scholarly journals Message in a Bottle: Unveiling the Magneto-Ionic Complexity of AGNs through the Stokes QU-Fitting Technique

Galaxies ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 56
Author(s):  
Alice Pasetto
Keyword(s):  
Linear Polarization ◽  
Broad Band ◽  
Polarized Light ◽  
Magnetized Plasma ◽  
Analytical Models ◽  
Stokes Parameters ◽  
Complex Structures ◽  
Radio Data ◽  
Polarization Behavior

Here, I overview one of the available techniques for the analysis of broad-band spectropolarimetric data, the Stokes QU-fitting. Since broad-band receivers have been installed at most radio facilities, the collection of radio data, both the total intensity and the linear polarization, is revealing interesting features in their spectra. The polarized light, and therefore its properties, i.e. the fractional polarization p and the polarized angle χ, are now finally well sampled in wide wavelength ranges. The new complex behaviors revealed by the data can be studied using the Stokes QU-fitting, which consists of modeling the Stokes parameters Q and U using wavelength-dependent analytical models, available in the literature. This technique provides a very good diagnostic of the nature and structure of the magnetized plasma, with the possibility to identify complex structures, internal or external, of the source of study. A summary of the available and most used models describing the polarization behavior, is presented. Moreover, some of the most significant observational works which use this technique are also summarized.

scholarly journals Alteration in non-classicality of light on passing through a linear polarization beam splitter

2016 ◽  
Vol 30 (21) ◽  
pp. 1650289
Author(s):  
Namrata Shukla ◽  
Ranjana Prakash
Keyword(s):  
Linear Polarization ◽  
Beam Splitter ◽  
Output Port ◽  
Polarization Beam Splitter ◽  
Stokes Parameters ◽  
Coherent Light ◽  
Squeezed Light ◽  
Squeezed Vacuum

We observe the polarization squeezing in the mixture of a two mode squeezed vacuum and a simple coherent light through a linear polarization beam splitter. Squeezed vacuum not being squeezed in polarization, generates polarization squeezed light when superposed with coherent light. All the three Stokes parameters of the light produced on the output port of polarization beam splitter are found to be squeezed and squeezing factor also depends upon the parameters of coherent light.

Simulation of Large and Complex Structures With Multiple Contacts and Wear

1992 ◽  
Author(s):  
B. S. Bagepalli ◽  
S. Dinc ◽  
B. Jlidi ◽  
I. Imam ◽  
J. Barnes ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Analytical Models ◽  
Contact Friction ◽  
Complex Structures ◽  
Accelerometer Data ◽  
Mechanism Analysis ◽  
Evaluation Tool ◽  
Simulation Code ◽  
Multiple Contacts ◽  
Field Samples

Abstract This paper deals with the simulation methodology of large and complex structures with multiple contacts and wear. The methodology developed is used to evaluate the dynamics and wear of gas turbine combustors. A unified approach of representing multiple rigid/elastic bodies with numerous contacts is developed. Representation is made, too, of the changing nature of these contacts — both geometric and material. The entire methodology is implemented in a generic and easy-to-use simulation code which serves as a useful generic design/analysis evaluation tool MAP (Mechanism Analysis Program). Appropriate analytical models for inter-material constitutive laws — both incremental (contact friction, pressure, damping, etc.) and cumulative (wear theories) — are incorporated in the tool. As applications of this approach, dynamic simulations of two different gas turbine combustor designs are run, and comparisons are made with real systems. Excellent correlations have been obtained, both with respect to laboratory test (accelerometer) data, and wear patterns at various contacts and junctions on field samples.

scholarly journals Polarization perception in humans: on the origin of and relationship between Maxwell’s spot and Haidinger’s brushes

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Gary P. Misson ◽  
Shelby E. Temple ◽  
Stephen J. Anderson
Keyword(s):  
Linear Polarization ◽  
Light Absorption ◽  
Polarized Light ◽  
Retinal Images ◽  
Clinical Use ◽  
Differential Absorption ◽  
Model Simulations ◽  
Eye Disorders ◽  
Absorption Of Light ◽  
Linearly Polarized

