http://xxx.uni-augsburg.de/abs/astro-ph/0112490
Astrophysics, abstract
astro-ph/0112490
From: Mike Harris <harris@tgrs2.gsfc.nasa.gov>
Date: Thu, 20 Dec 2001 17:41:17 GMT (122kb)
Limits from CGRO/EGRET Data on the Use of Antimatter as a Power Source by
Extraterrestrial Civilizations
Authors: Michael J. Harris (USRA/NASA-GSFC)
Comments: Submitted to "Astrobiology", 16 pp., 7 figs
I argue that the existence of cold antimatter in bulk is not
permitted by the Standard Model, so that if a gamma-ray signature
from antiproton annihilation were to be detected, it must
represent either new physics or the action of intelligence. Time
variability of the signal would strongly support the second
alternative. The entire sky was scanned at the relevant energies
(30 - 928 MeV) by the EGRET experiment on board the Compton Gamma
Ray Observatory during 1991 - 1995. A search of this database for
the antiproton annihilation signature yielded only upper limits on
the flux (an intriguing spectrum detected from QSO 2206+650 = 3EG
J2206+6602 is probably not related to SETI). The all-sky longterm
99% upper limit is 2.3 x 10^-8 photon/(cm2 s); it is a factor 10
worse in the Galactic plane due to the higher diffuse gamma-ray
background emission. I give brief, but quantitative, illustrations
of what this limit means for nearby intelligent activities.
Paper: Source (122kb), PostScript, or Other formats
************************************************************************
Amara Graps, PhD | Max-Planck-Institut fuer Kernphysik
Heidelberg Cosmic Dust Group | Saupfercheckweg 1
+49-6221-516-543 | 69117 Heidelberg, GERMANY
Amara.Graps@mpi-hd.mpg.de * http://www.mpi-hd.mpg.de/dustgroup/~graps
************************************************************************
"We came whirling out of Nothingness scattering stars like dust." --Rumi
This archive was generated by hypermail 2b30 : Sat May 11 2002 - 17:44:32 MDT