Galaxy mergers: No link to active galaxies?

Binary galaxy spin correlations arising from mergers of galaxies

Statistics of spin orientations in binary galaxies may be used as a tool to study the formation process of galaxies. Helou found that the spins of spiral galaxies in binary systems are anticorrelated, and he suggested that it may have to do with the inclination dependence of the galaxy merger process. We study this dependence in small groups of galaxies. An N-body code is developed which uses a...

Stellar Populations in the Central Galaxies of Fossil Groups

It is inferred from the symmetrical and luminous X-ray emission of fossil groups that they are mature, relaxed galaxy systems. Cosmological simulations and observations focusing on their dark halo and inter-galactic medium properties confirm their early formation. Recent photometric observations suggest that, unlike the majority of non-fossil brightest group galaxies (BGGs), the central early-t...

AGN Zoo and Classications of Active Galaxies

We review the variety of Active Galactic Nuclei (AGN) classes (so-calledAGN zoo") and classification schemes of galaxies by activity types based on their optical emission-line spectrum, as well as other parameters and other than optical wave-length ranges. A historical overview of discoveries of various types of active galaxies is given, including Seyfert galaxies, radio galaxies, QSOs, BL Lace...

Galaxies: Interactions and Mergers

Starburst in multiple galaxy mergers

We numerically investigate stellar and gaseous dynamical evolution of mergers between five identical late-type disk galaxies with the special emphasis on star formation history and chemical evolution of multiple galaxy mergers. We found that multiple encounter and merging can trigger repetitive massive starbursts (typically ∼ 100 M yr−1) owing to the strong tidal disturbance and the resultant g...