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The idea of a rapid sign-switching cosmological constant (mirror AdS-dS transition) in the late universe at $z\sim1.7$, known as the $\Lambda_{\rm s}$CDM model, has significantly improved the fit to observational data and provides a…

Cosmology and Nongalactic Astrophysics · Physics 2024-11-26 Özgür Akarsu , Antonio De Felice , Eleonora Di Valentino , Suresh Kumar , Rafael C. Nunes , Emre Özülker , J. Alberto Vazquez , Anita Yadav

We demonstrate a new method to constrain gravity on the largest cosmological scales by combining measurements of cosmic microwave background (CMB) lensing and the galaxy velocity field. $E_G$ is a statistic, constructed from a gravitational…

Cosmology and Nongalactic Astrophysics · Physics 2016-08-09 Anthony R. Pullen , Shadab Alam , Siyu He , Shirley Ho

Fine-grained image recognition is a longstanding computer vision challenge that focuses on differentiating objects belonging to multiple subordinate categories within the same meta-category. Since images belonging to the same meta-category…

Computer Vision and Pattern Recognition · Computer Science 2023-09-04 Yifan Pu , Yizeng Han , Yulin Wang , Junlan Feng , Chao Deng , Gao Huang

Convolutional Neural Networks (CNN) have recently been demonstrated on synthetic data to improve upon the precision of cosmological inference. In particular they have the potential to yield more precise cosmological constraints from weak…

Cosmology and Nongalactic Astrophysics · Physics 2019-09-17 Janis Fluri , Tomasz Kacprzak , Aurelien Lucchi , Alexandre Refregier , Adam Amara , Thomas Hofmann , Aurel Schneider

The field of meta-learning has seen a dramatic rise in interest in recent years. In existing meta-learning approaches, learning tasks for training meta-models are usually collected from public datasets, which brings the difficulty of…

Machine Learning · Computer Science 2021-11-23 Zhaoyang Hai , Xiabi Liu , Yuchen Ren , Nouman Q. Soomro

Deep artificial neural networks have made remarkable progress in different tasks in the field of computer vision. However, the empirical analysis of these models and investigation of their failure cases has received attention recently. In…

Computer Vision and Pattern Recognition · Computer Science 2016-02-10 Babak Saleh , Ahmed Elgammal , Jacob Feldman

Creation of Cold Dark Matter (CCDM) can macroscopically be described by a negative pressure, and, therefore, the mechanism is capable to accelerate the Universe, without the need of an additional dark energy component. In this framework we…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-28 J. F. Jesus , F. A. Oliveira , S. Basilakos , J. A. S. Lima

If we assume that we live in the center of a spherical inhomogeneous universe, we can explain the apparent accelerating expansion of the universe without introducing the unknown dark energy or modifying gravitational theory. Direct…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-04 Kent Yagi , Atsushi Nishizawa , Chul-Moon Yoo

Despite the broad successes of the flat $\Lambda$CDM model and its fitness to the various cosmological observations, it confronts challenges stemming from anomalies in the measurements of the Hubble constant ($H_0$) and the amplitude of…

Cosmology and Nongalactic Astrophysics · Physics 2025-01-28 Saeed Pourojaghi , Mohammad Malekjani

Machine learning models can greatly improve the search for strong gravitational lenses in imaging surveys by reducing the amount of human inspection required. In this work, we test the performance of supervised, semi-supervised, and…

Astrophysics of Galaxies · Physics 2023-08-17 Keerthi Vasan G. C. , Stephen Sheng , Tucker Jones , Chi Po Choi , James Sharpnack

We investigate the use of deep convolutional neural networks (deep CNNs) for automatic visual detection of galaxy mergers. Moreover, we investigate the use of transfer learning in conjunction with CNNs, by retraining networks first trained…

Instrumentation and Methods for Astrophysics · Physics 2018-06-13 Sandro Ackermann , Kevin Schawinski , Ce Zhang , Anna K. Weigel , M. Dennis Turp

As we enter the era of large-scale imaging surveys with the up-coming telescopes such as LSST and SKA, it is envisaged that the number of known strong gravitational lensing systems will increase dramatically. However, these events are still…

Instrumentation and Methods for Astrophysics · Physics 2021-07-14 Daniel Magro , Kristian Zarb Adami , Andrea DeMarco , Simone Riggi , Eva Sciacca

Although many real-world applications, such as disease prediction, and fault detection suffer from class imbalance, most existing graph-based classification methods ignore the skewness of the distribution of classes; therefore, tend to be…

Machine Learning · Computer Science 2024-07-01 Mahdi Mohammadizadeh , Arash Mozhdehi , Yani Ioannou , Xin Wang

The efficient classification of different types of supernova is one of the most important problems for observational cosmology. However, spectroscopic confirmation of most objects in upcoming photometric surveys, such as the The Rubin…

Cosmology and Nongalactic Astrophysics · Physics 2020-08-17 Marcelo Vargas dos Santos , Miguel Quartin , Ribamar R. R. Reis

The results of morphological galaxy classifications performed by humans and by automated methods are compared. In particular, a comparison is made between the eyeball classifications of 454 galaxies in the Sloan Digital Sky Survey (SDSS)…

Astrophysics · Physics 2007-05-23 Nicholas M. Ball

Global Navigation Satellite System (GNSS) signals are subject to different kinds of events causing significant errors in positioning. This work explores the application of Machine Learning (ML) methods of anomaly detection applied to GNSS…

Signal Processing · Electrical Eng. & Systems 2019-11-07 Evgenii Munin , Antoine Blais , Nicolas Couellan

Joint lensing and dynamical mass profile determinations of galaxy clusters are an excellent tool to constrain modification of gravity at cosmological scales. However, search for tiny departures from General Relativity calls for an accurate…

Cosmology and Nongalactic Astrophysics · Physics 2020-04-29 L. Pizzuti , B. Sartoris , S. Borgani , A. Biviano

The possibility to constrain cosmological parameters from galaxy surveys using field-level machine learning methods that bypass traditional summary statistics analyses, depends crucially on our ability to generate simulated training sets.…

Cosmology and Nongalactic Astrophysics · Physics 2026-02-11 Iñigo Sáez-Casares , Matteo Calabrese , Davide Bianchi , Marina S. Cagliari , Marco Chiarenza , Jean-Marc Christille , Luigi Guzzo

We present a method for automated classification of galaxies with low signal-to-noise (S/N) spectra typical of redshift surveys. We develop spectral simulations based on the parameters for the 2dF Galaxy Redshift Survey, and with these…

Astrophysics · Physics 2015-06-24 S. R. Folkes , O. Lahav , S. J. Maddox

Graph Neural Networks (GNNs) have achieved promising performance in semi-supervised node classification in recent years. However, the problem of insufficient supervision, together with representation collapse, largely limits the performance…

Machine Learning · Computer Science 2025-03-07 Xihong Yang , Yiqi Wang , Yue Liu , Yi Wen , Lingyuan Meng , Sihang Zhou , Xinwang Liu , En Zhu