An evolutionary continuum from nucleated dwarf galaxies to star clusters.

Systematic studies have revealed hundreds of ultra-compact dwarf galaxies (UCDs) in the nearby Universe. With half-light radii r of approximately 10-100 parsecs and stellar masses M≈ 10-10solar masses, UCDs are among the densest known stellar systems. Although similar in appearance to massive globular clusters, the detection of extended stellar envelopes, complex star formation histories, elevated mass-to-light ratio and supermassive black holes suggest that some UCDs are remnant nuclear star clusters of tidally stripped dwarf galaxies, or even ancient compact galaxies.

Kinematic Signatures of Impulsive Supernova Feedback in Dwarf Galaxies.

Impulsive supernova feedback and nonstandard dark matter models, such as self-interacting dark matter (SIDM), are the two main contenders for the role of the dominant core formation mechanism at the dwarf galaxy scale. Here we show that the impulsive supernova cycles that follow episodes of bursty star formation leave distinct features in the distribution function of stars: groups of stars with similar ages and metallicities develop overdense shells in phase space. If cores are formed through supernova feedback, we predict the presence of such features in star-forming dwarf galaxies with cored host halos.

Self-Interacting Dark Matter Subhalos in the Milky Way's Tides.

We study evolution of self-interacting dark matter subhalos in the Milky Way tidal field. The interaction between the subhalos and the Milky Way's tides lead to more diverse dark matter distributions in the inner region, compared to their cold dark matter counterparts. We test this scenario with two Milky Way satellite galaxies, Draco and Fornax, opposite extremes in the inner dark matter content, and find that they can be accommodated within the self-interacting dark matter model proposed to explain the diverse rotation curves of spiral galaxies in the field.

Radiofrequency ablation for management of malignant biliary obstruction: a single-center experience and review of the literature.

Background: Radiofrequency ablation (RFA) causes coagulative necrosis of tissue and may be beneficial prior to biliary stenting. We report our experience using RFA for malignant biliary obstruction and review the literature.

Methods: Retrospective analysis of all patients undergoing RFA for malignant biliary obstruction over the last two years.