Dimming of Continuum Captured in Mrk 841: New Clues on the Nature of the Soft X-Ray Excess
We report on a remarkable change in the spectral energy distribution (SED) of Mrk 841, providing new insights on how the soft X-ray excess emission in active galactic nuclei (AGNs) is produced. By Swift monitoring of a sample of Seyfert-1 galaxies, we found an X-ray spectral hardening event in Mrk 8...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
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IOP Publishing
2023-01-01
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| Series: | The Astrophysical Journal Letters |
| Subjects: | |
| Online Access: | https://doi.org/10.3847/2041-8213/ace053 |
| _version_ | 1797698338471018496 |
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| author | Missagh Mehdipour Gerard A. Kriss Jelle S. Kaastra Elisa Costantini Junjie Mao |
| author_facet | Missagh Mehdipour Gerard A. Kriss Jelle S. Kaastra Elisa Costantini Junjie Mao |
| author_sort | Missagh Mehdipour |
| collection | DOAJ |
| description | We report on a remarkable change in the spectral energy distribution (SED) of Mrk 841, providing new insights on how the soft X-ray excess emission in active galactic nuclei (AGNs) is produced. By Swift monitoring of a sample of Seyfert-1 galaxies, we found an X-ray spectral hardening event in Mrk 841. We thereby triggered our XMM-Newton, NuSTAR, and Hubble Space Telescope observations in 2022 to study this event. Our previous investigations of such events in other AGNs had shown that they are caused by obscuring winds. However, the event in Mrk 841 has different spectral characteristics and origin. We find it is the soft X-ray excess component that has become dimmer. This is, importantly, accompanied by a similar decline in the optical/UV continuum, suggesting a connection to the soft X-ray excess. In contrast, there is relatively little change in the X-ray power law and the reflection components. Our SED modeling suggests that the soft X-ray excess is the high-energy extension of the optical/UV disk emission, produced by warm Comptonization. We find the temperature of the disk dropped in 2022, explaining the observed SED dimming. We then examined the Swift data, taken over 15 yr, to further decipher the UV and X-ray variabilities of Mrk 841. A significant relation between the variabilities of the X-ray spectral hardness and that of the UV continuum is found, again suggesting that the soft excess and the disk emission are interlinked. This is readily explicable if the soft excess is produced by warm Comptonization. |
| first_indexed | 2024-03-12T03:52:57Z |
| format | Article |
| id | doaj.art-d95b5e7b8f614a9b9d6a0d61547568d0 |
| institution | Directory Open Access Journal |
| issn | 2041-8205 |
| language | English |
| last_indexed | 2024-03-12T03:52:57Z |
| publishDate | 2023-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astrophysical Journal Letters |
| spelling | doaj.art-d95b5e7b8f614a9b9d6a0d61547568d02023-09-03T12:15:42ZengIOP PublishingThe Astrophysical Journal Letters2041-82052023-01-019521L510.3847/2041-8213/ace053Dimming of Continuum Captured in Mrk 841: New Clues on the Nature of the Soft X-Ray ExcessMissagh Mehdipour0https://orcid.org/0000-0002-4992-4664Gerard A. Kriss1https://orcid.org/0000-0002-2180-8266Jelle S. Kaastra2https://orcid.org/0000-0001-5540-2822Elisa Costantini3https://orcid.org/0000-0001-8470-749XJunjie Mao4https://orcid.org/0000-0001-7557-9713Space Telescope Science Institute , 3700 San Martin Drive, Baltimore, MD 21218, USA ; mmehdipour@stsci.eduSpace Telescope Science Institute , 3700 San Martin Drive, Baltimore, MD 21218, USA ; mmehdipour@stsci.eduSRON Netherlands Institute for Space Research , Niels Bohrweg 4, 2333 CA Leiden, The Netherlands; Leiden Observatory, Leiden University , P.O. Box 9513, 2300 RA Leiden, The NetherlandsSRON Netherlands Institute for Space Research , Niels Bohrweg 4, 2333 CA Leiden, The Netherlands; Anton Pannekoek Institute, University of Amsterdam , Postbus 94249, 1090 GE Amsterdam, The NetherlandsSRON Netherlands Institute for Space Research , Niels Bohrweg 4, 2333 CA Leiden, The Netherlands; Department of Astronomy, Tsinghua University , Haidian DS 100084, Beijing, People’s Republic of ChinaWe report on a remarkable change in the spectral energy distribution (SED) of Mrk 841, providing new insights on how the soft X-ray excess emission in active galactic nuclei (AGNs) is produced. By Swift monitoring of a sample of Seyfert-1 galaxies, we found an X-ray spectral hardening event in Mrk 841. We thereby triggered our XMM-Newton, NuSTAR, and Hubble Space Telescope observations in 2022 to study this event. Our previous investigations of such events in other AGNs had shown that they are caused by obscuring winds. However, the event in Mrk 841 has different spectral characteristics and origin. We find it is the soft X-ray excess component that has become dimmer. This is, importantly, accompanied by a similar decline in the optical/UV continuum, suggesting a connection to the soft X-ray excess. In contrast, there is relatively little change in the X-ray power law and the reflection components. Our SED modeling suggests that the soft X-ray excess is the high-energy extension of the optical/UV disk emission, produced by warm Comptonization. We find the temperature of the disk dropped in 2022, explaining the observed SED dimming. We then examined the Swift data, taken over 15 yr, to further decipher the UV and X-ray variabilities of Mrk 841. A significant relation between the variabilities of the X-ray spectral hardness and that of the UV continuum is found, again suggesting that the soft excess and the disk emission are interlinked. This is readily explicable if the soft excess is produced by warm Comptonization.https://doi.org/10.3847/2041-8213/ace053X-ray active galactic nucleiSeyfert galaxiesActive galaxies |
| spellingShingle | Missagh Mehdipour Gerard A. Kriss Jelle S. Kaastra Elisa Costantini Junjie Mao Dimming of Continuum Captured in Mrk 841: New Clues on the Nature of the Soft X-Ray Excess The Astrophysical Journal Letters X-ray active galactic nuclei Seyfert galaxies Active galaxies |
| title | Dimming of Continuum Captured in Mrk 841: New Clues on the Nature of the Soft X-Ray Excess |
| title_full | Dimming of Continuum Captured in Mrk 841: New Clues on the Nature of the Soft X-Ray Excess |
| title_fullStr | Dimming of Continuum Captured in Mrk 841: New Clues on the Nature of the Soft X-Ray Excess |
| title_full_unstemmed | Dimming of Continuum Captured in Mrk 841: New Clues on the Nature of the Soft X-Ray Excess |
| title_short | Dimming of Continuum Captured in Mrk 841: New Clues on the Nature of the Soft X-Ray Excess |
| title_sort | dimming of continuum captured in mrk 841 new clues on the nature of the soft x ray excess |
| topic | X-ray active galactic nuclei Seyfert galaxies Active galaxies |
| url | https://doi.org/10.3847/2041-8213/ace053 |
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