SpitzerIRS Imaging and Spectroscopy of the Luminous Infrared Galaxy NGC 6052 (Mrk 297)

Abstract

We present photometric and spectroscopic data of the interacting starburst galaxy NGC 6052 obtained with the Spitzer Space Telescope. The mid-infrared (MIR) spectra of the three spatially resolved regions in the galaxy are remarkably similar and are consistent with dust emission from young, nearly coeval stellar populations. Analysis of the brightest infrared region of the system, which contributes ~18.5% of the total 16 μm flux, indicates that unlike similar off-nuclear infrared-bright regions found in Arp 299 or NGC 4038/4039, its MIR spectrum is inconsistent with an enshrouded hot dust (T > 300 K) component. Instead, the three brightest MIR regions all display dust continua of temperatures less than ~200 K. These low dust temperatures indicate the dust is likely in the form of a patchy screen of relatively cold material situated along the line of sight. We also find that emission from polycyclic aromatic hydrocarbons (PAHs) and the forbidden atomic lines is very similar for each region. We conclude that the ionization regions are similar and come from young (6 Myr) stellar populations. Emission from PAHs and the forbidden atomic lines is very similar for each region. The low dust temperatures indicate the dust is in the form of a patchy screen of colder material situated along the line of sight, and the similar PAH and atomic line emission suggest the young stellar clusters in each region have a similar structure.