PATHWAY TO THE GALACTIC DISTRIBUTION OF PLANETS: COMBINED<i>SPITZER</i>AND GROUND-BASED MICROLENS PARALLAX MEASUREMENTS OF 21 SINGLE-LENS EVENTS

Novati, S. Calchi; Gould, Andrew; Udalski, A.; Menzies, John; Bond, I. A.; Shvartzvald, Yossi; Street, R. A.; Hundertmark, M.; Beichman, C.; Yee, Jennifer C.; Carey, Sean; Poleski, R.; Skowron, J.; Kozłowski, S.; Mróz, P.; Pietrukowicz, P.; Pietrzyński, G.; Szymański, M. K.; Soszyński, I.; Ulaczyk, K.; Wyrzykowski, Ł.; Albrow, M. D.; Beaulieu, J. P.; Caldwell, J. A. R.; Cassan, A.; Coutures, C.; Danielski, Camilla; Prester, D. Dominis; Donatowicz, J.; Lončarić, K.; McDougall, Alistair; Morales, J. C.; Ranc, Clément; Zhu, Wei; Abe, F.; Barry, Richard; Bennett, D. P.; Bhattacharya, Atri; Fukunaga, D.; Inayama, K.; Koshimoto, Naoki; Namba, Susumu; Sumi, T.; Suzuki, D.; Tristram, P. J.; Wakiyama, Y.; Yonehara, A.; Maoz, Dan; Kaspi, S.; Friedmann, M.; Bachelet, E.; Jaimes, R. Figuera; Bramich, D. M.; Tsapras, Y.; Horne, K.; Snodgrass, C.; Wambsganß, J.; Steele, I. A.; Kains, N.; Bozza, V.; Dominik, M.; Jørgensen, U. G.; Alsubai, K. A.; Ciceri, S.; D’Ago, G.; Haugbølle, Troels; Hessman, F. V.; Hinse, T. C.; Juncher, D.; Korhonen, H.; Mancini, L.; Popovas, A.; Rabus, M.; Rahvar, S.; Scarpetta, G.; Schmidt, R. W.; Skottfelt, J.; Southworth, J.; Starkey, D.; Surdej, Jean; Wertz, O.; Zarucki, M.; Gaudi, B. Scott; Pogge, R. W.; Depoy, D. L.

doi:10.1088/0004-637x/804/1/20

Cited by 115 publications

(79 citation statements)

References 38 publications

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“…A key issue in the analysis of these events has been to break this fourfold degeneracy, in particular the twofold degeneracy that impacts the mass and distance estimates. Although in some cases Zhu et al 2015) this degeneracy has been broken by various fairly weak effects, in the great majority of cases, the degeneracy was broken only statistically (Calchi Novati et al 2015a;Zhu et al 2017b). …”

Section: Microlens Parallax From One and Two Satellitesmentioning

confidence: 99%

“…Calchi Novati et al (2015a) showed how the cumulative distribution of planetary events as a function of distance toward the Galactic bulge could be compared to that of the parent sample to determine whether planets are relatively more frequent in the Galactic disk or bulge. However, this comparison depends on the implicit assumption that there is no bias toward the selection of planetary events.…”

Section: Construction Of Blind Tests In the Facementioning

confidence: 99%

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OGLE-2016-BLG-1190Lb: The First Spitzer Bulge Planet Lies Near the Planet/Brown-dwarf Boundary

Ryu¹,

Yee²,

Udalski³

et al. 2017

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We report the discovery of OGLE-2016-BLG-1190Lb, which is likely to be the first Spitzer microlensing planet in the Galactic bulge/bar, an assignation that can be confirmed by two epochs of high-resolution imaging of the combined source-lens baseline object. The planet's mass, M p =13.4±0.9 M J , places it right at the deuteriumburning limit, i.e., the conventional boundary between "planets" and "brown dwarfs." Its existence raises the question of whether such objects are really "planets" (formed within the disks of their hosts) or "failed stars" (lowmass objects formed by gas fragmentation). This question may ultimately be addressed by comparing disk and bulge/bar planets, which is a goal of the Spitzer microlens program. The host is a G dwarf, M host =0.89±0.07 M e , and the planet has a semimajor axis a∼2.0 au. We use Kepler K2 Campaign 9 microlensing data to break the lens-mass degeneracy that generically impacts parallax solutions from Earth-Spitzer observations alone, which is the first successful application of this approach. The microlensing data, derived primarily from near-continuous, ultradense survey observations from OGLE, MOA, and three KMTNet telescopes, contain more orbital information than for any previous microlensing planet, but not quite enough to accurately specify the full orbit. However, these data do permit the first rigorous test of microlensing orbital-motion measurements, which are typically derived from data taken over <1% of an orbital period.

