Optical circular polarization in quasars

Hutsemékers, Damien; Borguet, B.; Sluse, Dominique; Cabanac, R.; Lamy, H.

doi:10.1051/0004-6361/201015359

Cited by 79 publications

(133 citation statements)

References 47 publications

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“…However, recent observations show that the universe may be deviating from isotropy. For example, the large-scale bulk flow [6][7][8], the alignments of low multipoles in CMB angular power spectrum [9][10][11][12][13], the large-scale alignments of the quasar polarization vectors [14,15], the spatial variation of the fine-structure constant [16][17][18][19], the CMB hemispherical asymmetry observed by WMAP [20,21] and the Planck satellite [4].…”

Section: Introductionmentioning

confidence: 99%

Constraining anisotropy of the universe from different groups of type-Ia supernovae

Chang

Lin

et al. 2014

Eur. Phys. J. C

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Recently released Planck data and other astronomical observations show that the universe may be anisotropic on large scales. Inspired by this, anisotropic cosmological models have been proposed. We note that the FinslerRanders spacetime provides an appropriate framework for the anisotropic cosmology. By adding an arbitrary 1-form to the Friedmann-Robertson-Walker line element, a privileged axis in the universe is picked out. The distance-redshift relation is modified to be direction-dependent. We wish that the anisotropic cosmological model may be tested crossly by independent observations. Type-Ia supernovae (SNe Ia) calibrated from four different light curve fitters are used to constrain the possible anisotropy of the universe. The magnitudes of anisotropy are all between 2-5 %, but the systematic uncertainty cannot be excluded. The directions of the privileged axis seem to differ from each other. The statistical significance is not high enough to make a convincing conclusion. Nevertheless, the 1σ contours in the (l, b) plane obtained from four groups of SNe Ia have an overlap, centering at (l, b) ≈ (170 • , 0 • ). Monte Carlo simulation shows that the anisotropy is unlikely to be caused by the selection effect.

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Section: Introductionmentioning

confidence: 99%

Constraining anisotropy of the universe from different groups of type-Ia supernovae

Chang

Lin

et al. 2014

Eur. Phys. J. C

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show abstract

“…(II) Absence of the circular polarization Although the objects are highly linearly polarized, the circular polarization is not observed [16]. This non-observation of circular polarization constrains |p circ | by…”

Section: The Polarization Of Light From Quasarmentioning

confidence: 96%

“…The degree of linear polarization is of the order of 1%. To explain the observation we require [16] 0.005 |p lin | 0.02,…”

Section: The Polarization Of Light From Quasarmentioning

confidence: 99%

“…In the last two to three decades [5], the axion-photon coupling and subsequent mixing or conversion scenarios has received a great deal of attention [6], both phenomenologically [7] and experimentally [8]. This is of particular interest in astrophysics, where this mixing of photons with axion makes the universe transparent to the former [10] and also changes their polarization properties [9].…”

Section: Introductionmentioning

confidence: 99%

“…However, the consequent observation of vanishing circular polarization [16] is a problem for the hypothesis. Therefore it is argued that the ALPs cannot explain the alignments and only constrain ALPs [17].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Quasar polarization with ultralight (pseudo-)scalars

2015

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Recently, it was shown, that the absence of circular polarization of visible light from quasars, severely constrains the interpretation of axion like particles (ALPs) as a solution for the generation of the linear polarization. Furthermore, the new observation of the linear polarization in the radio wavelength from quasars, similar to the earlier observation performed in the optical band, makes the ALPs scenario inconsistent with at least one of the two observations. In this study we extend this scenario, to two axion like particles, one scalar and another pseudoscalar. We find, that the effects from scalar and pseudoscalar cancel out each other, thereby suppressing the circular polarization, while preserving consistent linear polarization, as observed in both visible and radio waves bands.

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The Panchromatic Polarisation Signatures of Active Galactic Nuclei

Marin

2019

Astrophysics and Space Science Library

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Among all the astronomical sources investigated through the prism of polarimetry, active galactic nuclei (AGN) have proven to be the richest in terms of complex yet fundamental signatures that helped to understand their true nature. Indeed, AGN exhibit a wide range of wavelength-dependent polarimetric features that are intrinsically related to their multi-scale emission mechanisms. Each waveband is characterized by a different set of polarimetric signatures that can be related to various physical mechanisms that, from the radio band to the soft-γ rays, probe increasingly smaller AGN regions. In fact, panchromatic polarization measurements are the key to understand how and when AGN form, accrete, and impact the host galaxy they reside in. In this chapter, I will first introduce AGN without focusing on a particular observational technique. I will then review the discoveries and constraints that spectro-, imaging and broadband polarimetry have achieved. Finally, I will highlight the important questions that remain unanswered and how they can be solved with future large millimeter and radio antennas, 30-m class optical and infrared telescopes, and high energy satellites equipped with state-of-the-art polarimeters.

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Optical circular polarization in quasars

Cited by 79 publications

References 47 publications

Constraining anisotropy of the universe from different groups of type-Ia supernovae

Constraining anisotropy of the universe from different groups of type-Ia supernovae

Quasar polarization with ultralight (pseudo-)scalars

The Panchromatic Polarisation Signatures of Active Galactic Nuclei

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