Measuring the Microlensing Parallax from Various Space Observatories

Abstract

A few observational methods allow the measurement of the mass and distance of the lens-star for a microlensing event. A first estimate can be obtained by measuring the microlensing parallax effect produced by either the motion of the Earth (annual parallax) or the contemporaneous observation of the lensing event from two (or more) observatories (space or terrestrial parallax) sufficiently separated from each other. Further developing ideas originally outlined by Gould (2013) and Mogavero & Beaulieu (2016), we review the possibility of measuring systematically the microlensing parallax using a telescope based on the Moon surface and other space-based observing platforms including the upcoming WFIRST space-telescope. We first generalize the Fisher matrix formulation and present results demonstrating the advantage for each observing scenario. We conclude by outlining the limitation of the Fisher matrix analysis when submitted to a practical data modeling process. By considering a lunar-based parallax observation we find that parameter correlations introduce a significant loss in detection efficiency of the probed lunar parallax effect.

Predictions of the WFIRST Microlensing Survey. I. Bound Planet Detection Rates

“…There is also significant work needed on microlensing simulations to better understand the information that WFIRST will be able to measure for each planet it finds. This is especially the case for host mass measurements, which will be possible though one or more of the techniques: detecting the host as it separates from the source and measuring image elongation, color-dependent centroid shifts or directly resolving the lens (e.g., Bennett et al 2007;Henderson 2015;Bhattacharya et al 2017), measuring the microlensing parallax with or without finite source measurements (e.g., Yee et al 2013;Yee 2015;Bachelet et al 2018), or even measuring astrometric microlensing (Gould & Yee 2014). The error budget of these measurements is likely to be dominated by systematic errors, and so more detailed end-to-end simulations of the stacking, photometry and astrometry pipelines are likely necessary in order to fully understand WFIRST's capabilities.…”

WFIRST and EUCLID: Enabling the Microlensing Parallax Measurement from Space

“…Note that the lens distance has a significant impact on the magnitude of the parallax; our choice of a single value is designed to simplify the parameter space while providing a reasonable quantitative estimate of parallax detectability. Bachelet et al (2018) consider the L2-point to be inertial and ignore the effect of the annual parallax. To challenge this assumption we use equation 16 of Gould (2013) to estimate the uncertainty of a 1-dimensional annual parallax measurement for a short, reasonably high-magnification microlensing event.…”

“…We can combine this with our rough scaling for π E , and the cadence of WFIRST observations, to estimate the minimum event timescale for which annual parallax can provide interesting constraints. Bachelet et al (2018) also shown than the Fisher matrix formalism can be optimistic, therefore we require a 5 σ constraint on the the 1-d parallax, i.e. 5σ πE,1−d < π E .…”

“…To study the potential of simultaneous Euclid and WFIRST microlensing observations, we used the Fisher matrix formalism (Gould 2013;Mogavero & Beaulieu 2016;Bachelet et al 2018) to estimate the precision of parallax measurements of microlensing events observed by both spacecraft. Based on this formalism, Mogavero & Beaulieu (2016) defines the minimum error parallax measurement σ π E,min as:…”

Gamma-ray burst lensing parallax: Closing the primordial black hole dark matter mass window

“…Although stars are long-lasting, we assume to consider short time-segments as discussed; but annual parallaxes in the usual microlensing has been indeed stud-ied, e.g. [25,26]. We simply require the same lensingdetection criteria and benchmarks as in the GRB case; but prospects for realizing various ∆r and good resolution are higher here, as various IR-band space missions are already operating with such specs or planned to be achieving them.…”