A new calculation of the recombination epoch

被引:444
作者
Seager, S
Sasselov, DD
Scott, D
机构
[1] Harvard Univ, Dept Astron, Cambridge, MA 02138 USA
[2] Univ British Columbia, Dept Phys & Astron, Vancouver, BC V6T 1Z1, Canada
关键词
atomic processes; cosmic microwave background; cosmology : theory; early universe;
D O I
10.1086/312250
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
We have developed an improved recombination calculation of H, He I, and He II in the early universe that involves a line-by-line treatment of each atomic level. We find two major differences compared with previous calculations. First, the ionization fraction x(e) is approximately 10% smaller for redshifts less than or similar to 800 because of nonequilibrium processes in the excited states of H. Second, He I recombination is much slower than previously thought, and it is delayed until just before H recombines. We describe the basic physics behind the new results and present a simple way to reproduce our calculation. This should enable a fast computation of the ionization history (and of the quantities such as the power spectrum of cosmic microwave background anisotropies that depend on it) for arbitrary cosmologies, without the need to consider the hundreds of atomic levels used in our complete model.
引用
收藏
页码:L1 / L5
页数:5
相关论文
共 15 条
[1]   2-PHOTON DECAY OF SINGLET AND TRIPLET METASTABLE STATES OF HELIUM-LIKE IONS [J].
DRAKE, GWF ;
VICTOR, GA ;
DALGARNO, A .
PHYSICAL REVIEW, 1969, 180 (01) :25-&
[2]   The cosmic microwave background spectrum from the full COBE FIRAS data set [J].
Fixsen, DJ ;
Cheng, ES ;
Gales, JM ;
Mather, JC ;
Shafer, RA ;
Wright, EL .
ASTROPHYSICAL JOURNAL, 1996, 473 (02) :576-587
[3]   GENERALIZED LAGUERRE REPRESENTATION - APPLICATION TO RELATIVISTIC 2-PHOTON DECAY-RATES [J].
GOLDMAN, SP .
PHYSICAL REVIEW A, 1989, 40 (03) :1185-1193
[4]   EFFECT OF PHYSICAL ASSUMPTIONS ON THE CALCULATION OF MICROWAVE BACKGROUND ANISOTROPIES [J].
HU, W ;
SCOTT, D ;
SUGIYAMA, N ;
WHITE, M .
PHYSICAL REVIEW D, 1995, 52 (10) :5498-5515
[5]   Recombination of helium-like ions - I. Photoionization cross-sections and total recombination and cooling coefficients for atomic helium [J].
Hummer, DG ;
Storey, PJ .
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 1998, 297 (04) :1073-1078
[6]   TOTAL RECOMBINATION AND ENERGY-LOSS COEFFICIENTS FOR HYDROGENIC IONS AT LOW-DENSITY FOR 10-LESS-THAN-OR-EQUAL-TO-TE/Z2-LESS-THAN-OR-EQUAL-TO-10(7)-K [J].
HUMMER, DG .
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 1994, 268 (01) :109-112
[7]   DISSIPATION OF PRIMORDIAL TURBULENCE AND THERMAL HISTORY OF UNIVERSE [J].
MATSUDA, T ;
SATO, H ;
TAKEDA, H .
PROGRESS OF THEORETICAL PHYSICS, 1971, 46 (02) :416-&
[8]   RECOMBINATION OF PRIMEVAL PLASMA [J].
PEEBLES, PJE .
ASTROPHYSICAL JOURNAL, 1968, 153 (1P1) :1-&
[9]  
PEEBLES PJE, 1993, PRINCIPLES PHYSICAL, pCH6
[10]  
PEQUIGNOT D, 1991, ASTRON ASTROPHYS, V251, P680