J/ApJ/663/258 Rotation measures of extragalactic sources in SGPS (Brown+, 2007)
Rotation measures of extragalactic sources behind the southern Galactic plane:
new insights into the large-scale magnetic field of the inner Milky Way.
Brown J.C., Haverkorn M., Gaensler B.M., Taylor A.R., Bizunok N.S.,
McClure-Griffiths N.M., Dickey J.M., Green A.J.
<Astrophys. J., 663, 258-266 (2007)>
=2007ApJ...663..258B 2007ApJ...663..258B
ADC_Keywords: Radio sources ; Polarization
Keywords: Galaxy: structure - ISM: magnetic fields - polarization
Abstract:
We present new Faraday rotation measures (RMs) for 148 extragalactic
radio sources behind the southern Galactic plane
(253°≤l≤356°, |b|≤1.5°), and use these data in
combination with published data to probe the large-scale structure of
the Milky Way's magnetic field. We show that the magnitudes of these
RMs oscillate with longitude in a manner that correlates with the
locations of the Galactic spiral arms. The observed pattern in RMs
requires the presence of at least one large-scale magnetic reversal in
the fourth Galactic quadrant, located between the Sagittarius-Carina
and Scutum-Crux spiral arms. To quantitatively compare our
measurements to other recent studies, we consider all available
extragalactic and pulsar RMs in the region we have surveyed, and
jointly fit these data to simple models in which the large-scale field
follows the spiral arms.
Description:
The initial set of observations for the SGPS (i.e., Phase I) spans an
area of 253°≤l≤358° and |b|≤1.5°. The observations were
done with the Australia Telescope Compact Array (ATCA) in New South
Wales, Australia. For details about the SGPS observations and
polarimetric data reduction, see Gaensler et al. (2001ApJ...549..959G 2001ApJ...549..959G)
and Haverkorn et al. (2006ApJS..167..230H 2006ApJS..167..230H).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 54 148 Rotation Measures of the SGPS
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See also:
VII/6 : Polarization of extragalactic radio sources (Eichendorf+ 1980)
J/ApJS/45/97 : Extragal. radio sources Faraday rot. (Simard-Normandin+ 1981)
J/ApJ/642/868 : Rotation measures for 223 pulsars (Han+, 2006)
J/ApJS/145/213 : Rotation measures of compact sources in CGPS (Brown+, 2003)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 6 F6.2 deg GLON Galactic longitude (1)
8- 12 F5.2 deg GLAT Galactic latitude (1)
14- 15 I2 h RAh Hour of Right Ascension (J2000)
17- 18 I2 min RAm Minute of Right Ascension (J2000)
20- 23 F4.1 s RAs Second of Right Ascension (J2000)
25 A1 --- DE- Sign of the Declination (J2000)
26- 27 I2 deg DEd Degree of Declination (J2000)
29- 30 I2 arcmin DEm Arcminute of Declination (J2000)
32- 33 I2 arcsec DEs Arcsecond of Declination (J2000)
35- 38 I4 mJy I Peak-pixel interferometric Stokes I value
40- 43 F4.1 % m Fractional polarisation (2)
45- 49 I5 rad/m2 RM Faraday rotation measure
51- 52 I2 rad/m2 e_RM Uncertainty in RM
54 A1 --- f_RM [d] New value of RM (3)
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Note (1): The identified location is the peak of the gaussian fit to the
source in polarised intensity. All sources were either unresolved or
partially resolved. Source identified as [BHG2007] GLLL.ll+B.bb in Simbad
Note (2): Linear polarised intensity divided by Stokes I averaged over the
FWHM pixels used for rotation measure calculation.
Note (3): sources marked by 'd': a RM for this source was calculated by
Gaensler et al. (2001ApJ...549..959G 2001ApJ...549..959G) using a simpler approach than
the more rigorous method used here. These new values should replace
the previously determined values.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Patricia Vannier [CDS] 09-Aug-2009