Bumpy power spectra and galaxy clusters

Bumpy Power Spectra and ∆T/T

With the recent publication of the measurements of the radiation angular power spectrum from the BOOMERanG Antarctic flight (de Bernardis et al. 2000), it has become apparent that the currently favoured spatially–flat cold dark matter model (matter density parameter Ωm = 0.3, flatness being restored by a cosmological constant ΩΛ = 0.7, Hubble parameter h = 0.65, baryon density parameter Ωbh 2 =...

A Bayesian view on Faraday rotation maps - Seeing the magnetic power spectra in galaxy clusters

We present a Bayesian maximum likelihood analysis of Faraday rotation measure (RM) maps of extended radio sources to determine magnetic field power spectra in clusters of galaxies. Using this approach, it is possible to determine the uncertainties in the measurements. We apply this approach to the RM map of Hydra A and derive the power spectrum of the cluster magnetic field. For Hydra A, we mea...

Testing power-law cosmology with galaxy clusters

Aims. Power-law cosmologies, in which the cosmological scale factor evolves as a power law in the age, a ∝ t with α >∼ 1, regardless of the matter content or cosmological epoch, is comfortably concordant with a host of cosmological observations. Methods. In this article, we use recent measurements of the X-ray gas mass fractions in clusters of galaxies to constrain the α parameter with curvatur...

Mid - Infrared Spectra of Cool - Core Galaxy Clusters

We have obtained mid-infrared spectra of nine cool-core galaxy clusters with the Infrared Spectrograph aboard the Spitzer Space Telescope. X-ray, ultraviolet and optical observations have demonstrated that each of these clusters hosts a cooling flow which seems to be fueling vigorous star formation in the brightest cluster galaxy. Our goal is to use the advantages of the mid-infrared band to im...

Galaxy Clusters