Results are presented for [CII] 158 micron line fluxes observed with the
Herschel PACS instrument in 112 sources with both starburst and AGN
classifications, of which 102 sources have confident detections. Results are
compared with mid-infrared spectra from the Spitzer Infrared Spectrometer and
with L(IR) from IRAS fluxes; AGN/starburst classifications are determined from
equivalent width of the 6.2 micron PAH feature. It is found that the [CII] line
flux correlates closely with the flux of the 11.3 micron PAH feature
independent of AGN/starburst classification, log [f([CII] 158 micron)/f(11.3
micron PAH)] = -0.22 +- 0.25. It is concluded that [CII] line flux measures the
photodissociation region associated with starbursts in the same fashion as the
PAH feature. A calibration of star formation rate for the starburst component
in any source having [CII] is derived comparing [CII] luminosity L([CII]) to
L(IR) with the result that log SFR = log L([CII)]) - 7.08 +- 0.3, for SFR in
solar masses per year and L([CII]) in solar luminosities. The decreasing ratio
of L([CII]) to L(IR) in more luminous sources (the "[CII] deficit") is shown to
be a consequence of the dominant contribution to L(IR) arising from a luminous
AGN component because the sources with largest L(IR) and smallest
L([CII])/L(IR) are AGN.Comment: Accepted for publication in The Astrophysical Journa
