Traceurs du gaz neutre et froid

1
Gas and mm Dust emission
François Boulanger et Guilaine Lagache (Institut
d Astrophysique Spatiale, Orsay)

• Tracing diffuse ISM components in te Solar
  Neighborhood and across the Galaxy with mm dust
  emission
• mm dust properties across the HI/H2 transition

2
Gas Tracers

• Diffuse H II Pulsar dispersion measure
• H I 21 cm Line
• Misses cold H I
• H2 CO low J rotational lines
• several caveats optical thickness, CO
  photo-dissociation
• Misses  diffuse  H2 (seen in absorption and in
  gamma rays)
• Dust H I and H2
• Extinction clumping
• Far-IR emission per dust mass is temperature
  dependent
• mm dust emission Matter Tracer
• Galaxies and star forming cores (ground
  telescopes) ltgt diffuse ISM
• Dust emissivity How constant across the
  HII/HI/Diffuse H2/CO transitions?

3
IR-HI Correlation at 1.2mm
FIRAS HI all-sky survey
4
Molecular Gas
5
Longitude Profile
6
HI/H2 Transition Solar Neighorhood
H2 self-shielding HI ? H2 pour NHgt 5 1020
H/cm2   
Savage et al. 1977