Evidence of cross-correlation between the CMB lensing and the gamma-ray sky

Abstract

We report the measurement of the angular power spectrum of cross-correlation between the unresolved component of the Fermi-LAT gamma-ray sky-maps and the CMB lensing potential map reconstructed by the Planck satellite. The matter distribution in the Universe determines the bending of light coming from the last scattering surface. At the same time, the matter density drives the growth history of astrophysical objects, including their capability at generating non-thermal phenomena, which in turn give rise to gamma-ray emissions. The Planck lensing map provides information on the integrated distribution of matter, while the integrated history of gamma-ray emitters is imprinted in the Fermi-LAT sky maps. We report here the first evidence of their correlation. We find that the multipole dependence of the cross-correlation measurement is in agreement with current models of the gamma-ray luminosity function for AGN and star forming galaxies, with a statistical evidence of 3.0$\sigma$. Moreover, its amplitude can in general be matched only assuming that these extra-galactic emitters are also the bulk contribution of the measured isotopic gamma-ray background (IGRB) intensity. This leaves little room for a big contribution from galactic sources to the IGRB measured by Fermi-LAT, pointing toward a direct evidence of the extragalactic origin of the IGRB.

6 pages, 2 figures. v2: analysis updated with Planck 2015 lensing map and 3FGL catalogue, conclusions strengthened; to appear in ApJ Letters

References in corpus (4)

• Giant Gamma-ray Bubbles from Fermi-LAT: AGN Activity or Bipolar Galactic Wind?
• Cross-Correlation of Cosmic Shear and Extragalactic Gamma-ray Background: Constraints on the Dark Matter Annihilation Cross-Section
• Corrected Table for the Parametric Coefficients for the Optical Depth of the Universe to Gamma-rays at Various Redshifts
• Clustering of gamma-ray selected 2LAC Fermi Blazars

Cited by in corpus (14)

• The angular power spectrum of the diffuse gamma-ray emission as measured by the Fermi Large Area Telescope and constraints on its Dark Matter interpretation
• Modeling CMB Lensing Cross Correlations with {\sc CLEFT}
• Cross-correlating the gamma-ray sky with catalogs of galaxy clusters
• Cross-correlation of weak lensing and gamma rays: implications for the nature of dark matter
• Tomographic imaging of the Fermi-LAT gamma-ray sky through cross-correlations: A wider and deeper look
• Planck Lensing and Cosmic Infrared Background Cross-Correlation with Fermi-LAT: Tracing Dark Matter Signals in the Gamma-Ray Background
• Searching for Signal of Primordial Black Hole from CMB Lensing and $\gamma$-ray Emissions
• A Cross-correlation Study between IceCube Neutrino Events and the Fermi Unresolved Gamma-ray Sky
• Got plenty of nothing: cosmic voids as a probe of particle dark matter
• Constraints on dark matter and astrophysics from tomographic $\gamma$-ray cross-correlations
• High-Significance Detection of Correlation Between the Unresolved Gamma-Ray Background and the Large Scale Cosmic Structure
• Dark Matter and Galaxy Cross-Correlations with the Cherenkov Telescope Array Observatory
• KiDS-Legacy: WIMP dark matter constraints from the cross-correlation of weak lensing and Fermi-LAT gamma rays
• Wiener filtering and multi-tracer techniques for dark matter cross-correlations between gamma-ray emission and galaxy catalogs