Star formation in LINER host galaxies at z~0.3
  We present the results of a Herschel-PACS study of a sample of 97 LINERs at
redshift z\sim 0.3 selected from the zCOSMOS survey. Of these sources, 34 are
detected in a least one PACS band, enabling reliable estimates of the
far-infrared L(FIR) luminosities, and a comparison to the FIR luminosities of
local LINERs. Many of our PACS-detected LINERs are also UV sources detected by
Galex. Assuming that the FIR is produced in young dusty star-forming regions,
the typical star-formation rates (SFRs) for the host galaxies in our sample is
\sim 10 M_Sun yr-1, 1-2 orders of magnitude larger than in many local LINERs.
Given stellar masses inferred from optical/NIR photometry of the (unobscured)
evolved stellar populations, we find that the entire sample lies close to the
star-forming "main sequence" for galaxies at redshift 0.3. For young
star-forming regions, the H\alpha- and UV-based estimates of the SFRs are much
smaller than the FIR-based estimates, by factors \sim 30, even assuming that
all of the H\alpha\ emission is produced by O-star ionization rather than by
the AGNs. These discrepancies may be due to large (and uncertain) extinctions
towards the young stellar systems. Alternatively, the H\alpha\ and UV emissions
could be tracing residual star-formation in an older less obscured population
with decaying star formation. We also compare L(SF) and L(AGN) in local LINERs
and in our sample and comment on the problematic use of several line diagnostic
diagrams in cases similar to the sample under study.
