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A 2.5-5 μm spectroscopic study of hard X-ray selected AGNs with AKARI

Published online by Cambridge University Press:  25 July 2014

A. Castro
Affiliation:
Instituto de Astronomía - UNAM, Ensenada, Baja California, México, (mailing address: PO Box 439027, San Diego, CA 92143-9027, USA) email: [email protected]
T. Miyaji
Affiliation:
Instituto de Astronomía - UNAM, Ensenada, Baja California, México, (mailing address: PO Box 439027, San Diego, CA 92143-9027, USA) email: [email protected] University of California, San Diego, Center for Astrophysics and Space Sciences, USA
M. Shirahata
Affiliation:
Japan Aerospace Exploration Agency (JAXA), Sagamihara, Japan
S. Oyabu
Affiliation:
Graduate School of Science, Nagoya University, Nagoya, Japan
D. Clark
Affiliation:
Instituto de Astronomía - UNAM, Ensenada, Baja California, México, (mailing address: PO Box 439027, San Diego, CA 92143-9027, USA) email: [email protected]
K. Ichikawa
Affiliation:
Department of Astronomy, Faculty of Science, Kyoto University, Kyoto, Japan
M. Imanishi
Affiliation:
Subaru Telescope, National Astronomical Observatory of Japan, Hilo, USA
T. Nakagawa
Affiliation:
Japan Aerospace Exploration Agency (JAXA), Sagamihara, Japan
Y. Ueda
Affiliation:
Department of Astronomy, Faculty of Science, Kyoto University, Kyoto, Japan
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Abstract

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We explore the relationships between the 3.3 μm polycyclic aromatic hydrocarbon (PAH) feature and active galactic nucleus (AGN) properties of a sample of 54 hard X-ray selected bright AGNs, including both Seyfert 1 and Seyfert 2 type objects, using the InfraRed Camera (IRC) on board the infrared astronomical satellite AKARI. The sample is selected from the 9-month Swift/BAT survey in the 14-195 keV band and all of them have measured X-ray spectra at E ≲ 10 keV. These X-ray spectra provide measurements of the neutral hydrogen column density (NH) towards the AGNs. We use the 3.3 μm PAH luminosity (L3.3μm) as a proxy for star formation activity and hard X-ray luminosity (L14-195keV) as an indicator of the AGN activity. We searched for possible difference of star-formation activity between type 1 (un-absorbed) and type 2 (absorbed) AGNs. Our regression analysis of log L14-195keV versus log L3.3μm shows a positive correlation and the slope seems steeper for type 1/unobscured AGNs than that of type 2/obscured AGNs. The same trend has been found for the log (L14-195keV/MBH) versus log (L3.3μm/MBH) correlation. Our analysis show that the circum-nuclear star-formation is more enhanced in type 2/absorbed AGNs than type 1/un-absorbed AGNs for low X-ray luminosity/low Eddington ratio AGNs.

Type
Contributed Papers
Copyright
Copyright © International Astronomical Union 2014 

References

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