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East-Asia AGN Workshop 2019
January 21(Mon)-23(Wed), 2019
ASIAA Auditorium, 1st Floor AS/NTU Astronomy-Mathematics Building

Poster Presentation

"Dual-NB" emitters: A new wide-field search for high-z obscured AGNs

Author(s): Kohei Iwashita (Ehime Univ.), Tohru Nagao (Ehime Univ.), Takuji Yamashita (Ehime Univ.), Akio Inoue (Osaka-Sangyo Univ.), Yoshiaki Ono (Univ. of Tokyo), Masao Hayashi (NAOJ), and the CHORUS collaborators

Presenter: Kohei Iwashita (Ehime University)

We report the initial results of our study about a new method to search for high-z type-2 AGNs by utilizing the HSC NB data. It is important to study SMBHs and their cosmological evolution. For tackling this issue, it is crucial to carry out AGN surveys with a high completeness. However, optical broad-band color selection and variability-based selection are incomplete for obscured (i.e., type-2) AGNs. Sensitive hard X-ray surveys can detect type-2 AGNs, but they are not powerful for systematically survey of type-2 AGNs due to their small survey area.

Here we focus on a combination of two narrow-band filters, NB718 and NB921 equipped on HSC, which is powerful to search for high-z type-2 AGNs systematically, because these filters can detect Ly(alpha) 1216 and CIV1549 of emission-line galaxies at z ~ 4.9. The strong CIV emission is not seen in star-forming galaxies, so we can search for AGNs at z ~ 4.9 by selecting objects that shows flux excesses in both NB718 and NB921. This method should be able to detect also type-2 AGNs, not only type-1 AGNs, since those emission lines arise also from narrow-line regions in AGNs.

We have selected 33 objects which show NB718 and NB921 flux excesses simultaneously, by combining the catalogs of the HSC-SSP and CHORUS projects. The two objects among them show significant r-dropout features, meaning that they are high-z objects. In this poster, we report more detailed method and discussion about the selected dual emitters.

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