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Related papers: An Improved Method for 21cm Foreground Removal

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Fourier ptychographic microscopy (FPM) is a recently developed computational imaging technique for wide-field, high-resolution microscopy with a high space-bandwidth product. It integrates the concepts of synthetic aperture and phase…

Optics · Physics 2021-12-30 Chuanjian Zheng , Shaohui Zhang , Guocheng Zhou , Yao Hu , Qun Hao

The accurate and precise removal of 21-cm foregrounds from Epoch of Reionization redshifted 21-cm emission data is essential if we are to gain insight into an unexplored cosmological era. We apply a non-parametric technique, Generalized…

In this article, we report an imaging method, termed Fourier ptychographic microscopy (FPM), which iteratively stitches together a number of variably illuminated, low-resolution intensity images in Fourier space to produce a wide-field,…

Optics · Physics 2014-05-02 Guoan Zheng , Roarke Horstmeyer , Changhuei Yang

Image denoising stands as a critical challenge in image processing and computer vision, aiming to restore the original image from noise-affected versions caused by various intrinsic and extrinsic factors. This process is essential for…

Image and Video Processing · Electrical Eng. & Systems 2024-03-19 Peter Luvton , Alfredo Castillejos , Jim Zhao , Christina Chajo

For there to be a successful measurement of the 21 cm Epoch of Reionization (EoR) power spectrum, it is crucial that strong foreground contaminants be robustly suppressed. These foregrounds come from a variety of sources (such as Galactic…

Cosmology and Nongalactic Astrophysics · Physics 2014-07-25 Adrian Liu , Aaron R. Parsons , Cathryn M. Trott

The highly redshifted 21 cm line of neutral hydrogen has become recognized as a unique probe of cosmology from relatively low redshifts (z ~ 1) up through the Epoch of Reionization (z ~ 8) and even beyond. To date, most work has focused on…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-23 Jonathan C. Pober

We present new observations with the Precision Array for Probing the Epoch of Reionization (PAPER) with the aim of measuring the properties of foreground emission for 21cm Epoch of Reionization experiments at 150 MHz. We focus on the…

A proposed method for dealing with foreground emission in upcoming 21-cm observations from the epoch of reionization is to limit observations to an uncontaminated window in Fourier space. Foreground emission can be avoided in this way,…

Cosmology and Nongalactic Astrophysics · Physics 2015-12-23 Hannes Jensen , Suman Majumdar , Garrelt Mellema , Adam Lidz , Ilian T. Iliev , Keri L. Dixon

Studies of the cosmic dark ages ($30 \lesssim z \lesssim 150$) using the highly redshifted 21 cm line of neutral hydrogen offer unparalleled amounts of cosmological information, and recent years have seen the refinement of concepts for such…

Cosmology and Nongalactic Astrophysics · Physics 2025-08-01 Jonathan C. Pober , Willow Smith

We investigate the potential of second generation measurements of redshifted 21 cm radiation from before and during the epoch of reionization (EOR) to reconstruct the matter density fluctuations along the line of sight. To do so we…

Astrophysics · Physics 2008-11-26 Oliver Zahn , Matias Zaldarriaga

Observations of 21cm line from neutral hydrogen promise to be an exciting new probe of astrophysics and cosmology during the Cosmic Dawn and through the Epoch of Reionization (EoR) to when dark energy accelerates the expansion of the…

Cosmology and Nongalactic Astrophysics · Physics 2024-06-24 Tyler A. Cox , Aaron R. Parsons , Joshua S. Dillon , Aaron Ewall-Wice , Robert Pascua

Radio observation of the large-scale structure (LSS) of our Universe faces major challenges from foreground contamination, which is many orders of magnitude stronger than the cosmic signal. While other foreground removal techniques struggle…

Cosmology and Nongalactic Astrophysics · Physics 2025-03-27 Tian-Cheng Luan , Xin Wang , Jiacheng Ding , Qian Li , Xiao-Dong Li , Weishan Zhu

Spectral measurements of the 21 cm monopole background have the promise of revealing the bulk energetic properties and ionization state of our universe from z ~ 6-30. Synchrotron foregrounds are orders of magnitude larger than the…

Cosmology and Nongalactic Astrophysics · Physics 2014-10-08 Eric R. Switzer , Adrian Liu

Existing image inpainting methods typically fill holes by borrowing information from surrounding pixels. They often produce unsatisfactory results when the holes overlap with or touch foreground objects due to lack of information about the…

Computer Vision and Pattern Recognition · Computer Science 2019-04-23 Wei Xiong , Jiahui Yu , Zhe Lin , Jimei Yang , Xin Lu , Connelly Barnes , Jiebo Luo

Light field imaging introduced the capability to refocus an image after capturing. Currently there are two popular methods for refocusing, shift-and-sum and Fourier slice methods. Neither of these two methods can refocus the light field in…

Image and Video Processing · Electrical Eng. & Systems 2022-04-20 Eisa Hedayati , Timothy C. Havens , Jeremy P. Bos

Power spectrum estimators are an important tool in efforts to detect the 21 cm brightness temperature fluctuations from neutral hydrogen at early times. An initial detection will likely be statistical in nature, meaning that it will not be…

Cosmology and Nongalactic Astrophysics · Physics 2024-10-24 Jacob Burba , Philip Bull , Michael J. Wilensky , Fraser Kennedy , Hugh Garsden , Katrine A. Glasscock

Measurements of the one-point probability distribution function and higher-order moments (variance, skewness, and kurtosis) of the high-redshift 21 cm fluctuations are among the most direct statistical probes of the non-Gaussian nature of…

Cosmology and Nongalactic Astrophysics · Physics 2022-10-12 Piyanat Kittiwisit , Judd D. Bowman , Steven G. Murray , Bharat K. Gehlot , Daniel C. Jacobs , Adam P. Beardsley

We compare multiple foreground-cleaning pipelines for estimating the tensor-to-scalar ratio, $r$, using simulated maps of the planned CMB-S4 experiment within the context of the South Pole Deep Patch. To evaluate robustness, we analyze bias…

This paper presents a method to differentiate the foreground objects from the background of a color image. Firstly a color image of any size is input for processing. The algorithm converts it to a grayscale image. Next we apply canny edge…

Computer Vision and Pattern Recognition · Computer Science 2015-06-30 Subhajit Adhikari , Joydeep Kar , Jayati Ghosh Dastidar