Detecting the orientation of magnetic fields in galaxy clusters (2009)
Pfrommer, Christoph, Dursi, L. Jonathan
Clusters of galaxies, filled with hot, magnetised plasma, are the largest bound objects in existence and an important touchstone in understanding the formation of structures in our Universe. Because...
Gamma-rays from dark matter annihilations strongly constrain the substructure in halos (2009)
Pinzke, Anders, Pfrommer, Christoph, Bergstrom, Lars
Recently, it has been shown that electrons and positrons from dark matter (DM) annihilations provide an excellent fit to the Fermi, PAMELA, and HESS data. Using this DM model, which requires an...
Simulations of cosmic-ray feedback by active galactic nuclei in galaxy clusters (2008)
Sijacki, Debora, Pfrommer, Christoph, Springel, Volker, Ensslin, Torsten A.
Pfrommer, Christoph, Ensslin, Torsten A., Springel, Volker
The thermal plasma of galaxy clusters lost most of its information on how structure formation proceeded as a result of dissipative processes. In contrast, non-equilibrium distributions of cosmic rays...
Complementary views of galaxy clusters in the radio synchrotron, hard X-ray inverse Compton, and high-energy gamma-ray regimes are critical in calibrating them as high-precision cosmological probes....
Cosmic ray feedback in hydrodynamical simulations of galaxy and galaxy cluster formation (2006)
Pfrommer, Christoph, Springel, Volker, Jubelgas, Martin, Ensslin, Torsten A.
It is well known that cosmic rays (CRs) contribute significantly to the pressure of the interstellar medium in our own Galaxy, suggesting that they may play an important role in regulating star...
Cosmological structure formation shocks and cosmic rays in hydrodynamical simulations (2006)
Pfrommer, Christoph, Springel, Volker, Ensslin, Torsten A., Jubelgas, Martin
Cosmological shock waves during structure formation not only play a decisive role for the thermalization of gas in virializing structures but also for the acceleration of relativistic cosmic rays...
Pfrommer, Christoph, Ensslin, Torsten A., Springel, Volker, Jubelgas, Martin, Dolag, Klaus
We performed high-resolution simulations of a sample of 14 galaxy clusters that span a mass range from 5 x 10^13 M_solar/h to 2 x 10^15 M_solar/h to study the effects of cosmic rays (CRs) on thermal...
Detecting shock waves in cosmological smoothed particle hydrodynamics simulations (2006)
Pfrommer, Christoph, Springel, Volker, Ensslin, Torsten A., Jubelgas, Martin
We develop a formalism for the identification and accurate estimation of the strength of structure formation shocks during cosmological smoothed particle hydrodynamics simulations. Shocks not only...
Cosmic ray feedback in hydrodynamical simulations of galaxy formation (2006)
Jubelgas, Martin, Springel, Volker, Ensslin, Torsten A., Pfrommer, Christoph
It is well known that cosmic rays (CRs) contribute significantly to the pressure of the interstellar medium in our own Galaxy, suggesting that they may play an important role in regulating star...
Cosmic ray physics in calculations of cosmological structure formation (2006)
Ensslin, Torsten A., Pfrommer, Christoph, Springel, Volker, Jubelgas, Martin
Cosmic rays (CRs) play a decisive role within our own Galaxy. They provide partial pressure support against gravity, they trace past energetic events such as supernovae, and they reveal the...
On the role of cosmic rays in clusters of galaxies (2005)
We take a multi-faceted approach to study the relativistic cosmic ray (CR) proton population in galaxy clusters. CR protons may be accelerated by structure formation shock waves, injected from radio...
On the role of cosmic rays in clusters of galaxies (2005)
We take a multi-faceted approach to study the relativistic cosmic ray (CR) proton population in galaxy clusters. CR protons may be accelerated by structure formation shock waves, injected from radio...
Magnetic Fields in Clusters of Galaxies (2005)
Ensslin, Torsten A., Vogt, Corina, Pfrommer, Christoph
A brief overview about our knowledge on galaxy cluster magnetic fields is provided. Emphasize is given to the mutual dependence of our knowledge on relativistic particles in galaxy clusters and the...
The quest for cosmic ray protons in galaxy clusters (2004)
Pfrommer, Christoph, Ensslin, Torsten A.
There have been many speculations about the presence of cosmic ray protons (CRps) in galaxy clusters over the past two decades. However, no direct evidence such as the characteristic gamma-ray...
Pfrommer, Christoph, Ensslin, Torsten A., Sarazin, Craig L.
The Chandra X-ray Observatory is finding a large number of cavities in the X-ray emitting intra-cluster medium which often coincide with the lobes of the central radio galaxy. We propose...
Hamana, Takashi, Bartelmann, Matthias, Yoshida, Naoki, Pfrommer, Christoph
We investigate statistical distributions of differences in gravitational-lensing deflections between two light rays, the so-called lensing excursion angles. A probability distribution function of the...
Schaefer, Bjoern Malte, Pfrommer, Christoph, Bartelmann, Matthias, Springel, Volker, Hernquist, Lars
All-sky thermal and kinetic Sunyaev-Zel'dovich (SZ) maps are presented for assessing how well the PLANCK-mission can find and characterise clusters of galaxies, especially in the presence of primary...
Schaefer, Bjoern Malte, Pfrommer, Christoph, Hell, Reinhard, Bartelmann, Matthias
The PLANCK mission is the most sensitive all-sky CMB experiment currently planned. The High Frequency Instrument (HFI) will be especially suited for observing clusters of galaxies by their thermal...
Pfrommer, Christoph, Ensslin, Torsten A.
We wish to estimate magnetic field strengths of radio emitting galaxy clusters by minimising the non-thermal energy density contained in cosmic ray electrons (CRe), protons (CRp), and magnetic...
Schaefer, Bjoern Malte, Pfrommer, Christoph, Zaroubi, Saleem
A method for estimating redshifts of galaxy clusters based solely on resolved Sunyaev-Zel'dovich (SZ) images is proposed. Given a high resolution SZ cluster image (with FWHM of approx. 1 arcmin), the...
Magnetic fields and cosmic rays in cooling flows (2003)
Ensslin, Torsten, Vogt, Corina, Pfrommer, Christoph
Cooling flows are regions where the importance of non-thermal intra-cluster medium components such as magnetic fields and cosmic rays may be strongest within a galaxy cluster. They are also regions...
Pfrommer, Christoph, Ensslin, Torsten A.
We wish to constrain the cosmic-ray proton (CRp) population in galaxy clusters. By hadronic interactions with the thermal gas of the intra-cluster medium (ICM), the CRp produce gamma-rays for which...
Pfrommer, Christoph, Ensslin, Torsten A.
We examine the cosmic ray proton (CRp) population within the giant elliptical galaxy M 87 using the TeV gamma-ray detection of the HEGRA collaboration. In our scenario, the gamma-rays are produced by...