Fast Radio Burst Update

In 2019 I wrote that astronomers were collectively scratching their heads over a phenomenon called Fast Radio Bursts.  To recap:  Fast Radio Bursts are extremely energetic and short lived (milliseconds) signals coming from extreme distances (millions to billions of light years away).  The signals are weak after traveling such a distance, but the signal generator must be enormously powerful for them to make it at all!

Initially there were several hypotheses:  Distant extraterrestrial intelligence signals, black hole mergers, weird neutron stars, even weirder – Blitzars (spinning pulsar neutron star becoming a black hole), dark matter induced collapse of a neutron star into a black hole (reminds me of Arthur C. Clarke’s 2010: Odyssey Two, where millions of monoliths enter Jupiter, giving it enough mass to become a star).

The possibilities have now been reduced to one – weird neutron stars called Magnetars.

First, for the uninitiated, back to neutron stars.  Neutron stars are the end phase of a star 10-25 times more massive than our Sun.  Our Sun and stars up to about 8-10 times the Sun’s mass will end up as white dwarfs.  The limiting factor is called degeneracy.  For our Sun and stars 8-10 times more massive their core will eventually contract into a white-hot ball of electrons, a white dwarf, whose degeneracy pressure can withstand gravity.  For stars more massive, up to 25 times the Sun’s mass, at the end of their lives their cores are too massive (greater than 1.4 times the Sun) and electron degeneracy pressure cannot withstand gravity.  These star’s cores collapse further until neutron degeneracy pressure and nuclear forces stop it.  So, stars with about 10-25 solar masses will end up as neutron stars, having 1.5-2 solar masses.

Neutron stars are the most compact, dense objects (besides black holes) known.  A typical neutron star’s diameter is about the size of Canyon Lake.  Some spin, with an intense beam of plasma shooting out and are called Pulsars.  The ones thought to cause Fast Radio Bursts are Magnetars.

Magnetars are neutron stars with wild magnetic fields and rotate more slowly than other neutron stars.  Their magnetic fields are extreme even by neutron star standards and tend to be unstable.  Magnetars are thought to be the strongest magnetic sources in the universe.  Their magnetic fields are so strong they can strip the electron clouds from atoms at 1000 kilometers, so don’t get too close!

Magnetars appear to produce a Fast Radio Burst during “starquake” events, caused by scrambled magnetic fields disrupting the star’s surface.  An intense burst of radiation lasting a few milliseconds is released and will fry most anything in its path for many light years.  Luckily for us we aren’t in the fry zone of any magnetars.

What’s in the Sky?

Zodiacal light!  Now into April – find a dark location with a view of the western horizon.  Well after sunset look for a cone-shaped soft glow pointing upward.  This is dust in the ecliptic plane.