scholarly journals A novel analytical model of the magnetic field configuration in the Galactic center

2020 ◽  
Vol 644 ◽  
pp. A71
Author(s):  
M. Guenduez ◽  
J. Becker Tjus ◽  
K. Ferrière ◽  
R.-J. Dettmar
Keyword(s):  
Magnetic Field ◽  
Large Scale ◽  
Field Model ◽  
Galactic Center ◽  
Cosmic Ray ◽  
Field Structure ◽  
Magnetic Field Structure ◽  
Center Region ◽  
Magnetic Field Model ◽  
The Magnetic Field

Context. Cosmic-ray propagation is strongly dependent on the large-scale configuration of the Galactic magnetic field. In particular, the Galactic center region provides highly interesting cosmic-ray data from gamma-ray maps and it is clear that a large fraction of the cosmic rays detected at Earth originate in this region of the Galaxy. Yet because of confusion from line-of-sight integration, the magnetic field structure in the Galactic center is not well known and no large-scale magnetic field model exists at present. Aims. In this paper, we develop a magnetic field model, derived from observational data on the diffuse gas, nonthermal radio filaments, and molecular clouds. Methods. We derive an analytical description of the magnetic field structure in the central molecular zone by combining observational data with the theoretical modeling of the basic properties of magnetic fields. Results. We provide a first description of the large-scale magnetic field in the Galactic center region. We present first test simulations of cosmic-ray propagation and the impact of the magnetic field structure on the cosmic-ray distribution in the three dimensions. Conclusions. Our magnetic field model is able to describe the main features of polarization maps; it is particularly important to note that they are significantly better than standard global Galactic magnetic field models. It can also be used to model cosmic-ray propagation in the Galactic center region more accurately.

scholarly journals The magnetic field structure in NGC 253 in presence of a galactic wind

2008 ◽  
Vol 4 (S259) ◽  
pp. 509-514 ◽  
Author(s):  
Volker Heesen ◽  
M. Krause ◽  
R. Beck ◽  
R.-J. Dettmar
Keyword(s):  
Magnetic Field ◽  
Large Scale ◽  
Cosmic Ray ◽  
Field Structure ◽  
Radio Continuum ◽  
Magnetic Field Structure ◽  
Galactic Wind ◽  
Radio Halo ◽  
Large Scale Magnetic Field ◽  
The Magnetic Field

AbstractWe present radio continuum polarimetry observations of the nearby edge-on galaxy NGC 253 which possesses a very bright radio halo. Using the vertical synchrotron emission profiles and the lifetimes of cosmic-ray electrons, we determined the cosmic-ray bulk speed as 300±30 km s−1, indicating the presence of a galactic wind in this galaxy. The large-scale magnetic field was decomposed into a toroidal axisymmetric component in the disk and a poloidal component in the halo. The poloidal component shows a prominent X-shaped magnetic field structure centered on the nucleus, similar to the magnetic field observed in other edge-on galaxies. Faraday rotation measures indicate that the poloidal field has an odd parity (antisymmetric). NGC 253 offers the possibility to compare the magnetic field structure with models of galactic dynamos and/or galactic wind flows.

scholarly journals Recurrent flux emergence from dynamo-generated fields

2010 ◽  
Vol 6 (S271) ◽  
pp. 407-408
Author(s):  
Jörn Warnecke ◽  
Axel Brandenburg
Keyword(s):  
Magnetic Field ◽  
Time Series ◽  
Large Scale ◽  
Field Structure ◽  
Flux Emergence ◽  
Magnetic Field Structure ◽  
Forcing Function ◽  
Large Scale Magnetic Field ◽  
The Magnetic Field

Abstractwe investigate the emergence of a large-scale magnetic field. This field is dynamo-generated by turbulence driven with a helical forcing function. Twisted arcade-like field structures are found to emerge in the exterior above the turbulence zone. Time series of the magnetic field structure show recurrent plasmoid ejections.

scholarly journals Evolution of a Filament/CH/Magnetic Field Complex

1998 ◽  
Vol 167 ◽  
pp. 393-396
Author(s):  
B.A. Ioshpa ◽  
E.I. Mogilevsky ◽  
V.N. Obridko
Keyword(s):  
Magnetic Field ◽  
Active Region ◽  
Magnetic Fields ◽  
Large Scale ◽  
Coronal Holes ◽  
Field Structure ◽  
Potential Approximation ◽  
Magnetic Field Structure ◽  
Single Complex ◽  
The Magnetic Field

AbstractSOHO and YOHKOH images, as well as Hα filtergrams and magnetograms from IZMIRAN have been used to analyze the evolution of the related solar phenomena – filament, active region, and accompanying pair of coronal holes – during six solar rotations, with an emphasis on the events observed during August–September, 1996. The whole complex has been considered against the large–scale magnetic fields calculated under the potential approximation. A peculiar point has been found along the changing filament. It is shown that the phenomena under investigation (filament, active region, and coronal hole) form a single complex connected with the magnetic field structure.

