![]() ![]() © CAMBRIDGE UNIVERSITY PRESS 1999
| |
2.10. Mass, Luminosity, and Mass-to-Luminosity Ratio
The typical dynamical mass of rich clusters within 1.5h-1 Mpc radius sphere (determined from the virial theorem for an isothermal distribution) is
![]() | (24) |
The approximate range of masses for
R 0
clusters (within 1.5h-1 Mpc) is
![]() | (25) |
Comparable masses are obtained using the X-ray temperature and distribution of the hot intracluster gas (Hughes 1989; Bahcall and Cen 1993; Lubin and Bahcall 1993; Section 3).
The typical (median) blue luminosity of rich clusters (within 1.5h-1 Mpc) is
![]() | (26) |
The approximate range of rich cluster blue luminosities is
![]() | (27) |
The typical mass-to-luminosity ratio of rich clusters is thus
![]() | (28) |
The inferred mass-density in the universe based on cluster dynamics is
![]() | (29) |
(if mass follows light,
M L, on
scales
1h-1 Mpc).
= 1 corresponds to
the critical mass-density needed for a closed
universe and
/
LB
(
= 1)
1500h.