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Starburst to Quiescent from HST/ALMA: Stars and Dust Unveil Minor Mergers in Submillimeter Galaxies at z ~ 4.5

Gómez-Guijarro, C. and Capak, P. L. (2018) Starburst to Quiescent from HST/ALMA: Stars and Dust Unveil Minor Mergers in Submillimeter Galaxies at z ~ 4.5. Astrophysical Journal, 856 (2). Art. No. 121. ISSN 1538-4357.

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Dust-enshrouded, starbursting, submillimeter galaxies (SMGs) at z ≥ 3 have been proposed as progenitors of z ≥ 2 compact quiescent galaxies (cQGs). To test this connection, we present a detailed spatially resolved study of the stars, dust, and stellar mass in a sample of six submillimeter-bright starburst galaxies at z ~ 4.5. The stellar UV emission probed by HST is extended and irregular and shows evidence of multiple components. Informed by HST, we deblend Spitzer/IRAC data at rest-frame optical, finding that the systems are undergoing minor mergers with a typical stellar mass ratio of 1:6.5. The FIR dust continuum emission traced by ALMA locates the bulk of star formation in extremely compact regions (median r e = 0.70 ± 0.29 kpc), and it is in all cases associated with the most massive component of the mergers (median log(M*/M⊙) = 10.49 ± 0.32). We compare spatially resolved UV slope (β) maps with the FIR dust continuum to study the infrared excess (IRX = L_(IR)/L_(UV))–β relation. The SMGs display systematically higher IRX values than expected from the nominal trend, demonstrating that the FIR and UV emissions are spatially disconnected. Finally, we show that the SMGs fall on the mass–size plane at smaller stellar masses and sizes than the cQGs at z = 2. Taking into account the expected evolution in stellar mass and size between z = 4.5 and z = 2 due to the ongoing starburst and mergers with minor companions, this is in agreement with a direct evolutionary connection between the two populations.

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Gómez-Guijarro, C.0000-0002-4085-9165
Additional Information:© 2018 The American Astronomical Society. Received 2017 November 1; revised 2018 January 16; accepted 2018 February 20; published 2018 March 30. We thank I. Smail for his detailed comments and suggestions that help improve this manuscript; J. M. Simpson for providing the SCUBA2 data; C. Y. Peng and G. Barro for their advice on GALFIT; S. Zibetti for his support with ADAPTSMOOTH; C. M. Casey for providing the DSFG comparison data plotted in Figure 4; and D. Watson, J. Hjorth, I. Davidzon, H. Rhodin, K. K. Knudsen, P. Laursen, D. B. Sanders, M. P. Haynes, R. Pavesi, T. K. D. Leung, and S. Martín-Álvarez for helpful comments and suggestions. We are grateful to the anonymous referee, whose comments have been very useful to improving our work. C.G.G. and S.T. acknowledge support from the European Research Council (ERC) Consolidator Grant funding scheme (project ConTExt, grant number 648179). A.K., E.J.A., and F.B. acknowledge support by the Collaborative Research Centre 956, subproject A1, funded by the Deutsche Forschungsgemeinschaft (DFG). Support for B.M. was provided by the DFG priority program 1573, "The physics of the interstellar medium." D.R. acknowledges support from the National Science Foundation under grant number AST-1614213. V.S. acknowledges support from the European Union's Seventh Framework program under grant agreement 337595 (ERC Starting Grant, "CoSMass"). M.A. acknowledges partial support from FONDECYT through grant 1140099. ERD also acknowledge support by the Collaborative Research Centre 956, subproject C4, funded by the DFG. M.J.M. acknowledges the support of the National Science Centre, Poland, through POLONEZ grant 2015/19/P/ST9/04010; this project has received funding from the European Union's Horizon 2020 research and innovation program under Marie Skłodowska-Curie grant agreement No. 665778. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with program #13294. Support for program #13294 was provided by NASA through a grant from the Space Telescope Science Institute. This research made use of the following ALMA data: ADS/JAO.ALMA#2012.1.00978.S. ALMA is a partnership of the ESO (representing its member states), NSF (USA), and NINS (Japan), together with the NRC (Canada) and NSC and ASIAA (Taiwan), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by the ESO, AUI/NRAO, and NAOJ. This paper employed Astropy, a community-developed core Python package for Astronomy (Astropy Collaboration et al. 2013); APLpy, an open-source plotting package for Python (Robitaille & Bressert 2012); CASA (McMullin et al. 2007); Matplotlib (Hunter 2007); Numpy; Photutils (Bradley et al. 2016); PyBDSF; and R, a language and environment for statistical computing.
Group:COSMOS, Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
European Research Council (ERC)648179
Deutsche Forschungsgemeinschaft (DFG)956
Deutsche Forschungsgemeinschaft (DFG)1573
European Research Council (ERC)337595
Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT)1140099
National Science Centre (Poland)2015/19/P/ST9/04010
Marie Curie Fellowship665778
NASANAS 5-26555
Subject Keywords:galaxies: evolution – galaxies: formation – galaxies: high-redshift – galaxies: interactions – galaxies: ISM – galaxies: starburst
Record Number:CaltechAUTHORS:20180330-103323375
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Official Citation:C. Gómez-Guijarro et al 2018 ApJ 856 121
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:85529
Deposited By: Tony Diaz
Deposited On:30 Mar 2018 19:32
Last Modified:30 Mar 2018 19:32

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