Cosmology Views

Fast Radio Bursts

the post:

Most FRBs originate hundreds of millions of light-years away. This one came from inside the Milky Way.

the link to story:

Mysterious 'fast radio burst' detected closer to Earth than ever before

my comment:

Thank you for posting this. The story enables an interesting conjecture.

A Fast Radio Burst must be synchrotron radiation. Radio is at the low frequency end with gamma ray at the high end. This story covers both ends.

There are no atomic emission lines in that frequency range of radio. Thermal radiation ranges from UV down to infrared but never radio.

Wherever the FRB originates, there must be somewhat "slow" electrons diverting their path of motion due to a magnetic field.

Increasing the electron's velocity increases the peak frequency in synchrotron radiation.

For a radio burst, the source of these slow electrons is intermittent.

excerpt from the study:

This is the first burst with a radio counterpart observed from a soft γ-ray repeater and it strongly supports models based on magnetars that have been proposed for extragalactic fast radio bursts.

(excerpt end)

There is a "gamma ray repeater" here, associated with the FRB.

When the energy of gamma rays is absorbed by an atom, a wonder of particle physics occurs - particle-pair production. This pair is often an electron and positron. The energy absorbed measured in eV exactly matches the summed mass of the two particles measured in eV.

As a result, there are two slow moving charged particles. When their motion is altered by a magnetic field, they could be the source of synchrotron radiation down in the radio frequency range.

The radio burst would end as soon as the electron and positron mutually annihilate.

The story mentions a magnetar.

excerpt from Wikipedia:

A magnetar is a type of neutron star believed to have an extremely powerful magnetic field (∼10⁹ to 10¹¹ T, ∼10¹³ to 10¹⁵ G). The magnetic field decay powers the emission of high-energy electromagnetic radiation, particularly X-rays and gamma rays. The theory regarding these objects was proposed by Robert Duncan and Christopher Thompson in 1992, but the first recorded burst of gamma rays thought to have been from a magnetar had been detected on March 5, 1979. During the following decade, the magnetar hypothesis became widely accepted as a likely explanation for soft gamma repeaters (SGRs) and anomalous X-ray pulsars (AXPs). On 1 June 2020, astronomers reported narrowing down the source of Fast Radio Bursts (FRBs), which may now plausibly include "compact-object mergers and magnetars arising from normal core collapse supernovae".

(excerpt end)

The magnetar must be an energetic plasmoid with a very high velocity current in its torus to achieve gamma ray emission. This plasmoid must be somewhat unstable to cause of bursts in gamma rays, even to be called repeaters.

There is no defined requirement for which atoms can execute particle-pair production. Apparently whatever atoms are around the plasmoid execute this production.

I feel an opinion is appropriate here.

I suspect synchrotron radiation is never taught in a physics curriculum.

X-ray sources had no explanation, despite the discovery of synchrotrons in the 1950's.

When X-ray point sources were found in every galaxy, the ridiculous black hole and impossibly hot accretion disk was the only solution when ignoring a synchrotron.

Recently, gamma ray sources are found in the universe.

Again, when ignoring a synchroton, a "new" solution was needed so a magnetar is proposed. I have a strong suspicion this "extremely powerful magnetic field" is actually impossible, This is like the accretion disk whose temperature is actually impossible.
I really doubt this statement: "The magnetic field decay powers the emission of high-energy electromagnetic radiation, particularly X-rays and gamma rays."

Apparently cosmologists remain unaware that in recent years gamma rays are detected with extreme lightning bolts here on Earth.

I really doubt observed gamma rays from lightning bolts occur by "magnetic field decay" !

That lightning observation alone should force cosmologists to reconsider any distant celestial source of gamma rays. Instead we get a magnetar arising from a "core collapse supernovae" as if a tragic collapse is a viable solution for a repeater!

As long as cosmology ignores synchrotron radiation for its frequency range. mysteries like FRBs and SGRs will not be solved.