Slow and steady spirals
Article Abstract:
Anisotropic magnetic forces in magnetic spiral arms of galactic spirals lead to multiple wave modes, both fast and slow. The fast mode in a weak magnetic field corresponds to the standard spiral density wave, for which the magnetic field and density fluctuations are in phase. In a slow mode spiral wave, the magnetic and density fluctuations are 90 degrees out of phase, and the magnetic and density maxima are interleaved rather than coincident. The slow waves co-rotate with the galactic gas, confining the spiral pattern to a radial range corresponding to a narrow range of rotational velocities.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1996
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Detecting intergalactic magnetic fields using time delays in pulses of gamma-rays
Article Abstract:
It is possible to detect weak intergalactic magnetic fields (IGMFs) by probing their impact on the arrival times of gamma rays from extragalactic sources. The effect of IGMFs on electron cascades which causes the delay in arrival and which in turn is due to the scattering of gamma-ray photons, can be utilized for the measurement of fields as weak as 10(super -24) gauss. The delay caused by the IGMFs may have been noticed previously in the arrival times of high-energy photons following the main burst of a gamma-ray burster.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1995
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Time trials test the field
Article Abstract:
A new method for detecting magnetic fields in the 10 raised to -12 and 10 raised to -24 gauss region in Earth's galaxy has been proposed by nuclear physicist R. Plaga. The technique uses extragalactic transient gamma-ray events along with photons from high-energy gamma-rays to detect magnetic fields. A major role is played by the detection of field strength within the voids in studying and analyzing initial few microseconds of the evolution of the Universe.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1995
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