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

Guo, Hengxiao; Burke, Colin J.; Liu, Xin; Phadke, Kedar A.; Zhang, Kaiwen; Chen, Yu-Ching; Gruendl, R. A.; Lidman, C.; Shen, Yue; Morganson, E.; Aguena, M.; Allam, S.; Ávila, S.; Bertin, E.; Rosell, A. Carnero; Carollo, D.; Kind, M. Carrasco; Costanzi, M.; Costa, L. N. da; Vicente, J. De; Desai, S.; Doel, P.; Eifler, T. F.; Everett, S.; García-Bellido, J.; Gaztañaga, E.; Gerdes, D. W.; Gruen, D.; Gschwend, J.; Gutiérrez, G.; Hinton, S. R.; Hollowood, D. L.; Honscheid, K.; James, D. J.; Kuêhn, K.; Lima, M.; Maia, M. A. G.; Menanteau, F.; Miquel, R.; Möller, A.; Ogando, R. L. C.; Palmese, A.; Paz-Chinchón, F.; Plazas, A. A.; Romer, A. K.; Sánchez, E.; Scarpine, V.; Schubnell, M.; Serrano, S.; Smith, M.; Soares-Santos, M.; Sommer, N. E.; Suchyta, E.; Swanson, M. E. C.; Tarlè, G.; Tucker, B.; Varga, T. N.

doi:10.1093/mnras/staa1803

Cited by 9 publications

(7 citation statements)

References 123 publications

(121 reference statements)

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“…Also, by imposing the cut on the variability time-scale, we introduce a selection effect which may reduce the correlation. While based on only 11 data points and the results of Guo et al ( 2020 ), our results may suggest no significant redshift evolution in the M BH -M * scaling relation from redshift z ∼ 1 to z ∼ 0 (see also Ding et al 2020 ;Li et al 2021 ), which is consistent with previous results based on the M BH -σ * relation (e.g. Shen et al 2015 ;Sexton et al 2019 ).…”

Section: Comparison To Host Scaling Relationssupporting

confidence: 91%

“…This is consistent with fig. 7 of Guo et al ( 2020 ), which showed that DES-SN variability selection can only be matched by deep X-ray/radio imaging in the mass-redshift parameter space. In contrast, our technique co v ers a much larger area of the sky, but will miss Type II AGN with variability obscured in the optical.…”

Section: Discussionmentioning

confidence: 99%

“…Our deep-field variability-selected AGNs are at relatively lower mass at a given redshift than previous optically selected AGNs. This can only be matched by deep X-ray/radio imaging (Guo et al 2020 ). This enables a BH mass estimate independent of spectroscopic techniques or via indirect stellar mass estimation using SED fitting, which can suffer from strong model degeneracies or rely on the BHhost scaling relations which are still poorly constrained in dwarf galaxies particularly at high redshift.…”

Section: Variability Analysismentioning

confidence: 99%

“…The selection rates are expected to depend on the sensitivity/photometric precision of the surv e y and the exact selection criteria used (Burke et al 2022 ). Ho we ver, using v ariability as a complementary AGN selection technique to identify dwarf AGNs is a relatively new technique (Baldassare, Geha & Greene 2018 ;Baldassare, Geha & Greene 2020 ;Guo et al 2020 ;Mart ínez-Palomera et al 2020 ;Ward et al 2021a ) In this work, we perform a systematic search for variable AGN using Dark Energy Surv e y (DES; Dark Energy Surv e y Collaboration 2016 ) deep field imaging (Hartley et al 2022 ). We choose the DES deep fields because of the exceptional depth ( g ∼ 24.6), ∼7 d cadence with a total baseline of ∼6 yr, and availability of multiwavelength imaging and spectroscopy.…”

mentioning

confidence: 99%

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Dwarf AGNs from Optical Variability for the Origins of Seeds (DAVOS): insights from the dark energy survey deep fields

Burke

Liu

Shen

et al. 2022

Monthly Notices of the Royal Astronomical Society

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We present a sample of 706, z < 1.5 active galactic nuclei (AGNs) selected from optical photometric variability in three of the Dark Energy Survey (DES) deep fields (E2, C3, and X3) over an area of 4.64 deg2. We construct light curves using difference imaging aperture photometry for resolved sources and non-difference imaging PSF photometry for unresolved sources, respectively, and characterize the variability significance. Our DES light curves have a mean cadence of 7 days, a 6 year baseline, and a single-epoch imaging depth of up to g ∼ 24.5. Using spectral energy distribution (SED) fitting, we find 26 out of total 706 variable galaxies are consistent with dwarf galaxies with a reliable stellar mass estimate (M* < 109.5 M⊙; median photometric redshift of 0.9). We were able to constrain rapid characteristic variability timescales (∼ weeks) using the DES light curves in 15 dwarf AGN candidates (a subset of our variable AGN candidates) at a median photometric redshift of 0.4. This rapid variability is consistent with their low black hole masses. We confirm the low-mass AGN nature of one source with a high S/N optical spectrum. We publish our catalog, optical light curves, and supplementary data, such as X-ray properties and optical spectra, when available. We measure a variable AGN fraction versus stellar mass and compare to results from a forward model. This work demonstrates the feasibility of optical variability to identify AGNs with lower black hole masses in deep fields, which may be more ‘pristine’ analogs of supermassive black hole seeds.

