VODKA: Complex molecular gas dynamics in a kpc-separation z=2.17 dual quasar with ALMA

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Main Authors: Ishikawa, Yuzo, Zakamska, Nadia L., Chen, Yu-Ching, Shen, Yue, Liu, Xin, Vayner, Andrey, Hwang, Hsiang-Chih, Sankar, Swetha, Gross, Arran
Format: Preprint
Published: 2025
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author Ishikawa, Yuzo
Zakamska, Nadia L.
Chen, Yu-Ching
Shen, Yue
Liu, Xin
Vayner, Andrey
Hwang, Hsiang-Chih
Sankar, Swetha
Gross, Arran
author_facet Ishikawa, Yuzo
Zakamska, Nadia L.
Chen, Yu-Ching
Shen, Yue
Liu, Xin
Vayner, Andrey
Hwang, Hsiang-Chih
Sankar, Swetha
Gross, Arran
contents In galaxy mergers, dual quasars - two actively accreting supermassive black holes (SMBHs) - provide a unique opportunity to study the interplay between galaxy dynamics and quasar activity. However, very little is known about their molecular gas, which fuels star formation and quasar activity. In this study, we map the kinematics of the cold molecular gas in J0749+2255, a 3.8 kpc separation dual quasar at z=2.17 using the Atacama Large Millimeter Array (ALMA) Band 4. We detect CO(4-3)650um, which shows remarkably complex morphological and kinematic structures. While the integrated CO map suggested a lens-like ring, this feature disappears with kinematic decomposition. The kinematic analysis with ALMA resolves the ambiguities introduced by previous observations, further supporting the dual quasar interpretation of J0749+2255. We find two kinematically distinct molecular gas components: spatially extended, yet dynamically complex slow-moving gas (FWHM~130 km/s), and a compact, blueshifted, fast-moving, turbulent gas (FWHM~300 km/s). The disturbed kinematics, likely driven by the merger, show hints of rotation but no molecular outflows, suggesting circumnuclear flows. We estimate a large molecular gas reservoir ($M_{H2}\sim10^{10} M_{\odot}$), yet the starburst activity appears to exceed the available fuel. We detect an extended continuum in excess at rest-frame 455 GHz. The kinematic complexity of CO implicates the connection of mergers on the starburst and quasar activity in J0749+2255, yet whether J0749+2255 represents the dual quasar population remains unclear. Targeted kinematic studies of larger dual quasar samples will be essential to disentangling the nature of dual quasars.
format Preprint
id arxiv_https___arxiv_org_abs_2502_05327
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle VODKA: Complex molecular gas dynamics in a kpc-separation z=2.17 dual quasar with ALMA
Ishikawa, Yuzo
Zakamska, Nadia L.
Chen, Yu-Ching
Shen, Yue
Liu, Xin
Vayner, Andrey
Hwang, Hsiang-Chih
Sankar, Swetha
Gross, Arran
Astrophysics of Galaxies
In galaxy mergers, dual quasars - two actively accreting supermassive black holes (SMBHs) - provide a unique opportunity to study the interplay between galaxy dynamics and quasar activity. However, very little is known about their molecular gas, which fuels star formation and quasar activity. In this study, we map the kinematics of the cold molecular gas in J0749+2255, a 3.8 kpc separation dual quasar at z=2.17 using the Atacama Large Millimeter Array (ALMA) Band 4. We detect CO(4-3)650um, which shows remarkably complex morphological and kinematic structures. While the integrated CO map suggested a lens-like ring, this feature disappears with kinematic decomposition. The kinematic analysis with ALMA resolves the ambiguities introduced by previous observations, further supporting the dual quasar interpretation of J0749+2255. We find two kinematically distinct molecular gas components: spatially extended, yet dynamically complex slow-moving gas (FWHM~130 km/s), and a compact, blueshifted, fast-moving, turbulent gas (FWHM~300 km/s). The disturbed kinematics, likely driven by the merger, show hints of rotation but no molecular outflows, suggesting circumnuclear flows. We estimate a large molecular gas reservoir ($M_{H2}\sim10^{10} M_{\odot}$), yet the starburst activity appears to exceed the available fuel. We detect an extended continuum in excess at rest-frame 455 GHz. The kinematic complexity of CO implicates the connection of mergers on the starburst and quasar activity in J0749+2255, yet whether J0749+2255 represents the dual quasar population remains unclear. Targeted kinematic studies of larger dual quasar samples will be essential to disentangling the nature of dual quasars.
title VODKA: Complex molecular gas dynamics in a kpc-separation z=2.17 dual quasar with ALMA
topic Astrophysics of Galaxies
url https://arxiv.org/abs/2502.05327