A study of Kepler supernova remnant: angular power spectrum estimation from radio frequency data

Saha, Preetha and Bharadwaj, Somnath and Roy, Nirupam and Choudhuri, Samir and Chattopadhyay, Debatri (2019) A study of Kepler supernova remnant: angular power spectrum estimation from radio frequency data. In: MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 489 (4). pp. 5866-5875.

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Abstract

Supernova remnants (SNRs) have a variety of overall morphology as well as rich structures over a wide range of scales. Quantitative study of these structures can potentially reveal fluctuations of density and magnetic field originating from the interaction with ambient medium and turbulence in the expanding ejecta. We have used 1.5 GHz (L band) and 5 GHz (C band) VLA data to estimate the angular power spectrum C-l of the synchrotron emission fluctuations of the Kepler SNR. This is done using the novel, visibility-based, Tapered Gridded Estimator of C-l. We have found that, for l = (1.9-6.9) x 10(4), the power spectrum is a broken power law with a break at l = 3.3 x 10(4), and power-law index of -2.84 +/- 0.07 and -4.39 +/- 0.04 before and after the break, respectively. The slope -2.84 is consistent with 2D Kolmogorov turbulence and earlier measurements for the Tycho SNR. We interpret the break to be related to the shell thickness of the SNR (0.35 pc) which approximately matches l = 3.3 x 10(4) (i.e. 0.48 pc). However, for l > 6.9 x 10(4), the estimated C-l of L band is likely to have dominant contribution from the foregrounds while for C band the power-law slope -3.07 +/- 0.02 is roughly consistent with 3D Kolmogorov turbulence like that observed at large l for Cas A and Crab SNRs.

Item Type:	Journal Article
Publication:	MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
Publisher:	OXFORD UNIV PRESS
Additional Information:	Copyright of this article belongs to OXFORD UNIV PRESS
Keywords:	ISM: supernova remnants; ISM: individual: Kepler SNR; methods: statistical; turbulence; MHD
Department/Centre:	Division of Physical & Mathematical Sciences > Physics
Date Deposited:	31 Dec 2019 09:13
Last Modified:	31 Dec 2019 09:13
URI:	http://eprints.iisc.ac.in/id/eprint/63811

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