SN magnitude marginalisation in cosmomc
Posted: January 10 2006
I've noticed that cosmomc does the marginalisation over magnitude offset (equivalent to marginalisation over h) in riess SN code.
I've added SNLS sn data and run with either marginalisation switched on (done separatly for Riess and SNLS) and off and with no other data (no cmb, no lss). Constraints on Omega_\Lambda and Omega_m are unchanged, but without marginalisation, I get a *very* strong constraint on hubble, something like 64\pm1. Has anybody else found something like that? (note that H is still a derived parameter here, so prior on it is not flat).
As far as I know authors of SN data don't really advocate this marginalisation, (though it is a conservative thing to do).
I've added SNLS sn data and run with either marginalisation switched on (done separatly for Riess and SNLS) and off and with no other data (no cmb, no lss). Constraints on Omega_\Lambda and Omega_m are unchanged, but without marginalisation, I get a *very* strong constraint on hubble, something like 64\pm1. Has anybody else found something like that? (note that H is still a derived parameter here, so prior on it is not flat).
As far as I know authors of SN data don't really advocate this marginalisation, (though it is a conservative thing to do).