SPECTRAL ENERGY DISTRIBUTIONS OF LOCAL LUMINOUS AND ULTRALUMINOUS INFRARED GALAXIES

By U. Vivian, D. Sanders, J. Mazzarella, A. Evans, J. Howell, J. Surace, Lee Armus, K. Iwasawa, Dongchan Kim, C. Casey and 12 more. 2012

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Luminous (LIRGs; log (LIR/L☉) = 11.00–11.99) and ultraluminous infrared galaxies (ULIRGs; log (LIR/L☉) = 12.00–12.99) are the most extreme star-forming galaxies in the universe. The local (U)LIRGs provide a unique opportunity to study their multi-wavelength properties in detail for comparison with their more numerous counterparts at high redshifts. We present common large aperture photometry at radio through X-ray wavelengths and spectral energy distributions (SEDs) for a sample of 53 nearby (z < 0.083) LIRGs and 11 ULIRGs spanning log (LIR/L☉) = 11.14–12.57 from the flux-limited (f60 μm > 5.24 Jy) Great Observatories All-sky LIRG Survey. The SEDs for all objects are similar in that they show a broad, thermal stellar peak (∼0.3–2 μm), and a dominant FIR (∼40–200 μm) thermal dust peak, where νLν(60 μm)/νLν(V) increases from ∼2 to 30 with increasing LIR. When normalized at IRAS 60 μm, the largest range in the luminosity ratio, R(λ) ≡ log[νLν(λ)/νLν(60 μm)], observed over the full sample is seen in the hard X-rays (HX = 2–10 keV), where ΔRHX = 3.73 (). A small range is found in the radio (1.4 GHz), ΔR1.4 GHz = 1.75, where the mean ratio is largest, (). Total infrared luminosities, LIR(8–1000 μm), dust temperatures, and dust masses were computed from fitting thermal dust emission modified blackbodies to the mid-infrared (MIR) through submillimeter SEDs. The new results reflect an overall ∼0.02 dex lower luminosity than the original IRAS values. Total stellar masses were computed by fitting stellar population synthesis models to the observed near-infrared (NIR) through ultraviolet (UV) SEDs. Mean stellar masses are found to be log (M⋆/M☉) = 10.79 ± 0.40. Star formation rates have been determined from the infrared (SFRIR ∼ 45 M☉ yr−1) and from the monochromatic UV luminosities (SFRUV ∼ 1.3 M☉ yr−1), respectively. Multi-wavelength active galactic nucleus (AGN) indicators have be used to select putative AGNs: About 60% of the ULIRGs would have been classified as an AGN by at least one of the selection criteria.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/1ce2a1fc63ed27f2f6e2895db9ca0560db3c40ee