The Macho Project III: Probable Detection of Microlensing by Compact Halo Objects

Previous abstract Next abstract

Session 72 -- High Z Line Measurements; Gravitational Microlensing: Distance Determination
Display presentation, Friday, January 14, 9:30-6:45, Salons I/II Room (Crystal Gateway)

[72.07] The Macho Project III: Probable Detection of Microlensing by Compact Halo Objects

K. Cook, C. Alcock, R. Allsman, T. Axelrod, H.-S. Park (LLNL), C. Akerlof, D. Bennett, K. Griest, S. Marshall, S. Perlmutter, M. Pratt, C. Stubbs, W. Sutherland (CfPA), K. Freeman, B. Peterson, P. Quinn, A. Rodgers (MSSSO)

The Macho Project is entering the second year of a long-term, time resolved, photometric survey of the LMC and the Milky Way's bulge in an effort to detect the gravitational microlensing signature of dark, massive compact halo objects (MACHOs). Details of the Macho instrumental system, the Macho data reduction, analysis and efficiency calculations, and variable star astronomical results are presented in accompanying posters. We present in this poster light curves and their analyses representing our most probable detections of microlensing events toward the LMC and the Bulge. These events represent a range of amplifications from 1.4 to 7 and durations of a few weeks. The events were discovered in the analysis of about 300 observations of 6 million stars. We discuss and reject the possibility that our events are due to intrinsic stellar variability. We also present an unlensed spectrum of the star involved in our highest amplitude lensing event.

We examine the effect of various assumptions about dark matter mass distributions and spatial distributions on the derived characteristics of the detected lensing objects. Finally, we will present our strategies for further observations and analyses in order to determine the contribution of MACHOs to the halo mass.

Friday program listing