(CMB cold spot, WMAP cold spot)
(unusually colder spot in the CMB)
A cold spot (or cosmic microwave background cold spot or WMAP cold spot)
is an area of the celestial sphere
where the CMB indicates a slightly lower black body
temperature than the rest,
a difference on the order of 70 millionths of a kelvin.
The CMB black body temperature has a random
distribution around a specific value (about 2.72548 K)
except for this region.
There has been some investigation regarding whether the apparent
colder region corresponds to a void or voids in that direction,
e.g., from the Sachs-Wolfe effect.
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