A multi-frequency study of the SZE in giant radio galaxies

Abstract

Radio-galaxy (RG) lobes contain relativistic electrons embedded in a tangled magnetic field that produce, in addition to low-frequency synchrotron radio emission, inverse-Compton scattering (ICS) of the cosmic microwave background (CMB) photons. This produces a relativistic, non-thermal Sunyaev-Zel'dovich effect (SZE). We study the spectral and spatial properties of the non-thermal SZE in a sample of radio galaxies and make predictions for their detectability in both the negative and the positive part of the SZE, with space experiments like Planck, OLIMPO, and Herschel-SPIRE. These cover a wide range of frequencies, from radio to sub-mm. We model the SZE in a general formalism that is equivalent to the relativistic covariant one and describe the electron population contained in the lobes of the radio galaxies with parameters derived from their radio observations, namely, flux, spectral index, and spatial extension. We further constrain the electron spectrum and the magnetic field of the RG lobes using X-ray, gamma-ray, and microwave archival observations. We determine the main spectral features of the SZE in RG lobes, namely, the minimum, the crossover, and the maximum of the SZE. We show that these typical spectral features fall in the frequency ranges probed by the available space experiments. We provide the most reliable predictions for the amplitude and spectral shape of the SZE in a sample of selected RGs with extended lobes. In three of these objects, we also derive an estimate of the magnetic field in the lobe at the muG level by combining radio (synchrotron) observations and X-ray (ICS) observations. These data, together with the WMAP upper limits, set constraints on the minimum momentum of the electrons residing in the RG lobes and allow realistic predictions for the visibility of their SZE to be derived with Planck, OLIMPO, and Herschel-SPIRE. [abridged]

26 pages, 21 figures; Astronomy and Astrophysics, in press

References in corpus (10)

• The Herschel-SPIRE instrument and its in-flight performance
• Heating Hot Atmospheres with Active Galactic Nuclei
• Fermi Gamma-ray Imaging of a Radio Galaxy
• Planck early results: first assessment of the High Frequency Instrument in-flight performance
• Discovery of the low-energy cutoff in a powerful giant radio galaxy
• Extended inverse-Compton emission from distant, powerful radio galaxies
• Ordered magnetic fields around radio galaxies: evidence for interaction with the environment
• SZ effect from radio-galaxy lobes: astrophysical and cosmological relevance
• The energetics of giant radio galaxy lobes from inverse Compton scattering observations
• The X-ray and radio-emitting plasma lobes of 4C23.56: further evidence of recurrent jet activity and high acceleration energies

Cited by in corpus (8)

• CCAT-prime Collaboration: Science Goals and Forecasts with Prime-Cam on the Fred Young Submillimeter Telescope
• Optical and radio properties of extragalactic radio sources with recurrent jet activity
• Large-scale jets from active galactic nuclei as a source of ICM heating: cavities and shocks
• The correlation between radio power and Mach number for radio relics in galaxy clusters
• Is the radio emission in the Bullet cluster due to Dark Matter annihilation?
• Relativistic inverse Compton scattering of photons from the early universe
• Non-thermal Sunyaev-Zeldovich signal from radio galaxy lobes
• Constraining the average magnetic field in galaxy clusters with current and upcoming CMB surveys