The key diagnostic of the warm star-forming molecular clouds in galaxies is provided by their cooling radiation: CII and OI lines, butalso lines of CO, the main tracer of molecular gas. While in our Galaxycooling by CO lines is unimportant, this situation is totally different inlocal ULIRGs, where the CO is an important coolant, and the thermalbalance is totally different from that in our Galaxy. These resultsdemonstrate the enormous, as yet almost unexplored, diagnosticpower of these lines for probing physical conditions. Since these linesare very luminous, they can be used to probe galaxies out to veryhigh redshifts.Here we propose a systematic study with the SPIRE-FTS and PACS ofthe principal neutral gas cooling lines (CII, OI and the CO ladderfrom 5-4 to 13-12) in a 60 micron flux-limited sample of 32 galaxies:24 LIRGs and 8 ULIRGs.Aims of this key project are:- analysis of the neutral gas cooling budget, in particular the relativeimportance of CO and CII emission;- analysis of the CO rotational ladder to derive the mass of moleculargas as a function of temperature and density;- modeling of the data using advanced PDR/XDR models with the goalof separating UV-excited (starburst) and X-ray excited (AGN)components;- analysis of the implications for molecular mass measurements basedon CO lines, both at low and high redshift;- achieving statistical robustness, so that inferences can be made onthe infrared galaxy population in general, and trends with other galaxycharacteristics (IR luminosity, type of power source,...) can be traced.Only Herschel can provide the necessary high-J CO and cooling linedata. Combined with our extensive ground-based data (low-J CO, HCN lines) this dataset will elucidate the energy source and physicalconditions in local ULIRGs, and establish the critical link necessary forthe interpretation of observations of high-z galaxies in mid-J COlines and other luminous lines, which will become routine in theALMA era.
Publication
Strong C+ Emission in Galaxies at z ~ 1-2: Evidence for Cold Flow Accretion Powered Star Formation in the Early Universe | Brisbin Drew et al. | The Astrophysical Journal Volume 799 Issue 1 article id. 13 18 pp. (2015). | 799 | 10.1088/0004-637X/799/1/13 | 2015ApJ...799...13B | http://adsabs.harvard.edu/abs/2015ApJ...799...13B
A Herschel/PACS Far-infrared Line Emission Survey of Local Luminous Infrared Galaxies | Diaz-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 | http://adsabs.harvard.edu/abs/2017ApJ...846...32D
Far-infrared Line Spectra of Active Galaxies from the Herschel/PACS Spectrometer: The Complete Database | Fernandez-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 | http://adsabs.harvard.edu/abs/2016ApJS..226...19F
Extended C II Emission in Local Luminous Infrared Galaxies | Diaz-Santos T. et al. | The Astrophysical Journal Letters Volume 788 Issue 1 article id. L17 5 pp. (2014). | 788 | 10.1088/2041-8205/788/1/L17 | 2014ApJ...788L..17D | http://adsabs.harvard.edu/abs/2014ApJ...788L..17D
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 |
The applicability of far-infrared fine-structure lines as star formation rate tracers over wide ranges of metallicities and galaxy types | De Looze Ilse et al. | Astronomy & Astrophysics Volume 568 id.A62 34 pp. | 568 | 10.1051/0004-6361/201322489 | 2014A&A...568A..62D | http://adsabs.harvard.edu/abs/2014A%26A...568A..62D
Measuring Star Formation Rate and Far-infrared Color in High-redshift Galaxies Using the CO(7-6) and N II 205 mm Lines | Lu Nanyao et al. | The Astrophysical Journal Letters Volume 802 Issue 1 article id. L11 6 pp. (2015). | 802 | 10.1088/2041-8205/802/1/L11 | 2015ApJ...802L..11L | http://adsabs.harvard.edu/abs/2015ApJ...802L..11L
The Herschel Comprehensive (U)LIRG Emission Survey (HERCULES): CO Ladders Fine Structure Lines and Neutral Gas Cooling | Rosenberg M. J. F. et al. | The Astrophysical Journal Volume 801 Issue 2 article id. 72 18 pp. (2015). | 801 | 10.1088/0004-637X/801/2/72 | 2015ApJ...801...72R | http://adsabs.harvard.edu/abs/2015ApJ...801...72R
The Local C II 158 mm Emission Line Luminosity Function | Hemmati Shoubaneh et al. | The Astrophysical Journal Volume 834 Issue 1 article id. 36 10 pp. (2017). | 834 | 10.3847/1538-4357/834/1/36 | 2017ApJ...834...36H | http://adsabs.harvard.edu/abs/2017ApJ...834...36H
Neon and C II 158 mm Emission Line Profiles in Dusty Starbursts and Active Galactic Nuclei | Samsonyan Anahit et al. | The Astrophysical Journal Supplement Series Volume 226 Issue 1 article id. 11 18 pp. (2016). | 226 | 10.3847/0067-0049/226/1/11 | 2016ApJS..226...11S | http://adsabs.harvard.edu/abs/2016ApJS..226...11S
Early Science with the Large Millimeter Telescope: CO and C II Emission in the z = 4.3 AzTEC J095942.9+022938 (COSMOS AzTEC-1) | Yun Min S. et al. | Monthly Notices of the Royal Astronomical Society Volume 454 Issue 4 p.3485-3499 | 454 | 10.1093/mnras/stv1963 | 2015MNRAS.454.3485Y | http://adsabs.harvard.edu/abs/2015MNRAS.454.3485Y
Explaining the C II157.7 mm Deficit in Luminous Infrared Galaxies--First Results from a Herschel/PACS Study of the GOALS Sample | Diaz-Santos T. et al. | The Astrophysical Journal Volume 774 Issue 1 article id. 68 13 pp. (2013). | 774 | 10.1088/0004-637X/774/1/68 | 2013ApJ...774...68D | http://adsabs.harvard.edu/abs/2013ApJ...774...68D
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.
European Space Agency, van der werf et al., 2011, 'A Herschel survey of molecular lines in (U)LIRGs: physical conditions, the nature of the power source, and a benchmark for high-z observations', SPG v14.2.0, European Space Agency, https://doi.org/10.5270/esa-cg08kc2
