X-ray, UV, and optical time delays in the bright Seyfert galaxy Ark 120 with co-ordinated Swift and ground-based observations
| Autor: | Rumen Bachev, B. Debski, James Reeves, F. Pozo Nunez, S. M. Hu, Vladimir Kouprianov, Staszek Zola, Alex Markowitz, Daniel E. Reichart, Andrew Lobban, Daniel B. Caton, U. Pajdosz-Śmierciak, J. B. Haislip, J. Krzesiński, Gopal Bhatta, V. Braito, D. Carosati, D. Porquet, Goran Damljanović, E. Nardini |
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| Přispěvatelé: | Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES) |
| Jazyk: | angličtina |
| Rok vydání: | 2020 |
| Předmět: |
Physics
High Energy Astrophysical Phenomena (astro-ph.HE) I band Active galactic nucleus Accretion (meteorology) X-ray SKYNET FOS: Physical sciences Astronomy and Astrophysics Astrophysics 01 natural sciences accretion discs Galaxy galaxies [X-rays] Wavelength X-rays: galaxies Robotic telescope accretion 13. Climate action Space and Planetary Science 0103 physical sciences 010306 general physics Astrophysics - High Energy Astrophysical Phenomena [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph] 010303 astronomy & astrophysics |
| Zdroj: | Monthly Notices of the Royal Astronomical Society Monthly Notices of the Royal Astronomical Society, Oxford University Press (OUP): Policy P-Oxford Open Option A, 2020, 494 (1), pp.1165-1179. ⟨10.1093/mnras/staa630⟩ Monthly Notices of the Royal Astronomical Society, 2020, 494 (1), pp.1165-1179. ⟨10.1093/mnras/staa630⟩ |
| ISSN: | 0035-8711 1365-2966 |
| DOI: | 10.1093/mnras/staa630⟩ |
| Popis: | We report on the results of a multiwavelength monitoring campaign of the bright, nearby Seyfert galaxy, Ark 120 using a ~50-day observing programme with Swift and a ~4-month co-ordinated ground-based observing campaign, predominantly using the Skynet Robotic Telescope Network. We find Ark 120 to be variable at all optical, UV, and X-ray wavelengths, with the variability observed to be well-correlated between wavelength bands on short timescales. We perform cross-correlation analysis across all available wavelength bands, detecting time delays between emission in the X-ray band and the Swift V, B and UVW1 bands. In each case, we find that the longer-wavelength emission is delayed with respect to the shorter-wavelength emission. Within our measurement uncertainties, the time delays are consistent with the \tau ~ \lambda^{4/3} relation, as predicted by a disc reprocessing scenario. The measured lag centroids are \tau_{cent} = 11.90 +/- 7.33, 10.80 +/- 4.08, and 10.60 +/- 2.87 days between the X-ray and V, B, and UVW1 bands, respectively. These time delays are longer than those expected from standard accretion theory and, as such, Ark 120 may be another example of an active galaxy whose accretion disc appears to exist on a larger scale than predicted by the standard thin-disc model. Additionally, we detect further inter-band time delays: most notably between the ground-based I and B bands (\tau_{cent} = 3.46 +/- 0.86 days), and between both the Swift XRT and UVW1 bands and the I band (\tau_{cent} = 12.34 +/- 4.83 and 2.69 +/- 2.05 days, respectively), highlighting the importance of co-ordinated ground-based optical observations. Comment: 15 pages, 9 figures, 4 tables; accepted for publication in MNRAS |
| Databáze: | OpenAIRE |
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