Program: GS-2006A-DD-15

Recent {\it Spitzer} cosmological surveys have demonstrated that the majority of IR-selected galaxies at $z<1$ are in the LIRG class ($L_{\rm IR}=L[8-1000\mu {\rm m}] = 10^{11}-10^{12} L_\odot$) and that LIRGs make a significant contribution to the IR galaxy population at $1<z<2$. We propose to obtain T-ReCS $N$-band broad-band imaging and low resolution $10\,\mu$m spectroscopy of a sample of four low-$z$ LIRGs. These galaxies are part of a complete volume ($v<5200\,$km s$^{-1}$) limited sample of LIRGs for which we have obtained {\it HST}/NICMOS images to identify star clusters and H\,{\sc ii} regions. The sample covers different morphologies and a range of IR luminosities. The combination of high spatial resolution ($\simeq 0.25\arcsec$) mid-IR imaging and spectroscopy uniquely afforded by 8\,m class telescopes, and NICMOS observations will allow us to peer for the first time into the dust-enshrouded nuclear regions of LIRGs with the appropriate spatial resolution ($89-135\,$pc). Our goals are: (1) to identify heavily obscured AGN, not detected in the optical and near-IR, (2) to establish the properties of the nuclear starbursts as well as circumnuclear dusty H\,{\sc ii} regions, (3) to investigate the nature of the dominant energy source (AGN vs stellar emission), and (4) to produce local templates to be compared with the high-redshift bright-IR sources currently being observed by {\it Spitzer}.