Journal article · Preprint article
A new type of Ambiguity in the Planet and Binary Interpretations of Central Perturbations of High-magnification Gravitational Microlensing Events
Chungbuk National University1
Massey University2
The University of Auckland3
Victoria University of Wellington4
Okayama Astrophysical Observatory5
Nagano National College of Technology6
Tokyo Metropolitan College of Industrial Technology7
European Southern Observatory8
Max Planck Institute9
Liverpool John Moores University10
Las Cumbres Observatory Global Telescope Network, Inc.11
University of Warsaw12
Qatar Foundation13
University of Stuttgart14
University of Göttingen15
Chinese Academy of Sciences16
Aarhus University17
University of Copenhagen18
National Space Institute, Technical University of Denmark19
Astrophysics, National Space Institute, Technical University of Denmark20
IT-Department, National Space Institute, Technical University of Denmark21
ESO Headquarters22
Osaka University23
University of Manchester24
Sharif University of Technology25
Institut d'Astrophysique et de Géophysique26
Keele University27
Heidelberg University 28
Instituto Nacional de Pesquisas Espaciais29
Stardome Observatory and Planetarium30
Texas A&M University31
Institute for Advanced Study32
Korea Astronomy and Space Science Institute33
Ohio State University34
Centre for Backyard Astrophysics35
Kumeu Observatory36
Perth Exoplanet Survey Telescope37
University of Canterbury38
Sorbonne Université39
University of Tasmania40
University of Rijeka41
Vienna University of Technology42
South African Astronomical Observatory43
Space Telescope Science Institute44
University of Salerno45
University of St Andrews46
Université Fédérale Toulouse Midi-Pyrénées47
Nagoya University48
University of Notre Dame49
...and 39 moreHigh-magnification microlensing events provide an important channel to detect planets. Perturbations near the peak of a high-magnification event can be produced either by a planet or a binary companion. It is known that central perturbations induced by both types of companions can be generally distinguished due to the essentially different magnification pattern around caustics.
In this paper, we present a case of central perturbations for which it is difficult to distinguish the planetary and binary interpretations. The peak of a lensing light curve affected by this perturbation appears to be blunt and flat. For a planetary case, this perturbation occurs when the source trajectory passes the negative perturbation region behind the back end of an arrowhead-shaped central caustic.
For a binary case, a similar perturbation occurs for a source trajectory passing through the negative perturbation region between two cusps of an astroid-shaped caustic. We demonstrate the degeneracy for two high-magnification events of OGLE-2011-BLG-0526 and OGLE-2011-BLG-0950/MOA-2011-BLG-336. For OGLE-2011-BLG-0526, the χ2 difference between the planetary and binary model is ~3, implying that the degeneracy is very severe.
For OGLE-2011-BLG-0950/MOA-2011-BLG-336, the stellar binary model is formally excluded with Δχ2 ~ 105 and the planetary model is preferred. However, it is difficult to claim a planet discovery because systematic residuals of data from the planetary model are larger than the difference between the planetary and binary models.
Considering that two events observed during a single season suffer from such a degeneracy, it is expected that central perturbations experiencing this type of degeneracy is common.
| Language: | English |
|---|---|
| Year: | 2012 |
| Pages: | 48 |
| ISSN: | 15384365 , 00670049 , 0004637x and 15384357 |
| Types: | Journal article and Preprint article |
| DOI: | 10.1088/0004-637X/756/1/48 |
| ORCIDs: | Hornstrup, Allan and 0000-0001-7303-914X |
