Intensive X-ray/UVOIR continuum reverberation mapping of the Seyfert AGN MCG+08-11-11

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Main Authors: Kynoch, D., McHardy, I. M., Cackett, E. M., Gelbord, J., Santisteban, J. V. Hernández, Horne, K., Miller, J. A., Netzer, H., Done, C., Edelson, R., Fausnaugh, M. M., Goad, M. R., Peterson, B. M., Vincentelli, F. M.
Format: Preprint
Published: 2025
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author Kynoch, D.
McHardy, I. M.
Cackett, E. M.
Gelbord, J.
Santisteban, J. V. Hernández
Horne, K.
Miller, J. A.
Netzer, H.
Done, C.
Edelson, R.
Fausnaugh, M. M.
Goad, M. R.
Peterson, B. M.
Vincentelli, F. M.
author_facet Kynoch, D.
McHardy, I. M.
Cackett, E. M.
Gelbord, J.
Santisteban, J. V. Hernández
Horne, K.
Miller, J. A.
Netzer, H.
Done, C.
Edelson, R.
Fausnaugh, M. M.
Goad, M. R.
Peterson, B. M.
Vincentelli, F. M.
contents We present results from intensive (x3 daily), three-month-long X-ray, UV and optical monitoring of the bright Seyfert active galactic nucleus (AGN) MCG+08-11-11 with Swift, supported by optical-infrared ground-based monitoring. The 12 resultant, well-sampled, lightcurves are highly correlated; in particular, the X-ray to UV correlation r_max = 0.85 is, as far as we know, the highest yet recorded in a Seyfert galaxy. The lags increase with wavelength, as expected from reprocessing of central high-energy emission by surrounding material. Our lag spectrum is much shallower than that obtained from an optical monitoring campaign conducted a year earlier when MCG+08-11-11 was approximately 4 times brighter. After filtering out long-term trends in the earlier optical lightcurves we recover shorter lags consistent with our own - demonstrating concurrent reverberation signals from different spatial scales and the luminosity dependence of the measured lags. We use our lag spectrum to test several physical models, finding that disc reprocessing models cannot account for the observed 'excess' lags in the u and r-i-bands that are highly indicative of the Balmer and Paschen continua produced by reprocessing in the broad line region (BLR) gas. The structure seen in both the variable (rms) and lag spectra, and the large time delay between X-ray and UV variations (approximately 2 days) all suggest that the BLR is the dominant reprocessor. The hard X-ray spectrum (Gamma approximately 1.7) and faint, red, UV-optical spectrum both indicate that the Eddington accretion ratio is low: approximately 0.03. The bolometric luminosity then requires that the black hole mass is substantially greater than current reverberation mapping derived estimates.
format Preprint
id arxiv_https___arxiv_org_abs_2511_05342
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Intensive X-ray/UVOIR continuum reverberation mapping of the Seyfert AGN MCG+08-11-11
Kynoch, D.
McHardy, I. M.
Cackett, E. M.
Gelbord, J.
Santisteban, J. V. Hernández
Horne, K.
Miller, J. A.
Netzer, H.
Done, C.
Edelson, R.
Fausnaugh, M. M.
Goad, M. R.
Peterson, B. M.
Vincentelli, F. M.
Astrophysics of Galaxies
We present results from intensive (x3 daily), three-month-long X-ray, UV and optical monitoring of the bright Seyfert active galactic nucleus (AGN) MCG+08-11-11 with Swift, supported by optical-infrared ground-based monitoring. The 12 resultant, well-sampled, lightcurves are highly correlated; in particular, the X-ray to UV correlation r_max = 0.85 is, as far as we know, the highest yet recorded in a Seyfert galaxy. The lags increase with wavelength, as expected from reprocessing of central high-energy emission by surrounding material. Our lag spectrum is much shallower than that obtained from an optical monitoring campaign conducted a year earlier when MCG+08-11-11 was approximately 4 times brighter. After filtering out long-term trends in the earlier optical lightcurves we recover shorter lags consistent with our own - demonstrating concurrent reverberation signals from different spatial scales and the luminosity dependence of the measured lags. We use our lag spectrum to test several physical models, finding that disc reprocessing models cannot account for the observed 'excess' lags in the u and r-i-bands that are highly indicative of the Balmer and Paschen continua produced by reprocessing in the broad line region (BLR) gas. The structure seen in both the variable (rms) and lag spectra, and the large time delay between X-ray and UV variations (approximately 2 days) all suggest that the BLR is the dominant reprocessor. The hard X-ray spectrum (Gamma approximately 1.7) and faint, red, UV-optical spectrum both indicate that the Eddington accretion ratio is low: approximately 0.03. The bolometric luminosity then requires that the black hole mass is substantially greater than current reverberation mapping derived estimates.
title Intensive X-ray/UVOIR continuum reverberation mapping of the Seyfert AGN MCG+08-11-11
topic Astrophysics of Galaxies
url https://arxiv.org/abs/2511.05342