Investigating the delay between dust radiation and star-formation in
  local and distant quenching galaxies
  We investigate the timescale with which the IR luminosity decreases after a
complete and rapid quenching of star formation using observations of local and
high-redshift galaxies. From SED modelling, we derive the time since quenching
of a subsample of 14 galaxies from the Herschel Reference Survey suffering from
ram-pressure stripping due to the environment of the Virgo cluster and of a
subsample of 7 rapidly quenched COSMOS galaxies selected through a
state-of-the-art statistical method already tested on the determination of
galaxies' star formation history. Three out of the 7 COSMOS galaxies have an
optical spectra with no emission line, confirming their quenched nature.
Present physical properties of the two samples are obtained as well as the past
L$_{IR}$ of these galaxies, just before their quenching, from the long-term SFH
properties. This past L$_{IR}$ is shown to be consistent with the L$_{IR}$ of
reference samples of normally star-forming galaxies with same $M_*$ and $z$
than each of our quenched galaxies. We put constraints on the present to past
L$_{IR}$ ratio as a function of quenching time. The two samples probe different
dynamical ranges in terms of quenching age with the HRS galaxies exhibiting
longer timescales (0.2-3\,Gyr) compared to the COSMOS one ($<100$\,Myr).
Assuming an exponential decrease of the L$_{IR}$ after quenching, the COSMOS
quenched galaxies are consistent with short e-folding times less than a couple
of hundreds of Myr while the properties of the HRS quenched galaxies are
compatible with timescales of several hundreds of Myr. For the HRS sample, this
result is consistent with ram pressure stripping due to the environment. For
the COSMOS sample, different quenching processes are acting on short to
intermediate timescales. Processes such as galaxy mergers, disk instabilities
or environmental effects can produce such strong star formation variability.
