A new type of Ambiguity in the Planet and Binary Interpretations of Central Perturbations of High-magnification Gravitational Microlensing Events

J.-Y Choi; I.-G Shin; C. Han; A. Udalski; T. Sumi; A. Gould; V. Bozza; M. Dominik; P. Fouque´; K. Horne; M. K. Szyman´ski; M. Kubiak; I. Soszyn´ski; G. Pietrzyn´ski; R. Poleski; K. Ulaczyk; P. Pietrukowicz; S. Kozłowski; J. Skowron; Ł. Wyrzykowski; OGLE Collaboration; F. Abe; D. P. Bennett; I. A. Bond; C. S. Botzler; P. Chote; M. Freeman; A. Fukui; K. Furusawa; Y. Itow; S. Kobara; C. H. Ling; K. Masuda; Y. Matsubara; N. Miyake; Y. Muraki; K. Ohmori; K. Ohnishi; N. J. Rattenbury; To Saito; D. J. Sullivan; D. Suzuki; K. Suzuki; W. L. Sweatman; S. Takino; P. J. Tristram; K. Wada; P. C. M. Yock; MOA Collaboration; D. M. Bramich; C. Snodgrass; I. A. Steele; R. A. Street; Y. Tsapras; RoboNet Collaboration; K. A. Alsubai; P. Browne; M. J. Burgdorf; S. Calchi Novati; P. Dodds; S. Dreizler; X.-S Fang; F. Grundahl; C.-H Gu; S. Hardis; K. Harpsøe; T. C. Hinse; Allan Hornstrup; M. Hundertmark; J. Jessen-Hansen; U. G. Jørgensen; N. Kains; E. Kerins; C. Liebig; M. Lund; M. Lunkkvist; L. Mancini; M. Mathiasen; M. T. Penny; S. Rahvar; D. Ricci; G. Scarpetta; J. Skottfelt; J. Southworth; J. Surdej; J. Tregloan-Reed; J. Wambsganss; O. Wertz; L. A. Almeida; V. Batista; G. Christie; D. L. DePoy; Subo Dong; B. S. Gaudi; C. Henderson; F. Jablonski; C.-U Lee; J. McCormick; D. McGregor; D. Moorhouse; T. Natusch; H. Ngan; R. W. Pogge; T.-G Tan; G. Thornley; J. C. Yee; M. D. Albrow; E. Bachelet; J.-P Beaulieu; S. Brillant; A. Cassan; A. A. Cole; E. Corrales; C. Coutures; S. Dieters; D. Dominis Prester; J. Donatowicz; J. Greenhill; D. Kubas; J.-B Marquette; J. W. Menzies; K. C. Sahu; M. Zub

doi:10.1088/0004-637X/756/1/48

A new type of Ambiguity in the Planet and Binary Interpretations of Central Perturbations of High-magnification Gravitational Microlensing Events

J.-Y Choi
, I.-G Shin
, C. Han
, A. Udalski
, T. Sumi
, A. Gould
, V. Bozza
, M. Dominik
, P. Fouque´
, K. Horne
, M. K. Szyman´ski
, M. Kubiak
, I. Soszyn´ski
, G. Pietrzyn´ski
, R. Poleski
, K. Ulaczyk
, P. Pietrukowicz
, S. Kozłowski
, J. Skowron
, Ł. Wyrzykowski

OGLE Collaboration, F. Abe, D. P. Bennett, I. A. Bond, C. S. Botzler, P. Chote, M. Freeman, A. Fukui, K. Furusawa, Y. Itow, S. Kobara, C. H. Ling, K. Masuda, Y. Matsubara, N. Miyake, Y. Muraki, K. Ohmori, K. Ohnishi, N. J. Rattenbury, To Saito, D. J. Sullivan, D. Suzuki, K. Suzuki, W. L. Sweatman, S. Takino, P. J. Tristram, K. Wada, P. C. M. Yock, MOA Collaboration, D. M. Bramich, C. Snodgrass, I. A. Steele, R. A. Street, Y. Tsapras, RoboNet Collaboration, K. A. Alsubai, P. Browne, M. J. Burgdorf, S. Calchi Novati, P. Dodds, S. Dreizler, X.-S Fang, F. Grundahl, C.-H Gu, S. Hardis, K. Harpsøe, T. C. Hinse, Allan Hornstrup, M. Hundertmark, J. Jessen-Hansen, U. G. Jørgensen, N. Kains, E. Kerins, C. Liebig, M. Lund, M. Lunkkvist, L. Mancini, M. Mathiasen, M. T. Penny, S. Rahvar, D. Ricci, G. Scarpetta, J. Skottfelt, J. Southworth, J. Surdej, J. Tregloan-Reed, J. Wambsganss, O. Wertz, L. A. Almeida, V. Batista, G. Christie, D. L. DePoy, Subo Dong, B. S. Gaudi, C. Henderson, F. Jablonski, C.-U Lee, J. McCormick, D. McGregor, D. Moorhouse, T. Natusch, H. Ngan, R. W. Pogge, T.-G Tan, G. Thornley, J. C. Yee, M. D. Albrow, E. Bachelet, J.-P Beaulieu, S. Brillant, A. Cassan, A. A. Cole, E. Corrales, C. Coutures, S. Dieters, D. Dominis Prester, J. Donatowicz, J. Greenhill, D. Kubas, J.-B Marquette, J. W. Menzies, K. C. Sahu, M. Zub

