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Polarisation amplitude estimation is affected by a positive noise bias, particularly important in regions with low signal-to-noise ratio (SNR). We present a new approach to correct for this bias in the case there is additional information…

Instrumentation and Methods for Astrophysics · Physics 2016-06-29 Matias Vidal , J. P. Leahy , C. Dickinson

I discuss the physics of polarization in models with early reionization. For sufficiently high optical depth to recombination the polarization is boosted on large scales while it is suppressed on smaller scales. New peaks appear in the…

Astrophysics · Physics 2016-08-30 Matias Zaldarriaga

The anomalous microwave emission detected in the Perseus molecular complex by Watson \ea has been observed at 11 GHz through dual orthogonal polarizations with the COSMOSOMAS experiment. Stokes U and Q maps were obtained at a resolution of…

The matched filter (MF) represents one of the main tools to detect signals from known sources embedded in the noise. In the Gaussian case the noise is assumed to be the realization of a Gaussian random field (GRF). The most important…

Instrumentation and Methods for Astrophysics · Physics 2019-07-10 R. Vio , P. Andreani , A. Biggs , N. Hayatsu

This paper presents optimization issues of energy detection (ED) thresholds in cooperative spectrum sensing (CSS) with regard to general Gaussian noise. Enhanced ED thresholds are proposed to overcome sensitivity of multiple noise…

Information Theory · Computer Science 2018-01-01 He Huang

We present a broadband spectropolarimetric survey of 563 discrete, mostly unresolved radio sources between 1.3 \& 2.0 GHz using data taken with the Australia Telescope Compact Array (ATCA). We have used rotation measure synthesis to…

Astrophysics of Galaxies · Physics 2015-12-16 C. S. Anderson , B. M. Gaensler , I. J. Feain , T. M. O. Franzen

We present high sensitivity ($\sigma_P \simeq 0.6\,$mJy) polarimetric observations in seven bands, from $2.1$ to $38\,$GHz, of a complete sample of $104$ compact extragalactic radio sources brighter than $200\,$mJy at $20\,$GHz.…

In this paper, we present a framework for assessing the effect of non-stationary Gaussian noise and radio frequency interference (RFI) on the signal to noise ratio, the number of false positives detected per true positive and the…

Instrumentation and Methods for Astrophysics · Physics 2017-04-19 E. van Heerden , A. Karastergiou , S. J. Roberts

Given a set of images, whose pixel values can be considered as the components of a vector, it is interesting to estimate the modulus of such a vector in some localised areas corresponding to a compact signal. For instance, the…

Cosmology and Nongalactic Astrophysics · Physics 2010-11-02 F. Argueso , J. L. Sanz , D. Herranz , M. Lopez-Caniego , J. Gonzalez-Nuevo

Global (i.e. sky-averaged) $21$~cm signal experiments can measure the evolution of the universe from the Cosmic Dawn to the Epoch of Reionization. These measurements are challenged by the presence of bright foreground emission that can be…

Cosmology and Nongalactic Astrophysics · Physics 2019-09-25 Marta Spinelli , Gianni Bernardi , Mario G. Santos

New problems arise when the standard theory of joint detection and estimation is applied to a set of signals drawn from a continuous family; decision thresholds must be determined as a function of the continuous parameter x characterizing…

Statistics Theory · Mathematics 2014-07-17 D. Michael Milder , Robert G. Lindgren , Morris M. Berman

In many polarimetry applications, including observations in the X-ray band, the measurement of a polarization signal can be reduced to the detection and quantification of a deviation from uniformity of a distribution of measured angles. We…

Instrumentation and Methods for Astrophysics · Physics 2015-06-16 Tod E. Strohmayer , Tim R. Kallman

We consider non-binary polarization transform problem of polar codes. The focus of this work is on finding equidistant (or almost equidistant) polarizing transforms to maximize the minimum distance and to approach the equidistant distant…

Information Theory · Computer Science 2019-03-05 Sinan Kahraman

We study the polarisation properties of extragalactic sources at 95 and 150 GHz in the SPTpol 500 deg$^2$ survey. We estimate the polarised power by stacking maps at known source positions, and correct for noise bias by subtracting the mean…

The ability of NICMOS to perform high accuracy polarimetry is currently hampered by an uncalibrated residual instrumental polarization at a level of 1.2-1.5%. To better quantify and characterize this residual we obtained observations of…

Pulsar timing arrays (PTAs) seek to detect a nano-Hz stochastic gravitational-wave background (GWB) by searching for the characteristic Hellings and Downs angular pattern of timing residual correlations. So far, the evidence remains below…

Instrumentation and Methods for Astrophysics · Physics 2025-09-09 Rutger van Haasteren , Bruce Allen , Joseph D. Romano

We benchmark the reliability of the Rotation Measure (RM) synthesis algorithm using the 1005 Centaurus A field sources of Feain et al. (2009). The RM synthesis solutions are compared with estimates of the polarization parameters using…

Instrumentation and Methods for Astrophysics · Physics 2015-06-04 J. -P. Macquart , R. D. Ekers , I. Feain , M. Johnston-Hollitt

Numerical simulations offer the unique possibility to forecast the results of surveys and targeted observations that will be performed with next generation instruments like the Square Kilometre Array. In this paper, we investigate for the…

Astrophysics of Galaxies · Physics 2019-02-27 F. Loi , M. Murgia , F. Govoni , V. Vacca , I. Prandoni , A. Bonafede , L. Feretti

We present a new algorithm for fitting and classifying polarized radio sources, which is based on the QU fitting method introduced by O'Sullivan et al. and on our analysis of pulsars. Then we test this algorithm using Monte Carlo…

Instrumentation and Methods for Astrophysics · Physics 2020-06-17 D. H. F. M. Schnitzeler

The Polarisation Sky Survey of the Universe's Magnetism (POSSUM) will conduct a sensitive $\sim$1 GHz radio polarization survey covering 20 000 square degrees of the Southern sky with the Australian Square Kilometre Array Pathfinder…