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Related papers: Microlensing optical depth toward the Galactic Bul…

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Measurements of the microlensing optical depth and event rate toward the Large Magellanic Cloud (LMC) can be used to probe the distribution and mass function of compact objects in the direction toward that galaxy - in the Milky Way disk,…

We estimate the optical depth to self-lensing by stars in the Galactic bulge using the HST star counts of Holtzman et al and Zoccali et al as extrapolated by Gould into the brown-dwarf and remnant regimes and deprojected along the line of…

Astrophysics · Physics 2009-11-07 Cheongho Han , Andrew Gould

We examine the left-right asymmetry in the cleaned COBE/DIRBE near-infrared data of the inner Galaxy and show (i) that the Galactic bar is probably not seen very nearly end-on, and (ii) that even if it is, it is not highly elongated. The…

Astrophysics · Physics 2015-06-24 N. Bissantz , P. Englmaier , J. Binney , O. Gerhard

The analysis of the first two years of OGLE data revealed 9 microlensing events of the galactic bulge stars, with the characteristic time scales in the range $ 8.6 < t_0 < 62 $ days, where $ t_0 = R_E / V $. The optical depth to…

Astrophysics · Physics 2008-12-18 B. Paczynski , K. Z. Stanek , A. Udalski , M. Szymanski , J. Kaluzny , M. Kubiak , M. Mateo , W. Krzeminski

We present and study the largest and the most comprehensive catalog of microlensing events ever constructed. The sample of standard microlensing events comprises 3718 unique events from years 2001--2009, with 1409 not detected before in…

We review recent gravitational microlensing results from the EROS, MACHO, and OGLE collaborations, and present some details of the very latest MACHO results toward the Galactic Bulge. The MACHO collaboration has now discovered in excess of…

EROS has been monitoring few million stars in the Magellanic clouds, as well as toward the Galactic bulge and spiral arms since 1996, to search for microlensing events. In this paper, we present briefly the EROS setup and scientific program…

Astrophysics · Physics 2007-05-23 R. Ansari

We present the photometry and theoretical models for a Galactic bulge microlensing event OGLE-2000-BUL-43. The event is very bright with I=13.54 mag, and has a very long time scale, t_E=156 days. The long time scale and its light curve…

We present a catalog of 450 high signal-to-noise microlensing events observed by the MACHO collaboration between 1993 and 1999. The events are distributed throughout our fields and, as expected, they show clear concentration toward the…

Gravitational microlensing is not only a successful tool for discovering distant exoplanets, but it also enables characterization of the lens and source stars involved in the lensing event. In high magnification events, the lens caustic may…

Solar and Stellar Astrophysics · Physics 2015-05-18 P. Fouque , D. Heyrovsky , S. Dong , A. Gould , A. Udalski , M. D. Albrow , V. Batista , J. -P. Beaulieu , D. P. Bennett , I. A. Bond , D. M. Bramich , S. Calchi Novati , A. Cassan , C. Coutures , S. Dieters , M. Dominik , D. Dominis Prester , J. Greenhill , K. Horne , U. G. Jorgensen , S. Kozlowski , D. Kubas , C. -H. Lee , J. -B. Marquette , M. Mathiasen , J. Menzies , L. A. G. Monard , S. Nishiyama , I. Papadakis , R. Street , T. Sumi , A. Williams , J. C. Yee , S. Brillant , J. A. R. Caldwell , A. Cole , K. H. Cook , J. Donatowicz , N. Kains , S. R. Kane , R. Martin , K. R. Pollard , K. C. Sahu , Y. Tsapras , J. Wambsganss , M. Zub , D. L. DePoy , B. S. Gaudi , C. Han , C. -U. Lee , B. -G. Park , R. W. Pogge , M. Kubiak , M. K. Szymanski , G. Pietrzynski , I. Soszynski , O. Szewczyk , K. Ulaczyk , L. Wyrzykowski , F. Abe , A. Fukui , K. Furusawa , A. C. Gilmore , J. B. Hearnshaw , Y. Itow , K. ~Kamiya , P. M. Kilmartin , A. V. Korpela , W. Lin , C. H. Ling , K. Masuda , Y. Matsubara , N. Miyake , Y. Muraki , M. Nagaya , K. Ohnishi , T. Okumura , Y. Perrott , N. J. Rattenbury , To. Saito , T. Sako , S. Sato , L. Skuljan , D. Sullivan , W. Sweatman , P. J. Tristram , P. C. M. Yock , A. Allan , M. F. Bode , M. J. Burgdorf , N. Clay , S. N. Fraser , E. Hawkins , E. Kerins , T. A. Lister , C. J. Mottram , E. S. Saunders , C. Snodgrass , I. A. Steele , P. J. Wheatley , T. Anguita , V. Bozza , K. Harpsoe , T. C. Hinse , M. Hundertmark , P. Kjaergaard , C. Liebig , L. Mancini , G. Masi , S. Rahvar , D. Ricci , G. Scarpetta , J. Southworth , J. Surdej , C. C. Thone , A. Riffeser , S. ~Seitz , R. Bender

We present preliminary results of the analysis of 5 years of MACHO data on the Galactic bulge microlensing events with clump giants as sources. In particular, we discuss: 1) the selection of `giant' events, 2) distribution of impact…

Source blending in microlensing experiments is known to modify the Einstein time of the observed events. In this paper, we have conducted Monte-Carlo calculations, using the analytical relationships derived by Han (1999) to quantify the…

Astrophysics · Physics 2009-11-11 Yann Alibert , Gilles Chabrier , Gerard Massacrier

The primary goal of this paper is to provide the evidence that can either prove or falsify the hypothesis that dark matter in the Galactic halo can clump into stellar-mass compact objects. If such objects existed, they would act as lenses…

We present a systematic search for parallax microlensing events among a total of 512 microlensing candidates in the OGLE II database for the 1997-1999 seasons. We fit each microlensing candidate with both the standard microlensing model and…

Astrophysics · Physics 2009-11-07 M. C. Smith , S. Mao , P. R. Wozniak

For the first time we detected microlensing events at zero latitude in the Galactic bulge using the VISTA Variables in the Via Lactea Survey (VVV) data. We have discovered a total sample of N = 630 events within an area covering 20.7 sq.…

We analyze the first-year MACHO collaboration observations of microlensing towards the Galactic center using a new direct likelihood technique that is sensitive to the distribution of the events on the sky. We consider the full set of 41…

Astrophysics · Physics 2007-05-23 Geza Gyuk

We show that the statistical error, $\sigma_{\tau}$, in estimating the optical depth, $\tau$, due to microlensing is substantially higher than the naive Poisson estimate: $\sigma_{\tau} = \sqrt{\eta / N} \tau$, where $N$ is the number of…

Astrophysics · Physics 2009-10-22 Cheongho Han , Andrew Gould

Following the suggestion of Gould and Depoy (1998) we investigate the feasibility of studying the brightest microlensing events towards the Galactic bulge using a small aperture (~10 cm) telescope. We used one of the HAT telescopes to…

Astrophysics of Galaxies · Physics 2009-05-01 D. M. Nataf , K. Z. Stanek , G. A. Bakos

Microlensing events are usually selected among single-peaked non-repeating light curves in order to avoid confusion with variable stars. However, a microlensing event may exhibit a second microlensing brightening episode when the source…

Astrophysics · Physics 2009-11-13 J. Skowron , L. Wyrzykowski , S. Mao , M. Jaroszynski