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Michael Sabino
Michael Sabino
Joined: 6 Jun 05
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20 Jun 2005 15:36:39 UTC
Topic 189380
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    Hi,

    I was wondering how the einstein@home code works. I have two questions, first, are the LIGO and GEO detectors directional? there is a graphic depicting some place at the celestial sphere where they are pointed so I'm guessing that they are directional, but I also have heard that the LIGO antennas aren't directional. Secondly, I'm curious, you say that you use the F-statistic to compute the probability of the signal containing pulsar data, are simulations of the gravitational radiation emitted during pulsar inspiral used to figure anything out here?
    Thanks

    Michael S.

    barkster
    barkster
    Joined: 3 Apr 05
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    Einstein@home

    21 Jun 2005 7:44:17 UTC
    Message 12805
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      )

      Quote:

      Hi,

      I was wondering how the einstein@home code works. I have two questions, first, are the LIGO and GEO detectors directional? there is a graphic depicting some place at the celestial sphere where they are pointed so I'm guessing that they are directional, but I also have heard that the LIGO antennas aren't directional. Secondly, I'm curious, you say that you use the F-statistic to compute the probability of the signal containing pulsar data, are simulations of the gravitational radiation emitted during pulsar inspiral used to figure anything out here?
      Thanks

      Michael S.

      I'm not an expert (I don't even play one on TV)... I'm sure someone more highly qualified will also respond...

      Second question, first....

      E@H is using a "matched filtering technique" to compare analyzed results to predicted results (simulated data?) as a means for signaling a possible GR source detection. But, E@H is primarily looking for single pulsars... not binary systems. Why?... a combination of:
      1) the freq range of the the LIGOs and
      2) the idea that there are more lone "high spin rate" pulsars in the near galaxy than there are binary systems about to merge. Kinda like looking for the hay in the haystack... instead of the needle.

      On the first question...

      It's been asked before and answered by the true experts. LIGO is not directional (as I also initially surmised), but the "matched filtering process" includes using Earth/Sun Doppler variables that pre-determine the direction from which the data you are analyzing has "come from" (hence the moving crosshair). Here are some long but excellent threads you should read through.

      What kind of calculus do E@H? What kind of data is analizated?

      NASA Sees Orbiting Stars Flooding Space With Gravitational Waves

      A laymen's guide Gravity, Gravity Waves, LIGO, and how it all works

      How can they "aim" a LIGO?

      "No, I'm not a scientist... but I did stay at a Holiday Inn Express."

      Tom Awtry
      Tom Awtry
      Joined: 18 Jul 05
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      RE: What will happen when

      25 Jul 2005 4:20:25 UTC
      Message 12806
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        Quote:


        What will happen when a gravitational wave was found by my computer?
        This question is under discussion between the LIGO and GEO labs, and the LIGO Scientific Collaboration. It has not yet been answered. Here are a few facts that are relevant. (1) Einstein@Home participants are carrying out one step (the most computationally-intensive one) in a pulsar search. However the results are fed back into a later stage of search which looks for consistency between different independent results. So no single user 'makes the discovery'. (2) Since (for the purpose of validation) the work is done by several machines independently, belonging to different users, any credit should be shared between the different users who got that result.

        We expect to update this answer in the future.

        [BA]

        I understand the aforementioned quote, taken from your FAQ’s, but would like have an opinion of approximately when in the “future” this matter of joint credit will be considered and a some what better understanding of what scientific communities will be involved in the decision making process?

        Keep up the outstanding work!

        Tom

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

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