Oral Presentation

Discovery of Narrow-line Seyfert 1-type Quasars at z=2.3-6.0 with PFS-SSP

Author(s): Ayumi Takahashi

Presenter: Ayumi Takahashi (Kanagawa Univ.)

How supermassive black holes and their host galaxies evolve on co-evolutionary cosmological timescales remains one of the fundamental questions in astrophysics. Narrow-line Seyfert1 galaxies are classified as a subclass of AGNs, and more than tens of thousands of objects have been found in the local universe to date. This class is characterized by a narrow permitted line (FWHM of Hβ < 2000 km/s) and a flux ratio ([OIII]/Hβ < 3). It is known that the NLS1-class tend to have low-mass black holes (< 10^8 Msun) and high accretion ratios (> 0.1), and this population will play a critical role in addressing the SMBH-galaxy relation. However, identification of NLS1s uses Hβ lines; thus, z > 0.8 objects have lacked statistical investigation. We searched for NLS1-class objects using Lyα line widths from broad-line sources in AGN targets observed in the initial PFS-SSP survey and identified seven candidates with z > 2.5. We will discuss their physical properties estimated from the PFS spectra. This study serves as a pathfinder for comprehensive studies with larger samples targeting distant NLS1-class objects.