[Previous] | [Session 55] | [Next]
Y.-W. Lee, S. Yi, S.-J. Yoon, Y.-J. Sohn, S.-C. Rey, Y.-I. Byun (Center for Space Astrophysics, Yonsei University, Seoul 120-749, Korea)
Although there is a consensus that hot horizontal-branch (HB) and post-HB stars are the dominant UV sources in giant ellipticals, it is still debated whether the UV sources are metal-poor or metal-rich. The problem is that these two scenarios predict significantly different cosmological models. For example, if the metal-poor model is correct, then giant ellipticals are the oldest population in the Universe and would imply a non-zero cosmological constant from time scale test. We found that these two models predict substantially different UV-to-V flux ratios as functions of redshift (look-back time). We estimate this effect is detectable using GALEX by observing several dozens of not-so-dense clusters in the redshift range of 0.1 < z < 0.3 with the exposure times comparable to the GALEX DIS mode.
The author(s) of this abstract have provided an email address for comments about the abstract: sjyoon@csa.yonsei.ac.kr