Spitzer Space Telescope - General Observer Proposal #3327


Catching the bulk of non-thermal radiation from hot-spots:  proving
particle acceleration in extragalactic radio sources

Principal Investigator: Marco Bondi
           Institution: Istituto di Radioastronomia

Co-Investigators: 
Gianfranco Brunetti, Istituto di Radioastronomia                      
Giancarlo Setti, Dipartimento di Astronomia, Univ. di Bologna         
Karl-Heinz Mack, Istituto di Radioastronomia                          

Science Category: AGN/quasars/radio galaxies 
 Observing Modes: IracMap MipsPhot 
  Hours Approved: 3.1 

Abstract:
We request 3.1 hours of IRAC (3.6 through 8.0  $mu$m) and MIPS (24
$mu$m only) observations of a small sample of extragalactic hot-spots
(HSs) with published sensitive radio and optical data.  HSs are
compact regions in the radio lobes of powerful extragalactic radio
sources emitting synchrotron radiation.  In these regions electrons
are re-accelerated through shocks.  In the last years, arcsecond
resolution radio, optical and X-ray observations of hot-spots have
allowed to understand and model the physics of acceleration in these
regions.  Infrared observations are particularly relevant since the
emitting properties of the HSs in this band are almost unknown and it
is in this domain that the selected hot-spots are expected to release
the bulk of their synchrotron emission.  The proposed observations
represent a unique possibility to test the existent models of shock
emission and clearly discriminate between different interpretations,
in particular whether a single or multiple electron population is
responsible for the broad-band synchrotron emission.