Visit ASIAA Homepage Registration Deadline: November 27, 2019 (Taiwan Time)
East-Asian ALMA Science Workshop 2019
February 19(Wed)-21(Fri), 2020
ASIAA, Taipei, Taiwan

Poster Presentation

The radio-loud fraction of low-luminosity HSC quasars at z~6

Author(s): Kianhong Lee (U. Tokyo), Kotaro Kohno, Yoshiki Matsuoka, Tohru Nagao, Michael Strauss, Bunyo Hatsukade, Hideki Umehata, Takuma Izumi, Malte Schramm, Yoshiki Toba, Takuji Yamashita, Chien-Hsiu Lee, Masafusa Onoue, Masatoshi Imanishi, Toshihiro Kawaguchi

Presenter: Kianhong Lee (The University of Tokyo)

To constrain the radio-loud fraction of accreting SMBHs in the early universe, we conduct new radio observations of 23 low-luminosity (rest-frame ultraviolet luminosity M_1450 >-25 mag) quasars at z~6 with the Karl G. Jansky Very Large Array (JVLA) at 1.4 GHz. Our quasar sample is discovered with Subaru/HSC, lying at the faint-end of quasar luminosity function at z~6. The sensitivity of our observations (1 sigma~10-50 uJy) is about 3-10 times deeper than that of the VLA-FIRST survey. The radio luminosity (rest-frame 5 GHz) of 23 quasars is all lower than 10^25.5 W/Hz and we constrain the radio-loudness of 21 quasars to R=f_5GHz/f_4400 <100. This implies that the radio-loud fraction of low-luminosity quasars is lower than that of luminous ones, which is consistent with previous studies. And our median stacking image (1 sigma~5 uJy) constrains the mean radio-loudness of our sample to R<11. Combining with the IR luminosity derived from ALMA continuum observations of HSC quasars, we constrain their q value to >1.5.

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