On Saturday, June 29, 2019 at 3:45:02 PM UTC-5, John Clark wrote:
>
> On Sat, Jun 29, 2019 at 1:59 PM Lawrence Crowell <[email protected]
> <javascript:>> wrote:
>
> *> It sort of makes sense this might involve magnetars. If a neutron star
>> with a huge magnetic field, ~ 10^{10}T, collides with another neutron star
>> or black hole the sudden reconfiguration of the magnetic field might send a
>> huge electromagnetic pulse.*
>>
>
> Maybe, but to me that seems like a explanation of Gamma Bay Bursts, FRB's
> are something different, a single immensely powerful millisecond radio
> pulse with no accompanying gamma, X-ray or optical emissions. Of the 60
> known FRB's most never repeat but 2 of them have which would rule out any
> sort of catastrophic collision, at lest for those two, but we may be
> dealing with two different phenomenon with two different underlying
> mechanisms.
>
> One idea involves a very rapidly rotating neutron star of more than 2.2
> solar mass but less than 2.7, normally such a thing would collapse into a
> Black Hole but not if its spinning fast enough; however its its powerful
> magnetic field would gradually slow it down and when it reached a critical
> point it would collapse and form a Black Hole and maybe produce a radio
> pulse. But of course something like that couldn't repeat and at least 2
> FRB's do.
>
> Another idea for the cause involved the decay of Axion Miniclusters, but
> of course they couldn't repeat either:
>
> Fast Radio Bursts and Axion Miniclusters <https://arxiv.org/abs/1411.3900>
>
> Yet another weird idea involve superconducting cosmic strings, maybe that
> could repeat.
>
> Superconducting cosmic strings as sources of cosmological fast radio
> bursts <https://arxiv.org/abs/1705.10956>
>
> John K Clark
>
The first paper in the section on electrodynamics proposes how this would
happen. The first section involves a lot of phenomenology I am not familiar
with. Equations 6 throught 8 give the modified Maxwell equations. There is
in addition a wave equation for the axion. The axion obeys a Klein-Gordon
equation with an EM inhomogenous term such as
(□ + m^2) φ = -g*E*·*B*
Which has the solution for a stationary phase Ã(x,t) = Ã(x)e^{-iωt} has an
approximate solution
φ(x,t) ≈ φ_0exp(-i√{k^2 - m^2}x)e^{-iωt} + e^{-i√(g*E*·*B*/φ_0)t}
I think that is ok as a back of envelope calculation. One would really need
to work this out coupled with the Maxwell equations. For axions in a large
magnetic field they will be converted into EM radiation.
Axions are a fair prospect for dark matter. They are thought to have been
slowed in a sort of “quantum molasses” that caused these very light
particles, maybe as little as 10^{-11} times the mass of the electron, to
“freeze” into clumps. They are a candidate for dark matter which composes a
galactic halo. So far tests have eliminated a number of axion mass ranges.
Why these would suddenly burst seems odd.
For the second paper it is interesting that people are still thinking about
cosmic strings. They started to fade from attention 10 to 15 years ago.
There does not appear to be a lot of astrophysical evidence for them.
However, maybe some form of them does exist.
LC
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