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Modeling Dust and Starlight in Galaxies Observed by Spitzer and Herschel: The KINGFISH Sample

Aniano, G. and Armus, L. and Helou, G. (2020) Modeling Dust and Starlight in Galaxies Observed by Spitzer and Herschel: The KINGFISH Sample. Astrophysical Journal, 889 (2). Art. No. 150. ISSN 1538-4357.

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Interstellar dust and starlight are modeled for the galaxies of the project "Key Insights on Nearby Galaxies: A Far-Infrared Survey with Herschel." The galaxies were observed by the Infrared Array Camera and the Multiband Imaging Photometer for Spitzer on Spitzer Space Telescope, and the Photodetector Array Camera and Spectrometer and the Spectral and Photometric Imaging Receiver on Herschel Space Observatory. With data from 3.6 to 500 μm, dust models are strongly constrained. Using a physical dust model, for each pixel in each galaxy we estimate (1) dust surface density, (2) dust mass fraction in polycyclic aromatic hydrocarbons (PAHs), (3) distribution of starlight intensities heating the dust, (4) total infrared (IR) luminosity emitted by the dust, and (5) IR luminosity originating in subregions with high starlight intensity. The dust models successfully reproduce the observed global and resolved spectral energy distributions. With the angular resolution of Herschel, we obtain well-resolved maps (available online) for the dust properties. As in previous studies, we find the PAH fraction q_(PAH) to be an increasing function of metallicity, with a threshold oxygen abundance Z/Z⊙ ≈ 0.1, but we find the data to be fitted best with q_(PAH) increasing linearly with log(O/H) above a threshold value of 0.15(O/H)⊙. We obtain total dust masses for each galaxy by summing the dust mass over the individual map pixels; these "resolved" dust masses are consistent with the masses inferred from a model fit to the global photometry. The global dust-to-gas ratios obtained from this study are found to correlate with galaxy metallicities. Systems with Z/Z⊙ ≳ 0.5 have most of their refractory elements locked up in dust, whereas in systems with Z/Z⊙ ≾ 0.3 most of these elements tend to remain in the gas phase. Within galaxies, we find that q_(PAH) is suppressed in regions with unusually warm dust with vL_v(70 μm) ≳ 0.4L_(dust). With knowledge of one long-wavelength flux density ratio (e.g., f₁₆₀/f₅₀₀), the minimum starlight intensity heating the dust (U_(min)) can be estimated to within ~50%, despite a variation in U_(min) of more than two orders of magnitude. For the adopted dust model, dust masses can be estimated to within ~0.2 dex accuracy using the f₁₆₀/f₅₀₀ flux ratio and the integrated dust luminosity, and to ~0.07 dex accuracy using the 500 μm luminosity vL_v(500 µm) alone. There are additional systematic errors arising from the choice of dust model, but these are hard to estimate. These calibrated prescriptions for estimating starlight heating intensity and dust mass may be useful for studies of high-redshift galaxies.

Item Type:Article
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URLURL TypeDescription Paper
Aniano, G.0000-0001-9015-2654
Armus, L.0000-0003-3498-2973
Helou, G.0000-0003-3367-3415
Additional Information:© 2020 The American Astronomical Society. Received 2019 September 16; revised 2019 December 4; accepted 2019 December 5; published 2020 February. We thank the referee for helpful comments. We are grateful to R.H. Lupton for availability of the SM graphics program. L.K.H. thanks Princeton University for kind hospitality during a very pleasant and productive visit and acknowledges funding from the INAF PRIN-SKA 2017 program This research was supported in part by JPL grants 1329088 and 1373687, and by NSF grants AST-0406883, AST-1008570, and AST-1408723. K.S. was supported in part by NSF grant AST-1615728 and NASA ADP grant NNX17AF39G. Facilities: Spitzer Space Telescope - , Herschel Space Observatory - , Karl G. Jansky Very Large Array - , IRAM 30 m telescope - , Westerbork Synthesis Radio Telescope - , Nobeyama Radio Observatory. - Software: CASA (McMullin et al. 2007); SINGS Fifth Data Delivery Pipeline; Local Volume Legacy Project Pipeline; HIPE v11.1.0 (Ott 2010); Scanamorphos v24.0 (Roussel 2013); R (R Core Team 2014); SM.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Istituto Nazionale di Astrofisica (INAF)PRIN-SKA 2017
Subject Keywords:Astrophysical dust processes; Polycyclic aromatic hydrocarbons; Interstellar medium; Infrared galaxies
Issue or Number:2
Classification Code:Unified Astronomy Thesaurus concepts: Astrophysical dust processes (99); Polycyclic aromatic hydrocarbons (1280); Interstellar medium (847); Infrared galaxies (790)
Record Number:CaltechAUTHORS:20200204-074914004
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Official Citation:G. Aniano et al 2020 ApJ 889 150
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:101097
Deposited By: Tony Diaz
Deposited On:04 Feb 2020 17:30
Last Modified:16 Jul 2020 21:19

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