Open AccessJournal Article
The Optical Gravitational Lensing Experiment. The Optical Depth to Gravitational Microlensing in the Direction of the Galactic Bulge
Andrzej Udalski,Michał K. Szymański,Krzysztof Z. Stanek,Krzysztof Z. Stanek,Janusz Kaluzny,M. Kubiak,Mario Mateo,Wojtek Krzeminski,Bohdan Paczynski,R. Venkat +9 more
TLDR
In this paper, the first two years of the OGLE search for gravitational lenses towards the Galactic bulge were analyzed. And they found that the optical depth to microlensing is larger than 3.3 ± 1.2 × 10−6.Abstract:
We present the analysis of the first two years of the OGLE search for gravitational lenses towards the Galactic bulge. We detected 9 microlensing events in an algorithmic search of $ \\sim 10^8 $ measurements of $ \\sim 10^6 $ stars. The characteristic time scales are in the range $ 8.6 < t_0 < 62 $ days, where $ t_0 = R_E / V $. The distribution of amplitudes is consistent with theoretical expectation. The stars seem to be drawn at random from the overall distribution of the observed bulge stars. We find that the optical depth to microlensing is larger than $ ( 3.3 \\pm 1.2 ) \\times 10^{-6}$, in excess of current theoretical estimates.read more
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Unbound or distant planetary mass population detected by gravitational microlensing
Takahiro Sumi,Kisaku Kamiya,David P. Bennett,Ian A. Bond,Fumio Abe,C. S. Botzler,Akihiko Fukui,K. Furusawa,John B. Hearnshaw,Yoshitaka Itow,P. M. Kilmartin,A. V. Korpela,W. Lin,C. H. Ling,Kimiaki Masuda,Yutaka Matsubara,N. Miyake,M. Motomura,Yasushi Muraki,M. Nagaya,Shota Nakamura,Kouji Ohnishi,Teppei Okumura,Y. C. Perrott,Nicholas J. Rattenbury,To. Saito,T. K. Sako,Denis J. Sullivan,Winston L. Sweatman,P. J. Tristram,P. C. M. Yock,Andrzej Udalski,Michał K. Szymański,M. Kubiak,Grzegorz Pietrzyński,Radosław Poleski,Igor Soszyński,Łukasz Wyrzykowski,K. Ulaczyk +38 more
TL;DR: The discovery of a population of unbound or distant Jupiter-mass objects is reported, which are almost twice as common as main-sequence stars, based on two years of gravitational microlensing survey observations towards the Galactic Bulge.
Journal ArticleDOI
The MACHO Project Large Magellanic Cloud Microlensing Results from the First Two Years and the Nature of the Galactic Dark Halo
Charles Alcock,Charles Alcock,R. A. Allsman,David R. Alves,David R. Alves,Tim Axelrod,Andrew C. Becker,Andrew C. Becker,David P. Bennett,Kem H Cook,Kem H Cook,Kenneth C. Freeman,Kim Griest,Kim Griest,J. A. Guern,J. A. Guern,Matthew J. Lehner,Matthew J. Lehner,S. L. Marshall,S. L. Marshall,Bruce A. Peterson,M. R. Pratt,M. R. Pratt,M. R. Pratt,Peter J. Quinn,A. W. Rodgers,Christopher W. Stubbs,Christopher W. Stubbs,William J. Sutherland,Douglas L. Welch +29 more
TL;DR: In this paper, the authors estimate the total microlensing optical depth toward the LMC from events with 2 < < 200 days to be τ2002=2.9×10−7 based upon their eight event sample.
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