Astronomy and Astrophysics – Astrophysics
Scientific paper
1993-08-16
Astrophys.J. 439 (1995) 503-516
Astronomy and Astrophysics
Astrophysics
22 pages, plain TeX, 10 figures available upon request, FERMILAB-Pub-93/242-A
Scientific paper
10.1086/175191
Early reionization changes the pattern of anisotropies expected in the cosmic microwave background. To explore these changes, we derive from first principles the equations governing anisotropies, focusing on the interactions of photons with electrons. Vishniac (1987) claimed that second order terms can be large in a re-ionized Universe, so we derive equations correct to second order in the perturbations. There are many more second order terms than were considered by Vishniac. To understand the basic physics involved, we present a simple analytic approximation to the first order equation. Then turning to the sec- ond order equation, we show that the Vishniac term is indeed the only important one. We also present numerical results for a variety of ionization histories [in a standard cold dark matter Universe] and show quantitatively how the sig- nal in several experiments depends on the ionization history. The most pronounced indication of a re-ionized Universe would be seen in very small scale experiments; the expected signal in the Owens Valley experiment is smaller by a factor of order ten if the last scattering surface is at a redshift $z\simeq100$ as it would be if the Universe were re-ionized very early. On slightly larger scales, the expected signal in a re-ionized Universe {\it is} smaller than it would be with standard recombination, but only by a factor of two or so.
Dodelson Scott
Jubas Jay
No associations
LandOfFree
Re-Ionization and its Imprint on the Cosmic Microwave Background 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 Re-Ionization and its Imprint on the Cosmic Microwave Background, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Re-Ionization and its Imprint on the Cosmic Microwave Background will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-297425