scholarly journals Structure of the Local Galactic Magnetic Field

1990 ◽  
Vol 140 ◽  
pp. 44-46
Author(s):  
R. J. Rand ◽  
S. R. Kulkarni
Keyword(s):  
Magnetic Field ◽  
Local Field ◽  
Galactic Magnetic Field ◽  
Concentric Ring ◽  
The North ◽  
Ring Model ◽  
North Polar ◽  
Spiral Model

We have modeled the local Galactic magnetic field using pulsar rotation measures (RMs), of which there are now about 200 available. The North Polar Spur has a significant effect on pulsar RMs. Using RMs of 116 pulsars nearer than 3 kpc, we find that the local field has a strength B0 = 1.6 ± 0.2 μG toward longitude lB =96° ± 4°, with a reversal of the field at a distance Dr = 600 ± 80 pc toward the inner Galaxy. Relaxing the 3 kpc distance restriction, we find that a concentric ring model with reversals is superior to a bisymmetric spiral model as a fit to the data.

scholarly journals Revisiting the Distance to Radio Loops I and IV Using Gaia and Radio/Optical Polarization Data

2021 ◽  
Vol 922 (2) ◽  
pp. 210
Author(s):  
G. V. Panopoulou ◽  
C. Dickinson ◽  
A. C. S. Readhead ◽  
T. J. Pearson ◽  
M. W. Peel
Keyword(s):  
Magnetic Field ◽  
Galactic Center ◽  
Classical Method ◽  
Dust Emission ◽  
Galactic Latitude ◽  
Synchrotron Emission ◽  
Optical Polarization ◽  
The North ◽  
Significant Alignment ◽  
North Polar

Abstract Galactic synchrotron emission exhibits large angular scale features known as radio spurs and loops. Determining the physical size of these structures is important for understanding the local interstellar structure and for modeling the Galactic magnetic field. However, the distance to these structures is either under debate or entirely unknown. We revisit a classical method of finding the location of radio spurs by comparing optical polarization angles with those of synchrotron emission as a function of distance. We consider three tracers of the magnetic field: stellar polarization, polarized synchrotron radio emission, and polarized thermal dust emission. We employ archival measurements of optical starlight polarization and Gaia distances and construct a new map of polarized synchrotron emission from WMAP and Planck data. We confirm that synchrotron, dust emission, and stellar polarization angles all show a statistically significant alignment at high Galactic latitude. We obtain distance limits to three regions toward Loop I of 112 ± 17 pc, 135 ± 20 pc, and <105 pc. Our results strongly suggest that the polarized synchrotron emission toward the North Polar Spur at b > 30° is local. This is consistent with the conclusions of earlier work based on stellar polarization and extinction, but in stark contrast with the Galactic center origin recently revisited on the basis of X-ray data. We also obtain a distance measurement toward part of Loop IV (180 ± 15 pc) and find evidence that its synchrotron emission arises from chance overlap of structures located at different distances. Future optical polarization surveys will allow the expansion of this analysis to other radio spurs.

scholarly journals FARADAY TOMOGRAPHY OF THE NORTH POLAR SPUR: CONSTRAINTS ON THE DISTANCE TO THE SPUR AND ON THE MAGNETIC FIELD OF THE GALAXY

2015 ◽  
Vol 811 (1) ◽  
pp. 40 ◽  
Author(s):  
X. H. Sun ◽  
T. L. Landecker ◽  
B. M. Gaensler ◽  
E. Carretti ◽  
W. Reich ◽  
...  
Keyword(s):  
Magnetic Field ◽  
The North ◽  
The Galaxy ◽  
North Polar ◽  
The Magnetic Field

scholarly journals A Unified Model for the Fan Region and the North Polar Spur: A Bundle of Filaments in the Local Galaxy

2021 ◽  
Vol 923 (1) ◽  
pp. 58
Author(s):  
J. L. West ◽  
T. L. Landecker ◽  
B. M. Gaensler ◽  
T. Jaffe ◽  
A. S. Hill
Keyword(s):  
Observational Studies ◽  
Large Scale ◽  
Unified Model ◽  
Lower Latitude ◽  
Galactic Magnetic Field ◽  
Apparent Contradiction ◽  
Local Bubble ◽  
The North ◽  
Local Emission ◽  
North Polar

