| Title | NuSTAR Discovery of Dead Quasar Engine in Arp 187 |
| Authors | Ichikawa, Kohei Kawamuro, Taiki Shidatsu, Megumi Ricci, Claudio Bae, Hyun-Jin Matsuoka, Kenta Shin, Jaejin Toba, Yoshiki Ueda, Junko Ueda, Yoshihiro |
| Affiliation | Tohoku Univ, Frontier Res Inst Interdisciplinary Sci, Sendai, Miyagi 9808578, Japan Tohoku Univ, Astron Inst, Aoba Ku, Sendai, Miyagi 9808578, Japan Natl Astron Observ Japan, 2-21-1 Osawa, Tokyo 1818588, Japan Ehime Univ, Fac Sci, Dept Phys, Matsuyama, Ehime 7908577, Japan Univ Diego Portales, Fac Ingn, Nucleo Astron, Av Ejercito Libertador 441, Santiago, Chile Peking Univ, Kavli Inst Astron & Astrophys, Beijing 100871, Peoples R China Univ Ulsan, Dept Med, Coll Med, Seoul 05505, South Korea Ehime Univ, Res Ctr Space & Cosm Evolut, 2-5 Bunkyo Cho, Matsuyama, Ehime 7908577, Japan Seoul Natl Univ, Dept Phys & Astron, Astron Program, Seoul 151742, South Korea Kyoto Univ, Dept Astron, Sakyo Ku, Kitashirakawa Oiwake Cho, Kyoto 6068502, Japan Acad Sinica, Inst Astron & Astrophys, AS NTU, 11F Astron Math Bldg,1,Sect 4,Roosevelt Rd, Taipei 10617, Taiwan Harvard Smithsonian Ctr Astrophys, 60 Garden St, Cambridge, MA 02138 USA |
| Issue Date | 2019 |
| Publisher | ASTROPHYSICAL JOURNAL LETTERS |
| Abstract | Recent active galactic nucleus (AGN) and quasar surveys have revealed a population showing rapid AGN luminosity variability by a factor of similar to 10. Here we present the most drastic AGN luminosity decline by a factor of greater than or similar to 10(3) constrained by a NuSTAR X-ray observation of the nearby galaxy Arp 187, which is a promising "dead" quasar whose current activity seems quiet but whose past activity of L-bol similar to 10(46) erg s(-1) is still observable at a large scale by its light echo. The obtained upper bound of the X-ray luminosity is log(L2-10 keV/erg s(-1)) < 41.2, corresponding to log(L-bol/erg s(-1)) < 42.5, indicating an inactive central engine. Even if a putative torus model with N-H similar to 1.5 x 10(24) cm(-2) is assumed, the strong upper bound still holds with log(L2-10 keV/erg s(-1)) < 41.8 or log(L-bol/erg s(-1)) < 43.1. Given the expected size of the narrow-line region, this luminosity decrease by a factor of greater than or similar to 10(3) must have occurred within less than or similar to 10(4) yr. This extremely rapid luminosity/accretion shutdown is puzzling, and it requires one burst-like accretion mechanism producing a clear outer boundary for an accretion disk. We raise two possible scenarios realizing such an accretion mechanism: a mass accretion (1) by the tidal disruption of a molecular cloud and/or (2) by the gas depletion as a result of vigorous nuclear star formation after rapid mass inflow to the central engine. |
| URI | http://hdl.handle.net/20.500.11897/545077 |
| ISSN | 2041-8205 |
| DOI | 10.3847/2041-8213/ab3ebf |
| Indexed | SCI(E) EI |
| Appears in Collections: | 科维理天文与天体物理研究所 |
