Of `Cocktail Parties' and Exoplanets

Abstract

The characterisation of ever smaller and fainter extrasolar planets requires an intricate understanding of one's data and the analysis techniques used. Correcting the raw data at the 10^-4 level of accuracy in flux is one of the central challenges. This can be difficult for instruments that do not feature a calibration plan for such high precision measurements. Here, it is not always obvious how to de-correlate the data using auxiliary information of the instrument and it becomes paramount to know how well one can disentangle instrument systematics from one's data, given nothing but the data itself. We propose a non-parametric machine learning algorithm, based on the concept of independent component analysis, to de-convolve the systematic noise and all non-Gaussian signals from the desired astrophysical signal. Such a `blind' signal de-mixing is commonly known as the `Cocktail Party problem' in signal-processing. Given multiple simultaneous observations of the same exoplanetary eclipse, as in the case of spectrophotometry, we show that we can often disentangle systematic noise from the original light curve signal without the use of any complementary information of the instrument. In this paper, we explore these signal extraction techniques using simulated data and two data sets observed with the Hubble-NICMOS instrument. Another important application is the de-correlation of the exoplanetary signal from time-correlated stellar variability. Using data obtained by the Kepler mission we show that the desired signal can be de-convolved from the stellar noise using a single time series spanning several eclipse events. Such non-parametric techniques can provide important confirmations of the existent parametric corrections reported in the literature, and their associated results. Additionally they can substantially improve the precision exoplanetary light curve analysis in the future.

ApJ accepted

References in corpus (22)

• Characteristics of planetary candidates observed by Kepler, II: Analysis of the first four months of data
• Defining and cataloging exoplanets: The exoplanet.eu database
• Detection of Thermal Emission from an Extrasolar Planet
• Sodium Absorption From the Exoplanetary Atmosphere of HD189733b Detected in the Optical Transmission Spectrum
• Hubble Space Telescope Transmission Spectroscopy of the Exoplanet HD 189733b: High-altitude atmospheric haze in the optical and near-UV with STIS
• Efficient identification of exoplanetary transit candidates from SuperWASP light curves
• Possible thermochemical disequilibrium in the atmosphere of the exoplanet GJ 436b
• The Broadband Infrared Emission Spectrum of the Exoplanet HD 189733b
• Strong Water Absorption in the Dayside Emission Spectrum of the Planet HD 189733b
• Ground-based detection of sodium in the transmission spectrum of exoplanet HD209458b
• Using Stellar Limb-Darkening to Refine the Properties of HD 209458b
• The Optical and Near-Infrared Transmission Spectrum of the Super-Earth GJ1214b: Further Evidence for a Metal-Rich Atmosphere
• The Transit Light Curve Project. V. System Parameters and Stellar Rotation Period of HD 189733
• XO-2b: Transiting Hot Jupiter in a Metal-rich Common Proper Motion Binary
• A new look at NICMOS transmission spectroscopy of HD189733, GJ-436 and XO-1: no conclusive evidence for molecular features
• On the Mass of CoRoT-7b
• A Spitzer Transmission Spectrum for the Exoplanet GJ 436b, Evidence for Stellar Variability, and Constraints on Dayside Flux Variations
• HAT-P-5b: A Jupiter-like hot Jupiter Transiting a Bright Star
• Ground-based NIR emission spectroscopy of HD189733b
• 3.8-Micron Photometry During the Secondary Eclipse of the Extrasolar Planet HD 209458b
• Selective Principal Component Extraction and Reconstruction: A Novel Method for Ground Based Exoplanet Spectroscopy
• Blind component separation for polarized observations of the CMB

Cited by in corpus (36)

• Infrared Transmission Spectroscopy of the Exoplanets HD209458b and XO-1b Using the Wide Field Camera-3 on the Hubble Space Telescope
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• Foreground Removal using FastICA: A Showcase of LOFAR-EoR
• A Gemini ground-based transmission spectrum of WASP-29b: a featureless spectrum from 515 to 720nm
• Validation of Twelve Small Kepler Transiting Planets in the Habitable Zone
• Using Machine Learning for Discovery in Synoptic Survey Imaging
• The Transiting Exoplanet Community Early Release Science Program for JWST
• The optical transmission spectrum of the hot Jupiter HAT-P-32b: clouds explain the absence of broad spectral features?
• Features in the Broadband Eclipse Spectra of Exoplanets: Signal or Noise?
• Repeatability and Accuracy of Exoplanet Eclipse Depths Measured with Post-Cryogenic Spitzer
• Blind extraction of an exoplanetary spectrum through Independent Component Analysis
• Revisiting Spitzer transit observations with Independent Component Analysis: new results for the GJ436 system
• On signals faint and sparse: the ACICA algorithm for blind de-trending of Exoplanetary transits with low signal-to-noise
• The ground-based H, K, and L-band absolute emission spectra of HD 209458b
• Revisiting the potassium feature of WASP-31b at high-resolution
• The EChO science case
• A new look at Spitzer primary transit observations of the exoplanet HD189733b
• Near-IR transmission spectrum of HAT-P-32 b using HST/WFC3
• A New Concept for Spectro-photometry of Exoplanets with Space-based Telescopes
• Benchmark Tests for Markov Chain Monte Carlo Fitting of Exoplanet Eclipse Observations
• Repeatability of Spitzer/IRAC exoplanetary eclipses with Independent Component Analysis
• Hot Rocks Survey III: A deep eclipse for LHS 1140c and a new Gaussian process method to account for correlated noise in individual pixels
• Detrending Exoplanetary Transit Light Curves with Long Short-Term Memory Networks
• A blind method to detrend instrumental systematics in exoplanetary light-curves
• Spitzer thermal phase curve of WASP-121 b
• A SEA BASS on the exoplanet HD209458b
• Data analysis Pipeline for EChO end-to-end simulations
• Using Independent Component Analysis to detect exoplanet reflection spectrum from composite spectra of exoplanetary binary systems
• Knot a Bad Idea: Testing BLISS Mapping for Spitzer Space Telescope Photometry
• DIAmante TESS AutoRegressive Planet Search (DTARPS): I. Analysis of 0.9 Million Light Curves
• Galactic planetary science
• AutoRegressive Planet Search: Feasibility Study for Irregular Time Series
• Atmospheric characterization of hot Jupiters using hierarchical models of Spitzer observations
• Multiple component decomposition from millimeter single-channel data
• The Quantum Cocktail Party Problem