| Grant number: | 06/05787-5 |
| Support Opportunities: | Research Grants - Visiting Researcher Grant - International |
| Start date: | February 22, 2007 |
| End date: | April 14, 2007 |
| Field of knowledge: | Physical Sciences and Mathematics - Astronomy - Extragalactic Astrophysics |
| Principal Investigator: | Gastão Cesar Bierrenbach Lima Neto |
| Grantee: | Gastão Cesar Bierrenbach Lima Neto |
| Visiting researcher: | Renato de Alencar Dupke |
| Visiting researcher institution: | University of Michigan, United States |
| Host Institution: | Instituto de Astronomia, Geofísica e Ciências Atmosféricas (IAG). Universidade de São Paulo (USP). São Paulo , SP, Brazil |
Abstract
The ability to assess intraluster gas velocities directly is key to understanding the gas dynamics and determining the evolutionary stage of galaxy clusters. This ability was made possible only very recently, with the new generation of high spectral and spatial resolution X-ray spectrometers with good gain stability. We pioneered the technique to extract intracluster gas velocity distributions directly from X-ray spectroscopy and detected significant gas bulk velocities in several galaxy clusters. The high velocities found in clusters have an impact not only on the internal energetics of galaxy clusters and interaction with member galaxies but also indicate significant non-thermal support against gravity. This has a fundamental bearing on the derived clusters masses and baryon fraction widely used to constrain cosmological parameters. This proposal requests funding to continue the analysis of the astrophysical and cosmologically broad impact of intracluster gas bulk/or turbulent motions by measuring velocity distributions in a large sample of clusters observed with Chandra, XMM-Newton and Suzaku. This program will use a selected sample of clusters that focuses particularly on those, for which optical data can be used to complement the X-ray analysis, in collaboration with members of the X-ray galaxy cluster group in IAG/USP-INPE. The specific objectives of this proposal include: (1) To determine and characterize velocity gradients in the intracluster gas, using optical and X-ray data: measuring the magnitude, orientation and type (rotational or transient). (2) To correlate the characteristics of velocity gradients to those of the cluster of galaxies such as X-ray isophotes, ellipticity, nuclear substructure, metallicity and temperature anisotropies, etc. (3) To determine the impact of velocity gradients in the member galaxies. (4) To compare the velocity distributions obtained in optical and in X-rays to trace the evolutionary path of the baryonic (collisional) and dark matter (non-collisional) components. (5) To determine the energetic impact of velocity gradients to cluster dynamics, e.g., quantifying how much of the merger energy is used for heating as opposed to that used to maintain the kinetic component. (6) To determine the cosmological impact of velocity gradients, e.g. by comparing the velocity distribution curve from different cosmological recipes (through the Virtual Cluster Exploratory Database); To determine how the non-thermal component bias the use of clusters as cosmological tools. (AU)
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