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

Guo, Hengxiao and Burke, C J and Desai, Shantanu and et al, . (2020) Dark Energy Survey identification of a low-mass active galactic nucleus at redshift 0.823 from optical variability. Oxford University Press.

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Abstract

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 Hβ lines, confirming its nature as a broad-line AGN. Archival XMM-Newton X-ray observations suggest an intrinsic hard X-ray luminosity of L2-12 keV ≈ 7.6 ± 0.4 × 1043 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 Hβ from SDSS spectrum, we estimate a virial black hole (BH) mass of M• ≈ 106.43-106.72M_(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 stellarmass to beM* ≈1010.5 ± 0.3M_based on modelling the multiwavelength spectral energy distribution. DES J0218-0430 extends theM•-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. © 2020 Oxford University Press. All rights reserved.

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IITH Creators:

IITH Creators	ORCiD
Desai, Shantanu	http://orcid.org/0000-0002-0466-3288

Item Type:

Other

Additional Information:

Funding for DES Projects has been provided by the U.S. Department of Energy, the U.S. National Science Foundation, the Ministry of Science and Education of Spain, the Science and Technology Facilities Council of the United Kingdom, the Higher Education Funding Council for England, the National Center for Supercomputing Applications at the University of Illinois at Urbana-Champaign, the Kavli Institute of Cosmological Physics at the University of Chicago, the Center for Cosmology and Astro-Particle Physics at the Ohio State University, the Mitchell Institute for Fundamental Physics and Astronomy at Texas A&M University, Financiadora de Estudos e Projetos, Fundac¸ão Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro, Conselho Nacional de Desenvolvimento Científico e Tecnológico and the Ministério da Ciência, Tecnologia e Inovac¸ão, the Deutsche Forschungsgemeinschaft and the Collaborating Institutions in the Dark Energy Survey.

Uncontrolled Keywords:

Active galactic nuclei; Broad bands; Dark energy; Energy surveys; Light curves; Low-mass; Optical spectrum; Optical-; Red shift; Sloan Digital Sky Survey

Subjects:

Physics

Divisions:

Department of Physics

Depositing User:

. LibTrainee 2021

Date Deposited:

28 Oct 2022 04:35

Last Modified:

28 Oct 2022 04:35

URI:

http://raiithold.iith.ac.in/id/eprint/11086