We have to be clear. Downloading a copyrighted ROM for a game you do not own is copyright infringement. However, if you own a physical copy of the game , dumping your own cartridge for use on an emulator or modded Vita exists in a legal grey area (backup/archival rights, depending on your country).
If you are looking for "indir" (download) sources or ROM files for legal backup or emulation, the community often points to the following repositories: uncharted golden abyss ps vita rom indir top