NOAO >   Observing Info >   Approved Programs >   2017A-0172

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Program Information for 2017A-0172


PI: Tomoki Morokuma, University of Tokyo, tmorokuma@ioa.s.u-tokyo.ac.jp
Address: Institute of Astronomy, 2-21-1, Osawa, Mitaka, Tokyo 181-0015 Japan

CoI: Nozomu Tominaga, Konan University
CoI: Masaomi Tanaka, NAOJ
CoI: Yuki Taniguchi, University of Tokyo
CoI: Masaki Yamaguchi, University of Tokyo

Title: Measuring Black Hole Masses of Rapidly Variable AGN Candidates

Abstract: We propose optical spectroscopic observations with Blanco-4m COSMOS for short-time (a few hours to a day) variability-selected active galactic nuclei (AGN) probably hosting {it low-mass} active black holes (BHs) as small as $10^{4-6}$~M$_odot$. {it Low-mass} BHs are important building blocks for more massive BH formation in quasars and elliptical galaxies. Considering the small size of the system, {it low- mass} active BHs are expected to show rapid variability (at centers of host galaxies), which can be an effective method to select them as an alternative method to deep X-ray or deep optical spectroscopic observations if we carry out wide-field deep imaging observations with recently developed cameras. We have already succeeded in selecting a few tens of candidates of {it low-mass} active BHs based on our high- cadence (1-hour interval) imaging data obtained with Hyper Suprime-Cam (HSC, 1.77~deg$^{2}$ field-of-view) on the 8.2-m Subaru telescope and spectroscopically identifying one of the candidates with a $2.7times10^{6}$~M$_odot$ BH at $z=0.164$. In this proposal, we take spectra of 10 candidates to (1) measure the redshifts, (2) measure the H$alpha$ emission line widths to measure the BH masses, and (3) establish this new effective method to construct a sample of {it low- mass} active BHs. This method with Subaru HSC enables us to conduct the {it deepest} (i.e. effective for {it lowest-mass} active BHs) survey before 8m-class wide-field spectrograph like the Prime Focus Spectrograph on the Subaru telescope is available in several years.

Program Type: Standard/Extragalactic

Scheduled Nights:
Run 1 (2017A):  KP-4m/KOSMOS -- 4n on Jul 21 - Jul 24 2017


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