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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

A small deviation from scale invariance in the form of oscillations in the primordial correlation spectra has been predicted by various cosmological models. In this paper we review a recently developed method to search for these features in…

宇宙学与河外天体物理 · 物理学 2014-08-22 P. Daniel Meerburg , David N. Spergel , Benjamin D. Wandelt

We report new high-precision observations of the polarization of light scattered from the atmosphere of Venus, made 100 years after the pioneering studies by Bernard Lyot. The new observations include disk-integrated observations in a range…

地球与行星天体物理 · 物理学 2026-03-10 Jeremy Bailey , Daniel V. Cotton , Kimberly Bott , Ievgeniia Boiko

We have detected significant Rotation Measure variations for 9 bright pulsars, as a function of pulse longitude. An additional sample of 10 pulsars showed a rather constant RM with phase, yet a small degree of RM fluctuation is visible in…

星系天体物理 · 物理学 2015-05-13 A. Noutsos , A. Karastergiou , M. Kramer , S. Johnston , B. W. Stappers

Full polarization measurements of 1665 and 1667-MHz OH masers at sites of massive star formation have been made with the Parkes 64-m radio telescope. Here we present the resulting spectra for 104 northerly sources. For more than 20 masers…

星系天体物理 · 物理学 2014-02-12 J. L. Caswell , J. A. Green , C. J. Phillips

A statistical model is used to determine how stochastic fluctuations in the intensities of orthogonal polarization modes contribute to the modulation and depolarization of pulsar radio emission. General expressions for the distributions of…

高能天体物理现象 · 物理学 2023-12-19 M. M. McKinnon

Pulsar radio emission is modelled as a sum of two completely polarized non-orthogonal modes with the randomly varying Stokes parameters and intensity ratio. The modes are the result of polarization evolution of the original natural waves in…

天体物理学 · 物理学 2009-11-11 S. A. Petrova

Radio polarimetry is a three-dimensional statistical problem. The three-dimensional aspect of the problem arises from the Stokes parameters Q, U, and V, which completely describe the polarization of electromagnetic radiation and…

星系天体物理 · 物理学 2015-05-20 M. M. McKinnon

Polar faculae (PFe) are the footpoints of magnetic field lines near the Sun's poles that are seen as bright regions along the edges of granules. The time variation in the number of PFe has been shown to correlate with the strength of the…

太阳与恒星天体物理 · 物理学 2022-04-26 Beryl Hovis-Afflerbach , W. Dean Pesnell

In order to study precession and interstellar magnetic field variations, we measured the polarized position angle of 81 pulsars at several-month intervals for four years. We show that the uncertainties in a single-epoch measurement of…

太阳与恒星天体物理 · 物理学 2010-08-04 Joel M. Weisberg , John E. Everett , James M. Cordes , Justin J. Morgan , Drew G. Brisbin

We investigate the previously proposed possibility that multi-epoch broadband polarimetry could act as a complement or limited proxy for VLBI observations of blazars, in that the number of polarised emission components in the jet, and some…

星系天体物理 · 物理学 2019-02-20 C. S. Anderson , S. P. O'Sullivan , G. H. Heald , T. Hodgson , A. Pasetto , B. M. Gaensler

Polaris is one of the most observed stars in the night sky, with recorded observations spanning more than 200 years. From these observations, one can study the real-time evolution of Polaris via the secular rate of change of the pulsation…

太阳与恒星天体物理 · 物理学 2015-06-03 Hilding R. Neilson , Scott G. Engle , Ed Guinan , Norbert Langer , Richard P. Wasatonic , David B. Williams

Time series analysis finds wide applications in fields such as weather forecasting, anomaly detection, and behavior recognition. Previous methods attempted to model temporal variations directly using 1D time series. However, this has been…

机器学习 · 计算机科学 2024-11-08 Qiang Wu , Gechang Yao , Zhixi Feng , Shuyuan Yang

We have made polarimetric monitoring observations of millisecond pulsars visible from the northern hemisphere at 1410 MHz. Their emission properties are compared with those of normal pulsars. Although we demonstrated in paper I that…

We present high signal-to-noise ratio, multi-frequency polarization pulse profiles for 24 millisecond pulsars that are being observed as part of the Parkes Pulsar Timing Array (PPTA) project. The pulsars are observed in three bands, centred…

The polarimetry of the light scattered by planetary surfaces is a powerful tool to provide constraints on their microstructure. To improve the interpretation of polarimetric data from icy surfaces, we have developed the POLarimeter for ICE…

地球与行星天体物理 · 物理学 2018-09-25 Olivier Poch , Romain Cerubini , Antoine Pommerol , Bernhard Jost , Nicolas Thomas

Dimension reduction techniques for multivariate time series decompose the observed series into a few useful independent/orthogonal univariate components. We develop a spectral domain method for multivariate second-order stationary time…

统计方法学 · 统计学 2020-10-12 Raanju R. Sundararajan

In this paper, we present a study of orthogonal polarization modes in the radio emission of PSR B1133+16, conducted within the frame of simultaneous, multi-frequency, single-pulse observations. Simultaneously observing at two frequencies…

天体物理学 · 物理学 2009-11-07 A. Karastergiou , M. Kramer , S. Johnston , A. G. Lyne , N. D. R. Bhat , Y. Gupta

We report on variations in the mean position angle of the 20 millisecond pulsars being observed as part of the Parkes Pulsar Timing Array (PPTA) project. It is found that the observed variations are dominated by changes in the Faraday…

We point out some advantages of making observations of extrasolar planets in linearly polarized (LP) light. Older cool stars have quite low levels (~ 10^-4 to 10^-5) of fractional LP, while extrasolar planets can have relatively high…

天体物理学 · 物理学 2007-05-23 S. Saar , S. Seager