Synchrotron Emission from Hot Accretion Flows and the Cosmic Microwave Background Anisotropy

Abstract

Current estimates of number counts of radio sources in the frequency range where the most sensitive Cosmic Microwave Background (CMB) experiments are carried out significantly under-represent sources with strongly inverted spectra. Hot accretion flows around supermassive black holes in the nuclei of nearby galaxies are expected to produce inverted radio spectra by thermal synchrotron emission. We calculate the temperature fluctuations and power spectra of these sources in the Planck Surveyor 30 GHz energy channel, where their emission is expected to peak. We find that their potential contribution is generally comparable to the instrumental noise, and approaches the CMB anisotropy level at small angular scales. Forthcoming CMB missions, which will provide a large statistical sample of inverted-spectra sources, will be crucial for determining the distribution of hot accretion flows in nearby quiescent galactic nuclei. Detection of these sources in different frequency channels will help constrain their spectral characteristics, hence their physical properties.

10 pages, 4 figures, accepted for publication in ApJ

References in corpus (4)

• Resolving the extragalactic hard X-ray background
• Hydrodynamical Non-radiative Accretion Flows in Two-Dimensions
• Low radiative efficiency accretion in the nuclei of elliptical galaxies
• Hard X-ray emission from elliptical galaxies and its contribution to the X-ray background

Cited by in corpus (8)

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• Extragalactic source contributions to arcminute-scale Cosmic Microwave Background anisotropies
• Accretion flows in early-type galaxies and CMB experiments
• Lyman-alpha forest-CMB cross-correlation and the search for the ionized baryons at high redshift
• Foreground Predictions for the Cosmic Microwave Background Power Spectrum from Measurements of Faint Inverted Radio Sources at 5 GHz