Properties of polarized synchrotron emission from fluctuation-dynamo action - I. Application to galaxy clusters

Sur S, Basu A, Subramanian K (2021)
Monthly Notices of the Royal Astronomical Society 501(3): 3332-3349.

Zeitschriftenaufsatz | Veröffentlicht | Englisch
 
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Autor*in
Sur, Sharanya; Basu, AritraUniBi; Subramanian, Kandaswamy
Abstract / Bemerkung
Using magnetohydrodynamic simulations of fluctuation dynamos, we perform broad-bandwidth synthetic observations to investigate the properties of polarized synchrotron emission and the role that Faraday rotation plays in inferring the polarized structures in the intracluster medium (ICM) of galaxy clusters. In the saturated state of the dynamo, we find a Faraday depth (FD) dispersion sigma(FD) approximate to 100 rad m(-2), in agreement with observed values in the ICM. Remarkably, the FD power spectrum is qualitatively similar to M(k)/k, where M(k) is the magnetic spectrum and k the wavenumber. However, this similarity is broken at high k when FD is obtained by applying rotation measure (RM) synthesis to polarized emission from the ICM due to poor resolution and complexities of spectrum in FD space. Unlike the Gaussian probability distribution function (PDF) obtained for FD, the PDF of the synchrotron intensity is lognormal. A relatively large sigma(FD) in the ICM gives rise to strong frequency-dependent variations of the pixel-wise mean and peak polarized intensities at low frequencies (less than or similar to 1.5 GHz). The mean fractional polarization < p > obtained at the resolution of the simulations increases from <0.1 at 0.5 GHz to its intrinsic value of similar to 0.3 at 6 GHz. Beam smoothing significantly affects the polarization properties below less than or similar to 1.5 GHz, reducing < p > to less than or similar to 0.01 at 0.5 GHz. At frequencies greater than or similar to 5 GHz, polarization remains largely unaffected, even when recovered using RM synthesis. Thus, our results underline the need for high-frequency (greater than or similar to 5 GHz) observations with future radio telescopes to effectively probe the properties of polarized emission in the ICM.
Stichworte
dynamo; MHD; turbulence; galaxies: clusters: intracluster medium; galaxies: magnetic fields
Erscheinungsjahr
2021
Zeitschriftentitel
Monthly Notices of the Royal Astronomical Society
Band
501
Ausgabe
3
Seite(n)
3332-3349
ISSN
0035-8711
eISSN
1365-2966
Page URI
https://pub.uni-bielefeld.de/record/2953397

Zitieren

Sur S, Basu A, Subramanian K. Properties of polarized synchrotron emission from fluctuation-dynamo action - I. Application to galaxy clusters. Monthly Notices of the Royal Astronomical Society . 2021;501(3):3332-3349.
Sur, S., Basu, A., & Subramanian, K. (2021). Properties of polarized synchrotron emission from fluctuation-dynamo action - I. Application to galaxy clusters. Monthly Notices of the Royal Astronomical Society , 501(3), 3332-3349. https://doi.org/10.1093/mnras/staa3767
Sur, S., Basu, A., and Subramanian, K. (2021). Properties of polarized synchrotron emission from fluctuation-dynamo action - I. Application to galaxy clusters. Monthly Notices of the Royal Astronomical Society 501, 3332-3349.
Sur, S., Basu, A., & Subramanian, K., 2021. Properties of polarized synchrotron emission from fluctuation-dynamo action - I. Application to galaxy clusters. Monthly Notices of the Royal Astronomical Society , 501(3), p 3332-3349.
S. Sur, A. Basu, and K. Subramanian, “Properties of polarized synchrotron emission from fluctuation-dynamo action - I. Application to galaxy clusters”, Monthly Notices of the Royal Astronomical Society , vol. 501, 2021, pp. 3332-3349.
Sur, S., Basu, A., Subramanian, K.: Properties of polarized synchrotron emission from fluctuation-dynamo action - I. Application to galaxy clusters. Monthly Notices of the Royal Astronomical Society . 501, 3332-3349 (2021).
Sur, Sharanya, Basu, Aritra, and Subramanian, Kandaswamy. “Properties of polarized synchrotron emission from fluctuation-dynamo action - I. Application to galaxy clusters”. Monthly Notices of the Royal Astronomical Society 501.3 (2021): 3332-3349.

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