We investigate the X-ray properties of the K-band-selected galaxies at redshift 2 < z < 4 by using our deep near-infrared images obtained in the MOIRCS Deep Survey project and the published Chandra X-ray source catalog. 61 X-ray sources with the 2-10 keV luminosity L_X = 10^{42}-10^{44} erg/s are identified with the K-selected galaxies and we found that they are exclusively (90%) associated with the massive objects with stellar mass larger than 10^{10.5} Msun. Our results are consistent with the idea that the M_BH/M_str ratio of the galaxies at z=2-4 is similar to the present-day value. On the other hand, the AGN detection rate among the very massive galaxies with the stellar mass larger than 10^{11} Msun is high, 33% (26/78). They are active objects in the sense that the black-hole mass accretion rate is ~ 1-50% of the Eddington limit if they indeed have similar M_BH/M_str ratio with those observed in the local universe. The active duration in the AGN duty cycle of the high-redshift massive galaxies seems large.
@article{arxiv.0905.3320,
title = {MOIRCS Deep Survey III: Active Galactic Nuclei in Massive Galaxies at z=2-4},
author = {T. Yamada and M. Kajisawa and M. Akiyama and T. Ichikawa and M. Konishi and T. Nishimura and K. Omata and R. Suzuki and I. Tanaka and C. Tokoku and Y. K. Uchimoto and T. Yoshikawa},
journal= {arXiv preprint arXiv:0905.3320},
year = {2009}
}
Comments
33 pages, 12 figures, accepted for publication in ApJ