The Local Direction and Curvature of the Galactic Magnetic Field Derived from Starlight Polarization

Heiles, C.

doi:10.1086/177153

Cited by 129 publications

(111 citation statements)

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“…In the solar neighborhood, this occurs at Galactic longitudes = 90 • + p and = 270 • + p, where p is the magnetic pitch angle. Pavel et al (2012) found p = −6 • ± 2 • , similar to values found by other studies using a variety of techniques (Vallee 1988;Han & Qiao 1994;Heiles 1996;Beck 2007;Pshirkov et al 2011). For this magnetic pitch angle, the longitudes of vanishing polarization become = 84 • and 264 • , well outside the longitude range of GPIPS and where these Galactic bubbles are located.…”

Section: Starlight Polarimetry Toward Galactic Bubblessupporting

confidence: 85%

H Ii Region Driven Galactic Bubbles and Their Relationship to the Galactic Magnetic Field

Pavel

Clemens

2012

ApJ

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The relative alignments of mid-infrared traced Galactic bubbles are compared to the orientation of the mean Galactic magnetic field in the disk. The orientations of bubbles in the northern Galactic plane were measured and are consistent with random orientations-no preferential alignment with respect to the Galactic disk was found. A subsample of H ii region driven Galactic bubbles was identified, and as a single population they show random orientations. When this subsample was further divided into subthermal and suprathermal H ii regions, based on hydrogen radio recombination linewidths, the subthermal H ii regions showed a marginal deviation from random orientations, but the suprathermal H ii regions showed significant alignment with the Galactic plane. The mean orientation of the Galactic disk magnetic field was characterized using new near-infrared starlight polarimetry and the suprathermal H ii regions were found to preferentially align with the disk magnetic field. If suprathermal linewidths are associated with younger H ii regions, then the evolution of young H ii regions is significantly affected by the Galactic magnetic field. As H ii regions age, they cease to be strongly linked to the Galactic magnetic field, as surrounding density variations come to dominate their morphological evolution. From the new observations, the ratios of magnetic-to-ram pressures in the expanding ionization fronts were estimated for younger H ii regions.

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Section: Starlight Polarimetry Toward Galactic Bubblessupporting

confidence: 85%

H Ii Region Driven Galactic Bubbles and Their Relationship to the Galactic Magnetic Field

Pavel

Clemens

2012

ApJ

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“…Moreover, the derived constraints (between 7 • −10 • ) are fully compatible with the results obtained by other authors. In the literature, values also range from 7.2 • to 11 • (see Qiao 1994 andHan 2001 for values obtained with Faraday rotation of pulsars; and Heiles (1996), for values obtained with polarized starlight). For comparison purposes, Fig.…”

Section: The Magnetic Field In the Diskmentioning

confidence: 99%

Constraining the regular Galactic magnetic field with the 5-year WMAP polarization measurements at 22 GHz

Ruiz-Granados

Rubiño-Martín

Battaner

2010

A&A

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Context. The knowledge of the regular (large scale) component of the Galactic magnetic field gives important information about the structure and dynamics of the Milky Way, and also constitutes a basic tool to determine cosmic ray trajectories. It can also provide clear windows where primordial magnetic fields could be detected. Aims. We aim to obtain the regular (large scale) pattern of the magnetic field distribution of the Milky Way that better fits the polarized synchrotron emission as seen by the WMAP satellite in the 5 years data at 22 GHz. Methods. We have done a systematic study of a number of Galactic magnetic field models: axisymmetric (with and without radial dependence on the field strength), bisymmetric (with and without radial dependence), logarithmic spiral arms, concentric circular rings with reversals and bi-toroidal. We have explored the parameter space defining each of these models using a grid-based approach. In total, more than one million models were computed. The model selection was done using a Bayesian approach. For each model, the posterior distributions were obtained and marginalized over the unwanted parameters to obtain the marginal (one-parameter) probability distribution functions. Results. In general, axisymmetric models provide a better description of the halo component, although with regard to their goodnessof-fit, the other models cannot be rejected. In the case of the disk component, the analysis is not very sensitive for obtaining the disk large-scale structure, because of the effective available area (less than 8% of the whole map and less than 40% of the disk). Nevertheless, within a given family of models, the best-fit parameters are compatible with those found in the literature. Conclusions. The family of models that better describes the polarized synchrotron halo emission is the axisymmetric one, with magnetic spiral arms with a pitch angle of ≈24 • , and a strong vertical field of 1 μG at z ≈ 1 kpc. When a radial variation is fitted, models require fast variations.

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“…Starlight polarization data near the Galactic plane show that the orientation of magnetic fields in clouds, traced by the accumulated polarization due to absorption of dust grains preferentially oriented by the fields, are always parallel to the Galactic plane, except for high Galactic latitude data for very local features (Mathewson & Ford 1970a, Heiles 1996, Nishiyama et al 2010. Deep observations will probably reach the same conclusion with much more and new data.…”

Section: Magnetic Fields In the Galactic Diskmentioning

confidence: 86%

“…The measurements of starlight polarization of a few thousand stars (Mathewson & Ford 1970a;Heiles 2000) within a few kpc from the Sun show not only the field orientations mostly parallel to the Galactic plane in the disk but also the fields in the local halo of a few kpc (Heiles 1996). The most prominent feature is the polarization vectors following the north Galactic spur, which in fact is a very localized feature.…”

Section: Magnetic Fields In the Galactic Halomentioning

confidence: 99%

Magnetic fields in our Milky Way Galaxy and nearby galaxies

Han

2012

Proc. IAU

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Abstract. Magnetic fields in our Galaxy and nearby galaxies have been revealed by starlight polarization, polarized emission from dust grains and clouds at millimeter and submillimeter wavelength, the Zeeman effect of spectral lines or maser lines from clouds or clumps, diffuse radio synchrotron emission from relativistic electrons in interstellar magnetic fields, and the Faraday rotation of background radio sources as well as pulsars for our Milky Way. It is easy to get a global structure for magnetic fields in nearby galaxies, while we have observed many details of magnetic fields in our Milky Way, especially by using pulsar rotation measure data. In general, magnetic fields in spiral galaxies probably have a large-scale structure. The fields follow the spiral arms with or without the field direction reversals. In the halo of spiral galaxies magnetic fields exist and probably also have a large-scale structure as toroidal and poloidal fields, but seem to be slightly weaker than those in the disk. In the central region of some galaxies, poloidal fields have been detected as vertical components. Magnetic field directions in galaxies seem to have been preserved during cloud formation and star formation, from large-scale diffuse interstellar medium to molecular clouds and then to the cloud cores in star formation regions or clumps for the maser spots. Magnetic fields in galaxies are passive to dynamics.

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The Local Direction and Curvature of the Galactic Magnetic Field Derived from Starlight Polarization

Cited by 129 publications

References 0 publications

H Ii Region Driven Galactic Bubbles and Their Relationship to the Galactic Magnetic Field

H Ii Region Driven Galactic Bubbles and Their Relationship to the Galactic Magnetic Field

Constraining the regular Galactic magnetic field with the 5-year WMAP polarization measurements at 22 GHz

Magnetic fields in our Milky Way Galaxy and nearby galaxies

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