Wednesday Colloquium


"Galaxies with prolate rotation in the Illustris simulation"

Ivana Ebrova (NCAC, Warsaw)

Tens of early type galaxies have been recently reported to possess prolate rotation, i.e. significant amount of rotation around the major axis, including two cases in the Local Group. Although expected theoretically, this phenomenon is rarely observed and remains elusive. In order to explore its origin we study the population of well-resolved galaxies in the Illustris cosmological simulation. We follow their evolution back in time and find that the emergence of prolate rotation is strongly correlated with the time of the last significant merger the galaxy experienced. We examine properties of these mergers and compare them with mergers in the reference sample of galaxies drawn from Illustris.


"Superfluid neutron stars: from pinning forces to pulsar glitch amplitudes"

Marco Antonelli (Milano)

Neutron stars are extreme physics laboratories, allowing us to probe aspects of dense matter that cannot be tested on Earth. Issues involving nuclear superfluidity are though to play key roles for neutron star phenomenology. In particular pulsar glitches (sudden jumps in the period of otherwise steadily spinning down pulsars) offer a glimpse into the superfluid interior of a neutron star: within the currently accepted scenario these timing irregularities are explained in terms of an expulsion of the quantized vortex lines that permeate the superfluid in the crustal region of the star. Vortices can pin to the ions in the crust, providing the mechanism for storing the angular momentum that can be eventually released during a glitch. A simplified model for the angular momentum reservoir of pinned vorticity gives a general and quantitative inverse relation between size of the maximum glitch and the pulsar mass: I'll present a method to put some limits on the mass of a pulsar, using observations of the maximum glitch observed, together with models of the pinning interaction between superfluid vortices and ions in the crust. This procedure procedure will hopefully allow current and future pulsar timing observations to constrain the physics of glitch models and pinning forces.


"What was the last Nobel Prize in Physics given for?"

Tomasz Bulik (Astronomical Observatory, Warsaw University)

This year Nobel Prize in Physics was awarded for „decisive contributions to the LIGO detector and the observation of gravitational waves”. I will summarize the path that lead to construction of LIGO and to the direct detection of gravitational waves. I will outline the current state and the future for gravitational wave astronomy.