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Published September 25, 2018 | Submitted
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Inter-comparison of Radio-Loudness Criteria for Type 1 AGNs in the XMM-COSMOS Survey

Abstract

Limited studies have been performed on the radio-loud fraction in X-ray selected type 1 AGN samples. The consistency between various radio-loudness definitions also needs to be checked. We measure the radio-loudness of the 407 type 1 AGNs in the XMM-COSMOS quasar sample using nine criteria from the literature (six defined in the rest-frame and three defined in the observed frame): R_L = log(L_(5GHz)/L_B), q_(24) = log(L_(24μm)/L_(1.4GHz)), R_(uv) = log(L_(5GHz)/L _(2500°A)), R_i = log(L_(1.4GHz)/L_i), R_X = log(νL_ν (5GHz)/L_X), P_(5GHz) = log(P_(5GHz)(W/Hz/Sr)), R_(L,obs) = log(f_(1.4GHz)/f_B) (observed frame), R_(i,obs) = log(f_(1.4GHz)/f_i) (observed frame), and q_(24,obs) = log(f_(24μm)/f_(1.4GHz)) (observed frame). Using any single criterion defined in the rest-frame, we find a low radio-loud fraction of ≲5% in the XMM-COSMOS type 1 AGN sample, except for R_(uv). Requiring that any two criteria agree reduces the radio-loud fraction to ≲2% for about 3/4 of the cases. The low radio-loud fraction cannot be simply explained by the contribution of the host galaxy luminos ity and reddening. The P_(5GHz) = log(P_(5GHz)(W/Hz/Sr)) gives the smallest radio-loud fraction. Two of the three radio-loud fractions from the criteria defined in the observed frame without k-correction (R_(L,obs) and R_(i,obs)) are much larger than the radio-loud fractions from other criteria.

Additional Information

HH thank Belinda Wilkes for useful discussion. This work was supported in part by NASA Chandra grant number G07-8136A (HH, ME, CV). LCH acknowledges support from the Kavli Foundation, Peking University, and the Chinese Academy of Science through grant No. XDB09030100 (Emergence of Cosmological Structures) from the Strategic Priority Research Program. Support from the Italian Space Agency (ASI) under the contracts ASI-INAF I/088/06/0 and I/009/10/0 is acknowledged (AC and CV). MS acknowledges support by the German Deutsche Forschungsgemeinschaft, DFG Leibniz Prize (FKZ HA 1850/28-1). KS gratefully acknowledges support from Swiss National Science Foundation Grant PP00P2 138979/1.

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Additional details

Created:
August 22, 2023
Modified:
October 18, 2023