Oral Presentation

Environments around Type-2 Quasars Revealed with HSC-SSP

Author(s): Yuta Suzuki, Yoshiki Matsuoka (Ehime University)

Presenter: Yuta Suzuki (Ehime University)

Type-2 quasars are a population of quasars whose nuclear regions are obscured by gas and dust. They are characterized by strong narrow emission lines without broad lines and continuum emissions from accretion disk. To explain this characteristic, one classical picture suggests it is caused by an observing viewing angle, while another scenario proposes that they are progenitors of unobscured quasars in an evolutionary sequence. If the obscuring material of Type-2 quasars are perpendicular to the sky observed from the Earth, their surrounding fields are divided into “ultraviolet (UV) illuminated” and “UV blocked” regions in tangential directions. Since strong UV radiation suppresses galaxy formation and decreases galaxy density, density of galaxies around Type-2 quasars should exhibit anisotropy. Here, we report on a statistical analysis of Type-2 quasars environments at z~0.3-0.8, using data of Sloan Digital Sky Survey (SDSS) and Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP). We extract more than 100 SDSS Type-2 quasars without radio-emission in the HSC-SSP Wide layer, and investigate galaxy environments around them. Moreover, we examine density of galaxies in different tangential orientation angles. In this talk, we will present these results and discuss them in detail.