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The project Galactic Cold Cores has made Herschel observations of interstellar clouds where the Planck satellite survey has located cold and compact clumps. The sources range from starless clumps to protostellar cores. We examine 116…

Four microlensing collaborations are presently searching for compact matter in the Galaxy and all have detected possible candidates. Using the detection efficiencies recently published by the MACHO and OGLE collaborations, we present…

Astrophysics · Physics 2015-06-24 Eamonn J. Kerins

Extreme microlensing events, defined as events with maximum magnification $A_\max\gsim 200$ are a potentially powerful probe of the mass spectrum and spatial distribution of objects along lines of sight toward the Galactic bulge. About 75…

Astrophysics · Physics 2007-05-23 Andrew Gould

Microlensing has established itself as a powerful new method for the detection of baryonic dark matter in the Galaxy. The theory of microlensing is sketched and its similarity with the optical effect of twinkling is explained. The bulk of…

Astrophysics · Physics 2007-05-23 Wyn Evans

We completed the search for microlensing events in the zero latitude area of the Galactic bulge using the VVV Survey near-IR data obtained between 2010 and 2015. We have now a total sample of N = 630 events Using the near-IR Color-Magnitude…

Astrophysics of Galaxies · Physics 2018-09-26 María Gabriela Navarro , Dante Minniti , Rodrigo Contreras Ramos

The MACHO project carries out regular photometric monitoring of millions of stars in the Magellanic Clouds and Galactic Bulge, to search for very rare gravitational microlensing events due to compact objects in the galactic halo and disk. A…

We use high-resolution N-body simulations to study the galaxy-cluster cross-sections and the abundance of giant arcs in the $\Lambda$CDM model. Clusters are selected from the simulations using the friends-of-friends method, and their…

Astrophysics · Physics 2009-11-10 G. L. Li , S. Mao , Y. P. Jing , M. Bartelmann , X. Kang , M. Meneghetti

Foundations of standard theory of microlensing are described, namely we consider microlensing stars in Galactic bulge, the Magellanic Clouds or other nearby galaxies. We suppose that gravitational microlenses lie between an Earth observer…

Astrophysics · Physics 2007-05-23 A. F. Zakharov

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

Due to their scarcity, microlensing events in the Galactic disk are of great interest and high-cadence photometric observations, supplemented by spectroscopic follow-up, are necessary for constraining the physical parameters of the lensing…

The Galactic bulge and bar are critical to our understanding of the Milky Way. However, due to the lack of reliable stellar distances, the structure and kinematics of the bulge/bar beyond the Galactic center have remained largely…

We study the prospects for measuring the cosmological distribution and abundance of ionized electrons in the intergalactic medium using galaxy surveys. Optical light from distant galaxies is subject to Thomson screening by intervening…

Cosmology and Nongalactic Astrophysics · Physics 2024-04-18 Selim C. Hotinli , Gilbert P. Holder

Aims. We attempt to determine the optical depth of spiral galaxy disks by a statistical study of new Tully-Fisher data from the ongoing KLUN+ survey, and to clarify the difference between the true and apparent behavior of optical depth.…

Astrophysics · Physics 2009-11-13 E. Kankare , M. Hanski , G. Theureau , P. Teerikorpi

We examine the constraints on the epoch of reionization (redshift z_r) set by recent WMAP-3 observations of tau_e = 0.09 +/- 0.03, the electron-scattering optical depth of the cosmic microwave background (CMB), combined with models of…

Astrophysics · Physics 2007-05-23 Michael Shull , Aparna Venkatesan

This article summarizes the structural parameters of the Galactic bulge and disk, and discusses the interpretation of the bulge microlensing observations and the determination of the Milky Way's luminous mass from the terminal velocity…

Astrophysics · Physics 2007-05-23 Ortwin Gerhard

I derive a general expression for the optical depth $\tau$ for gravitational lensing of stars in a disk by Massive Compact Objects (Machos) in the same disk. For the more restricted case where the disk is self-gravitating and the stars and…

Astrophysics · Physics 2009-10-22 Andrew Gould

During microlensing events with a small impact parameter, the amplification of the source flux is sensitive to the surface brightness distribution of the source star. Such events provide a means for studying the surface structure of target…

Astrophysics · Physics 2009-10-31 David Heyrovsky , Dimitar Sasselov

We consider a contribution of microlensing in X-ray variability of high-redshifted QSOs. Such an effect could be caused by stellar mass objects (SMO) located in a bulge or/and in a halo of this quasar as well as at cosmological distances…

Astrophysics · Physics 2009-11-10 A. F. Zakharov , L. C. Popovic , P. Jovanovic

The most important uncertainty in the results of gravitational microlensing experiments comes from the difficulties of photometry caused by blending of source stars. Recently Nemiroff (1997) pointed out that the results of microlensing…

Astrophysics · Physics 2007-05-23 Seunghun Lee , Cheongho Han