Integral Disproves Dark Matter Origin For Mystery Radiation
The radiation they're talking about is 511 keV Gamma-Rays. That's 511,000 electron volts of Gamma-Ray energy. This is supposed to be the energy emission band when positrons and electrons interact and annihilate.
Several researchers have invoked a variety of dark matter to explain Integral’s observations. Dark matter is thought to exist throughout the Universe – undetectable matter that differs from the normal material that makes up stars, planets and us. It is also believed to be present within and around the Milky Way, in the form of a halo.
Hmmmmm. At least it's not dark something or other. Please, go on.The recent study has found that the ‘positrons’ fuelling the radiation are not produced from dark matter but from an entirely different, and much less mysterious, source: massive stars explode and leave behind radioactive elements that decay into lighter particles, including positrons, the antimatter counterparts of electrons.
The reasoning behind the original hypothesis was that positrons, being electrically charged, would be affected by magnetic fields and thus would not be able to travel far. As the radiation was observed in places that did not match the known distribution of stars, dark matter was invoked as an alternative for the origin of the positrons.
That's more like it.But the recent finding by a team of astronomers led by Richard Lingenfelter at the University of California at San Diego, proves otherwise. The astronomers show that the positrons formed by radioactive decay of elements left behind after explosions of massive stars are, in fact, able to travel great distances, with many leaving the thin Galactic disc.
Baby steps. Gotta start somewhere, eh?Taking this into account, dark matter is no longer required to explain what Integral saw. A better understanding of how positrons behave has explained the mysterious radiation in our Galaxy.
Maybe they should have looked into this research.
A plasma instability theory is presented for the prompt radiation from gamma-ray bursts. In the theory, a highly relativistic shell interacts with the external medium through the filamentation and the two-stream instabilities to convert bulk kinetic energy into electron thermal energy and magnetic field energy. The processes are not efficient enough to satisfy the Rankine-Hugoniot conditions, so a shock cannot form through this mechanism. Instead, the external medium passes through the shell, with the electrons radiating during this passage. Gamma rays are produced by synchrotron self-Compton emission. Prompt optical emission is also produced through this mechanism, while prompt radio emission is produced through synchrotron emission. The model timescales are consistent with the shortest burst timescales. To emit gamma rays, the shell's bulk Lorentz factor must be ≳103. For the radiative processes to be efficient, the external medium density must satisfy a lower limit that is a function of the bulk Lorentz factor. Because the limits operate as selection effects, bursts that violate them constitute new classes. In particular, a class of optical and ultraviolet bursts with no gamma-ray emission should exist. Efficient gamma-ray emission requires an external medium of relatively high density. Several tests of the theory are discussed, as are the next theoretical investigations that should be conducted.
When considering the "active" core of a galaxy, I think it's very likely that a similar process (@511keV) might be in a "stream" mode, instead of "burst" mode, around the plasmoid in the pinch zone?This theory opens a new line of research into the role of plasma physics in gamma-ray burst emission. Other researchers have examined the role of plasma physics in gamma-ray burst emission under different circumstances. The beam and magnetic barrier theory (Smolsky & Usov 1996, 2000), which has been developed in detail, is an earlier line of research into the interactions of a relativistic plasma beam with a strong magnetic field. That theory differs from the current work in its assumption that a strong magnetic field exists within a relativistic wind prior to any interaction with the external medium. Other lines of research have discussed plasma turbulence in the context of the shock acceleration of electrons (e.g., Katz 1994), although the plasma physics has not yet been developed in detail.
