Is the 0.36keV X-ray a Sign of the Existence of Antimatter Domains ? *

If the universe consisted of domains of matter and antimatter, annihilations of e⁺-e^- at the domain interface in the recombination time would leave an imprint on the x-ray band due to the high redshift. We found five ROSAT sources with the 0.36keV spectral line, especially the source lRXP J005510-3738.8 has a single sharp spectral line almost without a continuous spectrum. It is hard to be produced by any mechanism except the annihilations of e⁺-e^-.