Title: Dark Energy Survey identification of a low-mass active galactic nucleus at redshift 0.823 from optical variability

Abstract

Herein we report the identification of a low-mass active galactic nucleus (AGN), DES J0218–0430, in a redshift $$z$$ = 0.823 galaxy in the Dark Energy Survey (DES) Supernova field. We select DES J0218–0430 as an AGN candidate by characterizing its long-term optical variability alone based on DES optical broad-band light curves spanning over 6 yr. An archival optical spectrum from the fourth phase of the Sloan Digital Sky Survey shows both broad MgII and broad H$$β$$ lines, confirming its nature as a broad-line AGN. Archival XMM–Newton X-ray observations suggest an intrinsic hard X-ray luminosity of $$L_{{\rm 2-12\, keV}}\approx 7.6\pm 0.4\times 10^{43}$$ erg s^–1, which exceeds those of the most X-ray luminous starburst galaxies, in support of an AGN driving the optical variability. Based on the broad H$$β$$ from SDSS spectrum, we estimate a virial black hole (BH) mass of $$M_• ≈ 10^{6.43}–10^{6.72}M_⊙$$ (with the error denoting the systematic uncertainty from different calibrations), consistent with the estimation from OzDES, making it the lowest mass AGN with redshift > 0.4 detected in optical. We estimate the host galaxy stellar mass to be $$M_* ≈ 10^{10.5 ± 0.3} M_⊙$$ based on modelling the multiwavelength spectral energy distribution. DES J0218–0430 extends the $$M_•–M_*$$ relation observed in luminous AGNs at $z ~ 1$ to masses lower than being probed by previous work. Our work demonstrates the feasibility of using optical variability to identify low-mass AGNs at higher redshift in deeper synoptic surveys with direct implications for the upcoming Legacy Survey of Space and Time at Vera C. Rubin Observatory.

Authors:

Guo, Hengxiao  ^[1];

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Burke, Colin J.  ^[1];

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Liu, Xin ^[1]; Phadke, Kedar A. ^[2]; Zhang, Kaiwen ^[3]; Chen, Yu-Ching ^[1]; Gruendl, Robert A. ^[1]; Lidman, Christopher ^[4]; Shen, Yue ^[1]; Morganson, Eric ^[5]; Aguena, Michel ^[6]; Allam, Sahar ^[7]; Avila, Santiago ^[8]; Bertin, Emmanuel ^[9]; Brooks, David ^[10]; Rosell, Aurelio Carnero ^[11]; Carollo, Daniela ^[12]; Kind, Matias Carrasco ^[1]; Costanzi, Matteo ^[13]; da Costa, Luiz N. ^[14] more »; De Vicente, Juan ^[11]; Desai, Shantanu ^[15]; Doel, Peter ^[10]; Eifler, Tim F. ^[16]; Everett, Spencer ^[17]; García-Bellido, Juan ^[8]; Gaztanaga, Enrique ^[18]; Gerdes, David W. ^[19]; Gruen, Daniel ^[20]; Gschwend, Julia ^[14]; Gutierrez, Gaston ^[7]; Hinton, Samuel R. ^[21]; Hollowood, Devon L. ^[17]; Honscheid, Klaus ^[22]; James, David J. ^[23]; Kuehn, Kyler ^[24]; Lima, Marcos ^[6]; Maia, Marcio G. ^[14]; Menanteau, Felipe ^[1]; Miquel, Ramon ^[25]; Möller, Anais ^[26]; Ogando, Ricardo C. ^[14]; Palmese, Antonella ^[27]; Paz-Chinchón, Francisco ^[28]; Plazas, Andrés A. ^[29]; Romer, Anita K. ^[30]; Roodman, Aaron ^[31]; Sanchez, Eusebio ^[11]; Scarpine, Vic ^[7]; Schubnell, Michael ^[32]; Serrano, Santiago ^[18]; Smith, Mathew ^[33]; Soares-Santos, Marcelle ^[34]; Sommer, Natalia E. ^[4]; Suchyta, Eric ^[35]; Swanson, Molly C. ^[5]; Tarle, Gregory ^[32]; Tucker, Brad E. ^[4]; Varga, Tamas N. ^[36] « less

