Spitzer Local Volume Legacy (LVL) SEDs and physical properties

November 2014 • 2014MNRAS.445..899C

Authors • Cook, David O. • Dale, Daniel A. • Johnson, Benjamin D. • Van Zee, Liese • Lee, Janice C. • Kennicutt, Robert C. • Calzetti, Daniela • Staudaher, Shawn M. • Engelbracht, Charles W.

Abstract • We present the panchromatic spectral energy distributions (SEDs) of the Local Volume Legacy (LVL) survey which consists of 258 nearby galaxies (D < 11 Mpc). The wavelength coverage spans the ultraviolet to the infrared (1500 Å-24 μm) which is utilized to derive global physical properties (i.e. star formation rate, stellar mass, internal extinction due to dust). With these data, we find colour-colour relationships and correlated trends between observed and physical properties (i.e. optical magnitudes and dust properties, optical colour and specific star formation rate, and ultraviolet-infrared colour and metallicity). The SEDs are binned by different galaxy properties to reveal how each property affects the observed shape of these SEDs. In addition, due to the volume-limited nature of LVL, we utilize the dwarf-dominated galaxy sample to test star formation relationships established with higher mass galaxy samples. We find good agreement with the star-forming `main-sequence' relationship, but find a systematic deviation in the infrared `main sequence' at low luminosities. This deviation is attributed to suppressed polycyclic aromatic hydrocarbon (PAH) formation in low-metallicity environments and/or the destruction of PAHs in more intense radiation fields occurring near a suggested threshold in star formation rates (sSFR) at a value of log(sSFR) ∼ -10.2.

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David Cook

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