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Fundamental Limitations of High Contrast Imaging Set by Small Sample Statistics

Mawet, D. and Milli, J. and Wahhaj, Z. and Pelat, D. and Absil, O. and Delacroix, C. and Boccaletti, A. and Kasper, M. and Kenworthy, M. and Marois, C. and Mennesson, B. and Pueyo, L. (2014) Fundamental Limitations of High Contrast Imaging Set by Small Sample Statistics. Astrophysical Journal, 792 (2). Art. No. 97. ISSN 0004-637X. doi:10.1088/0004-637X/792/2/97.

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In this paper, we review the impact of small sample statistics on detection thresholds and corresponding confidence levels (CLs) in high-contrast imaging at small angles. When looking close to the star, the number of resolution elements decreases rapidly toward small angles. This reduction of the number of degrees of freedom dramatically affects CLs and false alarm probabilities. Naively using the same ideal hypothesis and methods as for larger separations, which are well understood and commonly assume Gaussian noise, can yield up to one order of magnitude error in contrast estimations at fixed CL. The statistical penalty exponentially increases toward very small inner working angles. Even at 5-10 resolution elements from the star, false alarm probabilities can be significantly higher than expected. Here we present a rigorous statistical analysis that ensures robustness of the CL, but also imposes a substantial limitation on corresponding achievable detection limits (thus contrast) at small angles. This unavoidable fundamental statistical effect has a significant impact on current coronagraphic and future high-contrast imagers. Finally, the paper concludes with practical recommendations to account for small number statistics when computing the sensitivity to companions at small angles and when exploiting the results of direct imaging planet surveys.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Mawet, D.0000-0002-8895-4735
Milli, J.0000-0001-9325-2511
Wahhaj, Z.0000-0001-8269-324X
Absil, O.0000-0002-4006-6237
Boccaletti, A.0000-0001-9353-2724
Kenworthy, M.0000-0002-7064-8270
Marois, C.0000-0002-4164-4182
Mennesson, B.0000-0003-4205-4800
Pueyo, L.0000-0003-3818-408X
Additional Information:© 2014 The American Astronomical Society. Received 2014 January 16; Accepted 2014 July 7; Published 2014 August 21. This work was carried out at the European Southern Observatory (ESO) site of Vitacura (Santiago, Chile). The authors thank the referee, Professor Dmitry Savransky, for his critical, thorough, and very constructive review of the manuscript. The research leading to these results has received funding from the European Research Council Under the European Union’s Seventh Framework Programme (ERC Grant Agreement n. 337569) and from the French Community of Belgium through an ARC grant for Concerted Research Action. Part of the research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.
Funding AgencyGrant Number
European Research Council (ERC)337569
Actions de Recherche Concertees (Communauté Française de Belgique)UNSPECIFIED
Subject Keywords:methods: statistical; techniques: high angular resolution
Issue or Number:2
Record Number:CaltechAUTHORS:20150526-113446870
Persistent URL:
Official Citation:Fundamental Limitations of High Contrast Imaging Set by Small Sample Statistics. D. Mawet et al. 2014 ApJ 792 97
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:57807
Deposited By: Joanne McCole
Deposited On:27 May 2015 14:05
Last Modified:10 Nov 2021 21:55

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