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+ Show Author Affiliations

1. Department of Astronomy, University of Illinois at Urbana-Champaign, 1002 W. Green Street, Urbana, IL 61801, USA;National Center for Supercomputing Applications, 1205 West Clark St, Urbana, IL 61801, USA
2. Department of Astronomy, University of Illinois at Urbana-Champaign, 1002 W. Green Street, Urbana, IL 61801, USA
3. Department of Physics, University of Illinois at Urbana-Champaign, 1110 West Green Street, Urbana, IL 61801, USA
4. The Research School of Astronomy and Astrophysics, Australian National University, ACT 2601, Australia
5. National Center for Supercomputing Applications, 1205 West Clark St, Urbana, IL 61801, USA
6. Departamento de Física Matemática, Instituto de Física, Universidade de São Paulo, CP 66318, São Paulo, SP 05314-970, Brazil;Laboratório Interinstitucional de e-Astronomia – LIneA, Rua Gal. José Cristino 77, Rio de Janeiro, RJ 20921-400, Brazil
7. Fermi National Accelerator Laboratory, P. O. Box 500, Batavia, IL 60510, USA
8. Instituto de Fisica Teorica UAM/CSIC, Universidad Autonoma de Madrid, E-28049 Madrid, Spain
9. CNRS, UMR 7095, Institut d’Astrophysique de Paris, F-75014 Paris, France;Institut d’Astrophysique de Paris, Sorbonne Universités, UPMC Univ Paris 06, UMR 7095, F-75014 Paris, France
10. Department of Physics & Astronomy, University College London, Gower Street, London WC1E 6BT, UK
11. Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas (CIEMAT), Madrid, Spain
12. INAF, Astrophysical Observatory of Turin, I-10025 Pino Torinese, Italy
13. INAF– Osservatorio Astronomico di Trieste, via G. B. Tiepolo 11, I-34143 Trieste, Italy;Institute for Fundamental Physics of the Universe, Via Beirut 2, I-34014 Trieste, Italy
14. Laboratório Interinstitucional de e-Astronomia – LIneA, Rua Gal. José Cristino 77, Rio de Janeiro, RJ 20921-400, Brazil;Observatório Nacional, Rua Gal. José Cristino 77, Rio de Janeiro, RJ 20921-400, Brazil
15. Department of Physics, IIT Hyderabad, Kandi, Telangana 502285, India
16. Department of Astronomy/Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721-0065, USA;Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Dr., Pasadena, CA 91109, USA
17. Santa Cruz Institute for Particle Physics, Santa Cruz, CA 95064, USA
18. Institut d’Estudis Espacials de Catalunya (IEEC), E-08034 Barcelona, Spain;Institute of Space Sciences (ICE, CSIC), Campus UAB, Carrer de Can Magrans, s/n, E-08193 Barcelona, Spain
19. Department of Astronomy, University of Michigan, Ann Arbor, MI 48109, USA;Department of Physics, University of Michigan, Ann Arbor, MI 48109, USA
20. Department of Physics, Stanford University, 382 Via Pueblo Mall, Stanford, CA 94305, USA;Kavli Institute for Particle Astrophysics & Cosmology, P. O. Box 2450, Stanford University, Stanford, CA 94305, USA;SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
21. School of Mathematics and Physics, University of Queensland, Brisbane, QLD 4072, Australia
22. Center for Cosmology and Astro-Particle Physics, The Ohio State University, Columbus, OH 43210, USA;Department of Physics, The Ohio State University, Columbus, OH 43210, USA
23. Center for Astrophysics | Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USA
24. Australian Astronomical Optics, Macquarie University, North Ryde, NSW 2113, Australia;Lowell Observatory, 1400 Mars Hill Rd, Flagstaff, AZ 86001, USA
25. Institució Catalana de Recerca i Estudis Avançats, E-08010 Barcelona, Spain;Institut de Física d’Altes Energies (IFAE), The Barcelona Institute of Science and Technology, Campus UAB, E-08193 Bellaterra (Barcelona), Spain
26. Universités Clermont Auvergne, CNRS/IN2P3, LPC, F-63000 Clermont-Ferrand, France
27. Fermi National Accelerator Laboratory, P. O. Box 500, Batavia, IL 60510, USA;Kavli Institute for Cosmological Physics, University of Chicago, Chicago, IL 60637, USA
28. National Center for Supercomputing Applications, 1205 West Clark St, Urbana, IL 61801, USA;Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK
29. Department of Astrophysical Sciences, Princeton University, Peyton Hall, Princeton, NJ 08544, USA
30. Department of Physics and Astronomy, Pevensey Building, University of Sussex, Brighton BN1 9QH, UK
31. Kavli Institute for Particle Astrophysics & Cosmology, P. O. Box 2450, Stanford University, Stanford, CA 94305, USA;SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
32. Department of Physics, University of Michigan, Ann Arbor, MI 48109, USA
33. School of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ, UK
34. Physics Department, Brandeis University, 415 South Street, Waltham, MA 02453, USA
35. Computer Science and Mathematics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
36. Max Planck Institute for Extraterrestrial Physics, Giessenbachstrasse, D-85748 Garching, Germany;Universitäts-Sternwarte, Fakultät für Physik, Ludwig-Maximilians Universität München, Scheinerstr 1, D-81679 München, Germany

Publication Date:

2020-06-23

Research Org.:

SLAC National Accelerator Lab., Menlo Park, CA (United States); Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Univ. of Michigan, Ann Arbor, MI (United States)

Sponsoring Org.:

USDOE Office of Science (SC), High Energy Physics (HEP); Alfred P. Sloan Foundation; National Science Foundation (NSF); USDOE Office of Science (SC), Advanced Scientific Computing Research (ASCR)

Contributing Org.:

DES Collaboration

OSTI Identifier:

1616310

Alternate Identifier(s):

OSTI ID: 1659585; OSTI ID: 1784658

Report Number(s):

arXiv:2003.10457; FERMILAB-PUB-20-103-AE
Journal ID: ISSN 0035-8711; oai:inspirehep.net:1787888; TRN: US2106438

Grant/Contract Number:  

AC02-07CH11359; AST-1715579; SC0019193; AC05-00OR22725

Resource Type:

Accepted Manuscript

Journal Name:

Monthly Notices of the Royal Astronomical Society

Additional Journal Information:

Journal Volume: 496; Journal Issue: 3; Journal ID: ISSN 0035-8711

Publisher:

Royal Astronomical Society

Country of Publication:

United States

Language:

English

Subject:

79 ASTRONOMY AND ASTROPHYSICS; black hole physics; galaxies: active; galaxies: high-redshift; galaxies: nuclei; quasars: general; surveys