skip to main content

DOE PAGESDOE PAGES

Title: Space Telescope and Optical Reverberation Mapping Project. VII. Understanding the Ultraviolet Anomaly in NGC 5548 with X-Ray Spectroscopy

During the Space Telescope and Optical Reverberation Mapping Project observations of NGC 5548, the continuum and emission-line variability became decorrelated during the second half of the six-month-long observing campaign. Here we present Swift and Chandra X-ray spectra of NGC 5548 obtained as part of the campaign. The Swift spectra show that excess flux (relative to a power-law continuum) in the soft X-ray band appears before the start of the anomalous emission-line behavior, peaks during the period of the anomaly, and then declines. This is a model-independent result suggesting that the soft excess is related to the anomaly. We divide the Swift data into on- and off-anomaly spectra to characterize the soft excess via spectral fitting. The cause of the spectral differences is likely due to a change in the intrinsic spectrum rather than to variable obscuration or partial covering. The Chandra spectra have lower signal-to-noise ratios, but are consistent with the Swift data. Our preferred model of the soft excess is emission from an optically thick, warm Comptonizing corona, the effective optical depth of which increases during the anomaly. In conclusion, this model simultaneously explains all three observations: the UV emission-line flux decrease, the soft-excess increase, and the emission-line anomaly.
Authors:
; ; ORCiD logo ; ORCiD logo ; ; ORCiD logo ; ; ; ; ORCiD logo ; ; ORCiD logo ; ; ; ORCiD logo ; ; ORCiD logo ; ; ORCiD logo ; ORCiD logo more »; ; ; ; ; ; ; ; ORCiD logo ; ; ORCiD logo ; ; ORCiD logo ; ; ORCiD logo ; ; ; ; ; ; ; ORCiD logo ; ; ; ; ORCiD logo ; ; ORCiD logo ; ; ; ; ; ; ; ORCiD logo ; ORCiD logo ; ; ; ; ORCiD logo ; ; ORCiD logo ; ORCiD logo ; ; ORCiD logo ; ; ; ; ; ; ; ; ORCiD logo ; ORCiD logo ; ; ; ; ; ; ORCiD logo ; ORCiD logo ; ORCiD logo ; ORCiD logo ; ; ; ; ; ; ; ; ORCiD logo ; ; ORCiD logo ; ; ; ; ; ORCiD logo ; ; ; ; ORCiD logo ; ; ; ; ; ; ; ORCiD logo ; ; ; ; ; ORCiD logo ; ; ORCiD logo ; ; ORCiD logo ; ; ORCiD logo ; ORCiD logo ; ; ; ORCiD logo ; ORCiD logo ; ; ; ; ORCiD logo ; ; ORCiD logo ; ; ; ; ORCiD logo ; ; ; ; ; ORCiD logo ; ; ORCiD logo ; ORCiD logo ; ; ; ; ; ; ; ; « less
Publication Date:
Grant/Contract Number:
AC02-76SF00515
Type:
Accepted Manuscript
Journal Name:
The Astrophysical Journal (Online)
Additional Journal Information:
Journal Name: The Astrophysical Journal (Online); Journal Volume: 846; Journal Issue: 1; Journal ID: ISSN 1538-4357
Publisher:
Institute of Physics (IOP)
Research Org:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; galaxies: active; galaxies: individual (NGC 5548); X-rays: galaxies; X-rays: individual (NGC 5548)
OSTI Identifier:
1394071

Mathur, S., Gupta, A., Page, K., Pogge, R. W., Krongold, Y., Goad, M. R., Adams, S. M., Anderson, M. D., Arévalo, P., Barth, A. J., Bazhaw, C., Beatty, T. G., Bentz, M. C., Bigley, A., Bisogni, S., Borman, G. A., Boroson, T. A., Bottorff, M. C., Brandt, W. N., Breeveld, A. A., Brown, J. E., Brown, J. S., Cackett, E. M., Canalizo, G., Carini, M. T., Clubb, K. I., Comerford, J. M., Coker, C. T., Corsini, E. M., Crenshaw, D. M., Croft, S., Croxall, K. V., Dalla Bontà, E., Deason, A. J., Denney, K. D., De Lorenzo-Cáceres, A., De