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Extending the MACHO search to about 10 exp 6 solar masses

1992; IOP Publishing; Volume: 392; Linguagem: Inglês

10.1086/171443

1538-4357

Andrew Gould,

History and Developments in Astronomy

view Abstract Citations (411) References (12) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Extending the MACHO Search to approximately 10 6 M sub sun Gould, Andrew Abstract The search for a microlensing (changing light-curve) signature of massive compact halo objects (Machos) by the Macho Collaboration is currently believed to be sensitive in the range 10^-7^-10^2^ M_sun_. Microlensing events from higher mass objects last longer than the 4 yr duration of the planned experiments and therefore, according to current beliefs, cannot be distinguished from long-term variables. In fact the signature of Machos in the range 10^2^-10^3^ M_sun_ can be distinguished from background events by the annual modulation in light magnification induced by the Earth's motion. For Machos in the range 10^3^-10^6^ M_sun_, Hubble Space Telescope (HST), or even ground-based measurements can resolve the split lensed images, thus confirming the lens interpretation of an event. If the HST's optics were repaired, it could resolve images for Machos >~ 300 M_sun_. The lower mass limit can be reduced to 4 x 10^-9^ M_sun_ by conducting 1 month of rapid repeat observations of a single field. The standard view is that a Macho light curve yields only one physically relevant parameter, the time scale of the event. The time scale is a combination of the four parameters one would like to know: the mass, the distance, and the two components of transverse velocity of the Macho. I show that for masses 4-100 M_sun_, annual parallax oscillations in the light curve can be used to determine the transverse velocity. In the range 10^-3^-10^6^ M_sun_ such measurements can be made using a small special-purpose satellite telescope. For masses 10^3^-10^6^ M_sun_, one may determine all four Macho parameters by combining a number of techniques. Publication: The Astrophysical Journal Pub Date: June 1992 DOI: 10.1086/171443 Bibcode: 1992ApJ...392..442G Keywords: Astronomical Photometry; Gravitational Lenses; Halos; Light Curve; Dark Matter; Hubble Space Telescope; Magellanic Clouds; Stellar Mass; Astrophysics; ASTROMETRY; COSMOLOGY: GRAVITATIONAL LENSING; GALAXY: HALO; TECHNIQUES: PHOTOMETRIC full text sources ADS | data products SIMBAD (1)