Title: The Evolution of Tidal-tail Dwarf Galaxies and their survival
　  Speaker：Gerhard Hensler (University of Vienna, Institute of Astrophysics)
　  Time: Thursday, 3:00pm, May 9
　  Location: Lecture Hall, 3rd floor

 Abstract:
　 Within the hierarchical structure formation scenario in Cosmology today’s massive galaxies are assumed to form by the accumulation of smaller, gas-rich cosmological “building blocks”. When massive galaxies merge, angular momentum and energy conservation lead to the expulsion of long, thin, and gas-rich tidal arms. These fragment into multiple self-gravitating and star-forming units, by this, resembling a new type of dwarf galaxies (DGs) denoted as Tidal DGs (TDGs). From the merger rate and the observable bright TDGs, it can be speculated that their production may provide an important contribution to the faint-end of the galaxy luminosity function. As the result of merger and due to their location these low-mass objects can merely be gravitationally supported by Cold Dark Matter halo, but show active star formation, so that the question arises, whether and which fraction of TDGs survive the re-accretion to the parent merger, its tidal action, and, most importantly, the stellar energy feedback. In order to understand their survival and to un­cover observable features that help distinguishing TDGs from “normal” CDM-dominated DGs, we perform self-consistent chemo-dynamical numerical 3D models. I will present the early stages of TDG evolutionary models under the aspect how and which processes affect their evolution and discuss structural and chemical signatures to distinguish tidally formed DM-free DGs from 'classical' ones.