2003/02/17 by K. C. Sahu, Kailash C. Sahu, Sahu, Kailash C.
Physics and Astronomy · #Astrophysics (astro-ph) #FOS: Physical sciences #History and Developments in Astronomy #Scientific Research and Discoveries #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/0302325
15 pages, including 4 figures. To appear in the Proceedings of the STScI Symposium on "Dark Universe: Matter, Energy, and Gravity"
arxiv created 2003/02/17 · openalex publication_date 2003/02/17 · arxiv updated 2009/12/01 · openalex created_date 2022/10/07 · openalex updated_date 2026/07/28
(Abridged) A close scrutiny of the microlensing results towards the\nMagellanic clouds reveals that the stars within the Magellanic clouds are major\ncontributors as lenses, and the contribution of MACHOs to dark matter is 0 to\n5%. The principal results which lead to this conclusion are the following.\n (i) Out of the ~17 events detected so far towards the Magellanic Clouds, the\nlens locations have been determined for four events where the lenses are most\nlikely within the Magellanic clouds.\n (ii) If caused by MACHOs, the event timescales would imply that the MACHOs in\nthe direction of the LMC and the SMC have masses of the order of 0.5 and 2\nsolar masses, respectively. This is inconsistent with even the most flattened\nmodel of the Galaxy. If caused by stars within the Magellanic Clouds, the\nmasses of the lenses are of the order of 0.2 solar mass for both the LMC as\nwell as the SMC.\n (iii) The fact that the two observed binary events are caused by lenses\nwithin the Magellanic Clouds would suggest that there should be a total of ~20\nevents caused by lenses within the Magellanic Clouds. This implies that most of\nthe microlensing events observed so far are probably caused by stars within the\nMagellanic Clouds.\n (iv) If the microlensing events are caused by MACHOs of 0.5 solar mass, ~15\nevents should have been detected by now towards the SMC, with timescales of ~40\ndays. The fact that both the events detected towards the SMC have been shown to\nbe due to self-lensing places severe constraints on the MACHO contribution and\nsuggests that the contribution of MACHOs to dark matter is consistent with\nzero, with an upper limit of 5%.\n