Rosa, G., Dietrich, M., Edelson, R., Ely, J., Eracleous, M., Evans, P. A., Fausnaugh, M. M., Ferland, G. J., Filippenko, A. V., Flatland, K., Fox, O. D., Gates, E. L., Gehrels, N., Geier, S., Gelbord, J. M., Gorjian, V., Greene, J. E., Grier, C. J., Grupe, D., Hall, P. B., Henderson, C. B., Hicks, S., Holmbeck, E., Holoien, T. W. -S., Horenstein, D., Horne, Keith, Hutchison, T., Im, M., Jensen, J. J., Johnson, C. A., Joner, M. D., Jones, J., Kaastra, J., Kaspi, S., Kelly, B. C., Kelly, P. L., Kennea, J. A., Kim, M., Kim, S., Kim, S. C., King, A., Klimanov, S. A., Kochanek, C. S., Korista, K. T., Kriss, G. A., Lau, M. W., Lee, J. C., Leonard, D. C., Li, M., Lira, P., Ma, Z., MacInnis, F., Manne-Nicholas, E. R., Malkan, M. A., Mauerhan, J. C., McGurk, R., McHardy, I. M., Montouri, C., Morelli, L., Mosquera, A., Mudd, D., Muller-Sanchez, F., Musso, R., Nazarov, S. V., Netzer, H., Nguyen, M. L., Norris, R. P., Nousek, J. A., Ochner, P., Okhmat, D. N., Ou-Yang, B., Pancoast, A., Papadakis, I., Parks, J. R., Pei, L., Peterson, B. M., Pizzella, A., Poleski, R., Pott, J. -U., Rafter, S. E., Rix, H. -W., Runnoe, J., Saylor, D. A., Schimoia, J. S., Schnülle, K., Sergeev, S. G., Shappee, B. J., Shivvers, I., Siegel, M., Simonian, G. V., Siviero, A., Skielboe, A., Somers, G., Spencer, M., Starkey, D., Stevens, D. J., Sung, H. -I., Tayar, J., Tejos, N., Turner, C. S., Uttley, P., Van Saders, J., Vestergaard, M., Vican, L., Villanueva Jr., S., Villforth, C., Weiss, Y., Woo, J. -H., Yan, H., Young, S., Yuk, H., Zheng, W., Zhu, W., and Zu, Y.. Space Telescope and Optical Reverberation Mapping Project. VII. Understanding the Ultraviolet Anomaly in NGC 5548 with X-Ray Spectroscopy. United States: N. p., Web. doi:10.3847/1538-4357/aa832b.
Mathur, S., Gupta, A., Page, K., Pogge, R. W., Krongold, Y., Goad, M. R., Adams, S. M., Anderson, M. D., Arévalo, P., Barth, A. J., Bazhaw, C., Beatty, T. G., Bentz, M. C., Bigley, A., Bisogni, S., Borman, G. A., Boroson, T. A., Bottorff, M. C., Brandt, W. N., Breeveld, A. A., Brown, J. E., Brown, J. S., Cackett, E. M., Canalizo, G., Carini, M. T., Clubb, K. I., Comerford, J. M., Coker, C. T., Corsini, E. M., Crenshaw, D. M., Croft, S., Croxall, K. V., Dalla Bontà, E., Deason, A. J., Denney, K. D., De Lorenzo-Cáceres, A., De Rosa, G., Dietrich, M., Edelson, R., Ely, J., Eracleous, M., Evans, P. A., Fausnaugh, M. M., Ferland, G. J., Filippenko, A. V., Flatland, K., Fox, O. D., Gates, E. L., Gehrels, N., Geier, S., Gelbord, J. M., Gorjian, V., Greene, J. E., Grier, C. J., Grupe, D., Hall, P. B., Henderson, C. B., Hicks, S., Holmbeck, E., Holoien, T. W. -S., Horenstein, D., Horne, Keith, Hutchison, T., Im, M., Jensen, J. J., Johnson, C. A., Joner, M. D., Jones, J., Kaastra, J., Kaspi, S., Kelly, B. C., Kelly, P. L., Kennea, J. A., Kim, M., Kim, S., Kim, S. C., King, A., Klimanov, S. A., Kochanek, C. S., Korista, K. T., Kriss, G. A., Lau, M. W., Lee, J. C., Leonard, D. C., Li, M., Lira, P., Ma, Z., MacInnis, F., Manne-Nicholas, E. R., Malkan, M. A., Mauerhan, J. C., McGurk, R., McHardy, I. M., Montouri, C., Morelli, L., Mosquera, A., Mudd, D., Muller-Sanchez, F., Musso, R., Nazarov, S. V., Netzer, H., Nguyen, M. L., Norris, R. P., Nousek, J. A., Ochner, P., Okhmat, D. N., Ou-Yang, B., Pancoast, A., Papadakis, I., Parks, J. R., Pei, L., Peterson, B. M., Pizzella, A., Poleski, R., Pott, J. -U., Rafter, S. E., Rix, H. -W., Runnoe, J., Saylor, D. A., Schimoia, J. S., Schnülle, K., Sergeev, S. G., Shappee, B. J., Shivvers, I., Siegel, M., Simonian, G. V., Siviero, A., Skielboe, A., Somers, G., Spencer, M., Starkey, D., Stevens, D. J., Sung, H. -I., Tayar, J., Tejos, N., Turner, C. S., Uttley, P., Van Saders, J., Vestergaard, M., Vican, L., Villanueva Jr., S., Villforth, C., Weiss, Y., Woo, J. -H., Yan, H., Young, S., Yuk, H., Zheng, W., Zhu, W., & Zu, Y.. Space Telescope and Optical Reverberation Mapping Project. VII. Understanding the Ultraviolet Anomaly in NGC 5548 with X-Ray Spectroscopy. United States. doi:10.3847/1538-4357/aa832b.