Effect of magnetic field structure on collisional drift waves

1999 ◽  
Vol 77 (6) ◽  
pp. 447-461
Author(s):  
J LV Lewandowski ◽  
M Persson
Keyword(s):  
Magnetic Field ◽  
Linear Growth ◽  
Field Model ◽  
Field Structure ◽  
Linear Growth Rate ◽  
Drift Waves ◽  
Initial Value ◽  
Magnetic Shear ◽  
Magnetic Field Structure ◽  
The Magnetic Field

A 3-field model for collisional drift waves, in the ballooning representation, for a low-pressure stellarator plasma is presented. The 3-field model, which includes the effects of a finite radial mode number (θk) , is solved as an initial-value problem along the magnetic field line. It is shown that for a stellarator with low global magnetic shear, θk= 0 corresponds to the fastest linear growth rate. The effects of the magnetic field structure for the tokamak and stellarator configurations are discussed in a comparative way. PACS Nos.: 52.35Kt, 52.30Jb, 52.35Ra

scholarly journals Zeeman-Doppler imaging of II Peg

2008 ◽  
Vol 4 (S259) ◽  
pp. 437-438 ◽  
Author(s):  
Thorsten A. Carroll ◽  
Markus Kopf ◽  
Klaus G. Strassmeier ◽  
Ilya Ilyin ◽  
Ilkka Tuominen
Keyword(s):  
Magnetic Field ◽  
Large Scale ◽  
Field Structure ◽  
Doppler Imaging ◽  
High Latitudes ◽  
Magnetic Vector ◽  
Magnetic Field Structure ◽  
Surface Magnetic Field ◽  
Large Scale Magnetic Field ◽  
The Magnetic Field

AbstractWe present Zeeman-Doppler images of the active K2 star II Peg for the years 2004 and 2007. The surface magnetic field was reconstructed with our new ZDI code iMap which provides a full polarized radiative transfer driven inversion to simultaneously reconstruct the surface temperature and magnetic vector field distribution. II Peg shows a remarkable large scale magnetic field structure for both years. The magnetic field is predominantly located at high latitudes and is arranged in active longitudes. A dramatic evolution in the magnetic field structure is visible for the two years, where a dominant and largely unipolar field in 2004 has changed into two distinct and large scale bipolar structures in 2007.

scholarly journals The Large-Scale Magnetic Field Structure Near the Galactic Centre

1990 ◽  
Vol 140 ◽  
pp. 369-372
Author(s):  
Wolfgang Reich
Keyword(s):  
Magnetic Field ◽  
High Frequency ◽  
Large Scale ◽  
Field Structure ◽  
Galactic Centre ◽  
Poloidal Magnetic Field ◽  
Magnetic Field Structure ◽  
Large Scale Magnetic Field ◽  
Centre Region ◽  
The Magnetic Field

High frequency polarization observations reveal the existence of a poloidal magnetic field structure in the Galactic Centre region on scales of about 200 pc. At lower frequencies large non–thermal spurs are seen tracing the magnetic field up to kpc distances from the Galactic Centre.

scholarly journals Probing the magnetic field structure in the filamentary cloud IC5146

2015 ◽  
Vol 11 (S315) ◽  
Author(s):  
Jia-Wei Wang ◽  
Chakali Eswaraiah ◽  
Shih-Ping Lai ◽  
D. P. Clemens ◽  
Wen-Ping Chen ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Physical Properties ◽  
Large Scale ◽  
Field Structure ◽  
Formation Mechanisms ◽  
Magnetic Field Structure ◽  
Gas Kinematics ◽  
The Magnetic Field ◽  
Co Observations ◽  
Main Filament

AbstractIC5146 is one of the filamentary clouds observed in Herschel Gould Belt Survey. Here we present our polarization observations toward IC5146 taken with AIMPOL, TRIPOL and Mimir. Our results reveal that the large scale structure of magnetic field is well perpendicular to the main filament, but is likely parallel to the sub-filaments, which are structure extended out from the main filaments. We have also conducted CO observations to reveal the gas kinematics along the filaments or magnetic field; this result suggests the gas is possibly confined by magnetic field in most of the region until reaching supercritical. Based on our results, we suggests that at least four types of filaments can be found in IC5146, behaving different physical properties and consistent with different formation mechanisms. Our conclusions reveal that filaments are a combination of a variety types of objects.

scholarly journals Observations of Linear Polarization at 32 Ghz of the Galactic Center Arc

1989 ◽  
Vol 136 ◽  
pp. 265-267 ◽  
Author(s):  
Wolfgang Reich
Keyword(s):  
Magnetic Field ◽  
Linear Polarization ◽  
Galactic Center ◽  
Field Structure ◽  
Direction Parallel ◽  
Magnetic Field Structure ◽  
Percentage Polarization ◽  
The Magnetic Field

The Galactic Center Arc has been observed with the Effelsberg 100-m telescope at 32 GHz. The percentage polarization is of the order of 50%. The magnetic field structure is uniform in a direction parallel to the Arc.

scholarly journals The Magnetic Be Star Sigma Orionis E

1987 ◽  
Vol 92 ◽  
pp. 82-83 ◽  
Author(s):  
C. T. Bolton ◽  
A. W. Fullerton ◽  
D. Bohlender ◽  
J. D. Landstreet ◽  
D. R. Gies
Keyword(s):  
Magnetic Field ◽  
Field Structure ◽  
High Signal ◽  
Rotational Period ◽  
Magnetic Field Structure ◽  
The Past ◽  
Distribution Of Elements ◽  
Be Star ◽  
Hα Emission ◽  
The Magnetic Field

Over the past two years, we have obtained high resolution high signal/noise (S/N) spectra of the magnetic Be star σ Ori E at the Canada-France-Hawaii Telescope and McDonald Observatory. These spectra, which cover the spectral regions 399-417.5 and 440-458.5 nm and the Hα line and have typical S/N>200 and spectral resolution ≃0.02 nm, were obtained at a variety of rotational phases in order to study the magnetic field structure, the distribution of elements in the photosphere, and the effects of the magnetic field on the emission envelope. Our analysis of these spectra confirms, refines and extends the results obtained by Landstreet & Borra (1978), Groote & Hunger (1982 and references therein), and Nakajima (1985).The Hα emission is usually double-peaked, but it undergoes remarkable variations with the 1.19081 d rotational period of the star, which show that the emitting gas is localized into two regions which co-rotate with the star.

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