Abstract: |
We introduce a novel approach, a Dense Shell Method (DSM), for measuring distances for cosmology using narrow-lines supernovae, SNIIn. The method is based on original Baade idea to relate absolute difference of photospheric radii with photospheric velocity. We demonstrate that this idea works: the new method does not rely on the Cosmic Distance Ladder and gives satisfactory results for the most luminous Type IIn Supernovae. This allows one to make them good primary distance indicators for cosmology. We apply the new method for illustration to two objects: SN2006gy and SN2009ip. The distance and Hubble parameter found using SN~2006gy have rather large error due to large uncertainty in reddening, while unobscured SN2009ip gives accuracy of a few percent. This is of course only formal estimate of accuracy. I will discuss in the talk what has to be done in the development of our understanding of SNIIn events and their models in order to avoid large systematic errors in cosmological distances. |