Pulsar re-detections in PALFA data

Martin Ryba
Martin Ryba
Joined: 9 Apr 09
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RE: just to get this thread

Message 93895 in response to message 93894

Quote:

just to get this thread updated:
we've just refreshed the re-discovery page. We're now at 31 detections of 19 different known pulsars, meaning we detect one pulsar about once a week.

The latest one we found is a very interesting one. J1939+2134 is the second fastest spinning known pulsar, rotating at incredible 691 Hz!

Cheers,
Ben

I'll agree that's one interesting pulsar...it's the original Millisecond Pulsar discovered by Don Backer and friends back in 1982. I know it better as B1937+21, but J1939+2134 is the same thing (1950 vs. 2000 coordinate reference). About half my Ph.D. thesis is based on this baby. Good to see it come through at many orders of significance (it probably saturated the detection analysis to some degree).

"Better is the enemy of the good." - Voltaire (should be memorized by every requirements lead)

Martin Ryba
Martin Ryba
Joined: 9 Apr 09
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RE: RE: Hi Mike, you

Message 93896 in response to message 93893

Quote:
Quote:

Hi Mike,

you won't see the profile in this plot. This plot shows the detection statistic as a function of the spin frequency and the DM of the pulsar.


So that's why I can't see it! :-)

Blush, of course ..... the graphic on the right side.

Quote:
The quoted peak however is fairly difficult to see for this one because this pulsar was emitting pulses only for about 20 seconds during the total 268 seconds of the observation. That's why the peak fairly weak, but is shown as this "denser part of the thicket" at DM channel ~350.

So I'd guess that would imply some reason at source to change the beam orientation on that timescale? Like it's in orbit around something, or precessing, so that the observation interval only partly overlapped it's interval of favourable alignment ( so the 20 seconds were contiguous? ). Could the mechanism turn on/off that quickly while we are still favourably aligned? I can see why these objects fascinate so .....

( edit ) I'm thinking the 'shape' is not reflecting some source characteristic that generates radiation in that pattern per se - but more that pulsar surfaces generically emit stuff roughly non-directionally but the magnetic ( and gravitational ) field constrains the path of escape to the distant universe. Sort of like blowing smoke rings, which you get by passage through a constriction and not ( necessarily ) because you burned material in donut pattern. A sort of aurora in reverse.

There's a lot we don't quite get about pulsar emission mechanisms. Slower pulsars do tend to have more sporadic emission (think of a balky spark plug/cylinder on a car). Some very strange pulsars only put out occasional pulses, so it's hard to figure out their spin periods. That's why you see some tests that look for individual dispersed pulses if you look at the PALFA papers on their web site.

The emission can also become localized in frequency due to how the signal propagates through the interstellar medium (think of twinkling stars in the sky). That's why some of the confirmation plots look for detectable pulsations across subsections of the band to help separate signal from noise.

"Better is the enemy of the good." - Voltaire (should be memorized by every requirements lead)

Grutte Pier [Wa Oars]~GP500
Grutte Pier [Wa...
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I looked at the discovery

I looked at the discovery page and found this short: MSP!

i could guess wat it means but could you tell me and maybe tell in on the pulsar-discovery-page

tullio
tullio
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RE: I looked at the

Message 93898 in response to message 93897

Quote:

I looked at the discovery page and found this short: MSP!

i could guess wat it means but could you tell me and maybe tell in on the pulsar-discovery-page


I think it stands for millisecond pulsar, which should allow to detect a GW if its frequency is measured comparing it to other MSP.
Tullio

tullio
tullio
Joined: 22 Jan 05
Posts: 2,046
Credit: 40,747,563
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After the disruptive fall

After the disruptive fall of Arecibo, I was addressed to a Green Bank radio telescope schedule in which I saw they are still running the Breakthrough Listen search for SETI but also a search for low frequency gravitational waves, I think using pulsars as timing clocks.

Tullio

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