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Compact Dust Emission in a Gravitationally Lensed Massive Quiescent Galaxy at z = 2.15 Revealed in ∼130 pc Resolution Observations by the Atacama Large Millimeter/submillimeter Array

Morishita, T. and Hirashita, H. and Newman, A. B. and Stiavelli, M. and Chiaberge, M. (2022) Compact Dust Emission in a Gravitationally Lensed Massive Quiescent Galaxy at z = 2.15 Revealed in ∼130 pc Resolution Observations by the Atacama Large Millimeter/submillimeter Array. Astrophysical Journal, 938 (2). Art. No. 144. ISSN 0004-637X. doi:10.3847/1538-4357/ac9055.

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We present new observations of MRG-M2129, a quiescent galaxy at z = 2.15, with the Atacama Large Millimeter/submillimeter Array (ALMA). With the combination of the effect of gravitational lensing by the foreground galaxy cluster and the angular resolution provided by ALMA, our data reveal 1.2 mm continuum emission at ∼130 pc angular resolution. Compact dust continuum is detected at 7.9σ in the target but displaced from its stellar peak position by 62 ± 38 mas, or ∼169 ± 105 pc in the source plane. We find a considerably high dust-to-stellar mass ratio, 4 × 10⁻⁴. From nondetection of the [C i] ³P₂ → ³P₁ line, we derive 3σ upper limits on the molecular gas-to-dust mass ratio δ_(GDR) < 60 and the molecular gas-to-stellar mass ratio f_(H2) < 2.3%. The derived δ_(GDR) is ≳2× smaller than the typical value assumed for quiescent galaxies in the literature. Our study supports the idea that there exists a broad range of δ_(GDR) and urges submillimeter follow-up observations of quenching/recently quenched galaxies at similar redshifts. Based on the inferred low δ_(GDR) and other observed properties, we argue that the central black hole is still active and regulates star formation in the system. Our study exhibits a rare case of a gravitationally lensed type 2 QSO harbored by a quiescent galaxy.

Item Type:Article
Related URLs:
URLURL TypeDescription
Morishita, T.0000-0002-8512-1404
Hirashita, H.0000-0002-4189-8297
Newman, A. B.0000-0001-7769-8660
Stiavelli, M.0000-0001-9935-6047
Chiaberge, M.0000-0003-1564-3802
Additional Information:We would like to thank the anonymous referee for providing constructive comments and suggestions, which improved the manuscript significantly. We are grateful to Katherine Whitaker for kindly providing their flux and dust mass measurements of MRG-M2129 presented in Whitaker et al. (2021a) and for helpful discussion. We are grateful to Dan Coe for his suggestions on our proposal planning. T.M. is grateful to George Helou, Andreas Faisst, Paul Goudfrooij, Seppo Laine, Matthew Malkan, and Colin Norman for their insightful comments on our findings. We are grateful to Justin Spilker and Ian Smail for their comments on the paper draft. This paper makes use of the following ALMA data: ADS/JAO.ALMA#2021.1.00847.S, 2016.1.01591.S, 2018.1.00035.L, and 2018.1.00276.S. ALMA is a partnership of ESO (representing its member states), NSF (USA) and NINS (Japan), together with NRC (Canada), MOST and ASIAA (Taiwan), and KASI (Republic of Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO, and NAOJ. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. Support for this study was provided by NASA through a grant HST-GO-15212 from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.
Group:Infrared Processing and Analysis Center (IPAC)
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Issue or Number:2
Record Number:CaltechAUTHORS:20221031-575177800.17
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:117656
Deposited By: Research Services Depository
Deposited On:09 Nov 2022 18:12
Last Modified:11 Nov 2022 17:38

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