Finite source sizes and the information content of macho-type lens search light curves

Nemiroff, Robert J.; Wickramasinghe, W. A. D. T.

doi:10.1086/187265

Cited by 168 publications

(156 citation statements)

References 12 publications

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“…1997(Alcock et h E al. , 2000Albrow et al 1999Albrow et al , 2000aAlbrow et al , 2000bAfonso et al 2000), all by using the source as an "" angular ruler ÏÏ (Gould 1994a ;Nemiro † & Wickramasinghe 1994 ;Witt & Mao 1994). Similarly, has been determined for only r8 E about a half-dozen events (Alcock et al 1995 ;Bennett et al 1997 ;Mao 1999).…”

Section: Geometrymentioning

confidence: 99%

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A Natural Formalism for Microlensing

Gould¹

2000

ApJ

255

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If the standard microlensing geometry is inverted so that the Einstein ring is projected onto the observer plane rather than the source plane, then the relations between the observables and the under-(h E , r8 E ) lying physical quantities become immediately obvious. Here and are the angular and (M, n rel ) h E r8 E projected Einstein radii, M is the mass of the lens, and is the lens-source relative parallax. I recast n rel the basic formalism of microlensing in light of this more natural geometry and in terms of observables. I then Ðnd that the relations between observable and physical quantities assume an exceptionally simple form. In an appendix, I propose a set of notational conventions.

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Section: Geometrymentioning

confidence: 99%

“…The geometry of point-lens microlensing (Einstein 1936 ;Refsdal 1964 ;1986) is so simple that students can Paczynski derive all the basic results in a few hours. Nonetheless, this geometry has never been boiled down to its essence : the relationship between the underlying physical quantities and the observables.…”

Section: Introductionmentioning

confidence: 99%

A Natural Formalism for Microlensing

Gould¹

2000

ApJ

255

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“…The event OGLE-2009-BLG-092/MOA-2009-BLG-137 exhibits caustic-induced perturbations at both peaks and thus it is required to consider the finite-source effect to describe deviations occurring when the source approaches and crosses over caustics (Nemiroff & Wickramasinghe 1994;Witt & Mao 1994;Gould 1994). The finite-source effect is parameterized by the ratio of the source radius θ to the Einstein radius θ E , i.e., ρ = θ /θ E (normalized source radius).…”

Section: Modelingmentioning

confidence: 99%

“…With the change of the separation, the lensing magnification varies in time. For an event caused by a single-mass lens, the brightness variation is characterized by its non-repeating symmetric light curve (Paczyński 1986).…”

Section: Introductionmentioning

confidence: 99%

Ogle-2009-BLG-092/Moa-2009-BLG-137: A Dramatic Repeating Event With the Second Perturbation Predicted by Real-Time Analysis

Ryu¹,

Han²,

Hwang³

et al. 2010

ApJ

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We report the result of the analysis of a dramatic repeating gravitational microlensing event OGLE-2009-BLG-092/MOA-2009, for which the light curve is characterized by two distinct peaks with perturbations near both peaks. We find that the event is produced by the passage of the source trajectory over the central perturbation regions associated with the individual components of a wide-separation binary. The event is special in the sense that the second perturbation, occurring ∼100 days after the first, was predicted by the real-time analysis conducted after the first peak, demonstrating that real-time modeling can be routinely done for binary and planetary events. With the data obtained from follow-up observations covering the second peak, we are able to uniquely determine the physical parameters of the lens system. We find that the event occurred on a bulge clump giant and it was produced by a binary lens composed of a K-and M-type main-sequence stars. The estimated masses of the binary components are M 1 = 0.69±0.11 M and M 2 = 0.36±0.06 M , respectively, and they are separated in projection by r ⊥ = 10.9±1.3 AU. The measured distance to the lens is D L = 5.6 ± 0.7 kpc. We also detect the orbital motion of the lens system.

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“…When the source can be approximated as a point, the magnification of a single-lens event is given by (Einstein 1936;Paczyński 1986)…”

Section: Finite-source Effectsmentioning

confidence: 99%

Mass measurement of a single unseen star and planetary detection efficiency for OGLE 2007-BLG-050

Batista¹,

Dong²,

Gould³

et al. 2009

A&A

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Aims. We analyze OGLE-2007-BLG-050, a high magnification microlensing event (A ∼ 432) whose peak occurred on 2 May, 2007, with pronounced finite-source and parallax effects. We compute planet detection efficiencies for this event in order to determine its sensitivity to the presence of planets around the lens star. Methods. Both finite-source and parallax effects permit a measurement of the angular Einstein radius θ E = 0.48 ± 0.01 mas and the parallax π E = 0.12 ± 0.03, leading to an estimate of the lens mass M = 0.50 ± 0.14 M and its distance to the observer D L = 5.5 ± 0.4 kpc. This is only the second determination of a reasonably precise (<30%) mass estimate for an isolated unseen object, using any method. This allows us to calculate the planetary detection efficiency in physical units (r ⊥ , m p ), where r ⊥ is the projected planet-star separation and m p is the planet mass. Results. When computing planet detection efficiency, we did not find any planetary signature, i.e. none of the planetary configurations provides a Δχ 2 improvement higher than 60, and our detection efficiency results reveal significant sensitivity to Neptune-mass planets, and to a lesser extent Earth-mass planets in some configurations. Indeed, Jupiter and Neptune-mass planets are excluded with a high confidence for a large projected separation range between the planet and the lens star, respectively [0.6-10] and [1.4-4] AU, and Earth-mass planets are excluded with a 10% confidence in the lensing zone, i.e. [1.8-3.1] AU.

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Finite source sizes and the information content of macho-type lens search light curves

Cited by 168 publications

References 12 publications

A Natural Formalism for Microlensing

A Natural Formalism for Microlensing

Ogle-2009-BLG-092/Moa-2009-BLG-137: A Dramatic Repeating Event With the Second Perturbation Predicted by Real-Time Analysis

Mass measurement of a single unseen star and planetary detection efficiency for OGLE 2007-BLG-050

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