University of Warsaw
Okayama Astrophysical Observatory
Qatar Foundation HQ
Max Planck Institute
Keele University
Kumeu Observatory
Chungbuk National University
University of Rijeka
TU Wien
University of Tasmania
The University of Osaka
Ohio State University
University of Salerno
University of St Andrews
Université Fédérale Toulouse Midi-Pyrénées
Nagoya University
University of Notre Dame
Massey University
The University of Auckland
Victoria University of Wellington
Nagano National College of Technology
Tokyo Metropolitan College of Industrial Technology
Liverpool John Moores University
Las Cumbres Observatory Global Telescope Network, Inc.
University of Stuttgart
University of Göttingen
Chinese Academy of Sciences
Aarhus University
ESO Headquarters
University of Manchester
Sharif University of Technology
Institut d'Astrophysique et de Géophysique
Heidelberg University
Instituto Nacional de Pesquisas Espaciais
Stardome Observatory and Planetarium
Texas A&M University
Institute for Advanced Study
Korea Astronomy and Space Science Institute
Centre for Backyard Astrophysics
Perth Exoplanet Survey Telescope
University of Canterbury
Sorbonne Université
University of Copenhagen
Space Telescope Science Institute
South African Astronomical Observatory
European Southern Observatory

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Abstract

High-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.

Original language	English
Journal	Astrophysical Journal
Volume	756
Issue number	1
Pages (from-to)	48
Number of pages	9
ISSN	0004-637X
DOIs	https://doi.org/10.1088/0004-637X/756/1/48
Publication status	Published - 2012

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Choi, J. .-Y., Shin, I. .-G., Han, C., Udalski, A., Sumi, T., Gould, A., Bozza, V., Dominik, M., Fouque´, P., Horne, K., Szyman´ski, M. K., Kubiak, M., Soszyn´ski, I., Pietrzyn´ski, G., Poleski, R., Ulaczyk, K., Pietrukowicz, P., Kozłowski, S., Skowron, J., ... Zub, M. (2012). A new type of Ambiguity in the Planet and Binary Interpretations of Central Perturbations of High-magnification Gravitational Microlensing Events. Astrophysical Journal, 756(1), 48. https://doi.org/10.1088/0004-637X/756/1/48

@article{e839423263c448219033e6f3b6585129,

title = "A new type of Ambiguity in the Planet and Binary Interpretations of Central Perturbations of High-magnification Gravitational Microlensing Events",

abstract = "High-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 \textasciitilde{}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 \textasciitilde{} 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.",