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Section: Comparison To Host Scaling Relationssupporting

confidence: 91%

Section: Discussionmentioning

confidence: 99%

Section: Variability Analysismentioning

confidence: 99%

mentioning

confidence: 99%

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Dwarf AGNs from Optical Variability for the Origins of Seeds (DAVOS): insights from the dark energy survey deep fields

Burke

Liu

Shen

et al. 2022

Monthly Notices of the Royal Astronomical Society

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“…Baldassare et al (2018) demonstrated the capability of SDSS imaging to identify dwarf AGNs using long-term variability. Guo et al (2020) demonstrated the capability of Dark Energy Survey photometry to identify dwarf AGNs at intermediate redshifts of z ∼ 0.8. A dwarf Type I AGN similar to the archetypal example NGC 4395 with SMBH mass of 10 5 M⊙ will vary photometrically at the ∼1 per cent level on a rest-frame timescale of a few days (Kelly et al 2009;Burke et al 2020b).…”

Section: Prospects For Future Surveysmentioning

confidence: 99%

On the AGN Nature of Broad Balmer Emission in Four Low-Redshift Metal-Poor Galaxies

Burke,

Liu,

Chen

et al. 2020

Preprint

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We report on continued, ∼15 year-long, broad Balmer emission lines in three metal-poor dwarf emission-line galaxies selected from Sloan Digital Sky Survey spectroscopy. The persistent luminosity of the broad Balmer emission indicates the galaxies are active galactic nuclei (AGNs) with virial black hole masses of 10 6.4 −10 6.7 M ⊙ . The lack of observed hard X-ray emission and the possibility that the Balmer emission could be due to a long-lived stellar transient motivated additional follow-up spectroscopy. We also identify a previously-unreported blueshifted narrow absorption line in the broad Hα feature in one of the AGNs, indicating an AGN-driven outflow with hydrogen column densities of order 10 17 cm −2 . We also extract light curves from the Catalina Real-Time Transient Survey, Pan-STARRS, and the Zwicky Transient Facility. We detect AGN-like variability in three galaxies, further supporting the AGN scenario. This also suggests the AGNs are not strongly obscured. This sample of galaxies are among the most metal-poor which host an AGN (Z = 0.05 -0.16 Z ⊙ ). We speculate they may be analogues to seed black holes which formed in unevolved galaxies at high redshift. Given the rarity of metal-poor AGNs and small sample size available, we investigate prospects for their identification in future spectroscopic and photometric surveys.

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On the AGN nature of broad balmer emission in four low-redshift metal-poor galaxies

Burke

Liu

Chen

et al. 2021

Monthly Notices of the Royal Astronomical Society

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We report on continued, ∼15 year-long, broad Balmer emission lines in three metal-poor dwarf emission-line galaxies selected from Sloan Digital Sky Survey spectroscopy. The persistent luminosity of the broad Balmer emission indicates the galaxies are active galactic nuclei (AGNs) with virial black hole masses of ∼106.7 − 107.0 M⊙. The lack of observed hard X-ray emission and the possibility that the Balmer emission could be due to a long-lived stellar transient motivated additional follow-up spectroscopy. We also identify a previously-unreported blueshifted narrow absorption line in the broad Hα feature in one of the AGNs, indicating an AGN-driven outflow with hydrogen column densities of order 1017 cm−2. We also extract light curves from the Catalina Real-Time Transient Survey and the Zwicky Transient Facility. We detect probable AGN-like variability in three galaxies, further supporting the AGN scenario. This also suggests the AGNs are not strongly obscured. This sample of galaxies are among the most metal-poor which host an AGN (Z = 0.05 – 0.16 Z⊙). We speculate they may be analogues to seed black holes which formed in unevolved galaxies at high redshift. Given the rarity of metal-poor AGNs and small sample size available, we investigate prospects for their identification in future spectroscopic and photometric surveys.

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

Cited by 9 publications

References 123 publications

Dwarf AGNs from Optical Variability for the Origins of Seeds (DAVOS): insights from the dark energy survey deep fields

Dwarf AGNs from Optical Variability for the Origins of Seeds (DAVOS): insights from the dark energy survey deep fields

On the AGN Nature of Broad Balmer Emission in Four Low-Redshift Metal-Poor Galaxies

On the AGN nature of broad balmer emission in four low-redshift metal-poor galaxies

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