The unusual smoothness of the extragalactic unresolved radio background

Research output: Contribution to journalArticlepeer-review


If the radio background is coming from cosmological sources, there should be some amount of clustering due to the large scale structure in the universe. Simple models for the expected clustering combined with the recent measurement by ARCADE-2 of the mean extragalactic temperature lead to predicted clustering levels that are substantially above upper limits from searches for anisotropy on arcminute scales using the Australia Telescope Compact Array and the Very Large Array. The rms temperature variations in the cosmic radio background appear to be more than a factor of 10 smaller (in temperature) than the fluctuations in the cosmic infrared background. It is therefore extremely unlikely that this background comes from galaxies, galaxy clusters, or any sources that trace dark matter halos at z ≲ 5, unless typical sources are smooth on arcminute scales, requiring typical sizes of several Mpc.

Original languageEnglish (US)
Article number112
JournalAstrophysical Journal
Issue number1
StatePublished - Jan 1 2014
Externally publishedYes


  • cosmic background radiation
  • diffuse radiation
  • large-scale structure of universe
  • radio continuum: galaxies

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


Dive into the research topics of 'The unusual smoothness of the extragalactic unresolved radio background'. Together they form a unique fingerprint.

Cite this