Magnetic fields in the Southern Galactic Plane Survey

Haverkorn, M.; Gaensler, B. M.; Brown, J. C.; McClure-Griffiths, N. M.; Dickey, John M.; Green, Anne

doi:10.1002/asna.200610565

Cited by 7 publications

(3 citation statements)

References 14 publications

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“…RM data from pulsars and polarized extragalactic point sources in the SGPS, combined with other available point source data, are being used to construct a model of the large-scale Galactic magnetic field ( Haverkorn et al 2006b;Brown et al 2006), discussing the strength of the regular magnetic field and the abundance and locations of magnetic field reversals.…”

Section: Science With the Sgpsmentioning

confidence: 99%

The Southern Galactic Plane Survey: Polarized Radio Continuum Observations and Analysis

Haverkorn¹,

Gaensler²,

McClure-Griffiths³

et al. 2006

ASTROPHYS J SUPPL S

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132

114

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The Southern Galactic Plane Survey (SGPS) is a radio survey in the 21 cm H i line and in 1.4 GHz full-polarization continuum, observed with the Australia Telescope Compact Array and the Parkes 64 m single-dish telescope. The survey spans a Galactic longitude of 253 < l < 358 and a latitude of jbj < 1N5 at a resolution of 100 00 and a sensitivity below 1 mJy beam À1 . This paper presents interferometer only polarized continuum survey data and describes the data taking, analysis processes, and data products. The primary data products are the four Stokes parameters I, Q, U, and V in 25 overlapping fields of 5N5 by 3 , from which polarized intensity, polarization angle, and rotation measure are calculated. We describe the effects of missing short spacings, and discuss the importance of the polarized continuum data in the SGPS for studies of fluctuations and turbulence in the ionized interstellar medium and for studying the strength and structure of the Galactic magnetic field.

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Section: Science With the Sgpsmentioning

confidence: 99%

The Southern Galactic Plane Survey: Polarized Radio Continuum Observations and Analysis

Haverkorn¹,

Gaensler²,

McClure-Griffiths³

et al. 2006

ASTROPHYS J SUPPL S

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132

114

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“…Further indication that the structure of the local Galactic magnetic field is rather complicated on pc and sub-pc scales comes from RM maps obtained from the diffuse Galactic synchrotron on which many reversals on small scales observed around 330 MHz with the WSRT (Haverkorn et al 2003a(Haverkorn et al , 2003b. Major progress can be expected from the new 1.4 GHz International Galactic Plane Survey observed at the DRAO and ATCA telescopes (Brown & Taylor 2001, Haverkorn et al 2006). It will provide high-resolution RM data of the diffuse emission and several 100 RM values of polarized background sources.…”

Section: Magnetic Field Reversals In the Milky Waymentioning

confidence: 99%

Magnetic Field Structure from Synchrotron Polarization

Beck

2007

EAS Publications Series

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Total magnetic fields in spiral galaxies, as observed through their total synchrotron emission, are strongest (up to \simeq 30\mu G) in the spiral arms. The degree of radio polarization is low; the field in the arms must be mostly turbulent or tangled. Polarized synchrotron emission shows that the resolved regular fields are generally strongest in the interarm regions (up to \simeq 15\mu G), sometimes forming 'magnetic arms' parallel to the optical arms. The field structure is spiral in almost every galaxy, even in flocculent and bright irregular types which lack spiral arms. The observed large-scale patterns of Faraday rotation in several massive spiral galaxies reveal coherent regular fields, as predicted by dynamo models. However, in most galaxies observed so far no simple patterns of Faraday rotation could be found. Either many dynamo modes are superimposed and cannot be resolved by present-day telescopes, or most of the apparently regular field is in fact anisotropic random, with frequent reversals, due to shearing and compressing gas flows. In galaxies with massive bars, the polarization pattern follows the gas flow. However, around strong shocks in bars, the compression of the regular field is much lower than that of the gas; the regular field decouples from the cold gas and is strong enough to affect the flow of the diffuse warm gas. -- The average strength of the total magnetic field in the Milky Way is 6\mu G near the sun and increases to 20-40\mu G in the Galactic center region. The Galactic field is mostly parallel to the plane, except in the center region. Rotation measure data from pulsars indicate several field reversals, unlike external galaxies, but some reversals could be due to distortions of the nearby field.Comment: 18 pages, 9 figures. To be published in "Polarisation 2005" (Proc. of the conference held in Paris, 12-15 Sept. 2005), eds. F. Boulanger and M.A. Miville-Deschenes, EAS Publications Series; Two small typos corrected, one reference added and three updated 23/06/200

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“…As an example of using the RM structure function to determine the outer scale of fluid turbulence, Haverkorn et al (2006a) found a zero gradient with an outer scale on the order of ∼ 10 pc for the inner Galactic Plane, indicating that the main source of turbulence had to be injected on a scale of ∼ 10 pc, which they attributed to H regions.…”

Section: Magneto-ionic Turbulencementioning

confidence: 99%

Heightened Faraday Complexity in the inner 1 kpc of the Galactic Centre

Livingston,

McClure-Griffiths,

Gaensler

et al. 2021

Preprint

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We have measured the Faraday rotation of 62 extra-galactic background sources in 58 fields using the CSIRO Australia Telescope Compact Array (ATCA) with a frequency range of 1.1 -3.1 GHz with 2048 channels. Our sources cover a region ∼ 12 deg × 12 deg (∼ 1kpc) around the Galactic Centre region. We show that the Galactic Plane for |𝑙 | < 10 • exhibits large Rotation Measures (RMs) with a maximum |RM| of 1691.2 ± 4.9 rad m −2 and a mean |RM| = 219 ± 42 rad m −2 . The RMs decrease in magnitude with increasing projected distance from the Galactic Plane, broadly consistent with previous findings. We find an unusually high fraction (95%) of the sources show Faraday complexity consistent with multiple Faraday components. We attribute the presences of multiple Faraday rotating screens with widely separated Faraday depths to small-scale turbulent RM structure in the Galactic Centre region. The second order structure function of the RM in the Galactic Centre displays a line with a gradient of zero for angular separations spanning 0.83 • − 11 • (∼ 120 − 1500 pc), which is expected for scales larger than the outer scale (or driving scale) of magneto-ionic turbulence. We place an upper limit on any break in the SF gradient of 66", corresponding to an inferred upper limit to the outer scale of turbulence in the inner 1 kpc of the Galactic Centre of 3 pc. We propose stellar feedback as the probable driver of this small-scale turbulence.

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Magnetic fields in the Southern Galactic Plane Survey

Cited by 7 publications

References 14 publications

The Southern Galactic Plane Survey: Polarized Radio Continuum Observations and Analysis

The Southern Galactic Plane Survey: Polarized Radio Continuum Observations and Analysis

Magnetic Field Structure from Synchrotron Polarization

Heightened Faraday Complexity in the inner 1 kpc of the Galactic Centre

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