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We consider strong gravitational lensing by nearby stars. Using our wave-optical treatment of lensing phenomena, we study Einstein rings that may form around nearby stellar lenses. It is remarkable that these rings are bright and large…

Instrumentation and Methods for Astrophysics · Physics 2023-02-13 Slava G. Turyshev , Viktor T. Toth

An automated search is carried out for microlensing events using a catalogue of 44554 variable superpixel lightcurves derived from our three-year monitoring program of M31. Each step of our candidate selection is objective and reproducible…

Microlensing of stars in strongly lensed galaxies can lead to temporary extreme magnification factors ($\mu\!>\!1000$), enabling their detection at high redshifts. Following the discovery of Icarus, several stars at cosmological distances…

Cosmology and Nongalactic Astrophysics · Physics 2024-07-03 J. M. Palencia , J. M. Diego , B. J. Kavanagh , J. Martinez

We investigate the chances that neutron stars act as the lense in a gravitational microlensing event towards the galactic bulge or a spiral arm. The observation of neutron stars by means of gravitational microlensing would allow the…

Astrophysics · Physics 2009-11-07 Dominik J. Schwarz , Dirk Seidel

Gravitational microlensing may detect dark stellar remnants - black holes or neutron stars - even if they are isolated. However, it is challenging to estimate masses of isolated dark stellar remnants using solely photometric data for…

Solar and Stellar Astrophysics · Physics 2021-09-15 P. Mroz , L. Wyrzykowski

An extra-solar planet can be detected by microlensing because the planet can perturb the smooth lensing light curve created by the primary lens. However, it was shown by Gaudi that a subset of binary-source events can produce light curves…

Astrophysics · Physics 2009-11-06 Cheongho Han

One possibility for detecting low-amplitude pulsational variations is through gravitational microlensing. During a microlensing event, the temporary brightness increase leads to improvement in the signal-to-noise ratio, and thereby better…

Solar and Stellar Astrophysics · Physics 2021-09-01 Sedighe Sajadian , Richard Ignace , Hilding Neilson

It has been shown by Paczy\'nski that gravitational microlensing is a useful method to detect brown dwarfs in the dark halo of our galaxy. At present several experiments are carried out to monitor several million stars in the Large…

Astrophysics · Physics 2008-02-03 Philippe Jetzer

The microlens parallax is a crucial observable for conclusively identifying the nature of lens systems in microlensing events containing or composed of faint (even dark) astronomical objects such as planets, neutron stars, brown dwarfs, and…

Currently astrometric microlensing is the only tool that can directly measure the mass of a single star, it can also help us to detect compact objects like isolated neutron stars and black holes. The number of microlensing events that are…

Solar and Stellar Astrophysics · Physics 2023-11-01 Jie Su , Jiancheng Wang , Yigong Zhang , Xiangming Cheng , Lei Yang

We present a comprehensive treatment of the pixel-lensing theory and apply it to lensing experiments and their results toward M31. Using distribution functions for the distances, velocities, masses, and luminosities of stars, we derive…

Astrophysics · Physics 2007-05-23 A. Riffeser , J. Fliri , S. Seitz , R. Bender

In addition to constructing a Galactic matter mass function free from the bias induced by the hydrogen-burning limit, gravitational microlensing allows one to construct a mass function which is less affected by the problem of unresolved…

Astrophysics · Physics 2009-10-31 Kyongae Chang , Cheongho Han

We investigate the possibilities that pulsars act as the lens in gravitational microlensing events towards the galactic bulge or a spiral arm. Our estimation is based on expectant survey and observations of FAST (Five hundred meter Aperture…

High Energy Astrophysical Phenomena · Physics 2015-05-14 S. Dai , R. X. Xu , A. Esamdin

We investigate properties of Galactic microlensing events in which a stellar object is lensed by a neutron star. For an all-sky photometric microlensing survey, we determine the number of lensing events caused by $\sim10^{5}$…

Astrophysics of Galaxies · Physics 2015-07-03 Shi Dai , Martin C. Smith , Mengxiang Lin , Youling Yue , George Hobbs , Renxin Xu

If the Dark Matter consists of primordial black holes (PBHs), we show that gravitational lensing of stars being monitored by NASA's Kepler search for extra-solar planets can cause significant numbers of detectable microlensing events. A…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-30 Kim Griest , Matthew J. Lehner , Agnieszka M. Cieplak , Bhuvnesh Jain

The effect of stars on the lensing properties of the supermassive black hole in the Galactic Center is similar to the effect of planets on microlensing by a star. We show that the dense stellar cluster around SgrA* increases by factors of a…

Astrophysics · Physics 2009-10-31 Tal Alexander , Abraham Loeb

Gravitational microlensing surveys target very dense stellar fields in the local group. As a consequence the microlensed source stars are often blended with nearby unresolved stars. The presence of `blending' is a cause of major uncertainty…

Astrophysics · Physics 2009-11-13 Martin C. Smith , Przemyslaw Wozniak , Shude Mao , Takahiro Sumi

We investigate gravitational microlensing signals produced by a spatially extended object transiting in front of a finite-sized source star. The most interesting features arise for lens and source sizes comparable to the Einstein radius of…

Cosmology and Nongalactic Astrophysics · Physics 2020-10-28 Djuna Croon , David McKeen , Nirmal Raj , Zihui Wang

Microlensing searches toward the inner galaxy $(|l|,|b|\leq 22.\hskip-2pt'5)$ have several major advantages. First, the event rate is strongly dominated by bulge-bulge lensing events where both the source and lens lie in the bulge. Second,…

Astrophysics · Physics 2009-10-22 Andrew Gould

We propose that some of the high-latitude unidentified EGRET gamma-ray sources could be the result of gravitational lensing amplification of the innermost regions of distant, faint, active galactic nuclei. These objects have gamma-ray…

Astrophysics · Physics 2009-11-07 Diego F. Torres , Gustavo E. Romero , Ernesto F. Eiroa