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Missions such as WMAP or Planck measure full-sky fluctuations of the cosmic microwave background and foregrounds, among which bright compact source emissions cover a significant fraction of the sky. To accurately estimate the diffuse…

天体物理仪器与方法 · 物理学 2015-06-19 F. C. Sureau , J. -L. Starck , J. Bobin , P. Paykari , A. Rassat

X-ray sources with very few counts can be identified with low-noise X-ray detectors such as ACIS onboard the Chandra X-ray Observatory. These sources are often too faint for parametric spectral modeling using well-established methods such…

太阳与恒星天体物理 · 物理学 2014-11-20 Konstantin V. Getman , Eric D. Feigelson , Patrick S. Broos , Leisa K. Townsley , Gordon P. Garmire

Dedicated 'Stage IV' observatories will soon observe the entire extragalactic sky, to measure the 'cosmic shear' distortion of galaxy shapes by weak gravitational lensing. To measure the apparent shapes of those galaxies, we present an…

宇宙学与河外天体物理 · 物理学 2022-02-08 Xiangchong Li , Yin Li , Richard Massey

Advances in vectorial polarisation-resolved imaging are bringing new capabilities to applications ranging from fundamental physics through to clinical diagnosis. Imaging polarimetry requires determination of the Mueller matrix (MM) at every…

Point source detection techniques are used to identify and localise point sources in radio astronomical surveys. With the development of the Square Kilometre Array (SKA) telescope, survey images will see a massive increase in size from…

计算机视觉与模式识别 · 计算机科学 2022-02-09 Duncan Tilley , Christopher W. Cleghorn , Kshitij Thorat , Roger Deane

Instrumentation designed to characterize potentially habitable planets may combine adaptive optics and high-resolution spectroscopy techniques to achieve the highest possible sensitivity to spectral signs of life. Detecting the weak signal…

天体物理仪器与方法 · 物理学 2018-11-13 Garreth Ruane , Ji Wang , Dimitri Mawet , Nemanja Jovanovic , Jacques-Robert Delorme , Bertrand Mennesson , J. Kent Wallace

Photonic circuits can be much faster than their electronic counterparts, but they are difficult to miniaturize below the optical wavelength scale. Nanoscale photonic circuits based on surface plasmon polaritons (SPs) are a promising…

We propose an innovative demodulation scheme for coherent detectors used in cosmic microwave background polarization experiments. Removal of non-white noise, e.g., narrow-band noise, in detectors is one of the key requirements for the…

天体物理仪器与方法 · 物理学 2012-05-22 K. Ishidoshiro , Y. Chinone , M. Hasegawa , M. Hazumi , M. Nagai , O. Tajima

We propose a new variant of nonnegative matrix factorization (NMF), combining separability and sparsity assumptions. Separability requires that the columns of the first NMF factor are equal to columns of the input matrix, while sparsity…

机器学习 · 计算机科学 2020-06-16 Nicolas Nadisic , Arnaud Vandaele , Jeremy E. Cohen , Nicolas Gillis

We aim to study the nature of the faint, polarised radio source population whose source composition and redshift dependence contain information about the strength, morphology, and evolution of magnetic fields over cosmic timescales. We use…

宇宙学与河外天体物理 · 物理学 2021-09-29 A. Berger , B. Adebahr , N. Herrera Ruiz , A. H. Wright , I. Prandoni , R. -J. Dettmar

We use XMM-Newton blank-sky and closed-cover background data to explore the background subtraction methods for large extended sources filling the EPIC field of view, such as nearby galaxy clusters, for which local background estimation is…

天体物理学 · 物理学 2009-11-11 J. Nevalainen , M. Markevitch , D. Lumb

We develop two algorithms, based on maximum likelihood (ML) inference, for estimating the parameters of polarized radio sources which emit at a single rotation measure (RM), e.g., pulsars. These algorithms incorporate the flux density…

天体物理仪器与方法 · 物理学 2017-10-25 D. H. F. M. Schnitzeler , K. J. Lee

The aim of this study is to probe the sub-mJy polarized source population with LOFAR. We present the method used to stack LOFAR polarization datasets, the resulting catalog of polarized sources, and the derived polarized source counts. The…

In experimental microwave maps, point-sources can strongly affect the estimation of the power-spectrum and/or the test of Gaussianity of the Cosmic Microwave Background (CMB) component. As a consequence, their removal from the sky maps…

宇宙学与河外天体物理 · 物理学 2015-05-19 Elsa Patricia R. G. Ramos , Roberto Vio , Paola Andreani

The weak-field approximation is one of the simplest models that allows us to relate the observed polarization induced by the Zeeman effect with the magnetic field vector present on the plasma of interest. It is usually applied for…

太阳与恒星天体物理 · 物理学 2015-05-27 A. Asensio Ramos

We present a polarization catalog of 533 extragalactic radio sources with 2.3 GHz total intensity above 420 mJy from the S-band Polarization All Sky Survey, S-PASS, with corresponding 1.4 GHz polarization information from the NRAO VLA Sky…

The bright polarized synchrotron emission, away from the Galactic plane, originates mostly from filamentary structures. We implement a filament finder algorithm which allows the detection of bright elongated structures in polarized…

宇宙学与河外天体物理 · 物理学 2023-04-26 F. A. Martire , A. J. Banday , E. Martínez-González , R. B. Barreiro

We are developing an X-ray polarimeter using micro-pixel CMOS sensors for solar flare X-ray polarimetry. The system consists of a 2.5-$\mu$m pixel CMOS image sensor with a 12.8$\times$12.8 mm$^2$ imaging area and a readout system based on a…

We introduce a pixel space method to detect dipole modulation or hemispherical power asymmetry in the cosmic microwave background (CMB) polarization. The method relies on the use of squared total polarized flux whose ensemble average picks…

宇宙学与河外天体物理 · 物理学 2020-07-15 Shamik Ghosh , Pankaj Jain

We report the experimental super-resolution of pairs of point-like fluorescent sources using a modified image inversion interferometer microscope. The technique is inspired by recent developments in the application of quantum parameter…