Probing Large-scale Coherence between Spitzer IR and Chandra X-Ray Source-subtracted Cosmic Backgrounds

N. Cappelluti, R. Arendt, A. Kashlinsky, Y. Li, G. Hasinger, K. Helgason, M. Urry, P. Natarajan, A. Finoguenov

Research output: Contribution to journalArticlepeer-review

17 Scopus citations


We present new measurements of the large-scale clustering component of the cross-power spectra of the source-subtracted Spitzer-IRAC cosmic infrared background and Chandra-ACIS cosmic X-ray background surface brightness fluctuations Our investigation uses data from the Chandra Deep Field South, Hubble Deep Field North, Extended Groth Strip/AEGIS field, and UDS/SXDF surveys, comprising 1160 Spitzer hours and ∼12 Ms of Chandra data collected over a total area of 0.3 deg2. We report the first (>5σ) detection of a cross-power signal on large angular scales >20″ between [0.5-2] keV and the 3.6 and 4.5 μm bands, at ∼5σ and 6.3σ significance, respectively. The correlation with harder X-ray bands is marginally significant. Comparing the new observations with existing models for the contribution of the known unmasked source population at z < 7, we find an excess of about an order of magnitude at 5σ confidence. We discuss possible interpretations for the origin of this excess in terms of the contribution from accreting early black holes (BHs), including both direct collapse BHs and primordial BHs, as well as from scattering in the interstellar medium and intra-halo light.

Original languageEnglish (US)
Article numberL11
JournalAstrophysical Journal Letters
Issue number1
StatePublished - Sep 20 2017
Externally publishedYes


  • X-rays: diffuse background
  • cosmology: observations
  • diffuse radiation
  • infrared: diffuse background
  • quasars: supermassive black holes

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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