Microlensing and Its Degeneracy Breakers: Parallax, Finite Source, High-Resolution Imaging, and Astrometry

Lee, Chien‐Hsiu

doi:10.3390/universe3030053

Cited by 6 publications

(4 citation statements)

References 81 publications

(73 reference statements)

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“…Here, obtaining the lens mass remains unresolved, as we have two unknown parameters: θ E and π rel . In order to break the degeneracy to obtain specific microlensing parameters, measuring the parallax, π E , offers once such solution [9,10]. If we obtain u 0 , we can solve for M, given π E .…”

Section: Microlensing Parallaxmentioning

confidence: 99%

Compressive Sensing Based Space Flight Instrument Constellation for Measuring Gravitational Microlensing Parallax

Korde-Patel

Barry

2022

Signals

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In this work, we provide a compressive sensing architecture for implementing on a space based observatory for detecting transient photometric parallax caused by gravitational microlensing events. Compressive sensing (CS) is a simultaneous data acquisition and compression technique, which can greatly reduce on-board resources required for space flight data storage and ground transmission. We simulate microlensing parallax observations using a space observatory constellation, based on CS detectors. Our results show that average CS error is less than 0.5% using 25% Nyquist rate samples. The error at peak magnification time is significantly lower than the error for distinguishing any two microlensing parallax curves at their peak magnification. Thus, CS is an enabling technology for detecting microlensing parallax, without causing any loss in detection accuracy.

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Section: Microlensing Parallaxmentioning

confidence: 99%

Compressive Sensing Based Space Flight Instrument Constellation for Measuring Gravitational Microlensing Parallax

Korde-Patel

Barry

2022

Signals

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“…We need to keep in mind that from the microlensing light curve we can only derive the mass ratio between the host star and the exoplanet, and we need further pieces of information to constrain the mass of the host star. In this regard, the exquisite spatial resolution can also help us to disentangle the lens light from the source several years after the peak of the microlensing event, where the photometry of the lens can be used to pin down the mass of the host star and the exoplanet [53].…”

Section: New Frontiersmentioning

confidence: 99%

Exoplanets: Past, Present, and Future

Lee

2018

Galaxies

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Our understanding of extra-solar planet systems is highly driven by advances in observations in the past decade. Thanks to high precision spectrograph, we are able to reveal unseen companions to stars with the radial velocity method. High precision photometry from the space, especially with the Kepler mission, enables us to detect planets when they transit their stars and dim the stellar light by merely one percent or smaller. Ultra wide-field, high cadence, continuous monitoring of the Galactic bulge from different sites around the southern hemisphere provides us the opportunity to observe microlensing effects caused by planetary systems from the solar neighborhood, all the way to the Milky Way center. The exquisite AO imaging from ground-based large telescopes, coupled with high-contrast coronagraph, captured the photons directly emitted by planets around other stars. In this article, I present a concise review of the extra-solar planet discoveries, discussing the strengths and weaknesses of the major planetary detection methods, providing an overview of our current understanding of planetary formation and evolution given the tremendous observations delivered by various methods, as well as on-going and planned observation endeavors to provide a clear picture of extra-solar planetary systems.

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“…The direction of relative motion also allows for putting additional constrains on the kinematics of the lens. The measurement of 𝜃 E would allow to solve the problem of determining the lens mass entirely; some possible methods are described in Lee (2017). With current observational possibilities, so far it has only been possible for several rare events -namely, image resolution with interferometry for extremely bright events (Dong et al 2019;Cassan et al 2021), or astrometry for known, extremely nearby lenses (Sahu et al 2017;Zurlo et al 2018).…”

Section: Introductionmentioning

confidence: 99%

Dark lenses through the dust: parallax microlensing events in the VVV

Kaczmarek,

McGill,

Evans

et al. 2022

Preprint

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We use near-infrared photometry and astrometry from the VISTA Variables in the Via Lactea (VVV) survey to analyse microlensing events containing annual microlensing parallax information. These events are located in highly extincted and low-latitude regions of the Galactic bulge typically off-limits to optical microlensing surveys. We fit a catalog of 1959 events previously found in the VVV and extract 21 microlensing parallax candidates. The fitting is done using nested sampling to automatically characterise the multi-modal and degenerate posterior distributions of the annual microlensing parallax signal. We compute the probability density in lens mass-distance using the source proper motion and a Galactic model of disc and bulge deflectors. By comparing the expected flux from a main sequence lens to the baseline magnitude and blending parameter, we identify 4 candidates which have probability > 50 % that the lens is dark. The strongest candidate corresponds to a nearby (≈ 0.78 kpc), medium-mass (1.46 +1.13 −0.71 𝑀 ) dark remnant as lens. In the next strongest, the lens is located at heliocentric distance ≈ 5.3 kpc. It is a dark remnant with a mass of 1.63 +1.15 −0.70 𝑀 . Both of those candidates are most likely neutron stars, though possibly high-mass white dwarfs. The last two events may also be caused by dark remnants, though we are unable to rule out other possibilities because of limitations in the data.

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Microlensing and Its Degeneracy Breakers: Parallax, Finite Source, High-Resolution Imaging, and Astrometry

Cited by 6 publications

References 81 publications

Compressive Sensing Based Space Flight Instrument Constellation for Measuring Gravitational Microlensing Parallax

Compressive Sensing Based Space Flight Instrument Constellation for Measuring Gravitational Microlensing Parallax

Exoplanets: Past, Present, and Future

Dark lenses through the dust: parallax microlensing events in the VVV

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