1. Merging Gas-rich Galaxies That Harbor Low-luminosity Twin Quasars at z = 6.05: A Promising Progenitor of the Most Luminous Quasars
- Author
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Takuma Izumi, Yoshiki Matsuoka, Masafusa Onoue, Michael A. Strauss, Hideki Umehata, John D. Silverman, Tohru Nagao, Masatoshi Imanishi, Kotaro Kohno, Yoshiki Toba, Kazushi Iwasawa, Kouichiro Nakanishi, Mahoshi Sawamura, Seiji Fujimoto, Satoshi Kikuta, Toshihiro Kawaguchi, Kentaro Aoki, and Tomotsugu Goto
- Subjects
Galaxy evolution ,Quasars ,Galaxy mergers ,Galaxy interactions ,Astrophysics ,QB460-466 - Abstract
We present Atacama Large Millimeter/submillimeter Array [C ii ] 158 μ m line and underlying far-IR continuum emission observations (0.″57 × 0.″46 resolution) toward a quasar–quasar pair system recently discovered at z = 6.05. The quasar nuclei (C1 and C2) are faint ( M _1450 ≳ −23 mag), but we detect very bright [C ii ] emission bridging the 12 kpc between the two objects and extending beyond them (total luminosity L _[C _ii _] ≃ 6 × 10 ^9 L _⊙ ). The [C ii ]-based total star formation rate of the system is ∼550 M _⊙ yr ^−1 (the IR-based dust-obscured star formation is ∼100 M _⊙ yr ^−1 ), with a [C ii ]-based total gas mass of ∼10 ^11 M _⊙ . The dynamical masses of the two galaxies are large (∼9 × 10 ^10 M _⊙ for C1 and ∼5 × 10 ^10 M _⊙ for C2). There is a smooth velocity gradient in [C ii ], indicating that these quasars are a tidally interacting system. We identified a dynamically distinct, fast-[C ii ] component around C1: detailed inspection of the line spectrum there reveals the presence of a broad-wing component, which we interpret as the indication of fast outflows with a velocity of ∼600 km s ^−1 . The expected mass-loading factor of the outflows, after accounting for multiphase gas, is ≳2 − 3, which is intermediate between AGN-driven and starburst-driven outflows. Hydrodynamic simulations in the literature predict that this pair will evolve to a luminous ( M _1450 ≲ −26 mag), starbursting (≳1000 M _⊙ yr ^−1 ) quasar after coalescence, one of the most extreme populations in the early Universe.
- Published
- 2024
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