Will E@H find many more pulsars?
18 Jun 2011 4:52:46 UTC
Topic 195831
(moderation:
I am not sure if this question might have been answered elsewhere. If so, please link me to the appropriate spot.
Otherwise, I was wondering what the expected probability was for the Pulsar search to find more results. I presume that most of the 'low hanging fruit' has been picked and that further detections will be more difficult. Based on where the scopes are pointing and the amount of data we have to work with, does anyone have a guess as to the likelihood of more detections (and re-detections)?
Is Parkes just pointing at a sparse area of sky? I am sure that a few must be waiting out there, but what is the expected yield of this kind of search (to the nearest order of magnitude)?
Thanks!
Will E@H find many more pulsars?
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I think it should, since Parkes scans the southern sky and I think that the galactic center is visible there. There should be more pulsars. They are visible in the graphics of the Binary Radio Pulsar search, where I see often white bars. But I never see, on my Linux box, graphics of GW. Why?
Tullio
When I've seen a BOINC
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When I've seen a BOINC workunit currently running being unable to display graphics, it was almost always because the application program for that workunit did not support graphics.
RE: When I've seen a BOINC
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Yes, but the "graphics" button is not grayed out as in such cases.
Tullio
Well, I overstated my
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Well, I overstated my question for effect. I assume that E@H will, at some point, find another pulsar. My question is really, "Roughly how many should we expect?"
0 < x < 10
??
RE: Well, I overstated my
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Don't know. But I see many more white bars now that we are crunching Parkes data then when we crunched Arecibo data, so I am hopeful.
Tullio
RE: Well, I overstated my
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Good question! But I don't know of anyone giving a formal estimate for our E@H detection rate. I gave an earlier ( rough, back of envelope ) prediction of 2 or 3 for the entire original Aricebo-only beam set, once the first one showed up, but that I think was a lucky phenomenological guess ..... :-) :-)
The low hanging fruit has certainly been picked, especially in the direction towards the galactic center where most ought be detectable. One particularly interesting feature of the two E@H has picked up is that they are 'rare birds' compared to the usual/traditional pulsar population.
Mind you, this is one key point of such surveys - you don't know what you will find and that's why you're looking. :-)
Cheers, Mike.
( edit ) Forgot to mention : the pulsar searching is not only to find new ones, as the parameters of known pulsars may also be refined by such analyses.
I have made this letter longer than usual because I lack the time to make it shorter ...
... and my other CPU is a Ryzen 5950X :-) Blaise Pascal
RE: the pulsar searching is
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This brings up an interesting question. Are there known pulsars that should show up in the Parkes data?
RE: RE: the pulsar
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Absolutely. See here for more detail about what they get up to at Parkes.
Cheers, Mike.
I have made this letter longer than usual because I lack the time to make it shorter ...
... and my other CPU is a Ryzen 5950X :-) Blaise Pascal
RE: Absolutely. See here
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Thanks for the link. Sorry to be slow figuring it all out! I just realized that, on the table of re-detections,
http://einstein.phys.uwm.edu/radiopulsar/html/rediscovery_page/rediscoveries.html
the ones marked "ATNF psrcat" are from the Parkes data? Or is that just where they were first catalogued? Considering how much CUDA computing power is being put into BRPS, why have there not been any more re-detections since December?
RE: RE: Absolutely. See
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ATNF is the body which runs the DownUnda radio astronomy research ( a LIGO-like division of our CSIRO which itself is sort of equivalent to the USA's NSF ), pulsars included. It is historically derived from ( WWII military radar ) scientists setting matters up in the early 1950's. ATNF manages a group of telescopes configured/used separately or as VLBI. It thus has accumulated catalogue(s) of it's findings over the decades ie. the low hanging fruit which is readily picked up - the 'bright & obvious' radio sources of pulsar type which the ATNF psrcat mentions. The Parkes MultiBeam produces data to include within our current E@H BRP work units. Initially only Aricebo data was used for BRP and is now mixed in with ATNF stuff.
Some background. The general concept of E@H BRP is Bruce Allen's idea after conversing with a colleague : Bruce needed something for us to do for a few years ( ie. now ) while advanced gravitational wave interferometers were being established/constructed/upgraded, and the colleague had some pulsar electromagnetic signal data streams that were wanting of analysis. The E@H gravity work is looking for continuous waves of which binary pulsars are a likely source thereof - so it's a 'natural' addition to the project. We've slurped up that Aricebo backlog since and are easily processing their realtime production rate, so the DownUnda work has been thrown in. BRP work was initially about 1/3rd of E@H's computing capacity now that has been bumped up to around 1/2.
There is post-processing ( post E@H that is ) so I'm unsure whether we haven't found any more or we have but the list is not updated. As I'll be in Hannover next week for the public event, I've just put your query on my 'to-do/inquire list'. :-) :-)
Note that I think the beams we're doing are in the anti-galactic-centre direction ( looking out of the galaxy as opposed to inwards ) so that's naturally rather more sparse as our Solar System is much closer to the edge than it is to galactic center and all stellar object densities are way higher closer in anyway. The graphics at the bottom of this page show the progress of our work vis-a-vis galactic direction. A galactic longitude of zero ( = 360 ) is directly to the centre, so 180 degrees is directly outwards from centre ...
Cheers, Mike.
( edit ) Although we have a natural urge to delight if we find something new, it doesn't mean that our time & effort is wasted if not. Far from it. Many surveys like this can put upper bounds on population statistics for objects of 'type X'. Meaning that one may conclude that if we didn't find something to within some degree of confidence then that places restraints on any modelling of that population type. The earlier E@H gravity science runs already have helped to refine models in precisely that way. So if some candidate theory predicts that we should have seen significantly more of 'X' than we did : then said theory is in trouble as it has contradicted observations. See The Hound of the Baskervilles ... :-) :-)
( edit ) There's a neat history of the origin of Aussie radio-astronomy in Robert Buderi's book The Invention That Changed The World : The Story Of Radar From War To Peace, Chapter 13 ( pp273 onwards ). A Welsh chap called Taffy Bowen did radar work during the war in the Pacific, liked Australia and stayed! With tons of war surplus equipment he really got in on the bottom floor of the deal. :-)
I have made this letter longer than usual because I lack the time to make it shorter ...
... and my other CPU is a Ryzen 5950X :-) Blaise Pascal