Unusual magnetic fields in the interacting spiral
NGC 3627

Soida, M.; Urbanik, M.; Beck, Rainer; Wielebinski, R.; Balkowski, C.

doi:10.1051/0004-6361:20011185

Cited by 57 publications

(71 citation statements)

References 20 publications

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“…Due to this mechanism magnetic arms could work as a tracer of spiral arms present at earlier time stages. For the first time we obtained rapid turning of the magnetic pitch angle between arm and interarm regions, which is also observed in NGC 3627 (Soida et al 2001) and in NGC 1365 (Shoutenkov et al 2000;Beck et al in prep. ;Lindblad 1999).…”

Section: Discussionsupporting

confidence: 69%

“…The interarm vectors run parallel to the bar turning suddenly towards the orientation of a spiral arm, which resembles the situation in the barred galaxy NGC 3627 as presented in Fig. 3 (Soida et al 2001 Fig. 3 where the arm and interarm B-vectors meet at right angles.…”

Section: The Polarization Mapssupporting

confidence: 58%

“…;Lindblad 1999). This gives the impression of two separate components, one in spiral arms and one between them, as suggested by some observers (Soida et al 2001). Simulations with different halo-to-disk mass ratios, resulting in a spiral pattern without a bar, did not show any difference between magnetic and optical pattern speeds (Elstner et al 2000).…”

Section: Discussionmentioning

confidence: 79%

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Magnetic Fields and Radio Polarization of Barred Galaxies

Otmianowska-Mazur

Elstner

2003

The Evolution of Galaxies

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Abstract.A three-dimensional (3D) MHD model is applied to simulate the evolution of a large-scale magnetic field in a barred galaxy possessing a gaseous halo extending to about 2.8 kpc above the galactic plane. As the model input we use a time-dependent velocity field of molecular gas resulting from self-consistent 3D N-body simulations of a galactic disk. We assume that the gaseous halo rotates differentially co-rotating with the disk or decreasing its velocity in the Z direction. The dynamo process included in the model yields the amplification of the magnetic field as well as the formation of field structures high above the galactic disk. The simulated magnetic fields are used to construct the models of a high-frequency (Faraday rotation-free) polarized radio emission that accounts for effects of projection and limited resolution, and is thus suitable for direct comparison with observations. We found that the resultant magnetic field correctly reproduces the observed structures of polarization B-vectors, forming coherent patterns well aligned with spiral arms and with the bar. The process initializing a wave-like behavior of the magnetic field, which efficiently forms magnetic maxima between the spiral arms, is demonstrated. The inclusion of the galactic halo constitutes a step towards a realistic model of galactic magnetic fields that includes as many dynamical components as needed for a realistic description.

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Section: Discussionsupporting

confidence: 69%

Section: The Polarization Mapssupporting

confidence: 58%

Section: Discussionmentioning

confidence: 79%

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Magnetic Fields and Radio Polarization of Barred Galaxies

Otmianowska-Mazur

Elstner

2003

The Evolution of Galaxies

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“…Some possible systematic variation in the Faraday depth can be discerned which we will comment on in Paper III. Note that Soida et al (2001) have published VLA and Effelsberg observations of this galaxy at 4.8 and 8.5 GHz which detect many of the same trends, although not detecting the same northern extent. The brighter lobe of a background triple source permits assessment of the Galactic foreground RM of +13 ± 1 rad m −2 .…”

Section: Notes On Individual Galaxiesmentioning

confidence: 75%

The Westerbork SINGS survey

Heald¹,

Braun

Edmonds

2009

A&A

210

292

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A sample of large northern Spitzer Infrared Nearby Galaxies Survey (SINGS) galaxies has recently been observed with the Westerbork Synthesis Radio Telescope (WSRT). We present observations of the linearly polarized radio continuum emission in this WSRT-SINGS galaxy sample. Of the 28 galaxies treated in this paper, 21 are detected in polarized radio continuum at 18-and 22-cm wavelengths. We utilize the rotation measure synthesis (RM-Synthesis) method, as implemented by Brentjens & de Bruyn (2005, A&A, 441, 1217, to coherently detect polarized emission from a large fractional bandwidth, while simultaneously assessing the degree of Faraday rotation experienced by the radiation along each line-of-sight. This represents the first time that the polarized emission and its Faraday rotation have been systematically probed down to ∼10 μJy beam −1 RMs for a large sample of galaxies. Non-zero Faraday rotation is found to be ubiquitous in all of the target fields, from both the Galactic foreground and the target galaxies themselves. In this paper, we present an overview of the polarized emission detected in each of the WSRT-SINGS galaxies. The most prominent trend is a systematic modulation of the polarized intensity with galactic azimuth, such that a global minimum in the polarized intensity is seen toward the kinematically receding major axis. The implied large-scale magnetic field geometry is discussed in a companion paper. A second novel result is the detection of multiple nuclear Faraday depth components that are offset to both positive and negative RM by 100−200 rad m −2 in all targets that host polarized (circum-)nuclear emission.

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“…NGC 2276 also has a radio tail noted by Condon (1983). Pitch angle asymmetries and an enhancement of the polarization on one side of the disk by field compression are found in the tidally interacting spiral NGC 3627 (Soida et al 2001 and references therein). We note also that the large-scale distribution of H  presented by Thornley & Mundy (1997) shows at intermediate radii a slightly larger gas extent and slower density decrease with radius along the southern semi-axis, where we find larger magnetic pitch angles.…”

Section: The Magnetic Field Structurementioning

confidence: 88%

Magnetic fields in the absence of spiral density waves – NGC 4414

Soida

Beck

Urbanik

et al. 2002

A&A

Self Cite

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Abstract. We present three-frequency VLA observations of the flocculent spiral galaxy NGC 4414 made in order to study the magnetic field structure in absence of strong density wave flows. NGC 4414 shows a regular spiral pattern of observed polarization B-vectors with a radial component comparable in strength to the azimuthal one. The average pitch angle of the magnetic field is about 20 • , similar to galaxies with a well-defined spiral pattern. This provides support for field generation by a turbulent dynamo without significant "contamination" from streaming motions in spiral arms. While the stellar light is very axisymmetric, the magnetic field structure shows a clear asymmetry with a stronger regular field and a smaller magnetic pitch angle in the northern disk. Extremely strong Faraday rotation is measured in the southern part of the disk, becoming Faraday thick at 6 cm. The distribution of Faraday rotation suggests a mixture of axisymmetric and higher-mode magnetic fields. The strong Faraday effects in the southern region suggest a much thicker magnetoionic disk and a higher content of diffuse ionized gas than in the northern disk portion. An elongation of the 20 cm total power emission is also seen towards the South. Although NGC 4414 is currently an isolated spiral, the asymmetries in the polarized radio emission may be sensitive tracers of previous encounters, including weak interactions which would chiefly affect the diffuse gas component without generating obvious longterm perturbations in the optical structure.

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Unusual magnetic fields in the interacting spiral NGC 3627

Cited by 57 publications

References 20 publications

Magnetic Fields and Radio Polarization of Barred Galaxies

Magnetic Fields and Radio Polarization of Barred Galaxies

The Westerbork SINGS survey

Magnetic fields in the absence of spiral density waves – NGC 4414

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