Direct detection of the kinetic Sunyaev-Zel’dovich effect in galaxy clusters

Authors:
  • HTHideki Tanimura
    Hideki Tanimura
  • SZSaleem Zaroubi
    Saleem Zaroubi
  • NANabila Aghanim
    Nabila Aghanim
Open Access
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Abstract
We report the direct detection of the kinetic Sunyaev-Zel’dovich (kSZ) effect in galaxy clusters with a 3.5σsignificance level. The measurement was performed by stacking thePlanckmap at 217 GHz at the positions of galaxy clusters from the Wen-Han-Liu (WHL) catalog. To avoid the cancelation of positive and negative kSZ signals, we used the large-scale distribution of the Sloan Digital Sky Survey (SDSS) galaxies to estimate the peculiar velocities of the galaxy clusters along the line of sight and incorporated the sign in the velocity-weighted stacking of the kSZ signals. Using this technique, we were able to measure the kSZ signal around galaxy clusters beyond 3 × R500. Assuming a standardβ-model, we also found that the gas fraction withinR500isfgas, 500 = 0.12 ± 0.04 for the clusters with the mass ofM500 ∼ 1.0 × 1014h−1 M⊙. We compared this result to predictions from the Magneticum cosmological hydrodynamic simulations as well as other kSZ and X-ray measurements, most of which show a lower gas fraction than the universal baryon fraction for the same mass of clusters. Our value is statistically consistent with results from the measurements and simulations and also with the universal value within our measurement uncertainty.

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