author = "J.-Y Choi and I.-G Shin and C. Han and A. Udalski and T. Sumi and A. Gould and V. Bozza and M. Dominik and P. Fouque´ and K. Horne and Szyman´ski, \{M. K.\} and M. Kubiak and I. Soszyn´ski and G. Pietrzyn´ski and R. Poleski and K. Ulaczyk and P. Pietrukowicz and S. Koz{\l}owski and J. Skowron and {\L}. Wyrzykowski and \{OGLE Collaboration\} and F. Abe and Bennett, \{D. P.\} and Bond, \{I. A.\} and Botzler, \{C. S.\} and P. Chote and M. Freeman and A. Fukui and K. Furusawa and Y. Itow and S. Kobara and Ling, \{C. H.\} and K. Masuda and Y. Matsubara and N. Miyake and Y. Muraki and K. Ohmori and K. Ohnishi and Rattenbury, \{N. J.\} and To Saito and Sullivan, \{D. J.\} and D. Suzuki and K. Suzuki and Sweatman, \{W. L.\} and S. Takino and Tristram, \{P. J.\} and K. Wada and Yock, \{P. C. M.\} and \{MOA Collaboration\} and Bramich, \{D. M.\} and C. Snodgrass and Steele, \{I. A.\} and Street, \{R. A.\} and Y. Tsapras and \{RoboNet Collaboration\} and Alsubai, \{K. A.\} and P. Browne and Burgdorf, \{M. J.\} and \{Calchi Novati\}, S. and P. Dodds and S. Dreizler and X.-S Fang and F. Grundahl and C.-H Gu and S. Hardis and K. Harps{\o}e and Hinse, \{T. C.\} and Allan Hornstrup and M. Hundertmark and J. Jessen-Hansen and J{\o}rgensen, \{U. G.\} and N. Kains and E. Kerins and C. Liebig and M. Lund and M. Lunkkvist and L. Mancini and M. Mathiasen and Penny, \{M. T.\} and S. Rahvar and D. Ricci and G. Scarpetta and J. Skottfelt and J. Southworth and J. Surdej and J. Tregloan-Reed and J. Wambsganss and O. Wertz and Almeida, \{L. A.\} and V. Batista and G. Christie and DePoy, \{D. L.\} and Subo Dong and Gaudi, \{B. S.\} and C. Henderson and F. Jablonski and C.-U Lee and J. McCormick and D. McGregor and D. Moorhouse and T. Natusch and H. Ngan and Pogge, \{R. W.\} and T.-G Tan and G. Thornley and Yee, \{J. C.\} and Albrow, \{M. D.\} and E. Bachelet and J.-P Beaulieu and S. Brillant and A. Cassan and Cole, \{A. A.\} and E. Corrales and C. Coutures and S. Dieters and \{Dominis Prester\}, D. and J. Donatowicz and J. Greenhill and D. Kubas and J.-B Marquette and Menzies, \{J. W.\} and Sahu, \{K. C.\} and M. Zub",

year = "2012",

doi = "10.1088/0004-637X/756/1/48",

language = "English",

volume = "756",

pages = "48",

journal = "Astrophysical Journal",

issn = "0004-637X",

publisher = "American Astronomical Society",

number = "1",

}

Choi, J-Y, Shin, I-G, Han, C, Udalski, A, Sumi, T, Gould, A, Bozza, V, Dominik, M, Fouque´, P, Horne, K, Szyman´ski, MK, Kubiak, M, Soszyn´ski, I, Pietrzyn´ski, G, Poleski, R, Ulaczyk, K, Pietrukowicz, P, Kozłowski, S, Skowron, J, Wyrzykowski, Ł, OGLE Collaboration, Abe, F, Bennett, DP, Bond, IA, Botzler, CS, Chote, P, Freeman, M, Fukui, A, Furusawa, K, Itow, Y, Kobara, S, Ling, CH, Masuda, K, Matsubara, Y, Miyake, N, Muraki, Y, Ohmori, K, Ohnishi, K, Rattenbury, NJ, Saito, T, Sullivan, DJ, Suzuki, D, Suzuki, K, Sweatman, WL, Takino, S, Tristram, PJ, Wada, K, Yock, PCM, MOA Collaboration, Bramich, DM, Snodgrass, C, Steele, IA, Street, RA, Tsapras, Y, RoboNet Collaboration, Alsubai, KA, Browne, P, Burgdorf, MJ, Calchi Novati, S, Dodds, P, Dreizler, S, Fang, X-S, Grundahl, F, Gu, C-H, Hardis, S, Harpsøe, K, Hinse, TC, Hornstrup, A, Hundertmark, M, Jessen-Hansen, J, Jørgensen, UG, Kains, N, Kerins, E, Liebig, C, Lund, M, Lunkkvist, M, Mancini, L, Mathiasen, M, Penny, MT, Rahvar, S, Ricci, D, Scarpetta, G, Skottfelt, J, Southworth, J, Surdej, J, Tregloan-Reed, J, Wambsganss, J, Wertz, O, Almeida, LA, Batista, V, Christie, G, DePoy, DL, Dong, S, Gaudi, BS, Henderson, C, Jablonski, F, Lee, C-U, McCormick, J, McGregor, D, Moorhouse, D, Natusch, T, Ngan, H, Pogge, RW, Tan, T-G, Thornley, G, Yee, JC, Albrow, MD, Bachelet, E, Beaulieu, J-P, Brillant, S, Cassan, A, Cole, AA, Corrales, E, Coutures, C, Dieters, S, Dominis Prester, D, Donatowicz, J, Greenhill, J, Kubas, D, Marquette, J-B, Menzies, JW, Sahu, KC & Zub, M 2012, 'A new type of Ambiguity in the Planet and Binary Interpretations of Central Perturbations of High-magnification Gravitational Microlensing Events', Astrophysical Journal, vol. 756, no. 1, pp. 48. https://doi.org/10.1088/0004-637X/756/1/48

TY - JOUR

T1 - A new type of Ambiguity in the Planet and Binary Interpretations of Central Perturbations of High-magnification Gravitational Microlensing Events

AU - Choi, J.-Y

AU - Shin, I.-G

AU - Han, C.

