J/ApJ/738/170 False positive Kepler planet candidates (Morton+, 2011)
On the low false positive probabilities of Kepler planet candidates.
Morton T.D., Johnson J.A.
<Astrophys. J., 738, 170 (2011)>
=2011ApJ...738..170M 2011ApJ...738..170M
ADC_Keywords: Stars, double and multiple ; Planets ; Models
Keywords: methods: statistical - planets and satellites: general -
stars: statistics
Abstract:
We present a framework to conservatively estimate the probability that
any particular planet-like transit signal observed by the Kepler
mission is in fact a planet, prior to any ground-based follow-up
efforts. We use Monte Carlo methods based on stellar population
synthesis and Galactic structure models, and report false positive
probabilities (FPPs) for every Kepler Object of Interest, assuming a
20% intrinsic occurrence rate of close-in planets in the radius range
0.5R{earth}<Rp<20R{earth}. Nearly 90% of the 1235 candidates
have FPP<10%, and over half have FPP<5%. This probability varies with
the magnitude and Galactic latitude of the target star, and with the
depth of the transit signal - deeper signals generally have higher
FPPs than shallower signals. We establish that a single deep
high-resolution image will be an effective follow-up tool for the
shallowest (Earth-sized) transits, providing the quickest route toward
probabilistically validating the smallest candidates by potentially
decreasing the FPP of an Earth-sized transit around a faint star from
>10% to <1%. Since Kepler has detected many more planetary signals
than can be positively confirmed with ground-based follow-up efforts
in the near term, these calculations will be crucial to using the
ensemble of Kepler data to determine population characteristics of
planetary systems. We also describe how our analysis complements the
Kepler team's more detailed BLENDER false positive analysis for planet
validation.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 91 1235 False positive probabilities for Kepler planet
candidates
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See also:
V/133 : Kepler Input Catalog (Kepler Mission Team, 2009)
J/ApJS/197/8 : Kepler's candidate multiple transiting planets (Lissauer+,
2011)
J/ApJS/197/2 : Transit timing observations from Kepler. I. (Ford+, 2011)
J/ApJ/736/L25 : HZs for Kepler planetary candidates (Kaltenegger+, 2011)
J/ApJ/736/19 : Kepler planetary candidates. II. (Borucki+, 2011)
J/ApJ/728/117 : Kepler planetary candidates. I. (Borucki+, 2011)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 7 F7.2 --- KOI [1.01/1609.01] Kepler identifier from Borucki
et al. 2011, Cat. J/ApJ/736/19
9- 16 E8.3 mag d Transit depth δ
18- 25 E8.3 --- Det Detection threshold (1)
27- 31 F5.2 mag Kpmag [8.22/16.42] Kepler magnitude
33- 34 I2 pix Ap [1/84]? Size of photometric aperture (2)
36- 40 F5.2 deg GLAT [5.87/21.14] Galactic latitude of target star
42- 48 F7.1 d Per [0.4/10389] Candidate period
50- 53 F4.2 Msun M* [0.21/1.84] Stellar mass (3)
55- 58 F4.2 Rsun R* [0.27/6.16] Stellar radius (3)
60- 67 E8.3 --- LBB Likelihood×prior for blended binary
69- 76 E8.3 --- LHT Likelihood×prior for eclipsing
hierarchical triple scenario
78- 85 E8.3 --- Lpl Likelihood×prior for transiting planet
87 A1 --- l_FPP Limit flag on FPP
88- 91 F4.2 --- FPP [0/1] False positive probability (4)
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Note (1): detectability threshold with S/N=3, according to Borucki et al.
(2011, Cat. J/ApJ/736/19).
Note (2): According to the publicly available pixel data. Pixels are
4" square each.
Note (3): According to the Kepler Input Catalog (Cat. V/133).
Note (4): FPP=1-Lpl/(Lpl+LBB+LHT) where LBB and LHT are
the corresponding terms for the two false positive scenarios.
See section 4.2 for further explanations.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 23-Jan-2013