Статья

Far-infrared spectral observations of the galaxy by COBE

Reach, W TUniversities Space Research Association, NASA Goddard Space Flight Center, Code 685, Greenbelt, MD 20771Dwek, ENASA Goddard Space Flight Center, Code 685, Greenbelt, MD 20771Fixsen, D JApplied Research Corporation, Code 685.3, Greenbelt, MD 20771Hewagama, THughes-STX, Code 685.9, Greenbelt, MD 20771Mather, J CNASA Goddard Space Flight Center, Code 685, Greenbelt, MD 20771Shafer, R ANASA Goddard Space Flight Center, Code 685, Greenbelt, MD 20771Banday, A JUniversities Space Research Association, NASA Goddard Space Flight Center, Code 685, Greenbelt, MD 20771Bennett, C LNASA Goddard Space Flight Center, Code 685, Greenbelt, MD 20771Cheng, E SNASA Goddard Space Flight Center, Code 685, Greenbelt, MD 20771Eplee, R EGeneral Sciences Corporation, Code 685.3, Greenbelt, MD 20771Leisawitz, D TNASA Goddard Space Flight Center, Code 631.0, Greenbelt, MD 20771Lubin, P MUCSB Physics Department, Santa Barbara, CS 93106Read, S MHughes-STX, Code 685.9, Greenbelt, MD 20771Rosen, L PHughes-STX, Code 685.9, Greenbelt, MD 20771Shuman, D BHughes-STX, Code 685.9, Greenbelt, MD 20771Smoot, G FLBL & SSL, Bldg 50-351, University of California, Berkeley, CA 94720Sodroski, T JApplied Research Corporation, Code 685.3, Greenbelt, MD 20771Wright, E L

1995en

ABI

Аннотация

We derive Galactic continuum spectra from 5-96/cm from COBE/FIRAS observations. The spectra are dominated by warm dust emission, which may be fit with a single temperature in the range 16-21 K (for nu^2 emissivity) along each line of sight. Dust heated by the attenuated radiation field in molecular clouds gives rise to intermediate temperature (10-14 K) emission in the inner Galaxy only. A widespread, very cold component (4-7 K) with optical depth that is spatially correlated with the warm component is also detected. The cold component is unlikely to be due to very cold dust shielded from starlight, because it is present at high latitude. We consider hypotheses that the cold component is due to enhanced submillimeter emissivity of the dust that gives rise to the warm component, or that it may be due to very small, large, or fractal particles. Lack of substantial power above the emission from warm dust places strong constraints on the amount of cold gas in the Galaxy. The microwave sky brightness due to interstellar dust is dominated by the cold component, and its angular variation could limit our ability to discern primordial fluctuations in the cosmic microwave background radiation.

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