Folded fields as the source of extreme radio-wave scattering in the galactic center

Goldreich, P.; Sridhar, S.

Please use this identifier to cite or link to this item: http://hdl.handle.net/2289/4865

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DC Field	Value	Language
dc.contributor.author	Goldreich, P.	-
dc.contributor.author	Sridhar, S.	-
dc.date.accessioned	2012-07-11T06:22:03Z	-
dc.date.available	2012-07-11T06:22:03Z	-
dc.date.issued	2006	-
dc.identifier.citation	The Astrophysical Journal, 2006, Vol.640, pL159	en
dc.identifier.issn	0004-637X	-
dc.identifier.issn	1538-4357 (Online)	-
dc.identifier.uri	http://hdl.handle.net/2289/4865	-
dc.description	Open Access	en
dc.description.abstract	A strong case has been made that radio waves from sources within about half a degree of the Galactic center undergo extreme diffractive scattering. However, problems arise when standard ("Kolmogorov") models of electron density fluctuations are employed to interpret the observations of scattering in conjunction with those of free-free radio emission. Specifically, the outer scale of a Kolmogorov spectrum of electron density fluctuations is constrained to be so small that it is difficult to identify an appropriate astronomical setting. Moreover, an unacceptably high turbulent heating rate results if the outer scale of the velocity field coincides with that of the density fluctuations. We propose an alternative model based on folded magnetic field structures that have been reported in numerical simulations of small-scale dynamos. Nearly isothermal density variations across thin current sheets suffice to account for the scattering. There is no problem of excess turbulent heating, because the outer scale for the velocity fluctuations is much larger than the widths of the current sheets. We speculate that interstellar magnetic fields could possess geometries that reflect their origins: fields maintained by the Galactic dynamo could have large correlation lengths, whereas those stirred by local energetic events might exhibit folded structures.	en
dc.language.iso	en	en
dc.publisher	IOP Publishing Ltd.	en
dc.relation.uri	http://dx.doi.org/10.1086/503668	en
dc.relation.uri	http://adsabs.harvard.edu/abs/2006ApJ...640L.159G	en
dc.relation.uri	http://arxiv.org/abs/astro-ph/0602532	en
dc.rights	2006 The American Astronomical Society	en
dc.title	Folded fields as the source of extreme radio-wave scattering in the galactic center	en
dc.type	Article	en
Appears in Collections:	Research Papers (A&A)

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