42
X-ray Masses
for Clusters
•Fabricant,
Lecar, and Gorenstein:
–Bremsstrahlung
spectrum is roughly flat up to X-ray energies, above which it cuts off exponentially. Cut-off is related to temperature. E = hν ~ kBT. The
measurement is a
projection onto 2D space.
Integrating emissivity and converting to intensity (surface brightness at the
projected radius
a):
