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Aims. H.E.S.S. observes an increasing number of large extended sources. A new technique based on the structure of the sky map is developed to account for these additional structures by comparing them with the common point source analysis.…

Instrumentation and Methods for Astrophysics · Physics 2013-07-12 D. Göring , M. A. Klatt , C. Stegmann , K. Mecke

We pursue a novel morphometric analysis to detect sources in very-high-energy gamma-ray counts maps by structural deviations from the background noise without assuming any prior knowledge about potential sources. The rich and complex…

Instrumentation and Methods for Astrophysics · Physics 2017-10-11 Michael A. Klatt , Klaus Mecke

We pursue a novel morphometric analysis to detect sources in very-high-energy gamma-ray counts maps by structural deviations from the background noise. Because the Minkowski functionals from integral geometry quantify the shape of the…

Instrumentation and Methods for Astrophysics · Physics 2017-10-11 Michael A. Klatt , Klaus Mecke

The study of shapes of the images of objects is an important issue not only because it reveals its dynamical state but also it helps to understand the object's evolutionary history. We discuss a new technique in cosmological image analysis…

Astrophysics · Physics 2016-01-27 Nurur Rahman , Sergei F. Shandarin

We develop a novel method for detection of signals and reconstruction of images in the presence of random noise. The method uses results from percolation theory. We specifically address the problem of detection of multiple objects of…

Applications · Statistics 2013-12-02 Mikhail Langovoy , Michael Habeck , Bernhard Schölkopf

Unexpected structure in images of astronomical sources often presents itself upon visual inspection of the image, but such apparent structure may either correspond to true features in the source or be due to noise in the data. This paper…

Instrumentation and Methods for Astrophysics · Physics 2016-02-19 Nathan M. Stein , David A. van Dyk , Vinay L. Kashyap , Aneta Siemiginowska

We propose a novel statistical hypothesis testing method for detection of objects in noisy images. The method uses results from percolation theory and random graph theory. We present an algorithm that allows to detect objects of unknown…

Statistics Theory · Mathematics 2013-12-02 Mikhail A. Langovoy , Olaf Wittich

We propose a novel probabilistic method for detection of objects in noisy images. The method uses results from percolation and random graph theories. We present an algorithm that allows to detect objects of unknown shapes in the presence of…

Statistics Theory · Mathematics 2011-02-24 Mikhail A. Langovoy , Olaf Wittich

A noise-based non-parametric technique for detecting nebulous objects, for example, irregular or clumpy galaxies, and their structure in noise is introduced. "Noise-based" and "non-parametric" imply that this technique imposes negligible…

Instrumentation and Methods for Astrophysics · Physics 2015-09-08 Mohammad Akhlaghi , Takashi Ichikawa

We suggest a set of morphological measures that we believe can help in quantifying the shapes of two-dimensional cosmological images such as galaxies, clusters, and superclusters of galaxies. The method employs non-parametric morphological…

Astrophysics · Physics 2009-07-30 Nurur Rahman , Sergei F. Shandarin

We study statistical detection of grayscale objects in noisy images. The object of interest is of unknown shape and has an unknown intensity, that can be varying over the object and can be negative. No boundary shape constraints are imposed…

Statistics Theory · Mathematics 2011-02-24 Mikhail A. Langovoy , Olaf Wittich

We present a new harmonic-domain approach for extracting morphological information, in the form of Minkowski Functionals (MFs), from weak lensing (WL) convergence maps. Using a perturbative expansion of the MFs, which is expected to be…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-27 Dipak Munshi , Ludovic van Waerbeke , Joseph Smidt , Peter Coles

We propose a novel probabilistic method for detection of objects in noisy images. The method uses results from percolation and random graph theories. We present an algorithm that allows to detect objects of unknown shapes in the presence of…

Statistics Theory · Mathematics 2013-12-02 Mikhail A. Langovoy , Olaf Wittich

We investigate the cosmological information in higher-order statistics of the cosmic microwave background (CMB) lensing convergence field for a near-term experiment with noise properties similar to the Simons Observatory (SO). Using a fully…

Cosmology and Nongalactic Astrophysics · Physics 2026-03-16 Shu-Fan Chen , J. Colin Hill , Zoltán Haiman

We study the morphology of convergence maps by perturbatively reconstructing their Minkowski Functionals (MFs). We present a systematics study using a set of three generalised skew-spectra as a function of source redshift and smoothing…

Cosmology and Nongalactic Astrophysics · Physics 2021-09-01 D. Munshi , T. Namikawa , J. D. McEwen , T. D. Kitching , F. R. Bouchet

We have observed an area of approximatley 27 deg^2 to an rms noise level of less than 0.2 mJy at 15.7 GHz, using the Arcminute Microkelvin Imager Large Array. These observations constitute the most sensitive radio-source survey of any…

We develop an unsupervised, nonparametric, and scalable statistical learning method for detection of unknown objects in noisy images. The method uses results from percolation theory and random graph theory. We present an algorithm that…

Statistics Theory · Mathematics 2018-07-16 Mikhail A. Langovoy , Olaf Wittich , Patrick Laurie Davies

Examining the detailed structure of galaxy populations provides valuable insights into their formation and evolution mechanisms. Significant barriers to such analysis are the non-trivial noise properties of real astronomical images and the…

Instrumentation and Methods for Astrophysics · Physics 2023-12-01 Alexandre Adam , Connor Stone , Connor Bottrell , Ronan Legin , Yashar Hezaveh , Laurence Perreault-Levasseur

Estimating the true background in an astronomical image is fundamental to detecting faint sources. In a typical low-photon count astronomical image, such as in the far and near-ultraviolet wavelength range, conventional methods relying on…

Instrumentation and Methods for Astrophysics · Physics 2024-11-27 Pushpak Pandey , Kanak Saha

We present a data-driven technique to analyze multifrequency images from upcoming cosmological surveys mapping large sky area. Using full information from the data at the two-point level, our method can simultaneously constrain the…

Cosmology and Nongalactic Astrophysics · Physics 2023-03-01 Yun-Ting Cheng , Benjamin D. Wandelt , Tzu-Ching Chang , Olivier Dore
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