NOAO >   Observing Info >   Approved Programs >   2002A-0205

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Proposal Information for 2002A-0205


PI: Masayuki Akiyama, National Astronomical Observatory of Japan, akiyama@subaru.naoj.org
Address: 650 North A'ohoku Place, Hilo, HI 96720, US

CoI: Kouji Ohta, Department of Astronomy, Kyoto University
CoI: Yoshihiro Ueda, ISAS
CoI: Toru Yamada, NAOJ

Title: Fraction of Red QSOs in Hard X-ray Selected Samples

Abstract: In order to examine fraction of red QSOs in hard X-ray selected samples, we propose near infrared (J-, H-, and K-bands) photometric observations of 51 AGNs detected in the \it ASCA Large Sky Survey and Medium Sensitivity Survey. Recently, many candidates of red absorbed QSOs are found in QSO surveys in radio, X-ray, and near- infrared wavelengths. The discoveries of large number of the red QSO populations imply that we have been missing significant fraction of nucleus with high activity in traditional optical/UV-selections of QSOs, due to absorption to the nucleus. However, the fraction of the red absorbed QSO in the entire QSO population is not clear yet, because of contamination by a red synchrotron component in a radio-loud QSO and biases of soft X-ray selections against heavily absorbed QSOs. A sample of hard X-ray selected QSOs is one of the best sample to examine the fraction of red absorbed QSOs. The number of QSOs with red J-K color in the \it ASCA hard X-ray selected QSO samples will tell us whether the fraction of red absorbed QSO is large (~50%) or not (\le10%). The \it ASCA samples are fairly complete and appropriate for study of luminous absorbed QSO population in the intermediate redshift universe in comparison with faint \it Chandra and \it XMM- Newton samples.


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