2009/08/26 by S. Calchi Novati, L. Mancini, G. Scarpetta +2 · 1 citation
Physics and Astronomy · #Astronomy #Astronomy and Astrophysical Research #Astrophysics #Galactic halo #Galaxies: Formation, Evolution, Phenomena #Galaxy #Gravitational lens #Gravitational microlensing #Halo #Large Magellanic Cloud #Mass ratio #Physics #Small Magellanic Cloud #Stars #Stellar, planetary, and galactic studies #astro-ph.GA
paper · pdf · doi:10.1111/j.1365-2966.2009.15570.x
published as MNRAS 400, 1625 (2009) · accepted for publication in MNRAS
arxiv created 2009/08/26 · openalex publication_date 2009/10/15 · arxiv updated 2015/05/14 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
In the framework of microlensing searches towards the Large Magellanic Cloud (LMC), we discuss the results presented by the Optical Gravitational Lensing Experiment (OGLE) collaboration for their OGLE-II campaign (Wyrzykowski et al). We evaluate the optical depth, the duration and the expected rate of events for the different possible lens populations: both luminous, dominated by the LMC self-lensing, and ‘dark’, the would be compact halo objects (massive compact halo objects) belonging to either the Galactic or the LMC halo. The OGLE-II observational results, two microlensing candidate events located in the LMC bar region with duration of 24.2 and 57.2 days, compare well with the expected signal from the luminous lens populations: nexp= 1.5, with typical duration, for LMC self-lensing, of about 50 days. Because of the small statistics at disposal, however, the conclusions that can be drawn as for the halo mass fraction, f, in the form of compact halo objects are not too severe. By means of a likelihood analysis we find an upper limit for f, at 95 per cent confidence level, of about 15 per cent in the mass range (10−2–10−1) M⊙ and 26 per cent for 0.5 M⊙.