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Traditional approaches to measuring the stellar mass function (MF) are fundamentally limited because objects are detected based on their luminosity, not their mass. These methods are thereby restricted to luminous and relatively nearby…

Astrophysics · Physics 2009-10-28 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 report on the first results from a large-scale observing campaign aiming to use astrometric microlensing to detect and place limits on the mass of single objects, including stellar remnants. We used the Hubble Space Telescope to monitor…

Solar and Stellar Astrophysics · Physics 2017-08-02 Noé Kains , A. Calamida , K. C. Sahu , S. Casertano , J. Anderson , A. Udalski , M. Zoccali , H. Bond , M. Albrow , I. Bond , T. Brown , M. Dominik , C. Fryer , M. Livio , S. Mao , M. Rejkuba

We present a statistical assessment of both, observed and reported, photometric uncertainties in the OGLE-IV Galactic bulge microlensing survey data. This dataset is widely used for the detection of variable stars, transient objects,…

Instrumentation and Methods for Astrophysics · Physics 2016-04-08 J. Skowron , A. Udalski , S. Kozłowski , M. K. Szymański , P. Mróz , Ł. Wyrzykowski , R. Poleski , P. Pietrukowicz , K. Ulaczyk , M. Pawlak , I. Soszyński

Galactic model plays an important role in the microlensing field, not only for analyses of individual events but also for statistics of the ensemble of events. However, the Galactic models used in the field varies, and some are…

Astrophysics of Galaxies · Physics 2021-02-24 Hongjing Yang , Shude Mao , Weicheng Zang , Xiangyu Zhang

Microlensing is a powerful and unique technique to probe isolated objects in the Galaxy. To study the characteristics of these interesting objects based on the microlensing method, measurement of the microlens parallax is required to…

Disk-halo models of the Galaxy and LMC are constructed and used to analyse the microlensing data-set. Deflectors in the LMC bar, disk and halo provide an optical depth to microlensing of $\sim 2 \times 10^{-7}$. Deflectors in the Galactic…

Astrophysics · Physics 2016-06-08 N. W. Evans

The EROS microlensing survey has monitored nearly 100 million stars for seven years, to search for halo brown dwarfs and compact objects in the Galactic disk. In this paper, we review the various EROS observation programs and the…

Astrophysics · Physics 2007-05-23 R. Ansari

In a recent series of three papers, Belokurov, Evans, and Le Du, and Evans and Belokurov, reanalysed the MACHO collaboration data and gave alternative sets of microlensing events and an alternative optical depth to microlensing toward the…

Astrophysics · Physics 2009-11-10 Kim Griest , Christian L. Thomas

Context: Gravitational microlensing is sensitive to compact-object lenses in the Milky Way, including white dwarfs, neutron stars or black holes, and could potentially probe a wide range of stellar remnant masses. However, the mass of the…

Solar and Stellar Astrophysics · Physics 2020-04-14 Łukasz Wyrzykowski , Ilya Mandel

Microlensing not only brings extra magnification lightcurves on top of the intrinsic ones but also shifts them in time domain, making the actual time-delays between images of strongly lensed active galactic nucleus change on the $\sim$…

Cosmology and Nongalactic Astrophysics · Physics 2021-01-06 Kai Liao

In the third part of the series presenting the Optical Gravitational Lensing Experiment (OGLE) microlensing studies of the dark matter halo compact objects (MACHOs) we describe results of the OGLE-III monitoring of the Large Magellanic…

Microlensing and pixel-lensing surveys play a fundamental role in the searches for galactic dark matter and in the study of the galactic structure. Recent observations suggest the presence of a population of old white dwarfs with high…

Astrophysics · Physics 2009-11-10 M. Hafizi , F. De Paolis , G. Ingrosso , A. A. Nucita

Optical depths of dense molecular gas are commonly used in Galactic and extragalactic studies to constrain the dense gas mass of the clouds or galaxies. The optical depths are often obtained based on spatially unresolved data, especially in…

Astrophysics of Galaxies · Physics 2023-09-19 Shu Liu , Junzhi Wang , Fei Li , Jingwen Wu , Zhi-Yu Zhang , Di Li , Ningyu Tang , Pei Zuo

We have used the full radial extent of images from the Hubble Space Telescope's Advanced Camera for Surveys and Wide Field Planetary Camera 2 to extract surface brightness profiles from a sample of six, local lenticular galaxy candidates.…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-15 Bililign T. Dullo , Alister W. Graham

Recently Sahu et al., using the Hubble Space Telescope to monitor stars in the direction of the old globular cluster M22, detected six events in which otherwise constant stars brightened by ~50% during a time of <1 day. They tentatively…

Astrophysics · Physics 2009-11-07 B. Scott Gaudi

By means of extensive galactic modeling we study the implications of the more than eighty microlensing events that have now been observed for the composition of the dark halo of the Galaxy, as well as for other properties of the Galaxy. We…

Astrophysics · Physics 2008-12-18 Evalyn I. Gates , Geza Gyuk , Michael S. Turner

[abridged] New near-infrared surveys, using the HST, offer an unprecedented opportunity to study rest-frame optical galaxy morphologies at z>1 and to calibrate automated morphological parameters that will play a key role in classifying…

We study the statistics and properties of microlensing events that can be detected by the Transiting Exoplanet Survey Satellite(TESS) based on Monte Carlo simulations. We simulate potential microlensing events from a sample of the TESS…

Earth and Planetary Astrophysics · Physics 2024-08-27 Sedighe Sajadian , Atousa Kalantari , Hossein Fatheddin , Somayeh Khakpash

The MACHO collaboration has recently analyzed 2.1 years of photometric data for about 8.5 million stars in the Large Magellanic Cloud (LMC). This analysis has revealed 8 candidate microlensing events and a total microlensing optical depth…