An Isolated Microlens Observed from K2, Spitzer, and Earth

Zhu, Wei; Udalski, A.; Huang, Chelsea X.; Novati, S. Calchi; Sumi, T.; Poleski, R.; Skowron, J.; Mróz, P.; Szymański, M. K.; Soszyński, I.; Kozłowski, S.; Ulaczyk, K.; Pawlak, M.; Beichman, Charles; Bryden, G.; Carey, Sean; Gaudi, B. Scott; Gould, Andrew; Henderson, Calen B.; Shvartzvald, Yossi; Yee, Jennifer C.; Team, Spitzer; Bond, I. A.; Bennett, D. P.; Suzuki, D.; Rattenbury, N. J.; Koshimoto, Naoki; Abe, F.; Asakura, Y.; Barry, Richard; Bhattacharya, Atri; Donachie, M.; Evans, P.; Fukui, A.; Hirao, Yuki; Itow, Y.; Kawasaki, Kohei; Li, M. C. A.; Ling, C. H.; Masuda, Kento; Matsubara, Y.; Miyazaki, Shota; Munakata, Hisaaki; Muraki, Y.; Nagakane, M.; Ohnishi, Koji; Ranc, Clément; Saito, To.; Sharan, A.; Sullivan, D. J.; Tristram, P. J.; Yamada, Tōru; Yonehara, A.

doi:10.3847/2041-8213/aa93fa

Cited by 45 publications

(16 citation statements)

References 31 publications

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“…The effect of microlensing parallax often causes subtle deviations and asymmetries relative to the standard Paczynski light curve in microlensing events lasting a few months or more, so that the Earth's orbital motion cannot be neglected. The parameter π E can also be obtained from simultaneous observations of the event from the ground and from a space observatory located ∼1AU away (e.g.,Spitzer or Kepler, e.g., Udalski et al 2015b, Calchi Novati et al 2015, Zhu et al 2017.…”

Section: Introductionmentioning

confidence: 99%

Constraining the masses of microlensing black holes and the mass gap with Gaia DR2

Wyrzykowski

Mandel

2020

A&A

139

114

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Context. Gravitational microlensing is sensitive to compact-object lenses in the Milky Way, including white dwarfs, neutron stars, or black holes, and could potentially probe a wide range of stellar-remnant masses. However, the mass of the lens can be determined only in very limited cases, due to missing information on both source and lens distances and their proper motions. Aims. Our aim is to improve the mass estimates in the annual parallax microlensing events found in the eight years of OGLE-III observations towards the Galactic Bulge with the use of Gaia Data Release 2 (DR2). Methods. We use Gaia DR2 data on distances and proper motions of non-blended sources and recompute the masses of lenses in parallax events. We also identify new events in that sample which are likely to have dark lenses; the total number of such events is now 18. Results. The derived distribution of masses of dark lenses is consistent with a continuous distribution of stellar-remnant masses. A mass gap between neutron star and black hole masses in the range between 2 and 5 solar masses is not favoured by our data, unless black holes receive natal kicks above 20-80 km/s. We present eight candidates for objects with masses within the putative mass gap, including a spectacular multi-peak parallax event with mass of 2.4 +1.9 −1.3 M located just at 600 pc. The absence of an observational mass gap between neutron stars and black holes, or conversely the evidence of black hole natal kicks if a mass gap is assumed, can inform future supernova modelling efforts.

