Luminous infrared galaxies (LIRGs) and ultraluminous infrared galaxies (ULIRGs) are galaxies with infrared (IR) luminosities (LIR) in the range between 1011 and 1012 L⊙, and >1012 L⊙, respectively. Intense star-formation bursts and/or an active galactic nucleus (AGN) are the power sources of these galaxies. These galaxies are unusual in the local universe, they represent less than 6 % of the IR emission in the local universe. Nevertheless, at high-redshift, z ∼ 1–2, (U)LIRGs have an important contribution to the star-formation rate (SFR) density of the Universe. Consequently, the study of local LIRGs is a fundamental piece to understanding their more distant counterparts.
This thesis is focused on the study of local LIRGs. For this purpose we defined a complete volume-limited sample of 53 local galaxies (0.009 < z < 0.017) with log(LIR/L⊙)>11.05. We analyzed mid-IR imaging and spectroscopic data obtained with Spitzer, and X-ray data from XMM-Newton and Chandra of these local LIRGs. The Spitzer spectroscopic data include observations from two GTO programs. Likewise the XMM-Newton X-ray data were obtained through two guest observer programs. In addition we used Spitzer, XMM-Newton, and Chandra archival data.
As a first step in our study, we characterized the mid-IR high-ionization emission lines produced by AGN and star-formation for a large sample of local galaxies, includ- ing LIRGs, observed with Spitzer (Chapter 3). In Chapter 4 we studied the spatially resolved mid-IR properties of a sample of 15 local LIRGs using Spitzer/IRS spectral mapping observations. Finally, in Chapter 5, we present the analysis of the X-ray prop- erties of a representative sample of 27 local LIRGs. […]