AU - Udalski, A.

AU - Sumi, T.

AU - Gould, A.

AU - Bozza, V.

AU - Dominik, M.

AU - Fouque´, P.

AU - Horne, K.

AU - Szyman´ski, M. K.

AU - Kubiak, M.

AU - Soszyn´ski, I.

AU - Pietrzyn´ski, G.

AU - Poleski, R.

AU - Ulaczyk, K.

AU - Pietrukowicz, P.

AU - Kozłowski, S.

AU - Skowron, J.

AU - Wyrzykowski, Ł.

AU - OGLE Collaboration,

AU - Abe, F.

AU - Bennett, D. P.

AU - Bond, I. A.

AU - Botzler, C. S.

AU - Chote, P.

AU - Freeman, M.

AU - Fukui, A.

AU - Furusawa, K.

AU - Itow, Y.

AU - Kobara, S.

AU - Ling, C. H.

AU - Masuda, K.

AU - Matsubara, Y.

AU - Miyake, N.

AU - Muraki, Y.

AU - Ohmori, K.

AU - Ohnishi, K.

AU - Rattenbury, N. J.

AU - Saito, To

AU - Sullivan, D. J.

AU - Suzuki, D.

AU - Suzuki, K.

AU - Sweatman, W. L.

AU - Takino, S.

AU - Tristram, P. J.

AU - Wada, K.

AU - Yock, P. C. M.

AU - MOA Collaboration,

AU - Bramich, D. M.

AU - Snodgrass, C.

AU - Steele, I. A.

AU - Street, R. A.

AU - Tsapras, Y.

AU - RoboNet Collaboration,

AU - Alsubai, K. A.

AU - Browne, P.

AU - Burgdorf, M. J.

AU - Calchi Novati, S.

AU - Dodds, P.

AU - Dreizler, S.

AU - Fang, X.-S

AU - Grundahl, F.

AU - Gu, C.-H

AU - Hardis, S.

AU - Harpsøe, K.

AU - Hinse, T. C.

AU - Hornstrup, Allan

AU - Hundertmark, M.

AU - Jessen-Hansen, J.

AU - Jørgensen, U. G.

AU - Kains, N.

AU - Kerins, E.

AU - Liebig, C.

AU - Lund, M.

AU - Lunkkvist, M.

AU - Mancini, L.

AU - Mathiasen, M.

AU - Penny, M. T.

AU - Rahvar, S.

AU - Ricci, D.

AU - Scarpetta, G.

AU - Skottfelt, J.

AU - Southworth, J.

AU - Surdej, J.

AU - Tregloan-Reed, J.

AU - Wambsganss, J.

AU - Wertz, O.

AU - Almeida, L. A.

AU - Batista, V.

AU - Christie, G.

AU - DePoy, D. L.

AU - Dong, Subo

AU - Gaudi, B. S.

AU - Henderson, C.

AU - Jablonski, F.

AU - Lee, C.-U

AU - McCormick, J.

AU - McGregor, D.

AU - Moorhouse, D.

AU - Natusch, T.

AU - Ngan, H.

AU - Pogge, R. W.

AU - Tan, T.-G

AU - Thornley, G.

AU - Yee, J. C.

AU - Albrow, M. D.

AU - Bachelet, E.

AU - Beaulieu, J.-P

AU - Brillant, S.

AU - Cassan, A.

AU - Cole, A. A.

AU - Corrales, E.

AU - Coutures, C.

AU - Dieters, S.

AU - Dominis Prester, D.

AU - Donatowicz, J.

AU - Greenhill, J.

AU - Kubas, D.

AU - Marquette, J.-B

AU - Menzies, J. W.

AU - Sahu, K. C.

AU - Zub, M.

PY - 2012

Y1 - 2012

N2 - High-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.

AB - High-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.

U2 - 10.1088/0004-637X/756/1/48

DO - 10.1088/0004-637X/756/1/48

M3 - Journal article

SN - 0004-637X

VL - 756

SP - 48

JO - Astrophysical Journal

JF - Astrophysical Journal

IS - 1

ER -

A new type of Ambiguity in the Planet and Binary Interpretations of Central Perturbations of High-magnification Gravitational Microlensing Events

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