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We use galaxy-galaxy lensing to study the statistical properties of the dark matter halos of galaxies. Our data is taken from the COMBO-17 survey which has imaged 1 square degree in 17 optical filters giving accurate photometric redshifts…

This study introduces a novel unsupervised medical image feature extraction method that employs spatial stratification techniques. An objective function based on weight is proposed to achieve the purpose of fast image recognition. The…

Image and Video Processing · Electrical Eng. & Systems 2024-06-28 Qishi Zhan , Dan Sun , Erdi Gao , Yuhan Ma , Yaxin Liang , Haowei Yang

This paper presents a machine learning-based method for the detection of the unique gravitational microlensing signatures of extended dark objects, such as boson stars, axion miniclusters and subhalos. We adapt MicroLIA, a machine…

Cosmology and Nongalactic Astrophysics · Physics 2025-03-10 Miguel Crispim Romão , Djuna Croon

Convolution Neural Networks trained for the task of lens finding with similar architecture and training data as is commonly found in the literature are biased classifiers. An understanding of the selection function of lens finding neural…

Cosmology and Nongalactic Astrophysics · Physics 2023-07-21 A. Herle , C. M. O'Riordan , S. Vegetti

Disentangling the stellar population in the central galaxy from the intrahalo light can help us shed light on the formation history of the host halo, as the properties of the stellar components are expected to retain traces of its formation…

Astrophysics of Galaxies · Physics 2024-07-02 I. Marini , A. Saro , S. Borgani , M. Boi

The identity of dark matter remains one of the most pressing questions in physics today. While many promising dark matter candidates have been put forth over the last half-century, to date the true identity of dark matter remains elusive.…

Cosmology and Nongalactic Astrophysics · Physics 2021-09-29 Stephon Alexander , Sergei Gleyzer , Hanna Parul , Pranath Reddy , Michael W. Toomey , Emanuele Usai , Ryker Von Klar

We describe the first results from two observational projects aimed at measuring the amount and spatial distribution of dark matter in distant early-type galaxies (E/S0s) and clusters of galaxies. At the galaxy scale, the Lenses Structure…

Astrophysics · Physics 2007-05-23 T. Treu , L. V. E. Koopmans , D. J. Sand , G. P. Smith , R. S. Ellis

While the direct detection of the dark-matter particle remains very challenging, the nature of dark matter could be possibly constrained by comparing the observed abundance and properties of small-scale sub-galactic mass structures with…

Astrophysics of Galaxies · Physics 2023-05-17 D. Bayer , L. V. E. Koopmans , J. P. McKean , S. Vegetti , T. Treu , C. D. Fassnacht , K. Glazebrook

In order to use a gravitational lens to measure the Hubble constant accurately, it is necessary to derive a reliable model of the lens surface potential. If the analysis is restricted to the locations and magnifications of point images, the…

Astrophysics · Physics 2007-05-23 Roger Blandford , Gabriela Surpi , Tomislav Kundic

We aim to improve segmentation through the use of machine learning tools during region agglomeration. We propose an active learning approach for performing hierarchical agglomerative segmentation from superpixels. Our method combines…

Computer Vision and Pattern Recognition · Computer Science 2015-03-13 Juan Nunez-Iglesias , Ryan Kennedy , Toufiq Parag , Jianbo Shi , Dmitri B. Chklovskii

The difficult task of observing Dark Matter subhaloes is of paramount importance since it would constrain Dark Matter particle properties (cold or warm relic) and confirm once again the longstanding $\Lambda$CDM model. In the near future…

Cosmology and Nongalactic Astrophysics · Physics 2019-10-16 Marco Chianese

Strong lensing of background galaxies provides important information about the matter distribution around lens galaxies. Traditional modelling of such strong lenses is both time and resource intensive. Fast and automated analysis methods…

Cosmology and Nongalactic Astrophysics · Physics 2025-06-09 Priyanka Gawade , Anupreeta More , Surhud More , Akisato Kimura , Alessandro Sonnenfeld , Masamune Oguri , Naoki Yoshida

Weak gravitational lensing is one of the most important probes of the nature of dark matter and dark energy. In order to extract cosmological information from next-generation weak lensing surveys (e.g., Euclid, Roman, LSST, and CSST) as…

Mergers of stellar-mass black holes were recently observed in the gravitational wave window opened by LIGO. This puts the spotlight on dense stellar systems and their ability to create intermediate-mass black holes (IMBHs) through repeated…

Astrophysics of Galaxies · Physics 2016-06-29 Mario Pasquato

This work presents AutoLens, the first entirely automated modeling suite for the analysis of galaxy-scale strong gravitational lenses. AutoLens simultaneously models the lens galaxy's light and mass whilst reconstructing the extended source…

Cosmology and Nongalactic Astrophysics · Physics 2018-06-06 James Nightingale , Simon Dye , Richard Massey

We present the analysis of a sample of twenty-four SLACS-like galaxy-galaxy strong gravitational lens systems with a background source and deflectors from the Illustris-1 simulation. We study the degeneracy between the complex mass…

Astrophysics of Galaxies · Physics 2020-05-27 W. Enzi , S. Vegetti , G. Despali , J. -W. Hsueh , R. B. Metcalf

One of the frontiers for advancing what is known about dark matter lies in using strong gravitational lenses to characterize the population of the smallest dark matter halos. There is a large volume of information in strong gravitational…

Cosmology and Nongalactic Astrophysics · Physics 2023-09-01 Ryan E. Keeley , Anna M. Nierenberg , Daniel Gilman , Simon Birrer , Andrew Benson , Tommaso Treu

Strong lensing is a sensitive probe of the small-scale density fluctuations in the Universe. We implement a novel approach to modeling strongly lensed systems using probabilistic cataloging, which is a transdimensional, hierarchical, and…

Cosmology and Nongalactic Astrophysics · Physics 2018-03-06 Tansu Daylan , Francis-Yan Cyr-Racine , Ana Diaz Rivero , Cora Dvorkin , Douglas P. Finkbeiner

In a strong gravitational lensing system, the distorted light from a source is analysed to infer the properties of the lens. However, light emitted by the lens itself can contaminate the image of the source, introducing systematic errors in…