Tuorla observatory seminar series

Tuorla seminars in Autumn 2017

Seminars will be streamed online unless otherwise informed. No registration required and the weblink is given later in the announcement of the seminar. The connection starts sligthly before the seminar. 

After the seminar you can ask questions by using the chat window in the ADOBE CONNECT interface. We hope to recieve a lot of questions!

The seminars are held on Thursdays at 14.30 unless otherwise noticed. The title of the talk will be added as the seminar approaches.

13.12 at 14.30 Andreas Schulze (NAOJ, EACOA Fellow): "New constraints on the black hole spin in radio-loud quasars”

Abstract:
One of the major unsolved questions on the understanding of the AGN population is the origin of the dichotomy between radio-quiet and radio-loud quasars. The most promising explanation is provided by the spin paradigm, which suggests radio-loud quasars to have higher black hole spin. However, the measurement of black hole spin remains extremely challenging. We here present results comparing the mean radiative efficiencies of carefully matched samples of radio-loud and radio-quiet SDSS quasars at 0.3<z<0.8. We find evidence for systematically larger radiative efficiencies by a factor > 1.5 in the radio-loud sample, suggesting that the radio-loud quasar population has on average higher black hole spin that the radio-quiet population. This provides strong observational support for the black hole spin paradigm.

14.12 at 14.30 Edward Brown (Michigan State University): "Journey to the center of a neutron star”

Abstract:
Neutron stars are composed of the densest observable matter in nature and occupy the intellectual frontier between astrophysics and nuclear physics. Many neutron stars are in binaries and accrete matter transferred from their companion. During the slow compression to nuclear density the accreted matter is transmuted from being proton-rich to being proton-poor. These reactions affect many observable phenomena -- from energetic explosions on the neutron star's surface to thermal relaxation of the surface layers -- that in turn inform us about the nature of the deep interior of the neutron star. In this talk, I shall describe what recent astronomical observations and nuclear physics experiments tell us about the nature of matter at nuclear densities. In particular, I will emphasize what we are learning from observations of transients, for which the accretion of matter is intermittent: the neutron star accretes rapidly for a time, and then is quiescent for a long time. I will discuss recent efforts to constrain the core heat capacity and neutrino emissivity of matter at densities above saturation from observations of the surface temperatures of quiescent neutron star transients immediately following an accretion outburst.

 
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