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Polarized Source Detection and Large Scale Magnetic Fields in NGC 2563

Presentation #342.20 in the session “Galaxy Evolution & Populations”.

Published onJan 11, 2021
Polarized Source Detection and Large Scale Magnetic Fields in NGC 2563

We present the results of an observational study to detect polarized sources and evidence of large-scale magnetic fields in the intragroup medium of the nearby galaxy group NGC 2563. Our data was collected in early 2020 using the Karl G Jansky Very Large Array (VLA) in the S-band of the radio spectrum (2-4 GHz). We examined these S-band waves from sources in, behind, and around galaxy group NGC 2563, seeking polarized sources. Standard data reduction and calibration procedures were followed to image nine sightlines through the galaxy group and nine around the group in Stokes I, Q, and U. We performed Faraday rotation measure synthesis on each field, and used these results to identify linearly polarized sources. With these sources, we can calculate the magnetic field in the galaxy group. Sources adjacent to the galaxy group’s line of sight show the effect of the Milky Way’s magnetic field, so we can distinguish it from NGC 2563’s magnetic field. Analysis showed the Milky Way’s contribution to Faraday rotation is ~14.9 rad m-2, which is slightly smaller than previous estimates (~19.5 rad m-2). We find that our sources’ spectral indices range between 0 and 1.98, indicating both thermal and non-thermal emission processes. Across the 18 total sightlines observed, 157 radio sources were detected, 24 of which were polarized. Since certain sightlines show that NGC 2563 has very high source density, future work could reexamine these fields at higher sensitivity and search for more polarized sources. Only a few of the sources we examined were identified in existing catalogs, indicating that our research could provide valuable expansions to these catalogs. Further research might also compare our findings with those of future, more extensive surveys. Gathering information on these magnetic fields may ultimately provide greater insight into galaxy group formation and the evolution of primordial magnetic fields.

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