Poster Presentation

Discovery of blue-excess dust-obscured galaxies from the Subaru Hyper Suprime-Cam survey

Author(s): A. Noboriguchi, T. Nagao, M. Kajisawa, Y. Matsuoka, Y. Terashima, T. Yamashita, M. Niida (Ehime U.), M. Onoue (MPIA), Y. Ueda, Y. Toba (Kyoto U.), Y. Komiyama (NAOJ), Y. Chang (ASIAA), T. Kawaguchi (Onomichi-city U.), and the HSC-SSP collaboration

Presenter: Akatoki Noboriguchi (Ehime University)

In this presentation, we report our discovery of "blue-excess" dust-obscured galaxies (BluDOGs). DOGs are faint in optical but very bright in mid-infrared (mid-IR), which are powered by active star-formation or AGN, or both. DOGs are believed to be a candidate population that are evolving to quasars from gas-rich mergers. On the other hand, a few hot dust-obscured galaxies (Hot DOGs) whose dust temperatures are higher than usual dust-obscured galaxies show a "blue excess" in optical bands. The blue-excess is thought to be leaked AGN light. However, the nature of this blue-excess feature and the evolutionary picture of BluDOGs are observationally unclear. By combining three multi wavelength catalog of optical (Subaru HSC), near-IR (VIKING), and mid-IR (ALLWISE), we have discovered 571 DOGs. By studying the spectral energy distribution in optical, we found that a few DOGs shows an extremely blue color. The possible origins of this blue excess are the leaked AGN light and/or stellar UV light from a nuclear starburst. We discuss a possibility that
the bluDOGs are in the transition phase from obscured AGNs to unobscured
AGNs.