1994A&A...290....7B

Merging galaxies sometimes show quasar-like activity, which suggests that the interstellar gas is efficiently transferred to the vicinity of their nucleus (where a massive black hole is considered to exist.). In order to elucidate gas fueling mechanism in galaxy mergers, we have numerically investigated the dynamical evolution of gas in the late phase of mergers. It is found that in some cases (e.g., a retrograde merger involving two compact galaxy cores), the dynamical heating by two sinking cores and subsequent dissipative cloud-cloud collisions drive a large fraction of disk gas (∼10⁸M_☉) into the central 10pc. It is also found that most of models have shown a qualitatively similar behavior that gas infall to the central 10pc becomes prominent only after the coalescence of two cores. This tendency of nuclear activity remains unchanged even if we include gas consumption by star formation in our models. Our numerical study predicts that the radiation emitted from the nuclear region of completed mergers showing a single nucleus originates from accretion power induced activity around a massive black hole whereas star formation is prime energy source of the radiation from less advanced mergers showing two distinct nuclei.