BAHAMAS: new SNIa analysis reveals inconsistencies with standard
  cosmology
  We present results obtained by applying our BAyesian HierArchical Modeling
for the Analysis of Supernova cosmology (BAHAMAS) software package to the 740
spectroscopically confirmed supernovae type Ia (SNIa) from the "Joint
Light-curve Analysis" (JLA) dataset. We simultaneously determine cosmological
parameters and standardization parameters, including host galaxy mass
corrections, residual scatter and object-by-object intrinsic magnitudes.
Combining JLA and Planck Cosmic Microwave Background data, we find significant
discrepancies in cosmological parameter constraints with respect to the
standard analysis: we find Omega_M = 0.399+/-0.027, 2.8\sigma\ higher than
previously reported and w = -0.910+/-0.045, 1.6\sigma\ higher than the standard
analysis. We determine the residual scatter to be sigma_res = 0.104+/-0.005.
  We confirm (at the 95% probability level) the existence of two
sub-populations segregated by host galaxy mass, separated at
log_{10}(M/M_solar) = 10, differing in mean intrinsic magnitude by
0.055+/-0.022 mag, lower than previously reported. Cosmological parameter
constraints are however unaffected by inclusion of host galaxy mass
corrections. We find ~4\sigma\ evidence for a sharp drop in the value of the
color correction parameter, beta(z), at a redshift z_trans = 0.662+/-0.055. We
rule out some possible explanations for this behaviour, which remains
unexplained.
