Why search for more pulsars?

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verty
verty
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1 Aug 2005 13:55:46 UTC
Topic 189645
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    I understand that Einstein@home is about searching the sky for pulsars. In the screen saver there are a bunch of known pulsars. Can't the scientists point the detectors to the known pulsars, to try to detect gravitational waves?

    I mean, why search for more pulsars? If the detectors are not sensitive enough, that could be calibrated by using the known pulsars. Surely the pulsars in our own galaxy are the nearest to us.

    verty
    verty
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    Why search for more pulsars?

    1 Aug 2005 17:01:03 UTC
    Message 14940
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      Quote:
      that could be calibrated ...

      I am no scientist, and certainly I don't think $300m+ would be invested in a detector if easier methods were available. I wasn't stating fact in this quote, I was just thinking to myself that a search of the whole sky seemed strange.

      I don't need an explanation. I'll leave the science to the scientists.

      There is one question I have. After the S4 and S5 data is analysed, and if no gravity waves are found, will that be the end of the project? Will there be conclusive proof either way either that gravity waves exist or that they don't?

      I don't want this just to be a search for unknown pulsars.

      Chipper Q
      Chipper Q
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      Hi, verty I'm not sure how

      1 Aug 2005 19:11:37 UTC
      Message 14941
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        Hi, verty

        I'm not sure how well this answers your questions - it's a few things mentioned by Ben Owen, in this thread: ”What's up with the data?”

        Quote:

        LIGO has been operational for several years now, in the sense of being able to measure strains. But it is a very complicated instrument (absolutely unprecedented in some respects) and therefore it is not a matter of just switching on. The first time you do that, it's not very sensitive. You track down one of the many subsystems which is giving the most trouble and beat down the noise from that subsystem. Then the instrument is a little more sensitive, and you look for the next thing, and so on. Sometimes you have to invent something completely new to get past a sticking point.

        The result of this is that LIGO has been shooting toward its target sensitivity for the last few years. It is now very close to that sensitivity. S3 is within a factor of a few. The S4 data, which is in the can and being prepped for analysis, is within a factor of two. S5, which will start later this year, will be at (or at some frequencies a little beyond) target sensitivity. Also, S5 will not be a few weeks' run between equipment upgrades; it will be a solid year, and that also improves the chances of detection.

        Another good thread to have a look at is 'How can they “aim” a LIGO?'

        It does say, on the Einstein@Home main page, that the search is for 'spinning neutron stars (also called pulsars)', but I don't think it necessarily implies a search for “more”...

        Hopefully that's correct,
        Chip

        verty
        verty
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        Thank you. I know all I need

        1 Aug 2005 20:05:34 UTC
        Message 14942 in response to message 14941
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          Thank you. I know all I need to now.

          Bruce Allen
          Bruce Allen
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          RE: I understand that

          1 Aug 2005 22:01:39 UTC
          Message 14943
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            Quote:
            I understand that Einstein@home is about searching the sky for pulsars. In the screen saver there are a bunch of known pulsars. Can't the scientists point the detectors to the known pulsars, to try to detect gravitational waves?

            We've done this, but not seen anything. No surprise -- the known pulsars are too far away. Journal-ref: Phys.Rev.Lett. 94 (2005) 181103 read it here

            Quote:
            I mean, why search for more pulsars? If the detectors are not sensitive enough, that could be calibrated by using the known pulsars. Surely the pulsars in our own galaxy are the nearest to us.

            Pulsars are detected via their electromagnetic emission: they are rapidly spinning neutron stars. Our hope is that there are many more such stars, closer to us, that are not visible electromagnetically, but instead via their gravitational radiation.

            Bruce

            Director, Einstein@Home

            verty
            verty
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            RE: Our hope is that there

            1 Aug 2005 22:21:32 UTC
            Message 14944 in response to message 14943
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              Quote:
              Our hope is that there are many more such stars, closer to us, that are not visible electromagnetically, but instead via their gravitational radiation.

              Hmm, it sounds like a long shot. I suppose you make do with what you can. If no such pulsars are detected, that won't be a refutation of gravitational waves per se, just a refutation of near pulsars, right?

              Chipper Q
              Chipper Q
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              RE: but I don't think it

              2 Aug 2005 0:51:32 UTC
              Message 14945
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                Quote:
                but I don't think it necessarily implies a search for “more”...


                Sorry about that, verty – I was quite wrong.

                Thanks for the correction, Bruce, and for helping to make a complicated science easier to understand (not to mention advancing it!).

                Tom Awtry
                Tom Awtry
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                RE: We've done this, but

                2 Aug 2005 1:13:26 UTC
                Message 14946 in response to message 14943
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                  Quote:

                  We've done this, but not seen anything. No surprise -- the known pulsars are too far away. Journal-ref: Phys.Rev.Lett. 94 (2005) 181103 read it here

                  Bruce – Thanks for the suggested reading, a group of us here have also had the same question as "Chipper O", and your provided link renders an excellent answer.

                  Keep-up the good work,
                  TA

                  Theory of Gravitational Waves & LIGO
                  Laser Interferometer Space Antenna - LISA
                  JPL-Caltech

                  Ben Owen
                  Ben Owen
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                  RE: RE: Our hope is that

                  6 Aug 2005 1:32:17 UTC
                  Message 14947 in response to message 14944
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                    Quote:
                    Quote:
                    Our hope is that there are many more such stars, closer to us, that are not visible electromagnetically, but instead via their gravitational radiation.

                    Hmm, it sounds like a long shot. I suppose you make do with what you can. If no such pulsars are detected, that won't be a refutation of gravitational waves per se, just a refutation of near pulsars, right?

                    Verty: Basically, yes. See this post.

                    Hope this helps,
                    Ben

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