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Section: Microlens Parallax From One and Two Satellitesmentioning

confidence: 99%

Section: Construction Of Blind Tests In the Facementioning

confidence: 99%

OGLE-2016-BLG-1190Lb: The First Spitzer Bulge Planet Lies Near the Planet/Brown-dwarf Boundary

Ryu¹,

Yee²,

Udalski³

et al. 2017

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“…In addition, Spitzer observations allowed Bozza et al (2016) to break a strong planet/binary degeneracy in the event OGLE-2015-BLG-1212, finding that the companion is a low-mass star and not a planet. These campaigns are the first steps for measuring the Galactic distribution of planets (Calchi Novati et al 2015a), a demographic regime that can currently only be explored by microlensing.…”

Section: Introductionmentioning

confidence: 99%

The First Simultaneous Microlensing Observations by Two Space Telescopes: Spitzer and Swift Reveal a Brown Dwarf in Event Ogle-2015-BLG-1319

Shvartzvald¹,

Li²,

Udalski³

et al. 2016

ApJ

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Simultaneous observations of microlensing events from multiple locations allow for the breaking of degeneracies between the physical properties of the lensing system, specifically by exploring different regions of the lens plane and by directly measuring the "microlens parallax." We report the discovery of a 30-65M J brown dwarf orbiting a K dwarf in the microlensing event OGLE-2015-BLG-1319. The system is located at a distance of ∼5 kpc toward the Galactic Bulge. The event was observed by several ground-based groups as well as by Spitzer and Swift, allowing a measurement of the physical properties. However, the event is still subject to an eight-fold degeneracy, in particular the well-known close-wide degeneracy, and thus the projected separation between the two lens components is either ∼0.25 au or ∼45 au. This is the first microlensing event observed by Swift, with the UVOT camera. We study the region of microlensing parameter space to which Swift is sensitive, finding that though Swift could not measure the microlens parallax with respect to ground-based observations for this event, it can be important for other events. Specifically, it is important for detecting nearby brown dwarfs and free-floating planets in high magnification events.

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“…Since 2014, the Spitzer Space Telescope has measured the microlens parallax E p for hundreds of microlensing (single and binary) events, proving it to be an excellent satellite for measuring microlensing parallax (Dong et al 2007;Calchi Novati et al 2015a;Udalski et al 2015b;Yee et al 2015b;Zhu et al 2015). However, the usefulness of Spitzer observations in characterizing binaries can extend beyond measuring parallax.…”

mentioning

confidence: 99%

“…Light curves of single-mass lensing events obtained from ground-based observatories and one space-based observatory typically yield a set of four degenerate solutions (Refsdal 1966;Gould 1994;Gould & Horne 2013;Calchi Novati et al 2015a;Yee et al 2015b), 22 which are often denoted as (+, +), (−, −), (+, −), and (−, +). Here the first and second signs in each parenthesis represent the signs of the lens-source impact parameters as seen from Earth and from the satellite, respectively.…”

mentioning

confidence: 99%

OGLE-2017-BLG-1130: The First Binary Gravitational Microlens Detected from Spitzer Only

Novati

Udalski

Gould

et al. 2018

ApJ

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We analyze the binary gravitational microlensing event OGLE-2017-BLG-1130 (mass ratio q∼0.45), the first published case in which the binary anomaly was detected only by the Spitzer Space Telescope. This event provides strong evidence that some binary signals can be missed by observations from the ground alone but detected by Spitzer. We therefore invert the normal procedure, first finding the lens parameters by fitting the space-based data and then measuring the microlensing parallax using ground-based observations. We also show that the normal four-fold space-based degeneracy in the single-lens case can become a weak eight-fold degeneracy in binary-lens events. Although this degeneracy is resolved in event OGLE-2017-BLG-1130, it might persist in other events.

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PATHWAY TO THE GALACTIC DISTRIBUTION OF PLANETS: COMBINEDSPITZERAND GROUND-BASED MICROLENS PARALLAX MEASUREMENTS OF 21 SINGLE-LENS EVENTS

Abstract: The version presented here may differ from the published version or from the version of the record. Please see the repository URL above for details on accessing the published version and note that access may require a subscription.

Cited by 115 publications

References 38 publications

OGLE-2016-BLG-1190Lb: The First Spitzer Bulge Planet Lies Near the Planet/Brown-dwarf Boundary

OGLE-2016-BLG-1190Lb: The First Spitzer Bulge Planet Lies Near the Planet/Brown-dwarf Boundary

The First Simultaneous Microlensing Observations by Two Space Telescopes: Spitzer and Swift Reveal a Brown Dwarf in Event Ogle-2015-BLG-1319

OGLE-2017-BLG-1130: The First Binary Gravitational Microlens Detected from Spitzer Only

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