| Annu. Rev. Astron. Astrophys. 1994. 32:
319-70 Copyright © 1994 by . All rights reserved |
Converting from multipole space
to angles
is
accomplished via the approximate formula
| (37) |
It is this equality that is used to make statements that certain
measurements are on a scale of
. This correspondence,
-1 radians,
seems most natural for large
[cf the window function,
Equation
(28)]; for small , it may be
better to think of
/
radians, but
in any case the correspondence is not exact. At any z >> 1,
an angle
degrees subtends a comoving distance of
105 (
0
h)-1 Mpc.
To convert from to comoving
wavenumber k we have
~ (6,
000h-1 Mpc)k. Additionally we have the
physical scales (at horizon crossing)
| (38) |
The redshifts of equality, recombination, and decoupling (Compton cooling) for standard recombination are
| (39) |
and for reionization with constant ionized fraction xe
| (40) |
The following angles are also useful:
| (41) |