Properties of Galactic cirrus clouds observed by BOOMERanG
  The physical properties of galactic cirrus emission are not well
characterized. BOOMERanG is a balloon-borne experiment designed to study the
cosmic microwave background at high angular resolution in the millimeter range.
The BOOMERanG 245 and 345GHz channels are sensitive to interstellar signals, in
a spectral range intermediate between FIR and microwave frequencies. We look
for physical characteristics of cirrus structures in a region at high galactic
latitudes (b~-40{\deg}) where BOOMERanG performed its deepest integration,
combining the BOOMERanG data with other available datasets at different
wavelengths. We have detected eight emission patches in the 345 GHz map,
consistent with cirrus dust in the Infrared Astronomical Satellite maps. The
analysis technique we have developed allows to identify the location and the
shape of cirrus clouds, and to extract the flux from observations with
different instruments at different wavelengths and angular resolutions. We
study the integrated flux emitted from these cirrus clouds using data from
Infrared Astronomical Satellite (IRAS), DIRBE, BOOMERanG and Wilkinson
Microwave Anisotropy Probe (WMAP) in the frequency range 23-3000 GHz (13 mm 100
micron wavelength). We fit the measured spectral energy distributions with a
combination of a grey body and a power-law spectra considering two models for
the thermal emission. The temperature of the thermal dust component varies in
the 7 - 20 K range and its emissivity spectral index is in the 1 - 5 range. We
identified a physical relation between temperature and spectral index as had
been proposed in previous works. This technique can be proficiently used for
the forthcoming Planck and Herschel missions data.
