The AT20G view of Swift/BAT selected AGN: high-frequency radio waves meet hard X-rays

Abstract

We cross-matched the 6-year Swift/Burst Alert Telescope (BAT) survey of active galactic nuclei (AGN) with the AT20G radio survey of the southern sky, which is one of the largest high-frequency radio surveys available. With these data we investigated the possible correlation between the radio and the X-ray emission at the highest radio and X-ray frequencies. We found 37 AGN with a high probability of association (>80 per cent), among which 19 are local Seyfert galaxies (with median redshift z = 0.03) and 18 blazars. We found that \approx 20 per cent of the AGN detected in hard X-rays are also bright radio sources at 20 GHz, but the apparent correlation between the radio and hard X-ray luminosity is completely driven by the different median redshifts of the two subgroups of AGN. When we consider only the local Seyfert sample we find no evidence of a correlation between their 20 GHz and 15-55 keV power. Therefore it appears that at high frequencies the radio-X connection, which had been previously observed at lower frequencies, disappears. The disappearance of the radio-X correlation at high radio and X-ray frequencies could be tested through Very Long Baseline Interferometry and the use of the Nuclear Spectroscopic Telescope Array (NuSTAR) satellite.

MNRAS accepted (21 Feb 2013). 10 pages, 7 figures, 2 tables

References in corpus (15)

• An XMM-Newton survey of broad iron lines in Seyfert galaxies
• Roma-BZCAT: A multifrequency catalogue of Blazars
• Swift BAT Survey of AGN
• The Molonglo Galactic Plane Survey (MGPS-2): Compact Source Catalogue
• The Radio-Loud Fraction of Quasars is a Strong Function of Redshift and Optical Luminosity
• The X-ray and Radio Connection in Low-luminosity Active Nuclei
• Unveiling the nature of INTEGRAL objects through optical spectroscopy. VI. A multi-observatory identification campaign
• The cosmological properties of AGN in the XMM-Newton Hard Bright Survey
• The Australia Telescope 20 GHz (AT20G) Survey: The Bright Source Sample
• BAT X-ray Survey - III: X-ray Spectra and Statistical Properties
• Unveiling the nature of INTEGRAL objects through optical spectroscopy. VII. Identification of 20 Galactic and extragalactic hard X-ray sources
• The black hole fundamental plane from a uniform sample of radio and X-ray emitting broad line AGNs
• Radio Properties of Low Redshift Broad Line Active Galactic Nuclei
• BAT X-ray Survey - I: Methodology and X-ray Identification
• Wide-Field Imaging and Polarimetry for the Biggest and Brightest in the 20GHz Southern Sky

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• BAT AGN Spectroscopic Survey - V. X-ray properties of the Swift/BAT 70-month AGN catalog
• The 1.4 GHz radio properties of hard X-ray selected AGN
• BAT AGN Spectroscopic Survey -- XV: The High Frequency Radio Cores of Ultra-hard X-ray Selected AGN
• BAT AGN Spectroscopic Survey -- XVII: The Parsec-scale Jet Properties of the Ultra Hard X-ray Selected Local AGN
• On the significance of relativistically hot pairs in the jets of FR II radio galaxies
• Possible Evidence of a Universal Radio/X-ray Correlation in a near-Complete Sample of Hard X-ray Selected Seyfert Galaxies
• Hard - X-rays selected Active Galactic Nuclei. I. A radio view at high-frequencies
• BASS XLVII: 22 GHz Radio Atlas of Swift-BAT Selected AGN
• ALMA polarimetry of radio-quiet AGNs