| Description |
Herschel PACS spectroscopy of the CII emission line at 158 microns is proposed for a carefully selected sample of 123 sources that already have complete low and high resolution mid-infrared spectra between 5 microns and 35 microns from the Spitzer Infrared Spectrograph, and which also have spectral energy distributions (SEDs) from IRAS and Akari photometry. CII 158 um is the strongest far-infrared emission line and therefore crucial to compare with other features in luminous, dusty galaxies. Sources have 0.004 < z < 0.34 and 43.0 < log L(IR) < 46.8 (erg per sec) and cover the full range of starburst galaxy and AGN classifications. Obtaining these CII line fluxes with PACS will allow: 1. determining how precisely CII luminosity measures star formation rate by comparing to PAH features and emission lines that arise in starburst galaxies; 2. determining how CII luminosity and equivalent width changes with starburst/AGN fraction, by comparing with strength and equivalent width of PAH and NeII emission arising from starbursts, and with strength of high ionization lines NeV and OIV and silicate absorption or emission arising from AGN; 3. determining how CII luminosity and equivalent width changes with dust temperature and bolometric luminosity, as derived from spectral energy distributions, and whether this depends on the starburst/AGN fraction. These determinations will allow interpretation of high redshift sources for which the only available diagnostics are the luminosity and equivalent width of the CII line and the far-infrared rest-frame SED. The total observing program requires 20.2 hours of Herschel observing time. |
