The Herschel Virgo Cluster Survey: VI. The far-infrared view of M87
  The origin of the far-infrared emission from the nearby radio galaxy M87
remains a matter of debate. Some studies find evidence of a far-infrared excess
due to thermal dust emission, whereas others propose that the far-infrared
emission can be explained by synchrotron emission without the need for an
additional dust emission component. We present Herschel PACS and SPIRE
observations of M87, taken as part of the science demonstration phase
observations of the Herschel Virgo Cluster Survey. We compare these data with a
synchrotron model based on mid-infrared, far-infrared, submm and radio data
from the literature to investigate the origin of the far-infrared emission.
Both the integrated SED and the Herschel surface brightness maps are adequately
explained by synchrotron emission. At odds with previous claims, we find no
evidence of a diffuse dust component in M87, which is not unexpected in the
harsh X-ray environment of this radio galaxy sitting at the core of the Virgo
Cluster.
