CosmoMC : Union 2.1 compilation

[Dhiraj Kumar Hazra]

Dear Prof. Lewis,

I was using union 2.1 with CosmoMC. If I use "Covariance Matrix with Systematics", I find the -log(Like) ~272 but without systematics it provides
65 only. This seems to be large.

To check in detail I compared the matrix provided in,
http://supernova.lbl.gov/Union/figures/ ... _nosys.txt and the one provided in cosmomc. The one in cosmomc contains non-zero off-diagonal terms which is zero in the Union website. In fact in the chains provided by Planck too, it seems that there is an addition of ~65 in the -log(like) when we add Union 2.1. So, aren't we encountering some large error when not considering systematics?
(In cosmomc systematics is not included by default).

Regards,
Dhiraj

[Antony Lewis]

Possibly, this is discussed briefly in 5.4.2 of the parameter paper.