AbstractUnder specific conditions of illumination and polarization, differential absorption of light by macular pigments is perceived as the entoptic phenomena of Maxwell’s spot (MS) or Haidinger’s brushes (HB). To simulate MS and HB, an existing computational model of polarization-dependent properties of the human macula was extended by incorporating neuronal adaptation to stabilized retinal images. The model predicted that polarized light modifies the appearance of MS leading to the perception of a novel phenomenon. The model also predicted a correlation between the observed diameters of MS and HB. Predictions were tested psychophysically in human observers, whose measured differences in the diameters of each entoptic phenomenon generated with depolarized and linearly polarized light were consistent with the model simulations. These findings support a common origin of each phenomenon, and are relevant to the clinical use of polarization stimuli in detecting and monitoring human eye disorders, including macular degeneration. We conclude: (i) MS and HB both result from differential light absorption through a radial diattenuator, compatible with the arrangement of macular pigments in Henle fibres; (ii) the morphology of MS is dependent on the degree of linear polarization; (iii) perceptual differences between MS and HB result from different states of neural adaptation.

scholarly journals Spectropolarimetric monitoring of WR140

1995 ◽  
Vol 163 ◽  
pp. 506-507
Author(s):  
R.E. Schulte-Ladbeck ◽  
K. H. Nordsieck ◽  
K. S. Bjorkman ◽  
M. R. Meade ◽  
B. L. Babler
Keyword(s):  
Detection Limit ◽  
Linear Polarization ◽  
Broad Band ◽  
Line Emission ◽  
Intrinsic Polarization ◽  
The Continuum

We report on eight years of spectropolarimetric monitoring of the WR140 binary. The broad-band linear polarization decreased systematically after the 1985 periastron passage. By 1991, it settled to a constant value at which it has remained through the 1993 periastron passage. We do not detect, in data taken after 1989, a line-effect in He II Λ4686. This suggests either that the continuum and the line emission scatter at the same region, or that any intrinsic polarization has been below our detection limit. We conclude that the presently observed polarization of WR140 is consistent with interstellar foreground polarization.

Broad-band linear polarization and magnetic intensification in rotating magnetic stars

1981 ◽  
Vol 249 ◽  
pp. 228 ◽  
Author(s):  
M. Landi Deglinnocenti ◽  
G. Calamai ◽  
E. Landi Deglinnocenti ◽  
P. Patriarchi
Keyword(s):  
Linear Polarization ◽  
Broad Band ◽  
Magnetic Stars

scholarly journals Interstellar Circular Polarization and the Composition of Interstellar Dust

1973 ◽  
Vol 52 ◽  
pp. 161-167 ◽  
Author(s):  
P. G. Martin
Keyword(s):  
Circular Polarization ◽  
Linear Polarization ◽  
Interstellar Dust ◽  
Principal Axis ◽  
Complex Refractive Index ◽  
Polarized Light ◽  
Position Angle ◽  
Optical Observations ◽  
Small Component ◽  
Linearly Polarized

This paper shows that optical observations of circular polarization produced by aligned interstellar grains could yield valuable information about the grain material. The interstellar medium is known to be linearly dichroic from observations of interstellar linear polarization; many different grain models using a large variety of compositions can be found to reproduce these observations. Since the same aligned grains make the medium linearly birefringent, a small component of circular polarization can result from incident linearly polarized light if the position angle of the linear polarization does not coincide with either principal axis of the medium. Here calculations are presented to demonstrate that the wavelength of the circular polarization is sensitive to the imaginary part of the complex refractive index of the grain material. This provides an opportunity of investigating whether the grains are characteristically dielectric or metallic. Some possible observations are suggested.

Relations between broad-band linear polarization and CA II H and K emission in late-type dwarf stars

1988 ◽  
Vol 329 ◽  
pp. 882 ◽  
Author(s):  
Juhani Huovelin ◽  
Steven H. Saar ◽  
Ilkka Tuominen
Keyword(s):  
Linear Polarization ◽  
Broad Band ◽  
Late Type ◽  
Dwarf Stars
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