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Section: Introductionmentioning

confidence: 99%

Constraining the masses of microlensing black holes and the mass gap with Gaia DR2

Wyrzykowski

Mandel

2020

A&A

139

114

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“…We recall in particular the analysis of MOA-2016-BLG-290, a single lens low mass star/brown dwarf in the Galactic bulge with the determination of the satellite microlensing parallax from both K2 and Spitzer(Zhu et al 2017b). …”

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confidence: 99%

Spitzer Microlensing Parallax for OGLE-2016-BLG-1067: A Sub-Jupiter Orbiting an M Dwarf in the Disk

Novati¹,

Suzuki²,

Udalski³

et al. 2019

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NASA Postdoctoral Program Fellow -3 -We report the discovery of a sub-Jupiter mass planet orbiting beyond the snow line of an M-dwarf most likely in the Galactic disk as part of the joint Spitzer and ground-based monitoring of microlensing planetary anomalies toward the Galactic bulge. The microlensing parameters are strongly constrained by the light curve modeling and in particular by the Spitzer -based measurement of the microlens parallax, π E . However, in contrast to many planetary microlensing events, there are no caustic crossings, so the angular Einstein radius, θ E has only an upper limit based on the light curve modeling alone. Additionally, the analysis leads us to identify 8 degenerate configurations: the four-fold microlensing parallax degeneracy being doubled by a degeneracy in the caustic structure present at the level of the ground-based solutions. To pinpoint the physical parameters, and at the same time to break the parallax degeneracy, we make use of a series of arguments: the χ 2 hierarchy, the Rich argument, and a prior Galactic model. The preferred configuration is for a host at D L = 3.73 +0.66 −0.67 kpc with mass M L = 0.30 +0.15 −0.12 M ⊙ , orbited by a Saturn-like planet with M planet = 0.43 +0.21 −0.17 M Jup at projected separation a ⊥ = 1.70 +0.38 −0.39 au, about 2.1 times beyond the system snow line. Therefore, it adds to the growing population of sub-Jupiter planets orbiting near or beyond the snow line of M-dwarfs discovered by microlensing. Based on the rules of the real-time protocol for the selection of events to be followed up with Spitzer, this planet will not enter the sample for measuring the Galactic distribution of planets.

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“…Microlensing parallax can be measured by the subtle effect of an accelerating observer on the lightcurve (so-called annual parallax), but generally requires timescales of 50 days for the effects to be detectable (e.g., Poindexter et al 2005). Alternatively, observations of a microlensing event from two well separated locations (∼AU), so-called satellite parallax, can yield a measurement of microlensing parallax (e.g., Refsdal 1966;Gould 1994;Zhu et al 2017). The measurement of the microlensing parallax alone is also a precious tool to explore the mass distribution towards the Galactic Bulge (Calchi Novati et al 2015).…”

Section: Introductionmentioning

confidence: 99%

WFIRST and EUCLID: Enabling the Microlensing Parallax Measurement from Space

Bachelet

Penny

2019

ApJL

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The Wide Field Infrared Survey Telescope (WFIRST) is expected to detect hundreds of free-floating planets, but it will not be able to measure their masses. However, simultaneous microlensing observations by both Euclid and WFIRST spacecraft, separated by ∼100, 000 km in orbits around the Sun-Earth L2 Lagrange point, will enable measurements of microlensing parallax for low-mass lenses such as free-floating planets. Using simple Fisher matrix estimates of the parallax measurement uncertainties, we show that high-cadence observations by Euclid could be used to measure ∼1 free-floating planet microlens parallax per 6 days of simultaneous Euclid observations. Accounting for Euclid's pointing constraints, it could therefore potentially measure ∼20 free-floating planet parallaxes with 120 days of observations split equally between Euclid's main mission and an extended mission, with a potential to increase this number if spacecraft pointing constraints can be relaxed after the end of the main mission. These Euclid observations would also provide additional mass measurements or cross-checks for larger numbers of WFIRST's bound planets, among other benefits to several science cases.

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An Isolated Microlens Observed from K2, Spitzer, and Earth

Cited by 45 publications

References 31 publications

Constraining the masses of microlensing black holes and the mass gap with Gaia DR2

Constraining the masses of microlensing black holes and the mass gap with Gaia DR2

Spitzer Microlensing Parallax for OGLE-2016-BLG-1067: A Sub-Jupiter Orbiting an M Dwarf in the Disk

WFIRST and EUCLID: Enabling the Microlensing Parallax Measurement from Space

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