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http://hdl.handle.net/20.500.12386/32440
Titolo: | A deep X-ray view of the bare AGN Ark 120. III. X-ray timing analysis and multiwavelength variability | Autori: | Lobban, Andrew Porquet, Delphine Reeves, James Markowitz, Alex NARDINI, EMANUELE Grosso, Nicolas |
Data pubblicazione: | 2018 | Rivista: | MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY | Numero: | 474 | Fascicolo: | 3 | Da pagina:: | 3237 | Abstract: | We present the spectral/timing properties of the bare Seyfert galaxy Ark 120 through a deep ~420ks XMM-Newton campaign plus recent NuSTAR observations and a ~6-month Swift monitoring campaign. We investigate the spectral decomposition through fractional rms, covariance and difference spectra, finding the mid- to long-timescale (~day-year) variability to be dominated by a relatively smooth, steep component, peaking in the soft X-ray band. Additionally, we find evidence for variable FeK emission red-ward of the FeK-alpha core on long timescales, consistent with previous findings. We detect a clearly-defined power spectrum which we model with a power law with a slope of alpha ~ 1.9. By extending the power spectrum to lower frequencies through the inclusion of Swift and RXTE data, we find tentative evidence of a high-frequency break, consistent with existing scaling relations. We also explore frequency-dependent Fourier time lags, detecting a negative ('soft') lag for the first time in this source with the 0.3-1 keV band lagging behind the 1-4 keV band with a time delay of ~900s. Finally, we analyze the variability in the optical and UV bands using the Optical/UV Monitor on-board XMM-Newton and the UVOT on-board Swift and search for time-dependent correlations between the optical/UV/X-ray bands. We find tentative evidence for the U-band emission lagging behind the X-rays with a time delay of 2.4 +/- 1.8 days, which we discuss in the context of disc reprocessing. | URI: | http://hdl.handle.net/20.500.12386/32440 | URL: | https://academic.oup.com/mnras/article/474/3/3237/4604788 http://arxiv.org/abs/1707.05536v2 |
ISSN: | 0035-8711 | DOI: | 10.1093/mnras/stx2889 | Bibcode ADS: | 2018MNRAS.474.3237L | Fulltext: | open |
È visualizzato nelle collezioni: | 1.01 Articoli in rivista |
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