Since 2002 Perimeter Institute has been recording seminars, conference talks, and public outreach events using video cameras installed in our lecture theatres. Perimeter now has 7 formal presentation spaces for its many scientific conferences, seminars, workshops and educational outreach activities, all with advanced audio-visual technical capabilities. Recordings of events in these areas are all available On-Demand from this Video Library and on Perimeter Institute Recorded Seminar Archive (PIRSA). PIRSA is a permanent, free, searchable, and citable archive of recorded seminars from relevant bodies in physics. This resource has been partially modelled after Cornell University's arXiv.org.
We build simple, 'top-down', models for the gas density and temperature profiles for clusters of galaxies based on current high precision XRay observations so as to 'exactly' satisfy observed XRay scaling relation between temperature and mass. The gas is assumed to be in hydrostatic equilibrium along with a component of non-thermal pressure due to dispersion and the gas fraction reaches universal value only at or beyond the virial radius. For these models, we calculate the Sunyaev-Zel'dovich Effect (SZE) scaling relations.
"Taking gravitational potential wells from a dark matter simulation, and assuming a polytropic equation of state and hydrostatic equilibrium, one can predict the state of the hot gas in clusters of galaxies. With reasonable values for star formation efficiency, energy input, and nonthermal pressure support, these model clusters can reproduce observed X-ray trends of gas temperature and gas mass fraction with cluster mass, as well as observed entropy and pressure profiles.
Normalizing to X-ray observations is a vital step in using such models to predict the SZ signal. "
Integrability in gauge/string dualities will be reviewed in a broad perspective with a particular emphasis on the recently proposed equations describing the full planar spectrum of anomalous dimensions in AdS/CFT [N.Gromov, V.Kazakov, PV].
The observed thermal properties of the ICM shows much greater dispersion than expected if the gas was subject only to shock-heating by mergers and during infall. This diversity can be best understood as a byproduct of AGN feedback occurring in galaxies destined to become cluster members, both before and after cluster formation. Theoretical considerations suggest that the level of preheating ought to vary from one proto-cluster region to another. The entropy profiles of roughly 50% of the clusters with long central cooling times require that the gas be "preheated" to high entropy.
Scaling relations among galaxy cluster observables, which will become available in large future samples of galaxy clusters, could be used to constrain not only cluster structure,but also cosmology. I will discuss the utility of this approach, employing a physically motivated parametric model to describe cluster structure, and applying it to the expected relation between the Sunyaev-Zel’dovich decrement (S_{\nu}) and the emission–weighted X–ray temperature (Tew). With a suitable choice of fiducial parameter values, the cluster model satisfies several existing observational constraints.
I discuss whether supernovae at high-redshift can result in a detectable SZ signal at small angular scales. I also discuss various aspects of AGN feedback on galaxy clusters.
The growing fascination with unconventional pairing is driven in part by continuing discoveries of exotic superconductors. The first of these, superfluid 3He, was found by Osheroff, Richardson, and Lee in 1971. This was followed soon thereafter by superconductivity in the heavy fermion compound, UPt3. And then an explosion of interest accompanied the observation of superconductivity in cuprates, Sr2RuO4, and organic materials. The newest discoveries are sperconducting compounds of FeAs.
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