Paging Cancer: Pulsars face irregularity in their old age?

[Sociotard]

http://www.newscientist.com/article/dn21304-astrophile-stopped-clocks-deepen-pulsar-enigmas.html

 

Fernando Camilo, an astronomer at Columbia University in New York, was astounded when the radio pulsar he had discovered and had been observing for a year – PSR J1841-0500 – suddenly stopped beaming its regular bursts. "At first I had a hard time believing what I was seeing," he recalls. "For the past year, the pulsar had been so reliable, pulsing brightly once every 1.9 seconds. I thought there must be an error with the equipment."

 

Other pulsars have switched off for short periods, but Camilo's has taken by far the longest break ever seen, raising new questions about just how reliable these cosmic clocks are. The finding also adds to the mystery surrounding pulsars, as exactly what makes them tick in the first place isn't well understood either.

 

Camilo suggests that some of the unpredictability of pulsars may be due to old age. As pulsars get older, the rate at which they rotate gradually slows down as their energy is lost into space. This makes it harder for the charged particles to be accelerated to the high speeds needed to maintain the beam.

[Cancer]

Re: Paging Cancer: Pulsars face irregularity in their old age?

 

I am not much of a pulsar guy, but that's very interesting. I went to arXiv, downloaded the preprint, and read it (anyone can do that).

 

As they report, that's the second pulsar that has been observed "on", then "turned off", and then "turned on" again. For the time interval they indicate, it spent more time "off" than "on". Important at this point is the leading sentence of the second paragraph in the paper's discussion section:

We do not know what causes these (or any) pulsars to turn off' date=' or back on.[/quote']

 

The idea that old pulsars my flicker on and off towards the end of their lifetime as pulars is interesting. It'd be even more interesting if one understood why.

[NuSoardGraphite]

Re: Paging Cancer: Pulsars face irregularity in their old age?

 

So are all neutron stars older pulsars that ran low on juice?

[Christopher]

Re: Paging Cancer: Pulsars face irregularity in their old age?

 

So are all neutron stars older pulsars that ran low on juice?

According to Wikipedia it's a cross between Neutron Star and White Dwarf. A Neutron Star with way to much leftover charge to be silent. It apparently happens when a fast rotating star goes supernova and you get a fast rotating Neutron Star.

 

So Pulsars a neutron Stars with very good spin...

[Cancer]

Re: Paging Cancer: Pulsars face irregularity in their old age?

 

And a very strong magnetic field. The pulsar phenomenon is one of rapidly rotating neutron stars, with a strong magnetic field. It's known that pulsars more or less all slow down in rotation as they age. It's also clear from the statistics that pulsars don't last forever. How they go from pulsar to quiescent neutron star isn't known. That this on-again-off-again phenomenon is now observed might mean that transition is more discontinuous and erratic than people are used to thinking about.

[Christopher]

Re: Paging Cancer: Pulsars face irregularity in their old age?

 

How they go from pulsar to quiescent neutron star isn't known.

Actually, that part we do know (it's one of the few things). Since they need their magnetic field to accelerate the particles, they also slowly loose momentum until it's not enough to maintain the beam anymore.

But we talk about really small losses over really long time, so they are still very acurate.

[Lucius]

Re: Paging Cancer: Pulsars face irregularity in their old age?

 

So are all neutron stars older pulsars that ran low on juice?

 

If we give them prune juice, will that make them regular?

 

Lucius Alexander

 

The palindromedary thinks trying to restore a pulsar's regularity with prune juice is repulsive

[Christopher]

Re: Paging Cancer: Pulsars face irregularity in their old age?

 

Anything electromagnetic is limited to the speed of light' date=' but the half-life of U-238 is approximately the age of the Sun and the half-life of Th-232 is approximately the age of the universe. Gravity in neutron star cores could exceed the speed of light if quantum mechanical tunneling of nuclei is faster than light at a large enough scale.[/quote']

How much room is there between "Gravity so strong, light can't escape" and "Gravity so strong, object become a Black hole"?

[McCoy]

Re: Paging Cancer: Pulsars face irregularity in their old age?

 

I am not much of a pulsar guy, but that's very interesting. I went to arXiv, downloaded the preprint, and read it (anyone can do that).

 

As they report, that's the second pulsar that has been observed "on", then "turned off", and then "turned on" again. For the time interval they indicate, it spent more time "off" than "on". Important at this point is the leading sentence of the second paragraph in the paper's discussion section:

 

 

The idea that old pulsars my flicker on and off towards the end of their lifetime as pulars is interesting. It'd be even more interesting if one understood why.

Wobble in the spin axis? Over time that would show a predictable pattern.

 

Magnetic field moving in relation to the spin axis? Like Earth's magnetic pole drifting and reversing, only faster?

 

Related to the last one, magnetic field "blinking" on and off?

 

Or if they just turned off collision with a superjupiter mass changing the spin axis ever so slightly, but that wouldn't allow for them turning on again.

 

How much room is there between "Gravity so strong' date=' light can't escape" and "Gravity so strong, object become a Black hole"?[/quote']

I'm going to say none, and those are different ways of saying the same thing.

[Cancer]

Re: Paging Cancer: Pulsars face irregularity in their old age?

 

Actually, that part we do know (it's one of the few things). Since they need their magnetic field to accelerate the particles, they also slowly loose momentum until it's not enough to maintain the beam anymore.

But we talk about really small losses over really long time, so they are still very acurate.

 

You're right in principle, but observationally, we haven't, because non-pulsar neutron stars are harder to see than pulsars are. By that I mean the theory isn't good enough to tell you when the pulsar ought to shut down and what it looks like as it's doing so. Unless this switch-between-on-and-off with "on" becoming a smaller portion of the duty cycle is it.

[Cancer]

Re: Paging Cancer: Pulsars face irregularity in their old age?

 

Wobble in the spin axis? Over time that would show a predictable pattern.

 

Precessing pulsar binaries are known ... and a Nobel Prize awarded for it, as that's the case establishing gravitational radiation. GR causes a period decrease, though, and not so much a change of the pulsar axis. I'm out of my depth here, though.

 

Magnetic field moving in relation to the spin axis? Like Earth's magnetic pole drifting and reversing, only faster?

 

That leads off toward magnetohydrodynamics in a highly degenerate, relativistic regime with rapid rotation and involving the equation of state for nuclear matter. You win the prize for invoking a boatload of hideous, intractable problems I know almost nothing about.

 

Or if they just turned off collision with a superjupiter mass changing the spin axis ever so slightly, but that wouldn't allow for them turning on again.

 

Quite right. Though I doubt something as small as a planet could cause that big a change in the spin axis at all. Change the pulsar period, yes, but not the orientation. It'd also be fun to watch, having a Jupiter-size object collide with something about 10 km in diameter ... and the Jupiter-size planet loses.

[Christopher]

Re: Paging Cancer: Pulsars face irregularity in their old age?

 

Quite right. Though I doubt something as small as a planet could cause that big a change in the spin axis at all. Change the pulsar period' date=' yes, but not the orientation. It'd also be fun to watch, having a Jupiter-size object collide with something about 10 km in diameter ... and the Jupiter-size planet loses.[/quote']

Yes, Neutron stars are funny:

[Badger]

Re: Paging Cancer: Pulsars face irregularity in their old age?

 

Was I the only one that thought "What isnt irregular in old age?"