The OGLE-III planet detection efficiency from six years of microlensing observations (2003–2008)

Tsapras, Y.; Hundertmark, M.; Wyrzykowski, Ł.; Horne, K.; Udalski, A.; Snodgrass, C.; Street, R. A.; Bramich, D. M.; Dominik, M.; Bozza, V.; Jaimes, R. Figuera; Kains, N.; Skowron, J.; Szymański, M. K.; Pietrzyński, G.; Soszyński, I.; Ulaczyk, K.; Kozłowski, S.; Poleski, R.

doi:10.1093/mnras/stw023

Cited by 38 publications

(24 citation statements)

References 54 publications

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“…Integration was done in each bin separately, assuming one companion for each star with given properties. Tsapras et al (2016) showed their results in physical projected separation and companion mass, which we translated back to (s, q) assuming r E = 2.3 AU and M l = 0.4 M . In Table 4 we present how many objects each of OGLE-2011-BLG-0173 analysis 23 these surveys would detect under our assumptions and how many were in fact detected.…”

Section: Ice Giant Occurrence Ratesmentioning

confidence: 90%

“…There are just a few detections of objects in the considered separation range, which prevent us from drawing definitive conclusions. We note that there are many events that were searched for distant companions, which resulted in only four detections altogether: on order of 20, 000 events alerted by the OGLE and MOA surveys, in addition to the Tsapras et al (2016) and Suzuki et al (2016) samples. The numbers presented in Table 4 suggest that companions in the lowest mass ratio range are common (see also Foreman-Mackey et al 2016).…”

Section: Ice Giant Occurrence Ratesmentioning

confidence: 91%

“…These bins are marked in Figure 6 by thick red, long-dashed blue, and short-dashed pink rectangles, respectively. We integrated the sensitivity of two recent statistical analyses of survey data: Tsapras et al (2016) for OGLE-III and Suzuki et al…”

Section: Ice Giant Occurrence Ratesmentioning

confidence: 99%

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An Ice Giant Exoplanet Interpretation of the Anomaly in Microlensing Event OGLE-2011-BLG-0173

Poleski

Gaudi

Udalski

et al. 2018

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We analyze the microlensing event OGLE-2011-BLG-0173, which shows a small perturbation at the end of the microlensing event caused by the primary lens. We consider both binary lens and binary source models and we explore their degeneracies, some of which have not previously been recognized.There are two families of binary lens solutions, one with a mass ratio q ≈ 4 × 10 −4 and a separation s ≈ 4.6 and the other with q ≈ 0.015 and s ≈ 0.22, i.e, both have companions in the planetary regime. We search for solutions by using Bayesian analysis that includes planet frequency as a prior and find that the s ≈ 4.6 family is the preferred one with ≈ 4 M Uranus mass planet on an orbit of ≈ 10 AU. The degeneracies arise from a paucity of information on the anomaly, demonstrating that high-cadence observations are essential for characterizing wide-orbit microlensing planets. Hence, we predict that the planned WFIRST microlensing survey will be less prone to these degeneracies than the ongoing ground-based surveys. We discuss the known low-mass, wide-orbit companions 2 Poleski et al. and we notice that for the largest projected separations the mass ratios are either high (consistent with brown dwarf companions) or low (consistent with Uranus analogs), but intermediate mass ratios (Jupiter analogs on wide orbits) have not been detected to date, despite the fact that the sensitivity to such planets should be higher than that of Uranus analogs. This is therefore tentative evidence of the existence of a massive ice giant desert at wide separations. On the other hand, given their low intrinsic detection sensitivity, Uranus analogs may be ubiquitous.

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Section: Ice Giant Occurrence Ratesmentioning

confidence: 90%

Section: Ice Giant Occurrence Ratesmentioning

confidence: 91%

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An Ice Giant Exoplanet Interpretation of the Anomaly in Microlensing Event OGLE-2011-BLG-0173

Poleski

Gaudi

Udalski

et al. 2018

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“…These 200−600 events include 5−10% anomalous events deviating from a simple static point lens and are reported by anomaly detectors. Examples of different anomaly types can be found in Tsapras et al (2016). Not all anomalous events can be monitored continuously, and even with two-to-three follow-up telescopes per site we can only cover a handful of events with high enough cadence.…”

Section: Priority and Planet Detection Zonesmentioning

confidence: 99%

RoboTAP: Target priorities for robotic microlensing observations

Hundertmark

Street

Tsapras

et al. 2018

A&A

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Context. The ability to automatically select scientifically-important transient events from an alert stream of many such events, and to conduct follow-up observations in response, will become increasingly important in astronomy. With wide-angle time domain surveys pushing to fainter limiting magnitudes, the capability to follow-up on transient alerts far exceeds our follow-up telescope resources, and effective target prioritization becomes essential. The RoboNet-II microlensing program is a pathfinder project, which has developed an automated target selection process (RoboTAP) for gravitational microlensing events, which are observed in real time using the Las Cumbres Observatory telescope network. Aims. Follow-up telescopes typically have a much smaller field of view compared to surveys, therefore the most promising microlensing events must be automatically selected at any given time from an annual sample exceeding 2000 events. The main challenge is to select between events with a high planet detection sensitivity, with the aim of detecting many planets and characterizing planetary anomalies. Methods. Our target selection algorithm is a hybrid system based on estimates of the planet detection zones around a microlens. It follows automatic anomaly alerts and respects the expected survey coverage of specific events. Results. We introduce the RoboTAP algorithm, whose purpose is to select and prioritize microlensing events with high sensitivity to planetary companions. In this work, we determine the planet sensitivity of the RoboNet follow-up program and provide a working example of how a broker can be designed for a real-life transient science program conducting follow-up observations in response to alerts; we explore the issues that will confront similar programs being developed for the Large Synoptic Survey Telescope (LSST) and other time domain surveys.

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“…The presence of these unseen planets is then revealed through the detection of brief but intense changes in the measured brightness. This method opens up a unique window to the population of low-mass exoplanets at or beyond the snow-line, which is unavailable to other detection methods (Tsapras et al 2016;Cassan et al 2012;Gould et al 2010).…”

Section: Introductionmentioning

confidence: 99%

ROME/REA: A Gravitational Microlensing Search for Exoplanets Beyond the Snow Line on a Global Network of Robotic Telescopes

Tsapras¹,

Street

Hundertmark³

et al. 2019

PASP

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Planet population synthesis models predict an abundance of planets with semi-major axes between 1-10 au, yet they lie at the edge of the detection limits of most planet finding techniques. Discovering these planets and studying their distribution is critical to understanding the physical processes that drive planet formation. ROME/REA is a gravitational microlensing project whose main science driver is to discover exoplanets in the cold outer regions of planetary systems. To achieve this, it uses a novel approach combining a multi-band survey with reactive follow-up observations, exploiting the unique capabilities of the Las Cumbres Observatory (LCO) global network of robotic telescopes combined with a Target and Observation Manager (TOM) system. We present the main science objectives and a technical overview of the project, including initial results.

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The OGLE-III planet detection efficiency from six years of microlensing observations (2003–2008)

Cited by 38 publications

References 54 publications

An Ice Giant Exoplanet Interpretation of the Anomaly in Microlensing Event OGLE-2011-BLG-0173

An Ice Giant Exoplanet Interpretation of the Anomaly in Microlensing Event OGLE-2011-BLG-0173

RoboTAP: Target priorities for robotic microlensing observations

ROME/REA: A Gravitational Microlensing Search for Exoplanets Beyond the Snow Line on a Global Network of Robotic Telescopes

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