Distribution of caustic-crossing intervals for Galactic binary-lens microlensing events

Han, Cheongho; Park, Seong-Hong; Lee, Yong-Sam

doi:10.1046/j.1365-8711.2000.03293.x

Cited by 5 publications

(2 citation statements)

References 35 publications

(41 reference statements)

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“…Such effects occur when the pointsource approximation is no longer valid, and persist in the light curve over the relatively short time scale of order t , the crossing time of the source radius by the lens. However, if the source trajectory is tangential to the caustic line for a binary, the duration of such effects can be longer (Han et al 2000).…”

Section: Synthetic Data Pointsmentioning

confidence: 99%

Identifying low-amplitude pulsating stars through microlensing observations

Sajadian,

Ignace,

Neilson

2021

Preprint

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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 detectability of pulsational signatures in light curves. We explore this possibility under two primary considerations. The first is when the standard point-source and point-lens approximation applies. In this scenario, dividing the observed light curve by the best-fitted microlensing model leads to residuals that result in pulsational features with improved uncertainties. The second is for transit events (single lens) or caustic crossing (binary lens). The point-source approximation breaks down, and residuals relative to a simple best-fitted microlensing model display more complex behavior. We employ a Monte-Carlo simulation of microlensing of pulsating variables toward the Galactic bulge for the surveys of OGLE and of KMTNet. We demonstrate that the efficiency for detecting pulsational signatures with intrinsic amplitudes of < 0.25 mag during single and binary microlensing events, at differences in χ 2 of ∆χ 2 > 350, is ∼ 50 − 60%. The maximum efficiency occurs for pulsational periods P 0.1 − 0.3 days. We also study the possibility that high-magnification microlensing events of non-radially pulsating stars (NRPs) could be misinterpreted as planetary or binary microlensing events. We conclude that small asymmetric features around lightcurve peaks due to stellar pulsations could be misdiagnosed with crossing (or passing close to) small caustic curves.

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Section: Synthetic Data Pointsmentioning

confidence: 99%

Identifying low-amplitude pulsating stars through microlensing observations

Sajadian,

Ignace,

Neilson

2021

Preprint

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“…The problem gained a new interest in connection with investigations of massive compact halo objects [61][62][63], see also [64][65][66][67][68][69][70][71] and references therein; for the extended source and extended lens effects see [11,[72][73][74]. The extragalactic topics are less studied [12,71,75,76].…”

Section: Preliminary Commentsmentioning

confidence: 99%

Analytical Methods in Gravitational Microlensing

Жданов

Alexandrov

Fedorova

et al. 2012

ISRN Astronomy and Astrophysics

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We discuss analytical results dealing with photometric and astrometric gravitational microlensing. The first two sections concern approximation methods that allow us to get solutions of the general lens equation near fold caustics and cusp points up to any prescribed accuracy. Two methods of finding approximate solutions near the fold are worked out. The results are applied to derive new corrections to total amplifications of critical source images. Analytic expressions are obtained in case of the Gaussian, power-law, and limb-darkening extended source models; here we present the first nonzero corrections to the well-known linear caustic approximation. Possibilities to distinguish different source models in observations are discussed on the basis of statistical simulations of microlensed light curves. In the next section, we discuss astrometric microlensing effects in various cases of extended sources and extended lenses, including a simple model of weak statistical microlensing by extended dark matter clumps. Random walks of a distant source image microlensed by stochastic masses are estimated. We note that the bulk motion of foreground stars induces a small apparent rotation of the extragalactic reference frame. Compact analytical relations describing the statistics of such motions are presented.

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Gravitational microlensing of stars with transiting planets

Lewis

2001

A&A

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Abstract. If planetary systems are ubiquitous then a fraction of stars should possess a transiting planet when being microlensed. This paper presents a study of the influence of such planets on microlensing light curves. For the giant planets recently identified, the deviations in the light curve can be substantial, although the specifics of the perturbations are dependent upon the radius of the planet relative to that of the star, the location of the planet over the stellar surface and the orientation of the sweeping caustic. Given that the instantaneous probability of transiting hot-Jupiter like planets is small, less than a percent, and only a proportion of microlensing events exhibit caustic crossing events, the probability of detecting a transiting planet during a microlensing event is small, ∼10 −6 . However, a number of factors influencing this probability, such as the number of solar type star that possess planets, are uncertain, and the prospect of detecting transiting planets in future large catalogues of microlensing light curves may be viable. The results of this study also have bearing on the gravitational microlensing of spots on the stellar surface.

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Distribution of caustic-crossing intervals for Galactic binary-lens microlensing events

Cited by 5 publications

References 35 publications

Identifying low-amplitude pulsating stars through microlensing observations

Identifying low-amplitude pulsating stars through microlensing observations

Analytical Methods in Gravitational Microlensing

Gravitational microlensing of stars with transiting planets

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