Mathur, S., Gupta, A., Page, K., Pogge, R. W., Krongold, Y., Goad, M. R., Adams, S. M., Anderson, M. D., Arévalo, P., Barth, A. J., Bazhaw, C., Beatty, T. G., Bentz, M. C., Bigley, A., Bisogni, S., Borman, G. A., Boroson, T. A., Bottorff, M. C., Brandt, W. N., Breeveld, A. A., Brown, J. E., Brown, J. S., Cackett, E. M., Canalizo, G., Carini, M. T., Clubb, K. I., Comerford, J. M., Coker, C. T., Corsini, E. M., Crenshaw, D. M., Croft, S., Croxall, K. V., Dalla Bontà, E., Deason, A. J., Denney, K. D., De Lorenzo-Cáceres, A., De Rosa, G., Dietrich, M., Edelson, R., Ely, J., Eracleous, M., Evans, P. A., Fausnaugh, M. M., Ferland, G. J., Filippenko, A. V., Flatland, K., Fox, O. D., Gates, E. L., Gehrels, N., Geier, S., Gelbord, J. M., Gorjian, V., Greene, J. E., Grier, C. J., Grupe, D., Hall, P. B., Henderson, C. B., Hicks, S., Holmbeck, E., Holoien, T. W. -S., Horenstein, D., Horne, Keith, Hutchison, T., Im, M., Jensen, J. J., Johnson, C. A., Joner, M. D., Jones, J., Kaastra, J., Kaspi, S., Kelly, B. C., Kelly, P. L., Kennea, J. A., Kim, M., Kim, S., Kim, S. C., King, A., Klimanov, S. A., Kochanek, C. S., Korista, K. T., Kriss, G. A., Lau, M. W., Lee, J. C., Leonard, D. C., Li, M., Lira, P., Ma, Z., MacInnis, F., Manne-Nicholas, E. R., Malkan, M. A., Mauerhan, J. C., McGurk, R., McHardy, I. M., Montouri, C., Morelli, L., Mosquera, A., Mudd, D., Muller-Sanchez, F., Musso, R., Nazarov, S. V., Netzer, H., Nguyen, M. L., Norris, R. P., Nousek, J. A., Ochner, P., Okhmat, D. N., Ou-Yang, B., Pancoast, A., Papadakis, I., Parks, J. R., Pei, L., Peterson, B. M., Pizzella, A., Poleski, R., Pott, J. -U., Rafter, S. E., Rix, H. -W., Runnoe, J., Saylor, D. A., Schimoia, J. S., Schnülle, K., Sergeev, S. G., Shappee, B. J., Shivvers, I., Siegel, M., Simonian, G. V., Siviero, A., Skielboe, A., Somers, G., Spencer, M., Starkey, D., Stevens, D. J., Sung, H. -I., Tayar, J., Tejos, N., Turner, C. S., Uttley, P., Van Saders, J., Vestergaard, M., Vican, L., Villanueva Jr., S., Villforth, C., Weiss, Y., Woo, J. -H., Yan, H., Young, S., Yuk, H., Zheng, W., Zhu, W., and Zu, Y.. 2017. "Space Telescope and Optical Reverberation Mapping Project. VII. Understanding the Ultraviolet Anomaly in NGC 5548 with X-Ray Spectroscopy". United States. doi:10.3847/1538-4357/aa832b. https://www.osti.gov/servlets/purl/1394071.
