Astronomy and Astrophysics – Astrophysics
Scientific paper
2005-04-07
Astronomy and Astrophysics
Astrophysics
16 pages, 6 figures. accepted in Astronomy and Astrophysics
Scientific paper
We reexamine in detail the various processes undergone by positrons in the ISM from their birth to their annihilation using the most recent results of positron interaction cross sections with H, H2 and He. The positrons' lives are divided into two phases: the 'in-flight' phase and the thermal phase. The first phase is treated with a Monte Carlo simulation that allows us to determine the fraction of positrons that form positronium and annihilate as well as the characteristics of the annihilation emission as a function of the medium conditions. The second phase is treated with a binary reaction rate approach, with cross sections adopted from experimental measurement or theoretical calculations. An extensive search and update of the knowledge of positron processes was thus undertaken. New reaction rates and line widths have been obtained. We investigate the treatment of the complicated interactions between positrons and interstellar dust grains. New reaction rates and widths of the line resulting from the annihilation inside and outside of the grain have been obtained. The final results of our calculations showed that dust is only important in the hot phase of the ISM, where it dominates all other processes. Combining the new calculations, we have constructed annihilation spectra for each phase of the ISM, considering various grain contents, as well as an overall combined spectrum for the ISM as a whole.
Gillard William
Guessoum Nidhal
Jean Pierre
No associations
LandOfFree
The lives and deaths of positrons in the interstellar medium does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with The lives and deaths of positrons in the interstellar medium, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The lives and deaths of positrons in the interstellar medium will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-363360