Recent analysis of the combined data of cosmic microwave background , galaxy clustering and supernovae type Ia observations have set strong constraints on the equation of state parameter w _ { X } .
The upper bound w _ { X } < -0.82 at 95 \% c.l .
rules out an important class of models , the domain walls ( -2 / 3 < w _ { X } < -1 / 3 ) .
Here we revisit the issue of domain walls as a possible alternative to the standard \Lambda -CDM model by questioning the assumptions made in the choice of priors of the data analysis .
The results of our investigation show that domain walls can provide a good fit to the WMAP data for a different choice of priors with “ lower ” values of the Hubble parameter ( h < 0.65 ) , ( as indicated by Sunyaev-Zeldovich and time delays for gravitational lensing observations ) , and “ higher ” values of the matter density ( \Omega _ { m } > 0.35 ) , ( in agreement with recent measurements of the temperature-luminosity relation of distant clusters observed with the XMM-Newton satellite ) .
In this new perspective , their existence would lead to important implications for the CMB constraints on cosmological and inflationary parameters .