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Improving signal-to-noise in the direct imaging of exoplanets and circumstellar disks with MLOCI

Wahhaj, Zahed and Cieza, Lucas A. and Mawet, Dimitri and Yang, Bin and Canovas, Hector and De Boer, Jozua and Casassus, Simon and Ménard, François and Schreiber, Matthias R. and Liu, Michael C. and Biller, Beth A. and Nielsen, Eric L. and Hayward, Thomas L. (2015) Improving signal-to-noise in the direct imaging of exoplanets and circumstellar disks with MLOCI. Astronomy and Astrophysics, 581 . Art. No. A24. ISSN 0004-6361. https://resolver.caltech.edu/CaltechAUTHORS:20150519-105102626

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Abstract

We present a new algorithm designed to improve the signal-to-noise ratio (S/N) of point and extended source detections around bright stars in direct imaging data.One of our innovations is that we insert simulated point sources into the science images, which we then try to recover with maximum S/N. This improves the S/N of real point sources elsewhere in the field. The algorithm, based on the locally optimized combination of images (LOCI) method, is called Matched LOCI or MLOCI. We show with Gemini Planet Imager (GPI) data on HD 135344 B and Near-Infrared Coronagraphic Imager (NICI) data on several stars that the new algorithm can improve the S/N of point source detections by 30–400% over past methods. We also find no increase in false detections rates. No prior knowledge of candidate companion locations is required to use MLOCI. On the other hand, while non-blind applications may yield linear combinations of science images that seem to increase the S/N of true sources by a factor >2, they can also yield false detections at high rates. This is a potential pitfall when trying to confirm marginal detections or to redetect point sources found in previous epochs. These findings are relevant to any method where the coefficients of the linear combination are considered tunable, e.g., LOCI and principal component analysis (PCA). Thus we recommend that false detection rates be analyzed when using these techniques.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1051/0004-6361/201525837DOIArticle
https://www.aanda.org/articles/aa/abs/2015/09/aa25837-15/aa25837-15.htmlPublisherArticle
http://arxiv.org/abs/1502.03092arXivDiscussion Paper
ORCID:
AuthorORCID
Wahhaj, Zahed0000-0001-8269-324X
Cieza, Lucas A.0000-0002-2828-1153
Mawet, Dimitri0000-0002-8895-4735
Canovas, Hector0000-0001-7668-8022
Liu, Michael C.0000-0003-2232-7664
Biller, Beth A.0000-0003-4614-7035
Nielsen, Eric L.0000-0001-6975-9056
Alternate Title:Improving Signal to Noise in the Direct Imaging of Exoplanets and Circumstellar Disks
Additional Information:© 2015 ESO. Article published by EDP Sciences. Received 6 February 2015; Accepted 14 May 2015; Published online 26 August 2015. Based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (USA), the Science and Technology Facilities Council (UK), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), Ministério da Ciência e Tecnologia (Brazil) and Ministerio de Ciencia, Tecnología e Innovación Productiva (Argentina). Our research has employed the 2MASS data products; NASA’s Astrophysical Data System; the SIMBAD database operated at the CDS, Strasbourg, France. L.A.C. was supported by ALMA-CONICYT grant number 31120009 and CONICYT-FONDECYT grant number 1140109. L.A.C., M.R.S., H.C., and S.C. acknowledge support from the Millennium Science Initiative (Chilean Ministry of Economy), through grant Nucleus RC13007. H.C. also thanks ALMA/CONICYT (grants 31100025 and 31130027) for their support.
Funders:
Funding AgencyGrant Number
Comisión Nacional de Investigación Científica y Tecnológica (CONICYT)31120009
Comisión Nacional de Investigación Científica y Tecnológica (CONICYT)1140109
Ministry of Economy (Chile)RC13007
Comisión Nacional de Investigación Científica y Tecnológica (CONICYT)31100025
Comisión Nacional de Investigación Científica y Tecnológica (CONICYT)31130027
Subject Keywords:planets and satellites: detection – instrumentation: adaptive optics – methods: data analysis – techniques: image processing
Record Number:CaltechAUTHORS:20150519-105102626
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20150519-105102626
Official Citation:Improving signal-to-noise in the direct imaging of exoplanets and circumstellar disks with MLOCI Zahed Wahhaj, Lucas A. Cieza, Dimitri Mawet, Bin Yang, Hector Canovas, Jozua de Boer, Simon Casassus, François Ménard, Matthias R. Schreiber, Michael C. Liu, Beth A. Biller, Eric L. Nielsen and Thomas L. Hayward A&A, 581 (2015) A24 DOI: https://doi.org/10.1051/0004-6361/201525837
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:57655
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:19 May 2015 20:56
Last Modified:09 Mar 2020 13:18

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