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
On the far-infrared metallicity diagnostics: applications to high-redshift galaxies | Rigopoulou D. et al. | Monthly Notices of the Royal Astronomical Society Volume 473 Issue 1 p.20-29 | 473 | 10.1093\\/mnras\\/stx2311 | 2018MNRAS.473...20R | http://adsabs.harvard.edu/abs/2018MNRAS.473...20R
HIFI Spectroscopy of H2O Submillimeter Lines in Nuclei of Actively Star-forming Galaxies | Liu L. et al. | The Astrophysical Journal Volume 846 Issue 1 article id. 5 35 pp. (2017). | 846 | 10.3847\\/1538-4357\\/aa81b4 | 2017ApJ...846....5L | http://adsabs.harvard.edu/abs/2017ApJ...846....5L
Neutral Carbon Emission in Luminous Infrared Galaxies: The C I Lines as Total Molecular Gas Tracers | Jiao Qian et al. | The Astrophysical Journal Letters Volume 840 Issue 2 article id. L18 7 pp. (2017). | 840 | 10.3847\\/2041-8213\\/aa6f0f | 2017ApJ...840L..18J | http://adsabs.harvard.edu/abs/2017ApJ...840L..18J
HERUS: A CO Atlas from SPIRE Spectroscopy of Local ULIRGs | Pearson Chris et al. | The Astrophysical Journal Supplement Series Volume 227 Issue 1 article id. 9 25 pp. (2016). | 227 | 10.3847\\/0067-0049\\/227\\/1\\/9 | 2016ApJS..227....9P | http://adsabs.harvard.edu/abs/2016ApJS..227....9P
Herschel observations of water vapour in Markarian 231 | Gonzalez-Alfonso E. et al. | Astronomy and Astrophysics Volume 518 id.L43 5 pp. | 518 | 10.1051\\/0004-6361\\/201014664 | 2010A&A...518L..43G | http://adsabs.harvard.edu/abs/2010A%26A...518L..43G
Black hole accretion and star formation as drivers of gas excitation and chemistry in Markarian 231 | van der Werf P. P. et al. | Astronomy and Astrophysics Volume 518 id.L42 5 pp. | 518 | 10.1051\\/0004-6361\\/201014682 | 2010A&A...518L..42V | http://adsabs.harvard.edu/abs/2010A%26A...518L..42V
Stacked Average Far-infrared Spectrum of Dusty Star-forming Galaxies from the Herschel/SPIRE Fourier Transform Spectrometer | Wilson Derek et al. | The Astrophysical Journal Volume 848 Issue 1 article id. 30 31 pp. (2017). | 848 | 10.3847\\/1538-4357\\/aa8cc7 | 2017ApJ...848...30W | http://adsabs.harvard.edu/abs/2017ApJ...848...30W
Star Formation Relations and CO Spectral Line Energy Distributions across the J-ladder and Redshift | Greve T. R. et al. | The Astrophysical Journal Volume 794 Issue 2 article id. 142 16 pp. (2014). | 794 | 10.1088\\/0004-637X\\/794\\/2\\/142 | 2014ApJ...794..142G | http://adsabs.harvard.edu/abs/2014ApJ...794..142G
AGN impact on the molecular gas in galactic centres as probed by CO lines | Esposito Federico et al. | Monthly Notices of the Royal Astronomical Society | null | null | 2022MNRAS.512..686E |
Instrument
SPIRE_SpireSpectrometer_
Temporal Coverage
2009-12-09T07:17:14Z/2009-12-09T09:16:15Z
Version
SPG v14.1.0
Mission Description
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., 2010, 'A Herschel survey of molecular lines in openParUcloseParLIRGs: physical conditions comma the nature of the power source comma and a benchmark for high-z observations', SPG v14.1.0, European Space Agency, https://doi.org/10.5270/esa-ntsgtkr
