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H2O maser emission from the Seyfert 2 galaxy IC 2560: evidence for a super-massive black hole and a probe for mass-accretion rate

Published online by Cambridge University Press:  03 August 2017

Yuko Ishihara ,
Naomasa Nakai ,
Naoko Iyomoto ,
Kazuo Makishima ,
Phil Diamond  and
Peter Hall
Yuko Ishihara
Affiliation:
Nobeyama Radio Observatory, Minamimaki Minamisaku, Nagano 384-1305, Japan
Naomasa Nakai
Affiliation:
Nobeyama Radio Observatory, Minamimaki Minamisaku, Nagano 384-1305, Japan
Naoko Iyomoto
Affiliation:
Department of Physics, The University of Tokyo, 7-3-1 Hongo Bunkyo, Tokyo 113-0033, Japan
Kazuo Makishima
Affiliation:
Department of Physics, The University of Tokyo, 7-3-1 Hongo Bunkyo, Tokyo 113-0033, Japan
Phil Diamond
Affiliation:
Jodrell Bank Observatory, University of Manchester, Macclesfield, Cheshire SK11 9DL, UK
Peter Hall
Affiliation:
Australia Telescope National Facility, CSIRO, PO Box 76 Epping, NSW 1710, Australia

Abstract

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Our observations of H2O masers have detected some high-velocity features and a secular velocity drift of the systemic features in the Seyfert 2 Galaxy IC 2560. The high-velocity features were blue- and red-shifted from the systemic velocity of 220-420 km s−1 and 210-350 km s−1, respectively. The velocity of the systemic features drifted at a secular rate of 2.62 km s−1 yr−1. Assuming the existence of a compact rotating disk as in NGC 4258, IC 2560 possesses a nuclear disk with inner and outer radii of 0.07 pc and 0.26 pc, respectively, and a confined mass of 2.8 × 106M⊙ at the center, making the central density > 2.1 × 109M⊙ pc−3. Such a dense object cannot be a cluster of stars, and this strongly suggests that the central mass is a super-massive black hole. Since the 2-10 keV luminosity of IC 2560 is 1 × 1041 erg s−1, the mass accretion rate of the suggested black hole must be 2 × 10−5M⊙ yr−1.

Type
Part 5. Extragalactic Nuclear Masers
Information
Symposium - International Astronomical Union , Volume 206: Cosmic Masers: From Protostars to Blackholes , 2002 , pp. 400 - 403
Copyright
Copyright © Astronomical Society of the Pacific 2002 

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