A Natural Formalism for Microlensing

Gould, Andrew

doi:10.1086/317037

Cited by 255 publications

(262 citation statements)

References 20 publications

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“…Direct measurement of the lens mass, distance, and projected separation of the lens components requires microlensing parallax π E (Gould 2000) to be measured. We cannot measure or even put meaningful constraints on π E for MOA-2012-BLG-006 because the host subevent is too short and the value of u 0 is too large.…”

Section: If Moa Data Are Included)mentioning

confidence: 99%

A companion on the planet/brown dwarf mass boundary on a wide orbit discovered by gravitational microlensing

Poleski

Udalski

Bond

et al. 2017

A&A

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We present the discovery of a substellar companion to the primary host lens in the microlensing event MOA-2012-BLG-006. The companion-to-host mass ratio is 0.016, corresponding to a companion mass ofThus, the companion is either a high-mass giant planet or a low-mass brown dwarf, depending on the mass of the primary M * . The companion signal was separated from the peak of the primary event by a time that was as much as four times longer than the event timescale. We therefore infer a relatively large projected separation of the companion from its host of ≈ 10 a.u.(M * /0.5M ) 1/2 for a wide range (3-7 kpc) of host star distances from the Earth. We also challenge a previous claim of a planetary companion to the lens star in microlensing event OGLE-2002-BLG-045.

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Section: If Moa Data Are Included)mentioning

confidence: 99%

A companion on the planet/brown dwarf mass boundary on a wide orbit discovered by gravitational microlensing

Poleski

Udalski

Bond

et al. 2017

A&A

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“…If the parallax effect and finite source effect are measured in a gravitational microlensing event, we can calculate the lens properties uniquely by assuming the distance to the source star, D s , as M L =θ E /(κπ E ) and (Gould 2000).…”

Section: Parallax Modelmentioning

confidence: 99%

OGLE-2013-BLG-1761Lb: A Massive Planet around an M/K Dwarf

Hirao

Udalski

Sumi

et al. 2017

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We report the discovery and the analysis of the planetary microlensing event, OGLE-2013-BLG-1761. There are some degenerate solutions in this event because the planetary anomaly is only sparsely sampled. However,the detailed lightcurve analysis ruled out all stellar binary models and shows the lens to be a planetary system. There is the so-called close/wide degeneracy in the solutions with the planet/host mass ratio of q∼(7.0±2.0)×10 −3 and q∼(8.1±2.6)×10−3 with the projected separation in Einstein radius units of s=0.95 (close) and s=1.18 (wide), respectively. The microlens parallax effect is not detected, but the finite source effect is detected. Our Bayesian analysis indicates that the lens system is located = . The preference of the large lens distance in the Bayesian analysis is due to the relatively large observed source star radius. The distance and other physical parameters may be constrained by the future high-resolution imaging by large groundtelescopes orHST. If the estimated lens distance is correct, thenthis planet provides another sample for testing the claimed deficit of planets in the Galactic bulge.-

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“…The measured parameter associated with these effects is ρ * , corresponding to the angular size of the source θ * in units of θ E . The measurement of θ E constrains the physical properties of the lens and so leads to the first part of a full solution for an event (Gould 2000),…”

Section: Mass and Distance Estimates Of The Lens Starmentioning

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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A Natural Formalism for Microlensing

Cited by 255 publications

References 20 publications

A companion on the planet/brown dwarf mass boundary on a wide orbit discovered by gravitational microlensing

A companion on the planet/brown dwarf mass boundary on a wide orbit discovered by gravitational microlensing

OGLE-2013-BLG-1761Lb: A Massive Planet around an M/K Dwarf

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

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