Spitzer Local Volume Legacy (LVL) SEDs and Physical Properties

TL;DR

This study presents comprehensive spectral energy distributions for 258 nearby galaxies, analyzing their physical properties and how these relate to observed colors, with insights into star formation and dust characteristics across different galaxy types.

Contribution

It provides a detailed analysis of galaxy SEDs from ultraviolet to infrared, revealing how galaxy properties influence their spectral energy distributions and testing star formation relations in low-mass galaxies.

Findings

Good agreement with star-forming main-sequence.

Deviation in infrared main-sequence at low luminosities.

Suppressed PAH formation in low metallicity environments.

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 $\textrm{\AA}$ to 24 $\mu$m) 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 color-color relationships and correlated trends between observed and physical properties (i.e., optical magnitudes and dust properties, optical color and specific star formation rate, and ultraviolet-infrared color 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 sSFR at a value of log($sSFR$) $\sim$ $-$10.2.