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Abstract The AGN STORM 2 campaign is a large, multiwavelength reverberation mapping project designed to trace out the structure of Mrk 817 from the inner accretion disk to the broad emission line region and out to the dusty torus. As part of this campaign, Swift performed daily monitoring of Mrk 817 for approximately 15 months, obtaining observations in X-rays and six UV/optical filters. The X-ray monitoring shows that Mrk 817 was in a significantly fainter state than in previous observations, with only a brief flare where it reached prior flux levels. The X-ray spectrum is heavily obscured. The UV/optical light curves show significant variability throughout the campaign and are well correlated with one another, but uncorrelated with the X-rays. Combining the Swift UV/optical light curves with Hubble Space Telescope UV continuum light curves, we measure interband continuum lags,τ(λ), that increase with increasing wavelength roughly followingτ(λ) ∝λ4/3, the dependence expected for a geometrically thin, optically thick, centrally illuminated disk. Modeling of the light curves reveals a period at the beginning of the campaign where the response of the continuum is suppressed compared to later in the light curve—the light curves are not simple shifted and scaled versions of each other. The interval of suppressed response corresponds to a period of high UV line and X-ray absorption, and reduced emission line variability amplitudes. We suggest that this indicates a significant contribution to the continuum from the broad-line region gas that sees an absorbed ionizing continuum.
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This content will become publicly available on March 26, 2026
Markarian 590: the AGN awakens
ABSTRACT Changing-look active galactic nucleus Mkn 590 recently underwent a sudden ‘re-ignition’, marked by substantial increases in optical/ultravilolet (UV) and X-ray continuum flux since last couple of years. Swift-XRT observations revealed the re-emergence of a soft X-ray excess as the source transitioned from a low-flux state in July 2023 to a significantly higher flux state in October 2024. This evolution was in response to an order-of-magnitude increase in extreme-UV continuum emission, detected by Swift-UVOT. Follow-up optical spectra from FLOYDS/Faulkes confirmed the enhancement of dynamically broadened Balmer lines, He ii emission, and Fe ii complex. As the Eddington fraction increased by a factor of $$\sim$$20 over the last 20 months, we found clear evidence of formation of a warm corona, strongly linked to the cold accretion disc underneath. Based on our multiwavelength study on recent data, we propose that Mkn 590 is currently becoming a Seyfert-1.2, similar to its state in 1990s.
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- Award ID(s):
- 1911225
- PAR ID:
- 10653570
- Publisher / Repository:
- MNRAS
- Date Published:
- Journal Name:
- Monthly Notices of the Royal Astronomical Society: Letters
- Volume:
- 540
- Issue:
- 1
- ISSN:
- 1745-3925
- Page Range / eLocation ID:
- L14 to L20
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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