Looking for dark matter via gravitational microlensing: A report from the MACHO collaboration
- Center for Particle Astrophysics, University of California, Berkeley, California 94720 (United States)
- Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)
- Mount Stromlo and Siding Springs Observatories, Australian National University, Weston, ACT 2611 (Australia)
There is convincing evidence that the mass of ordinary galaxies, like our own, is much greater than that measured in the form of stars, gas, and dust. If this dark matter is in the form of compact objects it can be detected via gravitational microlensing of background stars. The MACHO project is in its second year of a time resolved photometric survey of the Magellanic Clouds and galactic bulge to search for the rare microlensing signature of compact objects in the halo and disk of our galaxy. We are using a dedicated 1.3-m telescope at Mt. Stromlo Observatory and a dual focal plane CCD mosaic camera with a 0.5 square degree field to image up to 10 million stars per night simultaneously in two passbands. As of October 1994, 26,000 images have been taken with this system. A preliminary analysis of more than 8 million stars in the LMC for one year has yielded three stars which undergo time-symmetric achromatic photometric excursions consistent with gravitational microlensing. In a similar analysis of {approximately}10 million stars in the galactic bulge we have also found more than 40 likely microlensing candidates, several of which reach peak amplifications of greater than ten. The relatively high rate toward the bulge is consistent with a {open_quote}{open_quote}maximal{close_quote}{close_quote} disk that accounts for most of the galactic mass interior to the solar radius or microlensing by a galactic bar.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 279568
- Report Number(s):
- CONF-9409150-; ISSN 0094-243X; TRN: 96:018358
- Journal Information:
- AIP Conference Proceedings, Vol. 342, Issue 1; Conference: CAM `94: Canadian-American-Mexican physics meeting, Cancun (Mexico), 26-30 Sep 1994; Other Information: PBD: Aug 1995
- Country of Publication:
- United States
- Language:
- English
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