Kernel-phase detection limits

Ceau, Alban; Mary, David; Greenbaum, Alexandra Z.; Martinache, Frantz; Sivaramakrishnan, A.; Laugier, R.; N’Diaye, Mamadou

doi:10.1051/0004-6361/201935247

Cited by 15 publications

(28 citation statements)

References 39 publications

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“…Closure-and kernel-phase based observing programs are becoming more and more ambitious with instruments that make it theoretically possible in some cases to probe for planetary mass companions (Sallum & Skemer 2019;Ceau et al 2019) down to…”

Section: Resultsmentioning

confidence: 99%

Kernel-phase analysis: Aperture modeling prescriptions that minimize calibration errors

Martinache

Ceau

Laugier

et al. 2020

A&A

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Context. Kernel-phase is a data analysis method based on a generalization of the notion of closure-phase invented in the context of interferometry, but that applies to well corrected diffraction dominated images produced by an arbitrary aperture. The linear model upon which it relies theoretically leads to the formation of observable quantities robust against residual aberrations. Aims. In practice, detection limits reported thus far seem to be dominated by systematic errors induced by calibration biases not sufficiently filtered out by the kernel projection operator. This paper focuses on the impact the initial modeling of the aperture has on these errors and introduces a strategy to mitigate them, using a more accurate aperture transmission model. Methods. The paper first uses idealized monochromatic simulations of a non trivial aperture to illustrate the impact modeling choices have on calibration errors. It then applies the outlined prescription to two distinct data-sets of images whose analysis has previously been published.Results. The use of a transmission model to describe the aperture results in a significant improvement over the previous type of analysis. The thus reprocessed data-sets generally lead to more accurate results, less affected by systematic errors. Conclusions. As kernel-phase observing programs are becoming more ambitious, accuracy in the aperture description is becoming paramount to avoid situations where contrast detection limits are dominated by systematic errors. Prescriptions outlined in this paper will benefit any attempt at exploiting kernel-phase for high-contrast detection.

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Section: Resultsmentioning

confidence: 99%

Kernel-phase analysis: Aperture modeling prescriptions that minimize calibration errors

Martinache

Ceau

Laugier

et al. 2020

A&A

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“…Although our proposition for the matrix L may seem mathematically simplistic compared to some of the more advanced forms of ADI, it was designed for the purposes of a flawless integration with our kernel-phase pipeline, especially with regard to the statistical whitening and hypothesis testing proposed by Ceau et al (2019). Furthermore, the mathematical framework provided in appendix A can be used even with more elaborate definitions of the bias signal by replacing the matrix U f with the appropriate matrices.…”

Section: Resultsmentioning

confidence: 99%

“…Based on the revised covariance estimation, sensitivity maps were drawn following the energy detector T E test proposed by Ceau et al (2019). They were determined for a detection probability of 0.95 and false alarm rate of 0.01 for the region of interest, which is plotted in Fig.…”

Section: Performance Comparisonmentioning

confidence: 99%

Angular differential kernel phases

Laugier

Martinache

Cvetojevic

et al. 2020

A&A

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Context. To reach its optimal performance, Fizeau interferometry requires that we work to resolve instrumental biases through calibration. One common technique used in high contrast imaging is angular differential imaging, which calibrates the point spread function and flux leakage using a rotation in the focal plane. Aims. Our aim is to experimentally demonstrate and validate the efficacy of an angular differential kernel-phase approach, a new method for self-calibrating interferometric observables that operates similarly to angular differential imaging, while retaining their statistical properties. Methods. We used linear algebra to construct new observables that evolve outside of the subspace spanned by static biases. On-sky observations of a binary star with the SCExAO instrument at the Subaru telescope were used to demonstrate the practicality of this technique. We used a classical approach on the same data to compare the effectiveness of this method.Results. The proposed method shows smaller and more Gaussian residuals compared to classical calibration methods, while retaining compatibility with the statistical tools available. We also provide a measurement of the stability of the SCExAO instrument that is relevant to the application of the technique. Conclusions. Angular differential kernel phases provide a reliable method for calibrating biased observables. Although the sensitivity at small separations is reduced for small field rotations, the calibration is effectively improved and the number of subjective choices is reduced.Article number, page 1 of 11

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“…We find that kernel phase interferometry, applied to high-Strehl images in the mid-infrared, is a powerful technique to achieve the highest possible angular resolution with single-dish telescopes. The adaptive optics-corrected VISIR-NEAR instrument provides a unique opportunity to perform such observations from the ground, while kernel phase will also find increased application in space-based observations with the James Webb Space Telescope (e.g., Ceau et al 2019).…”

Section: Discussionmentioning

confidence: 99%

Mid-infrared photometry of the T Tauri triple system with kernel phase interferometry

Kammerer

Kasper

Ireland

et al. 2021

A&A

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Context. T Tauri has long been the prototypical young pre-main-sequence star. However, with increasing resolution and sensitivity, T Tauri has now been decomposed into a triple system with a complex disk and outflow geometry. Aims. We aim to measure the brightness of all three components of the T Tauri system (T Tau N, T Tau Sa, and T Tau Sb) in the mid-infrared in order to obtain photometry around the ∼9.7 μm silicate feature. This allows us to study their variability and to investigate the distribution of dust and the geometry of circumstellar and circumbinary disks in this complex system. Methods. We observe the T Tauri system with the Very Large Telescope (VLT)/VISIR-NEAR instrument, performing diffraction-limited imaging in the mid-infrared. With kernel phase interferometry post-processing of the data, and using the astrometric positions of all three components from VLT/SPHERE, we measure the three components’ individual brightnesses (including the southern binary at an angular separation down to ∼0.2λ/D) and obtain their photometry. In order to validate our methods, we simulate and recover mock data of the T Tauri system using the observed reference point-spread function of HD 27639. Results. We find that T Tau N is rather stable and shows weak silicate emission, while T Tau Sa is highly variable and shows prominent silicate absorption. T Tau Sb became significantly fainter compared to data from 2004 and 2006, suggesting increased extinction by dust. The precision of our photometry is limited by systematic errors in kernel phase interferometry, which is consistent with previous studies using this technique. Conclusions. Our results confirm the complex scenario of misaligned disks in the T Tauri system that had been observed previously, and they are in agreement with the recently observed dimming of T Tau Sb in the near-infrared. Our mid-infrared photometry supports the interpretation that T Tau Sb has moved behind the dense region of the Sa-Sb circumbinary disk on its tight orbit around Sa, therefore suffering increased extinction.

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Kernel-phase detection limits

Cited by 15 publications

References 39 publications

Kernel-phase analysis: Aperture modeling prescriptions that minimize calibration errors

Kernel-phase analysis: Aperture modeling prescriptions that minimize calibration errors

Angular differential kernel phases

Mid-infrared photometry of the T Tauri triple system with kernel phase interferometry

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