Röntgenastronomie, Galaxienhaufen, Kosmologie

• Antragsteller: Professor Dr. Thomas H. Reiprich
• Fachliche Zuordnung: Astrophysik und Astronomie
• Förderung: Förderung von 2010 bis 2015
• Projektkennung: Deutsche Forschungsgemeinschaft (DFG) - Projektnummer 158967163

• Erstellungsjahr: 2018

Zusammenfassung der Projektergebnisse

Galaxy clusters are the biggest clearly defined objects in the Universe. Their masses can exceed that of our Sun a quadrillion times; most of their mass is composed of dark matter. Detailed analyses of individual clusters can reveal physical processes acting over large scales and systematic analyses of well-defined samples can lead to insights about the cluster population as a whole as well as to cosmological constraints. Galaxy groups are the low-mass counterparts of galaxy clusters. They appear similar to clusters once properly scaled; however, they do differ in certain aspects. Moreover, some groups have rather different properties than other groups; one such deviating class is that of the so-called fossil groups. The next major breakthrough in statistical X-ray galaxy group and cluster studies will come with the eROSITA telescope onboard the SRG satellite. In this project we studied large X-ray selected cluster samples, a fossil group sample, and prepared for eROSITA. Using high-quality X-ray data we determined precise intracluster gas masses and cluster total masses for a complete cluster sample. Additionally, we determined independent dynamical masses using a large number of cluster galaxy velocities. Both mass estimates agree very well on average, though significant scatter is present. The cosmologically important X-ray luminosity–mass relation was constrained correcting self-consistently for selection effects. We could show that galaxy groups exhibit a significantly steeper slope compared to clusters. Constraints on cosmological parameters were also derived. During the statistical analysis of one of the cluster samples, we discovered a cluster galaxy leaving behind a very long tail of stripped gas; this finding was also featured in a press release by the Chandra X-ray Center. We studied a fossil group sample to investigate the properties of their cores. The sample consists of relaxed cool core groups, showing short central cooling times and only small center shifts. Galaxy clusters having these properties are known to show a central temperature drop. We determined the central temperature profiles of the fossil groups and found that some of them indeed also show a central drop; however, several do not, and some even show centrally rising temperature profiles, despite their short cooling times. We performed detailed simulations of eROSITA observations for a variety of different situations. For example, we demonstrated, given current knowledge of the expected instrumental performance, that with eROSITA we will be able to constrain the thermodynamic properties of cluster outskirts and, possibly, intercluster emission, already very early on during the Performance Verification phase.

Projektbezogene Publikationen (Auswahl)

• The long X-ray tail in Zwicky 8338, Astronomy & Astrophysics, Volume 583, id.L2, 4 pp., 2015
  Schellenberger, G.; Reiprich, T. H.
  
• Investigating the cores of fossil systems with Chandra. Astronomy & Astrophysics, Volume 585, id.A125, 14 pp., 2016
  Bharadwaj, V.; Reiprich, T. H.; Sanders, J. S.; Schellenberger, G.
  
• The XXL Survey II. The bright cluster sample: catalogue and luminosity function, Astronomy & Astrophysics, Volume 592, id.A2, 25 pp., 2016
  Pacaud, F.; . . . , Reiprich, T.H. et al.
  
• X-ray analysis of the galaxy group UGC 03957 beyond R200 with Suzaku, Astronomy & Astrophysics, Volume 592, id.A37, 15 pp., 2016
  Thölken, Sophia; Lovisari, Lorenzo; Reiprich, Thomas H.; Hasenbusch, Jan
  
• Follow-up of eROSITA and Euclid Galaxy Clusters with XMM-Newton, Astronomische Nachrichten, Volume 338, issue 2-3, pp. 349-353, 2017
  Reiprich, T.H.
  
• HICOSMO - cosmology with a complete sample of galaxy clusters - I. Data analysis, sample selection and luminosity-mass scaling relation. Monthly Notices of the Royal Astronomical Society, Volume 469, Issue 3, pp. 3738-3761, 2017
  Schellenberger, G.; Reiprich, T. H.
  
• HIFLUGCS: X-ray luminosity-dynamical mass relation and its implications for mass calibrations with the SPIDERS and 4MOST surveys, Astronomy & Astrophysics, Volume 599, id.A138, 15 pp., 2017
  Zhang, Y.-Y.; Reiprich, T.H. et al.
  
• Radial metal abundance profiles in the intra-cluster medium of cool-core galaxy clusters, groups, and ellipticals, Astronomy & Astrophysics, Volume 603, id.A80, 27 pp., 2017
  Mernier, F.; . . . ; Reiprich, T. H. et al.