@article{osti_1394071,
title = {Space Telescope and Optical Reverberation Mapping Project. VII. Understanding the Ultraviolet Anomaly in NGC 5548 with X-Ray Spectroscopy},
author = {Mathur, S. and Gupta, A. and Page, K. and Pogge, R. W. and Krongold, Y. and Goad, M. R. and Adams, S. M. and Anderson, M. D. and Arévalo, P. and Barth, A. J. and Bazhaw, C. and Beatty, T. G. and Bentz, M. C. and Bigley, A. and Bisogni, S. and Borman, G. A. and Boroson, T. A. and Bottorff, M. C. and Brandt, W. N. and Breeveld, A. A. and Brown, J. E. and Brown, J. S. and Cackett, E. M. and Canalizo, G. and Carini, M. T. and Clubb, K. I. and Comerford, J. M. and Coker, C. T. and Corsini, E. M. and Crenshaw, D. M. and Croft, S. and Croxall, K. V. and Dalla Bontà, E. and Deason, A. J. and Denney, K. D. and De Lorenzo-Cáceres, A. and De Rosa, G. and Dietrich, M. and Edelson, R. and Ely, J. and Eracleous, M. and Evans, P. A. and Fausnaugh, M. M. and Ferland, G. J. and Filippenko, A. V. and Flatland, K. and Fox, O. D. and Gates, E. L. and Gehrels, N. and Geier, S. and Gelbord, J. M. and Gorjian, V. and Greene, J. E. and Grier, C. J. and Grupe, D. and Hall, P. B. and Henderson, C. B. and Hicks, S. and Holmbeck, E. and Holoien, T. W. -S. and Horenstein, D. and Horne, Keith and Hutchison, T. and Im, M. and Jensen, J. J. and Johnson, C. A. and Joner, M. D. and Jones, J. and Kaastra, J. and Kaspi, S. and Kelly, B. C. and Kelly, P. L. and Kennea, J. A. and Kim, M. and Kim, S. and Kim, S. C. and King, A. and Klimanov, S. A. and Kochanek, C. S. and Korista, K. T. and Kriss, G. A. and Lau, M. W. and Lee, J. C. and Leonard, D. C. and Li, M. and Lira, P. and Ma, Z. and MacInnis, F. and Manne-Nicholas, E. R. and Malkan, M. A. and Mauerhan, J. C. and McGurk, R. and McHardy, I. M. and Montouri, C. and Morelli, L. and Mosquera, A. and Mudd, D. and Muller-Sanchez, F. and Musso, R. and Nazarov, S. V. and Netzer, H. and Nguyen, M. L. and Norris, R. P. and Nousek, J. A. and Ochner, P. and Okhmat, D. N. and Ou-Yang, B. and Pancoast, A. and Papadakis, I. and Parks, J. R. and Pei, L. and Peterson, B. M. and Pizzella, A. and Poleski, R. and Pott, J. -U. and Rafter, S. E. and Rix, H. -W. and Runnoe, J. and Saylor, D. A. and Schimoia, J. S. and Schnülle, K. and Sergeev, S. G. and Shappee, B. J. and Shivvers, I. and Siegel, M. and Simonian, G. V. and Siviero, A. and Skielboe, A. and Somers, G. and Spencer, M. and Starkey, D. and Stevens, D. J. and Sung, H. -I. and Tayar, J. and Tejos, N. and Turner, C. S. and Uttley, P. and Van Saders, J. and Vestergaard, M. and Vican, L. and Villanueva Jr., S. and Villforth, C. and Weiss, Y. and Woo, J. -H. and Yan, H. and Young, S. and Yuk, H. and Zheng, W. and Zhu, W. and Zu, Y.},
abstractNote = {During the Space Telescope and Optical Reverberation Mapping Project observations of NGC 5548, the continuum and emission-line variability became decorrelated during the second half of the six-month-long observing campaign. Here we present Swift and Chandra X-ray spectra of NGC 5548 obtained as part of the campaign. The Swift spectra show that excess flux (relative to a power-law continuum) in the soft X-ray band appears before the start of the anomalous emission-line behavior, peaks during the period of the anomaly, and then declines. This is a model-independent result suggesting that the soft excess is related to the anomaly. We divide the Swift data into on- and off-anomaly spectra to characterize the soft excess via spectral fitting. The cause of the spectral differences is likely due to a change in the intrinsic spectrum rather than to variable obscuration or partial covering. The Chandra spectra have lower signal-to-noise ratios, but are consistent with the Swift data. Our preferred model of the soft excess is emission from an optically thick, warm Comptonizing corona, the effective optical depth of which increases during the anomaly. In conclusion, this model simultaneously explains all three observations: the UV emission-line flux decrease, the soft-excess increase, and the emission-line anomaly.},
doi = {10.3847/1538-4357/aa832b},
journal = {The Astrophysical Journal (Online)},
number = 1,
volume = 846,
place = {United States},
year = {2017},
month = {8}
}