1 / 12

Milagro-EGRET Correlation

This study investigates the correlation between Milagro sources and EGRET catalogs, focusing on the overlap probabilities of detected gamma-ray sources in a specific region of the Galaxy. We analyze several Milagro candidates, such as MGRO J2031+41 and MGRO J2019+37, and assess their proximity to EGRET sources. By employing Monte Carlo simulations and combinatorial techniques, we evaluate the statistical significance of overlap. The findings suggest the need for careful consideration of diffuse models in source identification and the significance of claims made regarding new discoveries in high-energy astrophysics.

kadeem
Télécharger la présentation

Milagro-EGRET Correlation

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. MGRO J2031+41 (GeV J2035+4214) MGRO J2005+33 (high matter density?) MGRO J2226+60 (Boomerang PWN) MGRO J2019+37 (GeV J2020+3658) MGRO J2044+36 (no counterpart) MGRO J1908+06 (GeV J1907+0557) MGRO J2031+36 (extension of J2019?) MGRO J0634+17 (Geminga) Crab nebula Milagro-EGRET Correlation

  2. Milagro/EGRET Overlap Probability • 14 EGRET sources in the GeV catalog (in this region of the Galaxy) • N(=6,7,8?) Milagro sources • 5 EGRET sources are “close” to Milagro candidates • “close” = falls within a 3x3 bin drawn around each Milagro candidate • What is the probability of this? • Monte Carlo • Analytic (not quite correct)

  3. Monte Carlo 20 190

  4. 8 Milagro Sources 8 x 10-6 chance that 5 of 8 overlap w/EGRET

  5. 6 Milagro Sources 2 x 10-6 chance that 5 of 6 overlap w/EGRET

  6. Analytic Method • Place 8 (6?) Milagro sources with 3x3 degree bins around each within a 190x20 degree region. • Throw 1 EGRET source • Probability (P1) to land in a Milagro region • Nsources x Bin Area/ Regional Area • 8 x 9 / (190x20) = 0.019 • 6 x 9 / (190x20) = 0.014

  7. Combinatorics • 14 Choose j (= # overlaps) possible combinations (not quite correct, there are more). • Then sum to get probability of N overlaps or more

  8. 3 4 5 6 7 8 N of 8 Milagro Sources Overlap 5 x 10-6 chance that 5 of 8 overlap w/EGRET

  9. N of 6 Milagro Sources Overlap 3 4 5 6 1 x 10-6 chance that 5 of 6 overlap w/EGRET

  10. MGRO J2019+37 MGRO J2032+41 MGRO J2005+33 MGRO J2031+36 MGRO J2044+36 Diffuse vs. Point Source

  11. Post Trial Significance 0. 4.2% 0. 30% 0. 9.e-3 4.2e-7 .003 30% Assume 150,000 trials

  12. Conclusion • We need to know what we are claiming to see • We need to know what we mean by “close to” • Given my assumptions overlap probability (5 of 8 Milagro candidates) is 8 x 10-6 (4.3 ) • We should incorporate diffuse model in source search • We should be careful about claiming discovery with marginal significance and a posteriori hypotheses

More Related