http://arxiv.org/abs/1601.01717
We have applied the concept of superradiance introduced by Dicke in 1954 to the ISM by extending the corresponding analysis to the magnetic dipole interaction characterizing the atomic hydrogen 21 cm line. Although it is unlikely that superradiance could take place in thermally relaxed regions, in situations where the conditions necessary for superradiance are met (i.e., close atomic spacing, high velocity coherence, population inversion, and long dephasing time-scales compared to those related to coherent behavior), our results suggest that relatively low levels of population inversion over short astronomical length-scales (e.g., as compared to those required for maser amplification) can lead to the cooperative behavior required for superradiance in the ISM. Given the results of our analysis, we expect the observational properties of superradiance to be characterized by the emission of high intensity, spatially compact, burst-like features potentially taking place over short periods ranging from minutes to days.
F. Rajabi and M. Houde
Mon, 11 Jan 16
2/57
Comments: 38 pages, 7 figures, submitted to the ApJ
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