| Description |
Luminous Infrared Galaxies (LIRGs; having LIR > 10^11 Lsun), emit a significant fraction of their bolometric luminosity in the far-infrared and are a mixture of single galaxies, interacting systems and mergers, exhibiting enhanced star formation rates and a higher fraction of Active Galactic Nuclei (AGN) compared to less luminous galaxies. With the Great Observatories All-sky LIRG Survey (GOALS), we are measuring the properties of a large, complete sample of 202 low-redshift LIRGs across the electromagnetic spectrum using Herschel, Spitzer, HST, Chandra, GALEX and a suite of ground-based observatories. As part of an accepted OT1 proposal, we are targeting the entire GOALS sample in the CII 157.7 and OI 63.2 micron emission lines and the OH 79 micron absorption feature, along with half the sample in the OIII 88 micron emission line. Here, we propose to complete our OIII emission line survey, and observe the brightest GOALS sources in the important NII 122 micron line with PACS. We will target 123 galaxies in OIII and 122 galaxies in NII line for a total requested time of 69.8 hrs. The PACS data will allow us to penetrate the dust and measure the spatial distribution, dynamics and overall energy budgets in a large sample of LIRGs at low redshift for the first time. In addition to providing a measure of the physical conditions in the warm, neutral and ionized ISM in LIRGs, the complete dataset will allow us to establish a precise, quantitative FIR-based measure of the star formation rate that can be used across a wide range of galactic luminosities, even in the presence of powerful AGN. GOALS, with its rich ancillary dataset that covers X-ray through millimeter wavelengths, provides the perfect sample for this study. Our proposed Herschel/PACS observations will greatly extend the work started with ISO, and lay the foundation for high-redshift extra-galactic studies with future facilities that will target the FIR and sub-mm spectral regions over the next decade. |
