Oral Presentation

Impact of jets at cosmic noon through radio galaxies selected by the gzK selection

Author(s): Seira Kobayashi (Ehime Univ.), Tohru Nagao (Ehime Univ.), Yuta Yamamoto (Ehime Univ.), Mariko Kubo (Kwansei Gakuin Univ.), Hisakazu Uchiyama (Hosei Univ.), Yoshiki Toba (Ritsumeikan Univ.), Kohei Ichikawa (Tohoku Univ.), Akatoki Noboriguchi (Shinsyu Univ.), Kohei Shibata (Ehime Univ.), Taketo Yoshida (Ehime Univ.)

Presenter: Seira Kobayashi (Ehime University)

Understanding how star formation was quenched in massive galaxies is key to understanding galaxy evolution. Radio jets from active galactic nuclei (AGNs) are thought to suppress star formation by heating and/or expelling interstellar gas in their host galaxies. To investigate the role of radio jets on galaxies at cosmic noon, we searched for HzRGs at z ~ 2 by combining deep, wide-field optical, near-infrared, and radio data from Subaru/HSC-SSP, VISTA/VIKING, and FIRST surveys in ~ 291 deg^2. We selected z ~ 2 galaxy candidates using the gzK color selection and matched them with the FIRST radio source catalog. Consequently, a new sample of 52 star-forming and 11 passive radio galaxies was constructed.
We derived physical properties and examined the statistical characteristics of the sample by fitting the spectral energy distribution. We found that the passive radio galaxies likely underwent rapid quenching of star formation, with e-folding times shorter than 1 Gyr. Comparing this result with theoretical expectations suggests that the radio jet is not the primary mechanism to cause this quenching. However, we found that the passive fraction of radio galaxies is higher than that of non-radio galaxies. This suggests that, although jets do not directly quench star formation at z ~ 2, they play a role in regulating or maintaining the suppression of star formation.