A search for stellar obscuration events due to dark clouds
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Date
2003
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Abstract
The recent detections of a large population of faint submillimeter sources, an excess halo gamma-ray background, and the extreme scattering events observed for extragalactic radio sources have been explained as being due to baryonic dark matter in the form of small, dark gas clouds. In this paper, we present the results of a search for the transient stellar obscurations such clouds are expected to cause. We examine the MACHO project light curves of 48 x 10(6) stars toward the Galactic bulge, Large Magellanic Cloud, and Small Magellanic Cloud for the presence of dark cloud extinction events. We find no evidence for a population of dark gas clouds with A(V) > 0.2 in the masses range from similar to10(-4) to 2 x 10(-2) M-., in either the Galactic disk or halo. However, it is possible that such dark cloud populations could exist if they are clustered in regions away from the observed lines of sight.
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Keywords
dark matter, dust, extinction, Galaxy : halo, ISM : clouds