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The prospects for accomplishing x-ray polarization measurements of astronomical sources have grown in recent years, after a hiatus of more than 37 years. Unfortunately, accompanying this long hiatus has been some confusion over the…

Instrumentation and Methods for Astrophysics · Physics 2015-06-11 Ronald F. Elsner , Stephen L. O'Dell , Martin C. Weisskopf

We present the results of three-dimensional simulations of quasar polarizations in the presence of pseudoscalar-photon mixing in the intergalactic medium. The intergalactic magnetic field is assumed to be uncorrelated in wave vector space…

Cosmology and Nongalactic Astrophysics · Physics 2017-09-15 Nishant Agarwal , Pavan K. Aluri , Pankaj Jain , Udit Khanna , Prabhakar Tiwari

We test the hypothesis that the polarization vectors of flat-spectrum radio sources (FSRS) in the JVAS/CLASS 8.4-GHz surveys are randomly oriented on the sky. The sample with robust polarization measurements is made of $4155$ objects and…

Cosmology and Nongalactic Astrophysics · Physics 2015-08-24 Vincent Pelgrims , Damien Hutsemékers

We present results of searching for the possible typical scales in the spatial distribution of QSOs. Our method is based on the second derivative of the two-point correlation function. This statistic is sensitive to the scale of the maximum…

Astrophysics · Physics 2009-10-22 Zugan Deng , Xiaoyang Xia , Li-Zhi Fang

Properties of galaxies like their absolute magnitude and their stellar mass content are correlated. These correlations are tighter for close pairs of galaxies, which is called galactic conformity. In hierarchical structure formation…

Astrophysics of Galaxies · Physics 2018-07-25 Martin Kerscher

Recently, we have used, pulsar polarisation datasets, on circular polarisation degree & linear polarisation position angle, to relate with well established theories, on ellipticity parameter and linear polarisation position angles, accrued…

High Energy Astrophysical Phenomena · Physics 2020-01-22 Karam Chand , Subhayan Mandal

A new, different kind of intensity correlation, denoted as polarization based intensity correlation, is proposed and investigated to study the correlation between different polarization components of polarization speckle, which has…

Optics · Physics 2019-11-20 Abhijit Roy , Maruthi M. Brundavanam

A recently discovered inverse correlation between QSO redshift and long-term continuum variability timescales was suggested to be the signature of microlensing on cosmological scales (Hawkins 1993). A general theoretical method for…

Astrophysics · Physics 2015-06-24 Tal Alexander

The magnification effects of clustered matter produce variations in the image sizes and number density of galaxies across the sky. This paper advocates the use of these effects in wide field surveys to map large-scale structure and the…

Astrophysics · Physics 2009-11-07 Bhuvnesh Jain

We detect a positive angular correlation between bright, high-redshift QSOs and foreground galaxies. The QSOs are taken from the optically selected LBQS Catalogue, while the galaxies are from the APM Survey. The correlation amplitude is…

Astrophysics · Physics 2009-10-30 Liliya L. R. Williams , Mike Irwin

We report on the detection of the alignment between galaxies and large-scale structure at z~0.6 based on the CMASS galaxy sample from the Baryon Oscillation Spectroscopy Survey data release 9. We use two statistics to quantify the alignment…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-15 Cheng Li , Y. P. Jing , A. Faltenbacher , Jie Wang

We investigate the effects of pseudoscalar-photon mixing on electromagnetic radiation in the presence of correlated extragalactic magnetic fields. We model the Universe as a collection of magnetic domains and study the propagation of…

High Energy Physics - Phenomenology · Physics 2011-03-21 Nishant Agarwal , Archana Kamal , Pankaj Jain

Lyman-alpha forest data probing the post-reionization Universe shows surprisingly large opacity fluctuations over rather large ($\ge$50 comoving Mpc/h) spatial scales. We model these fluctuations using a hybrid approach utilizing the large…

Cosmology and Nongalactic Astrophysics · Physics 2017-03-21 Jonathan Chardin , Ewald Puchwein , Martin G. Haehnelt

We present a fully relativistic calculation of the observed galaxy number counts in the linear regime. We show that besides the density fluctuations and redshift-space distortions, various relativistic effects contribute to observations at…

Cosmology and Nongalactic Astrophysics · Physics 2023-06-09 Camille Bonvin

We have used integral two-point spatial correlation function and its second derivative to analyze the distribution of quasars in three very deep surveys published in the literature. Statistically significant ($\sim 2-3\sigma $) correlations…

Astrophysics · Physics 2007-05-23 Andrey V. Kravtsov

Recent independent observations using several different telescope systems an analysis methods have provided evidence of parity violation between the number of galaxies that spin in opposite directions. On the other hand, other studies…

Cosmology and Nongalactic Astrophysics · Physics 2023-09-08 Lior Shamir

Handling big data has largely been a major bottleneck in traditional statistical models. Consequently, when accurate point prediction is the primary target, machine learning models are often preferred over their statistical counterparts for…

Methodology · Statistics 2021-04-02 Arindam Fadikar , Stefan M. Wild , Jonas Chaves-Montero

We study the problem of applying spectral clustering to cluster multi-scale data, which is data whose clusters are of various sizes and densities. Traditional spectral clustering techniques discover clusters by processing a similarity…

Machine Learning · Computer Science 2020-06-09 Xiang Li , Ben Kao , Caihua Shan , Dawei Yin , Martin Ester

Recently discovered quasar pairs at high redshifts ($z\gtrsim$5) are likely precursors to supermassive black hole mergers, providing a promising window to high redshift quasar growth mechanisms. However, the large uncertainties on their…

Astrophysics of Galaxies · Physics 2026-04-16 Huanqing Chen , Camille Avestruz , Jakob Wiest

A generalized theory of spatial coherence for superposition of two speckle patterns with polarization diversity is presented. The presented theory deals with superposition in different scenarios i.e. superposition of two fully correlated,…

Optics · Physics 2021-11-17 Abhijit Roy