Related papers: Correlated X-ray/Ultraviolet/Optical Variability i…

Disk continuum reverberation mapping is one of the primary ways we learn about active galactic nuclei (AGN) accretion disks. Reverberation mapping assumes that time-varying X-rays incident on the accretion disk drive variability in…

We study accretion disk-corona connection in Seyfert 1 galaxies using simultaneous UV/X-ray observations of NGC 4593 (July 14-18, 2016) and NGC 7469 (October 15-19, 2017) performed with AstroSat. We use the X-ray (0.5-7.0 keV) data acquired…

We present 1.8 years of near-daily Swift monitoring of the bright, strongly variable Type 1 AGN Fairall 9. Totaling 575 successful visits, this is the largest such campaign reported to date. Variations within the UV/optical are…

We present the ground-based imaging campaign and light curves of Markarian 817 as part of the multiwavelength monitoring program AGN STORM\,2. Observations were carried out over 1.4 years in \emph{uBgVriz} filters, with a median cadence of…

We conduct a multiwavelength continuum variability study of the Seyfert 1 galaxy NGC 5548 to investigate the temperature structure of its accretion disk. The 19 overlapping continuum light curves (1158 to 9157 angstroms) combine…

The UV/optical variations in many AGN are very well correlated, showing delays which increase with increasing wavelength. It is thought that this is due to thermal reprocessing of the X-ray emission by the accretion disk. In this scenario,…

UV and optical continuum reverberation mapping is powerful for probing the accretion disk and inner broad-line region. However, recent reverberation mapping campaigns in the X-ray, UV, and optical have found lags consistently longer than…

The Seyfert 1 galaxy NGC 4593 was monitored spectroscopically with the Hubble Space Telescope as part of a reverberation mapping campaign that also included Swift, Kepler and ground-based photometric monitoring. During 2016 July 12 - August…

Over the last years, a number of broadband reverberation mapping campaigns have been conducted to explore the short-term UV and optical variability of nearby AGN. Despite the extensive data collected, the origin of the observed variability…

We present the results of a ~ 3 year campaign to monitor the low luminosity active galactic nucleus (LLAGN) NGC 7213 in the radio (4.8 and 8.4 GHz) and X-ray bands (2-10 keV). With a reported X-ray Eddington ratio of 7 x 10^-4 L_Edd, NGC…

We report the results of a six-month Swift monitoring campaign of Ark120, a prototypical bare Seyfert1 galaxy. The lack of intrinsic absorption combined with the nearly contemporaneous coverage of the UV and X-ray bands makes it possible to…

We report on the XMM-Newton timing properties of the most X-ray variable, radio-quiet, NLS1 IRAS 13224-3809. IRAS 13224-3809 continues to display the extremely variable behavior that was previously observed with ROSAT and ASCA; however, no…

Active galactic nuclei (AGN) light curves observed with different wavebands show that the variability in longer wavelength bands lags the variability in shorter wavelength bands. Measuring these lags, or reverberation mapping, is used to…

We have undertaken near-continuous monitoring of the Seyfert 1 galaxy NGC 7469 in the X-ray with RXTE over a ~30d baseline. The source shows strong variability with a root-mean-square (rms) amplitude of ~16 per cent, and peak-to-peak…

We present our analysis of the X-ray variability of two ultraluminous X-ray sources (ULXs) based on multiple XMM--Newton observations. We show the linear rms-flux relation is present in eight observations of NGC5408 X-1 and also in three…

We present results from the optical, ultraviolet and X-ray monitoring of the NLS1 galaxy IRAS 13224-3809 taken with Swift and XMM-Newton during 2016. IRAS 13224-3809 is the most variable bright AGN in the X-ray sky and shows strong X-ray…

Recent intensive monitoring campaigns of active galactic nuclei (AGN) have provided simultaneous X-ray, UV, and optical data of unprecedented quality. The observations reveal a strong correlation between the UV and optical variability, but…

We have measured the wavelength-dependent lags between the X-ray, UV and optical bands in the high accretion rate ($L/L_{\rm Edd}\approx40\%$) Active Galactic Nucleus Mrk 110 during two intensive monitoring campaigns in February and…

We report the results of long-term simultaneous X-ray and UV monitoring of the nearby (z=0.03145) Seyfert 1.5 galaxy Mrk 817 using the Neil Gehrels Swift Observatory XRT and UVOT. Prior work has revealed that the X-ray flux from Mrk 817 has…

We report on daily monitoring of the Seyfert galaxy NGC 7469, around 95 GHz and 143 GHz, with the IRAM 30 m radio telescope, and with the Swift X-Ray and UV/Optical telescopes, over an overlapping period of 45 days. The source was observed…