Monday, July 29, 2013

FRB


We do not know what causes the phenomena we call a Fast Radio Burst (FRB.)  They are similar to the pulses known to emanate from pulsars, and gamma ray bursts (GRB) except they do not repeat cyclically. Also, the known signals from pulsars are close, relatively speaking.  Most known pulsars are inside the Milky Way, or the Magellanic Clouds. FRBs seem to originate outside our galaxy, 5 - 10 billion light years away.

The first FRB was only detected in 2007. Duncan Lorimer and David Narkevic of West Virginia University in Morgantown detected a single burp lasting under 5 milliseconds.  In 2012 Evan Keane,and his colleagues began detecting similarly brief events. By comparison a GRB usually lasts around 50 milliseconds.  But their pulse dispersions both arrive first at higher frequencies and then progressively moved to lower frequencies before stopping.


But part of that sweeping effect is caused by the signal traveling through space. Space isn't all void, it's filled with random atoms, and particles. The radio waves at lower frequencies get slowed down more than the ones at higher frequencies. That means that the higher frequencies arrive first. But that distortion allows us to theorize about their immense power and the great distance they have traveled, but not the cause. More here.