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 wil...l target the FIR and sub-mm spectral regions over the next decade.
Publication
A Herschel-PACS Far-infrared Line Emission Survey of Local Luminous Infrared Galaxies . Díaz-Santos T. et al. . The Astrophysical Journal, Volume 846, Issue 1, article id. 32, 22 pp. (2017). . 846 . 10.3847/1538-4357/aa81d7 . 2017ApJ...846...32D , Far-infrared Line Spectra of Active Galaxies from the Herschel-PACS Spectrometer: The Complete Database . Fernández-Ontiveros Juan Antonio et al. . The Astrophysical Journal Supplement Series, Volume 226, Issue 2, article id. 19, 26 pp. (2016). . 226 . 10.3847/0067-0049/226/2/19 . 2016ApJS..226...19F , Regulating Star Formation in Nearby Dusty Galaxies: Low Photoelectric Efficiencies in the Most Compact Systems . McKinney J. et al. . The Astrophysical Journal . null . null . 2021ApJ...908..238M , Herschel-PACS OH Spectroscopy of Seyfert, LINER, and Starburst Galaxies . Runco Jordan N. et al. . The Astrophysical Journal . null . null . 2020ApJ...905...57R ,
Herschel was launched on 14 May 2009! It is the fourth 'cornerstone' mission in the ESA science programme. With a 3.5 m Cassegrain telescope it is the largest space telescope ever launched. It is performing photometry and spectroscopy in approximately the 55-671 µm range, bridging the gap between earlier infrared space missions and groundbased facilities.
