• Paul Baines
  • Alanna Connors
  • Vinay Kashyap
  • Xiao-Li Meng
  • Taeyoung Park
  • Pavlos Protopapas
  • Jeff Scargle
  • Aneta Siegiminowska
  • Jack Steiner
  • David van Dyk
  • C. Alex Young
  • Andreas Zezas

*will be updated. Let me (hlee at cfa dot know if you wish to be included or excluded or if you wish to add your profile next to you name.

  1. nestor:

    has anyone read this paper?. it has been accepted by ApJ Letters.

    can multiple 2-sigma detections a detection make without stacking?. i would appreciate any comments. a baffled scientist.


    12-04-2009, 4:03 am
  2. vlk:

    It seems that what they are doing is to compute a significance for every source in their catalog and compare the distribution of significances to what would be expected from a Gaussian distribution. They find 7 sources at significances >2sigma. Seeing 7 out of 27 (25%) at >2sigma is not very probable, so, in conjunction with the coincidence of these sources with known pulsars, they claim the detection. 2 sigma implies that 5% of the time a random deviation can produce numbers greater than that threshold. Because it is a two-sided distribution, on the upper side that is a 2.5% probability, which, for 27 sources, implies 0.6 sources are expected to exceed that number.

    I think the methodology is fine. It is a combination of marginal detections superposed on known catalog sources that makes the cut.

    12-04-2009, 12:30 pm
  3. nestor:

    Thanks for the comment Vinay. Yes I see that. I am just intrigued at the
    way people bin and report their findings. A 0.2 sigma shift for a
    couple of sources would create a nearly normal
    distribution. This experiment has only detected the Crab nebula at 6 sigma
    and now it’s making a significant leap in its detection limits albeit at a
    purported 2 sigma. The equivalent in X-rays would be an experiment that only
    detects is the Crab at 5 sigma, sees nothing in between and then
    publishes a paper claiming two sigma detections for the faintest sources
    in the Chandra deep field under the same argument. Would you believe
    such a claim?. It looks statistically sound but there is counterintuitive here
    that just doesn’t compute. Thanks again.

    12-16-2009, 6:13 am
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