Fakultäten » Mathematisch-naturwissenschaftliche Fakultät » Physik-Institut » Prof. Dr. Philippe Jetzer » Miranda

Completed research project

Title / Titel Galaxy clusters: Multi-wavelength analyses
PDF Abstract (PDF, 14 KB)
Summary / Zusammenfassung Joint multi-wavelength analyses can allow a deep insight on the properties of galaxy clusters. A very suitable approach is to combine X-ray, Sunyaev-Zeldovich (SZ) temperature decrement and optical measurements. Knowledge of the intrinsic shape of galaxy clusters is very important in investigating cosmic structure formation and astrophysical processes.
In fact, the intrinsic structure directly suggests how material aggregates from large-scale
perturbations and also contains evidence about the nature and mechanisms of interaction of baryons and dark matter, since processes such as virialization, dissipation or gas cooling tend to make systems more spherical, especially in the inner regions. Our group is actively working on this eld.
We completed our analyses about the deprojection of 2-dimensional X-ray, SZ and/or
gravitational lensing observations. Due to some intrinsic degeneracies, an unique
inversion is not possible. Assuming that the cluster is axially symmetric is likely to
overestimate the intrinsic ellipticity, whereas the system always looks rounder performing the inversion under the hypothesis of a triaxial cluster aligned with the line of sight. The feasibility of inferring the dynamical status of a cluster of galaxies through a combined X-ray and strong lensing analysis was explored considering RX J1347.5-1145, one of the most luminous galaxy clusters at X-ray wavelengths [?]. We completed our analysis by considering new HST data. We showed that evidence from strong lensing alone strongly argues in favor of a complex structure. Such a complex structure could be a signature of a recent major merger as further supported by X-ray data. A temperature map of the cluster, based on deep Chandra observations, revealed a hot front located between the rst main component and an X-ray emitting South Eastern sub-clump. A merger scenario in the plane of the sky between two dark matter sub-clumps is consistent with both lensing and X-ray analyses, and can explain previous discrepancies with mass estimates based on the virial theorem. A new study of AC 114 is now under work.
Finally we considered the possibility to infer the motion of galaxy clusters from either
SZ e ect or GL observations. Even if interesting under a theoretical point of view the
kinematic status of galaxy clusters do not seem e ective enough to produce sizable e ects.
Publications / Publikationen M. Sereno, 2007, On the deprojection of clusters of galaxies combining X-ray,
Sunyaev-Zeldovich temperature decrement and gravitational lensing maps, MNRAS,
380, 1207
M. Miranda, M. Sereno, E. De Filippis, M. Paolillo, 2008, The dynamical state of
RX J1347.5-1145 from a combined strong lensing and X-ray analysis, MNRAS 385,
Project leadership and contacts /
Projektleitung und Kontakte
Dr Mauro Sereno  
Dr Marco Miranda (Project Leader)  
Prof Philippe Jetzer  
Funding source(s) /
Unterstützt durch
Universität Zürich (position pursuing an academic career), SNF (Personen- und Projektförderung)
Duration of Project / Projektdauer Jan 2008 to Nov 2008