问题:
Recently, the improved local measurement
km s
Mpc
from Riess et al. 2016 (hereafter R16) exhibits a stronger tension with the Planck 2016 release
km s
Mpc
(hereafter P15) at the
level. ... The value of the Hubble constant
is consistent with the P15’s result at the
confidence level.
How do we figure and
level out?
解决:
Trivially, if you have
and
, then
can be determined (assuming the usual approximations of independent uncertainties that are normally distributed) with a precision of
.
In this case, the difference in the two determinations ofis
km/s per Mpc. i.e. different from zero by 3.4 error bars. The σ refers to the size of the uncertainty ; or more specifically, it represents the 68% confidence interval in a normal distribution.
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