Superdense massive galaxies in the nearby universe

At high-z the most superdense massive galaxies are supposed to be the result of gas-rich mergers resulting in compact remnant (Khochfar & Silk (2006); Naab at al.(2007)). After this, dry mergers are expected to be the mechanism that moves these very massive galaxies towards the current stellar mass size relation. Main these merging scenarios, a. non-negligible fraction (1-10%) of these galaxies is expected to survive since that epoch retaining their compactness and presenting old stellar populations in the past universe. Using the NYU Value-Added Galaxy Catalog (DR6), we find only a tiny fraction of galaxies (similar to 0.03%) with r(c) <= 1.5 kpc and M-* >= 8x10(10) M-circle dot in the local Universe (z similar to 0.2). Surprisingly, they are relatively young (similar to 2Gyr) and metal rich ([Z/H]similar to 0.2) These results have been published in Trujillo at al.(2009)