http://arxiv.org/abs/1703.00394
Macroscopic magnetic dipoles are considered as a component of the cosmic dark matter. Permanent magnetism in relativistic field structures can involve some form of superconductivity, one example being current-carrying string loops (`springs’) in which the net relativistic tension vanishes. We derive the cross section for free classical dipoles to collide, finding it depends weakly on orientation when mutual precession is rapid. The collision rate of `spring’ loops with tension ${\cal T} \sim (10^{-8}$-$10^{-7})c^4/G$ in galactic halos approaches the measured rate of fast radio bursts (FRBs) if i) they comprise a significant fraction of the dark matter, and ii) have a mass $\sim 10^{20}$ g. A large superconducting dipole (LSD) with such a mass and size $\sim 1$ mm will form a $\sim 100$ km magnetosphere moving through interstellar plasma. Although the hydromagnetic drag is generally weak, it is strong enough to capture some LSDs into long-lived rings orbiting supermassive black holes (SMBHs) that form by the direct collapse of massive gas clouds. Repeated collisions near young SMBHs could dominate the global collision rate, thereby broading the dipole mass spectrum. Colliding LSDs produce tiny, hot electromagnetic explosions. The accompanying paper shows that these explosions couple effectively to low-frequency electromagnetic modes in the surrounding plasma, with the output peaking at 0.1-1 THz. We describe several constraints and predictions of LSDs as a component of the cosmic dark matter. The shock formed by an infalling LSD triggers self-sustained thermonuclear burning in a C/O white dwarf (WD) of mass $\gtrsim 1\,M_\odot$, and ONeMg WD of mass $\gtrsim 1.3\,M_\odot$. The spark is generally located well off the center of the WD. The rate of LSD-induced explosions matches the observed rate of Type Ia supernovae.
C. Thompson
Thu, 2 Mar 17
34/44
Comments: 22 pages, 19 figures, submitted to the Astrophysical Journal
You must be logged in to post a comment.