OGLE-2018-BLG-0677Lb: A Super-Earth Near the Galactic Bulge

Herrera-Martín, Antonio; Albrow, M. D.; Udalski, A.; Gould, Andrew; Ryu, Yoon-Hyun; Yee, Jennifer C.; Chung, Sun-Ju; Han, Cheongho; Hwang, Kyu-Ha; Jung, Youn Kil; Lee, C. U.; Shin, In-Gu; Shvartzvald, Yossi; Zang, Weicheng; M., S.; Kim, D. J.; Kim, H. W.; Kim, S. L.; Lee, D. J.; Lee, Y.; Park, B. G.; Pogge, Richard W.; Szymański, M. K.; Mróz, P.; Skowron, J.; Poleski, R.; Soszyński, I.; Kozłowski, S.; Ulaczyk, K.; Rybicki, K.; Iwanek, P.; Wrona, Marcin

doi:10.3847/1538-3881/ab893e

Cited by 25 publications

(13 citation statements)

References 64 publications

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“…The source passes "outside" the tips of these structures. Herrera-Martín et al (2020) were the first to recognize that this pair of caustic morphologies is the "inner/outer" degeneracy. Indeed, the light curve of OGLE-2018-BLG-0677, which they analyzed, looks remarkably similar to that of KMT-2018-BLG-1976, except that the duration of the dip is much shorter.…”

Section: Kmt-2018-blg-1976mentioning

confidence: 99%

Three microlensing planets with no caustic-crossing features

Han

Udalski

Kim

et al. 2021

A&A

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Aims. We search for microlensing planets with signals exhibiting no caustic-crossing features, considering the possibility that such signals may be missed due to their weak and featureless nature. Methods. For this purpose, we reexamine the lensing events found by the KMTNet survey before the 2019 season. From this investigation, we find two new planetary lensing events, KMT-2018-BLG-1976 and KMT-2018-BLG-1996. We also present the analysis of the planetary event OGLE-2019-BLG-0954, for which the planetary signal was known but no detailed analysis had previously been presented. We identify the genuineness of the planetary signals by checking various interpretations that can generate short-term anomalies in lensing light curves. Results. From Bayesian analyses conducted with the constraint from available observables, we find that the host and planet masses are (M1, M2) ~ (0.65 M⊙, 2 MJ) for KMT-2018-BLG-1976L, ~(0.69 M⊙, 1 MJ) for KMT-2018-BLG-1996L, and ~(0.80 M⊙, 14 MJ) for OGLE-2019-BLG-0954L. The estimated distance to OGLE-2019-BLG-0954L, 3.63−1.64+1.22 kpc, indicates that it is located in the disk, and the brightness expected from the mass and distance matches the brightness of the blend well, indicating that the lens accounts for most of the blended flux. The lens of OGLE-2019-BLG-0954 may be resolved from the source by conducting high-resolution follow-up observations in and after 2024.

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Section: Kmt-2018-blg-1976mentioning

confidence: 99%

Three microlensing planets with no caustic-crossing features

Han

Udalski

Kim

et al. 2021

A&A

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“…In June 2008, using the MOA-II telescope, the observatory discovered the smallest planet known outside of our Solar System called MOA-2007-BLG-192Lb [80]. Recently, in 2020, an Earth-like planet was discovered by New Zealand astronomers [81].…”

Section: The Impact On Professional and Amateur Astronomical Observationsmentioning

confidence: 99%

Looking Up to the Stars. A Call for Action to Save New Zealand’s Dark Skies for Future Generations to Come

Zielińska-Dabkowska

Xavia²

2021

Sustainability

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The rapid development of technology coupled with humanity’s desire to reach beyond terra firma, has resulted in more than 60 years of Outer Space activities. Although the exploration of space has provided many advantages and benefits to society so far, including vast, new information that has greatly added to our understanding of our planet and beyond, unfortunately, mankind’s footprint has negative aspects that need to be minimised as much as possible. In recent decades, a major worldwide problem has emerged in regard to the significant increase in light pollution from ground-based illuminations, as well as a lack of proper regulatory frameworks to mitigate the issue in order to protect the night sky and astronomical research. More recently, due to the escalating demand of air space for microsatellites and the rapid development of these new space technologies, as well as unmanned aerial vehicles (UAV), a new problem has arisen connected to visual light pollution (VLP). New Zealand has been especially affected, as, because of its dark skies, it has the third highest number of astronomical observatories in the world. The aim of this research is to identify critical areas for broader investigation; an action plan to improve the impact of new technologies is urgently required, not only at a national level but also worldwide. This is crucial in order to preserve humanity’s right to access the night sky and to also enable continual professional and amateur night-time observations for the present and the future, as well as for New Zealand to become a Dark Sky Nation.

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“…More generally, an expensive grid search is usually conducted over a subset of parameters to which the magnification pattern is hyper-sensitive: i.e., binary separation, mass ratio, and the source trajectory angle of approach (e.g. Herrera-Martín et al (2020)). At each grid-point, the remaining parameters are searched for with simple Nelder-Mead optimization (Nelder & Mead 1965) or MCMC.…”

mentioning

confidence: 99%

Real-time Likelihood-free Inference of Roman Binary Microlensing Events with Amortized Neural Posterior Estimation

Zhang

Bloom

Gaudi

et al. 2021

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Fast and automated inference of binary-lens, single-source (2L1S) microlensing events with sampling-based Bayesian algorithms (e.g., Markov Chain Monte Carlo, MCMC) is challenged on two fronts: the high computational cost of likelihood evaluations with microlensing simulation codes, and a pathological parameter space where the negative-log-likelihood surface can contain a multitude of local minima that are narrow and deep. Analysis of 2L1S events usually involves grid searches over some parameters to locate approximate solutions as a prerequisite to posterior sampling, an expensive process that often requires human-in-the-loop domain expertise. As the next-generation, space-based microlensing survey with the Roman Space Telescope is expected to yield thousands of binary microlensing events, a new fast and automated method is desirable. Here, we present a likelihood-free inference approach named amortized neural posterior estimation, where a neural density estimator (NDE) learns a surrogate posterior as an observation-parameterized conditional probability distribution, from pre-computed simulations over the full prior space. Trained on 291,012 simulated Roman-like 2L1S simulations, the NDE produces accurate and precise posteriors within seconds for any observation within the prior support without requiring a domain expert in the loop, thus allowing for real-time and automated inference. We show that the NDE also captures expected posterior degeneracies. The NDE posterior could then be refined into the exact posterior with a downstream MCMC sampler with minimal burn-in steps.

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OGLE-2018-BLG-0677Lb: A Super-Earth Near the Galactic Bulge

Cited by 25 publications

References 64 publications

Three microlensing planets with no caustic-crossing features

Three microlensing planets with no caustic-crossing features

Looking Up to the Stars. A Call for Action to Save New Zealand’s Dark Skies for Future Generations to Come

Real-time Likelihood-free Inference of Roman Binary Microlensing Events with Amortized Neural Posterior Estimation

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