Astrophysical Journal
| Autor: | Michael Fausnaugh, K. T. Korista, I. M. Mc Hardy, Bradley M. Peterson, E. Dalla Bontà, P. A. M. van Hoof, D. A. Starkey, R. Williams, Gerard A. Kriss, M. Dehghanian, M. R. Goad, Jelle Kaastra, Misty C. Bentz, R. W. Pogge, N. Arav, G. De Rosa, Marios Chatzikos, Gary J. Ferland, Christian Knigge, W. N. Brandt, J. M. Gelbord, Susanna Bisogni, Anchal Gupta, Keith Horne, Marianne Vestergaard, Aaron J. Barth, F. Guzmán, D. M. Crenshaw, M. Mehdipour, S. Mathur |
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| Přispěvatelé: | Physics, Science & Technology Facilities Council, University of St Andrews. School of Physics and Astronomy, University of St Andrews. St Andrews Centre for Exoplanet Science, USA |
| Jazyk: | angličtina |
| Rok vydání: | 2019 |
| Předmět: |
Active galactic nucleus
010504 meteorology & atmospheric sciences Astrophysics::High Energy Astrophysical Phenomena Continuum (design consultancy) galaxies: active NDAS nuclei [galaxies] galaxies: individual (NGC 5548) galaxies: nuclei galaxies: Seyfert line: formation FOS: Physical sciences Astrophysics Astrophysics::Cosmology and Extragalactic Astrophysics 01 natural sciences Spectral line formation [line] Spitzer Space Telescope Seyfert [galaxies] 0103 physical sciences QB Astronomy Emission spectrum 010303 astronomy & astrophysics QC Astrophysics::Galaxy Astrophysics 0105 earth and related environmental sciences Line (formation) QB Physics Astronomy and Astrophysics Astrophysics - Astrophysics of Galaxies Black hole QC Physics 13. Climate action Space and Planetary Science Astrophysics of Galaxies (astro-ph.GA) active [galaxies] individual (NGC 5548) [galaxies] Reverberation mapping |
| Zdroj: | Dehghanian, M, Ferland, G J, Kriss, G A, Peterson, B M, Mathur, S, Mehdipour, M, Guzmán, F, Chatzikos, M, Van Hoof, P A M, Williams, R J R, Arav, N, Barth, A J, Bentz, M C, Bisogni, S, Brandt, W N, Crenshaw, D M, Bonta, E D, De Rosa, G, Fausnaugh, M M, Gelbord, J M, Goad, M R, Gupta, A, Horne, K, Kaastra, J, Knigge, C, Korista, K T, McHardy, I M, Pogge, R W, Starkey, D A & Vestergaard, M 2019, ' Space Telescope and Optical Reverberation Mapping Project. X. Understanding the Absorption-line Holiday in NGC 5548 ', Astrophysical Journal, vol. 877, no. 2, 119 . https://doi.org/10.3847/1538-4357/ab1b48 |
| Popis: | The flux variations in the emission lines in active galactic nuclei (AGNs) are driven by variations in the ionizing continuum flux --which are usually reflected in the observable UV-optical continuum. The "Reverberation mapping" technique measures the delay between line and continuum variations to determine the size of the line emitting region, this is the basis for measurements of the central black hole mass in AGNs. The Space Telescope and Optical Reverberation Mapping Project (AGN STORM) on NGC 5548 in 2014 is the most intensive multi-wavelength AGN monitoring campaign ever. For most of the campaign, the emission-line variations followed changes in the continuum with a time lag, as expected. However, the lines varied independently of the observed UV-optical continuum during a 60 -- 70 day "holiday." To understand this remarkable phenomenon, we study the intrinsic absorption lines present in NGC 5548. We identify a novel cycle that reproduces the absorption line variability and thus identify the physics that allows the holiday to occur. In our model, variations in this obscurer's line-of-sight covering factor modify the soft X-ray continuum. This leads to changes in the ionization of helium gas in the broad-line region. Ionizing radiation produced by recombining helium then affects the ionization of other species as observed during the AGN STORM holiday. It is likely that any other model which selectively changes the soft X-ray part of the continuum during the holiday can also explain the anomalous emission line behavior observed. Comment: This is the version accepted by ApJ. Will be published shortly |
| Databáze: | OpenAIRE |
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