[time-nuts] Pulsar Source?

Jim Palfreyman jim77742 at gmail.com
Wed Mar 28 23:50:26 UTC 2012


Folks, I'm currently writing my thesis on pulsars, but I need to spend time
on it rather than here. :-) But since a lot of this discussion is right at
the front of my brain, here's a summary.

Some pulsars "glitch" or speed up. The Vela pulsar (PSR J0835-4510) does
this (this is the pulsar I've been studying) and yes these type of pulsars
are bad clocks. A jump of its pulse rate of the order of 10^-6 s/s randomly
every few years is not good. It does nearly settle back to its original
rate after a few months.

The nature of these glitches (in Vela at least) is not well understood, but
three theories have been put forward:

   - An orbiting planet - but this has been discarded due to their
   irregularity.
   - Star quakes caused by a separation of the crust on the surface of the
   neutron star from its super-fluid interior. (Not very popular any more)
   - The effects of tiny micro vortices in the internal super-fluid. (If
   you can understand this paper - good luck to you!)

Now faster pulsars, in particular millisecond pulsars (~700 Hz from memory
is the fastest) are quite good clocks and they do rival atomic clocks. The
hunt is on to find as many of these as they can, well spread across the
sky, so they can look at the effects of gravitational waves on the beams of
these super accurate clocks. This is one proposed method to detect
gravitational waves.

The main problem I see from the original suggestion is that most pulsars
are quite faint and you need a very decent telescope to see individual
pulses. Vela is very bright, and the 26m telescope I used can only just see
the average pulse. I'm studying bright pulses and we can see those easily.

So to dedicate a massive radio telescope (or two) pointing at a millisecond
pulsar just so we can re-transmit it, is probably not sensible. However,
studies of these remarkable pulsars is ongoing.


Jim



On 29 March 2012 10:20, Hal Murray <hmurray at megapathdsl.net> wrote:

>
> > All that is of course correct. But ultimately the pulsars are a better
> > source, I see it as an application question, could it be utilized?
> Perhaps
> > building an algorithm and basing corrections on multiple pulsars x-ray
> > pulses like a GPS constellation for the next generation of conventional
> GPS.
>
> I think modern atomic clocks are better than Pulsars.
>
> Unfortunately, I don't have a good reference handy.  I think the theorists
> have several ideas for why the period of Pulsars change.
>
>
> --
> These are my opinions, not necessarily my employer's.  I hate spam.
>
>
>
>
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