Abstract We present a simple, unified model that can explain two of the brightest, large-scale, diffuse, polarized radio features in the sky, the North Polar Spur (NPS) and the Fan Region, along with several other prominent loops. We suggest that they are long, magnetized, and parallel filamentary structures that surround the Local arm and/or Local Bubble, in which the Sun is embedded. We show that this model is consistent with the large number of observational studies on these regions and is able to resolve an apparent contradiction in the literature that suggests that the high-latitude portion of the NPS is nearby, while lower-latitude portions are more distant. Understanding the contributions of this local emission is critical to developing a complete model of the Galactic magnetic field. These very nearby structures also provide context to help understand similar nonthermal, filamentary structures that are increasingly being observed with modern radio telescopes.

scholarly journals A High-Resolution Polarization Survey of the North Polar Spur

1974 ◽  
Vol 60 ◽  
pp. 151-154
Author(s):  
G. Westerhout ◽  
D. Bechis
Keyword(s):  
Magnetic Field ◽  
Fine Structure ◽  
High Resolution ◽  
Polarization Distribution ◽  
The North ◽  
Angular Scale ◽  
North Polar ◽  
The Magnetic Field

Observations have been made at 21 cm with a resolution of 11′ to look for fine structure in the polarization distribution. In the North Polar Spur, the angular scale of the polarization parameters varies with latitude. This is attributed to an increase in the irregularity of the magnetic field in the Spur with latitude.

scholarly journals The Need for High Resolution for Polarization Studies of Galactic Background Radiation

1990 ◽  
Vol 140 ◽  
pp. 62-62
Author(s):  
G.L. Verschuur ◽  
T. A. Th. Spoelstra
Keyword(s):  
Magnetic Field ◽  
High Resolution ◽  
Background Radiation ◽  
Limited Data ◽  
Polarization Data ◽  
The North ◽  
Polarization Studies ◽  
North Polar ◽  
Galactic Background ◽  
Scale Length

Polarization data at 390 and 826 MHz were obtained with the 300-foot telescope in February 1987. A survey of selected regions of sky planned for December 1988 had to be postponed. However, our limited data at 390 MHz show that the 30′ beam detected polarization temperatures between four to six times larger than found in surveys with a 1.3 arcmin resolution. This was true in both the highly polarized region around 1=140 degrees and in the North Polar Spur where polarization structures appear to be unresolved (<0.9 pc at the distance of the spur). High resolution observations will be critical to our understanding of the interstellar magnetic field and the scale-length of depolarizing structures.

Observing the galactic magnetic field

1967 ◽  
Vol 31 ◽  
pp. 375-380
Author(s):  
H. C. van de Hulst
Keyword(s):  
Magnetic Field ◽  
Fair Agreement ◽  
Solar Neighbourhood ◽  
Galactic Magnetic Field ◽  
The Magnetic Field

Various methods of observing the galactic magnetic field are reviewed, and their results summarized. There is fair agreement about the direction of the magnetic field in the solar neighbourhood:l= 50° to 80°; the strength of the field in the disk is of the order of 10-5gauss.

Structure in the radiation of the galactic disk

1967 ◽  
Vol 31 ◽  
pp. 355-356
Author(s):  
R. D. Davies
Keyword(s):  
Magnetic Field ◽  
Galactic Disk ◽  
Galactic Magnetic Field ◽  
Measured Polarization

Observations at various frequencies between 136 and 1400 MHz indicate a considerable amount of structure in the galactic disk. This result appears consistent both with measured polarization percentages and with considerations of the strength of the galactic magnetic field.

The galactic magnetic field

1977 ◽  
Vol 121 (4) ◽  
pp. 679 ◽  
Author(s):  
T.A.T. Spoelstra
Keyword(s):  
Magnetic Field ◽  
Galactic Magnetic Field
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