129 of the 258 LVL galaxies, we find a correlation between metallicity and the aromatic-to-total infrared emission ratio but not the aromatic-to-total 8 μm dust emission ratio. A possible explanation is that metallicity plays a role in the abundance of aromatic molecules relative to the total dust content, but other factors, such as star formation and/or the local radiation field, affect the excitation of those molecules.
|Additional Information:||© 2010 The American Astronomical Society. Received 2009 December 16; accepted 2010 April 7; published 2010 April 29. This work is part of the Spitzer Space Telescope Legacy Science Program and was supported by National Aeronautics and Space Administration (NASA) through contract 1336000 issued by the Jet Propulsion Laboratory (JPL), California Institute of Technology (Caltech) under NASA contract 1407. Additionally, this publication makes use of data products from the Two Micron All Sky Survey, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center (IPAC) at Caltech, funded by NASA and the National Science Foundation. This research has made use of the NASA/IPAC Extragalactic Database, which is operated by JPL/Caltech, under contract with NASA. Finally, we thank the referee for helpful comments and suggestions that resulted in an improved paper. Facilities: Spitzer(IRAC, IRS, MIPS)|
|Subject Keywords:||galaxies: ISM; infrared: galaxies; surveys; techniques: photometric|
|Classification Code:||PACS: 95.80.+p; 98.58.Bz; 98.58.Ca; 98.62.Qz; 95.85.Kr; 98.58.Jg|
|Official Citation:||A. R. Marble et al 2010 ApJ 715 506 doi: 10.1088/0004-637X/715/1/506|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Ruth Sustaita|
|Deposited On:||11 Jun 2010 22:24|
|Last Modified:||26 Dec 2012 12:08|
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