Joseph Silk

Publications (2)10.92 Total impact

• Article: Cluster abundances and Sunyaev–Zel'dovich power spectra: effects of non‐Gaussianity and early dark energy

  Sharon Sadeh, Yoel Rephaeli, Joseph Silk
  [show abstract] [hide abstract]
  ABSTRACT: In the standard Λ cold dark matter cosmological model with a Gaussian primordial density fluctuation field, the relatively low value of the mass variance parameter (σ8= 0.74+0.05−0.06, obtained from the Wilkinson Microwave Anisotropy Probe three-year data) results in a reduced likelihood that the measured level of cosmic microwave background anisotropy on the scales of clusters is due to the Sunyaev–Zel'dovich (S–Z) effect. To assess the feasibility of producing higher levels of S–Z power, we explore two alternative models which predict higher cluster abundance. In the first model the primordial density field has a χ21 distribution, whereas in the second an early dark energy component gives rise to the desired higher cluster abundance. We carry out the necessary detailed calculations of the levels of S–Z power spectra, cluster number counts, and angular two-point correlation function of clusters, and compare (in a self-consistent way) their predicted redshift distributions. Our results provide a sufficient basis on which the viability of the three models may be tested by future high-quality measurements.
  Monthly Notices of the Royal Astronomical Society 09/2007; 380(2):637 - 645. · 4.90 Impact Factor
• Source

  Available from: articles.adsabs.harvard.edu

  Article: Energetic proton heating of gas in the core of the Perseus cluster

  Yoel Rephaeli, Joseph Silk
  [show abstract] [hide abstract]
  ABSTRACT: Gas in the inner cores of rich clusters that contain central radio sources may be permeated by a high flux of energetic protons. Heating by these protons is likely to play a significant role in the thermal balance of the gas, thereby reducing the inferred cooling and mass accretion rates. This is shown to be the case in the radio halo region of NGC 1275 in the Perseus cluster.
  The Astrophysical Journal 02/1995; 442:91-95. · 6.02 Impact Factor