OGLE-2014-BLG-1112LB: A Microlensing Brown Dwarf Detected through the Channel of a Gravitational Binary-lens Event

Han, Cheongho; Udalski, A.; Bozza, V.; Szymański, M. K.; Soszyński, I.; Skowron, J.; Mróz, P.; Poleski, R.; Kozłowski, S.; Ulaczyk, K.; Wyrzykowski, Ł.; Novati, S. Calchi; D’Ago, G.; Dominik, M.; Hundertmark, M.; Jørgensen, U. G.; Scarpetta, G.

doi:10.3847/1538-4357/aa762f

Cited by 29 publications

(7 citation statements)

References 37 publications

(45 reference statements)

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“…Moreover, the microlensing event rate Γ is proportional to the area of the sky swept by the Einstein ring: Γ ∝ θ E µ rel . The high lens-source relative proper motion makes an event more likely to be found, but events with µ rel > 10 mas yr −1 are very rare (Han et al 2017). Strong finite source effects make the duration of an event longer, especially if ρ 1, which makes giant source events easier to detect.…”

Section: Discussionmentioning

confidence: 99%

Two new free-floating or wide-orbit planets from microlensing

Mróz

Udalski

Bennett

et al. 2019

A&A

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Planet formation theories predict the existence of free-floating planets that have been ejected from their parent systems. Although they emit little or no light, they can be detected during gravitational microlensing events. Microlensing events caused by rogue planets are characterized by very short timescales tE (typically below two days) and small angular Einstein radii θE (up to several μas). Here we present the discovery and characterization of two ultra-short microlensing events identified in data from the Optical Gravitational Lensing Experiment (OGLE) survey, which may have been caused by free-floating or wide-orbit planets. OGLE-2012-BLG-1323 is one of the shortest events discovered thus far (tE = 0.155 ± 0.005 d, θE = 2.37 ± 0.10μas) and was caused by an Earth-mass object in the Galactic disk or a Neptune-mass planet in the Galactic bulge. OGLE-2017-BLG-0560 (tE = 0.905 ± 0.005 d, θE = 38.7 ± 1.6μas) was caused by a Jupiter-mass planet in the Galactic disk or a brown dwarf in the bulge. We rule out stellar companions up to a distance of 6.0 and 3.9 au, respectively. We suggest that the lensing objects, whether located on very wide orbits or free-floating, may originate from the same physical mechanism. Although the sample of ultrashort microlensing events is small, these detections are consistent with low-mass wide-orbit or unbound planets being more common than stars in the Milky Way.

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Section: Discussionmentioning

confidence: 99%

Two new free-floating or wide-orbit planets from microlensing

Mróz

Udalski

Bennett

et al. 2019

A&A

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“…Although present for all such observations, it is usually only detectable for events with a timescale t E 30 days. The effect manifests as a sinusoidal perturbation on an otherwise-linear projected source trajectory in the lens plane (see, e.g., Furusawa et al 2013;Park et al 2015;Han et al 2017aHan et al , 2017b).…”

Section: Parallax Constraintsmentioning

confidence: 99%

OGLE-2016-BLG-1266: A Probable Brown Dwarf/Planet Binary at the Deuterium Fusion Limit

Albrow

Yee

Udalski

et al. 2018

ApJ

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We report the discovery, via the microlensing method, of a new very low mass binary system. By combining measurements from Earth and from the Spitzer telescope in Earth-trailing orbit, we are able to measure the microlensing parallax of the event, and we find that the lens likely consists of a (12.0±0.6)M J +(15.7±1.5)M J super-Jupiter/brown dwarf pair. The binary is located at a distance of 3.08±0.18 kpc in the Galactic plane, and the components have a projected separation of 0.43±0.03 au. Two alternative solutions with much lower likelihoods are also discussed, an 8M J and 6M J model and a 90M J and 70M J model. If all photometric measurements were independent and Gaussian distributed with known variances, these alternative solutions would be formally disfavored at the 3σ and 5σ levels. We show how the more massive of these models could be tested with future direct imaging.

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“…The planets detected by microlensing are represented as red circles, in which open and filled circles indicate planets whose masses were estimated by Bayesian analyses and directly measured by higher order microlensing effects, respectively. The green circles indicate the microlensing binary events with large mass ratios of q > 0.1, which are brown-dwarf binaries or brown dwarfs orbiting around VLMS (Choi et al 2013;Jung et al 2015;Han et al 2016;Han et al 2017). They are likely formed by a different mechanism from that of planetary systems with q < 0.03.…”

Section: Discussionmentioning

confidence: 99%

“…Though there are still large uncertainties because the masses of the objects detected by direct imaging were estimated based on assumed ages, lower mass ratio (i.e., q ≤ 0.3) binaries would be very uncommon among field VLMS and BDs. However, there have been several discoveries of binary BDs (Han et al 2017) as well as a BD orbiting an M dwarf (Han et al 2016) with small mass ratios (q < 0.3) by microlensing. In addition, Han et al (2013) found a system that consists of a several Jupiter-mass planet orbiting a BD and suggested that the planetary mass companion might have been formed in a proto-planetary disk surrounding the BD.…”

Section: Introductionmentioning

confidence: 99%

MOA-2015-BLG-337: A Planetary System with a Low-mass Brown Dwarf/Planetary Boundary Host, or a Brown Dwarf Binary

Miyazaki¹,

Sumi²,

Bennett³

et al. 2018

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We report the discovery and the analysis of the short timescale binary-lens microlensing event, MOA-2015-BLG-337. The lens system could be a planetary system with a very low mass host, around the brown dwarf/planetary mass boundary, or a brown dwarf binary. We found two competing models that explain the observed light curves with companion/host mass ratios of q ∼ 0.01 and ∼ 0.17, respectively. A significant finite source effect in the best-fit planetary model (q ∼ 0.01) reveals a small angular Einstein radius of θ E ≃ 0.03 mas which favors a low mass lens. We obtain the posterior probability distribution of the lens properties from a Bayesian analysis. The results for the planetary models strongly depend on a power-law index in planetary mass regime, α pl , in the assumed mass function. In summary, there are two solutions of the lens system: (1) a brown dwarf/planetary mass boundary object orbited by a super-Neptune (the planetary model with α pl = 0.49) and (2) a brown dwarf binary (the binary model). If the planetary models are correct, this system can be one of a new class of planetary system, having a low host mass and also a planetary mass ratio (q < 0.03) between the companion and its host. The discovery of the event is important for the study of planetary formation in very low mass objects. In addition, it is important to consider all viable solutions in these kinds of ambiguous events in order for the future comprehensive statistical analyses of planetary/binary microlensing events.

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OGLE-2014-BLG-1112LB: A Microlensing Brown Dwarf Detected through the Channel of a Gravitational Binary-lens Event

Cited by 29 publications

References 37 publications

Two new free-floating or wide-orbit planets from microlensing

Two new free-floating or wide-orbit planets from microlensing

OGLE-2016-BLG-1266: A Probable Brown Dwarf/Planet Binary at the Deuterium Fusion Limit

MOA-2015-BLG-337: A Planetary System with a Low-mass Brown Dwarf/Planetary Boundary Host, or a Brown Dwarf Binary

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