2008A&A...478..435R


C.D.S. - SIMBAD4 rel 1.7 - 2020.07.02CEST15:21:29

2008A&A...478..435R - Astronomy and Astrophysics, volume 478, 435-442 (2008/2-1)

Magnetic field near the central region of the Galaxy: rotation measure of extragalactic sources.

ROY S., PRAMESH RAO A. and SUBRAHMANYAN R.

Abstract (from CDS):

We determine the properties of the Faraday screen and the magnetic field near the central region of the Galaxy. We measured the Faraday rotation measure (RM) towards 60 background extragalactic source components through the -6°<l<6°, -2°<b<2° region of the Galaxy using the 4.8 and 8.5GHz bands of the ATCA and VLA. Here we use the measured RMs to estimate the systematic and the random components of the magnetic fields. The measured RMs are found to be mostly positive for the sample sources in the region. This is consistent with either a large scale bisymmetric spiral magnetic fields in the Galaxy or with fields oriented along the central bar of the Galaxy. The outer scale of the RM fluctuation is found to be about 40pc, which is much larger than the observed RM size scales towards the non thermal filaments (NTFs). The RM structure function is well-fitted with a power law index of 0.7±0.1 at length scales of 0.3 to 100pc. If Gaussian random processes in the ISM are valid, the power law index is consistent with a two dimensional Kolmogorov turbulence. If there is indeed a strong magnetic field within ∼1° (radius 150pc) from the GC, the strength of the random field in the region is estimated to be ∼20µG. Given the highly turbulent magnetoionic ISM in this region, the strength of the systematic component of the magnetic fields would most likely be close to that of the random component. This suggests that the earlier estimated milliGauss magnetic field near the NTFs is localised and does not pervade the central 300pc of the Galaxy.

Abstract Copyright:

Journal keyword(s): ISM: magnetic fields - Galaxy: center - techniques: polarimetric

Simbad objects: 7

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Number of rows : 7

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 NAME Pelican Filament Rad 17 41 00.3 -29 39 47           ~ 15 0
2 NAME the Ripple Filament Rad 17 43 52.0 -29 13 47           ~ 47 1
3 NAME Gal Center Snake Rad 17 44 17.9 -29 46 00           ~ 51 1
4 2LC 359.872+0.178 rG 17 44 37.06 -28 57 09.4           ~ 19 0
5 NAME NTFs PoC 17 45.2 -29 03           ~ 37 2
6 NAME Gal Center reg 17 45 40.04 -29 00 28.1           ~ 11532 0
7 NAME Galactic CENTRE LOBE Rad 17 46 18.10 -29 38 36.5           ~ 45 0

    Equat.    Gal    SGal    Ecl

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2020.07.02-15:21:29

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