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.
"There is considerable uncertainty in the theoretical predictions for the angular power spectrum from the Sunyaev-Zeldovich effect (SZe). The level of precision reached by ACT, SPT, and Planck for measurements of the normalization of the SZe power spectrum, sigma_8, will be limited by the uncertainty in the theoretical models for the angular power spectrum. The uncertainties in the predicted spectrum arise from the complicated physics of the ICM.
This talk will describe the theoretical history "THEN" of CITA's semi-analytic and simulation forecasts of the "ambient" (aka blank field) SZ effect, from the beginnings in the mid-80s to the "NOW" and near future of copious ACT and SPT ambient-SZ cluster detections, Along the way, we will recall the simulation and analytic state of SZ analysis of the CBI excess power in 2002 (and 2008) and the impact of ACBAR and BIMA on the results, now punctuated by recent QuAD and SZA releases, NOW the ACT, SPT and Planck pressure of high precision imminence in SZ is re-focussing us on pressure uncerta
Clusters of galaxies provide us the opportunity to study an "ecosystem" - a volume that is a high-density microcosm of the rest of the Universe. At the same time clusters are excellent laboratories for studying plasma physical processes as well as for studying how super-massive black holes interact with the ambient cluster plasma. Guided by high-resolution simulations of galaxy clusters that self-consistently follow dissipative gas and cosmic ray physics, I will show how non-thermal processes in clusters build up over cosmic time.
Clusters of galaxies are unique probes of cosmology and astrophysics, promising to provide new insights into both the nature of dark energy and dark matter and the physics of galaxy formation. One of the key challenges facing this approach lies in our understanding of cluster physics and their impact on cluster structure and evolution. In this talk, I will present numerical simulations of galaxy clusters and their comparisons to recent Chandra X-ray observations, with focus on thermodynamics of intracluster plasma.
The XMM Cluster Survey (XCS) is a serendipitous galaxy cluster survey being conducted using publicly available X-ray data from the XMM-Newton Science Archive. One of the primary aims of the XCS is to determine the form of the evolution of the cluster gas - knowledge of which is crucial for the use of X- ray or SZ selected clusters in constraining cosmological parameters - through measuring the X-ray scaling relations using a large, well characterised cluster sample spanning ~7 Gyr in lookback time.
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.