Program: GS-2018B-Q-127

Title:Optical Follow-Up Observations for IceCube High-Energy Neutrino Sources
PI:Tomoki Morokuma
Co-I(s): Shigeru Yoshida, Herman Lee, Nozomu Tominaga, Kouji Ohta, Koji Kawabata, Masaomi Tanaka, Masayuki Yamanaka, Yousuke Utsumi, Yoshiyuki Inoue, Shigehiro Nagataki, Michitoshi Yoshida, Ryosuke Itoh

Abstract

We here propose 3-night ToO observations for identifying optical counterparts of IceCube high-energy TeV-PeV neutrino sources. Identification and characterization of electromagnetic counterparts of high-energy neutrinos provide unique information about cosmic-ray acceleration mechanisms and their acceleration sites. Recent observational results (HESE-35 and IceCube-170922A) indicate that relativistic jets associated with AGN, blazars, are their sources. Considering the incompleteness of the previous blazar catalogs (BZCAT, Fermi blazars), deep optical imaging surveys over the entire error region (~0.8 deg radius) are required and deep and wide HSC observations would provide unique and effective dataset. Even if a plausible counterpart is (luckily) a bright source, there is a blazar population of BL Lac type objects showing featureless continuum with very weak emission and/or absorption lines. This also requires deep spectroscopy with 8-m class telescopes as done for the IceCube-170922A counterpart TXS 0506+056. Then, we consider multiple ToO observing strategies which include (1) a search for candidates with Subaru/HSC and (2) spectroscopic/photometric characterization of the candidates with other Subaru/Gemini instruments.

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