500 citations · 4k across the 75 of their papers we have counts for
10 papers · 1 filter
In the Eye of the Storm: The Third Giant X-ray Outburst of the Extreme Changing-look AGN IC 3599
D. Grupe, S. Komossa, W. Zheng +10
We report the discovery and multiwavelength follow-up observations of a giant (factor >100) X-ray outburst of the exceptional changing-look active galactic nucleus (AGN) IC 3599. T…
Extreme line profile variations in the repeating changing-look active galactic nucleus IRAS23226-3843
Wolfram Kollatschny, Dirk Grupe, Hartmut Winkler +7
IRAS23226-3843 has been identified as a highly variable Seyfert galaxy and even as a changing-look active galactic nucleus based on optical spectra. Here we present follow-up obser…
Multiwavelength continuum, emission line and BAL variability with prominent PV absorption in the X-ray-weakest quasar PG0043+039
Wolfram Kollatschny, Norbert Schartel, Malte A. Probst +3
PG0043+039 has been identified as an extremely X-ray-weak quasar and as a peculiar broad-absorption-line quasar based on UV HST spectra. We took simultaneous deep X-ray observation…
Changing-look NLS1 galaxies, their detection with SVOM, and the case of NGC 1566
D. W. Xu, S. Komossa, D. Grupe +15
We discuss applications of the study of the new and barely explored class of changing-look (CL) narrow-line Seyfert 1 (NLS1) galaxies and comment on their detection with the space…
Optical and X-ray discovery of the changing-look AGN IRAS23226-3843 showing extremely broad and double-peaked Balmer profiles
W. Kollatschny, D. Grupe, M. L. Parker +6
We detected a very strong X-ray decline in the galaxy IRAS23226-3843 within the XMM-Newton slew survey in 2017. Subsequently, we carried out multi-band follow-up studies to investi…
Swift, NuStar and XMM-Newton observations of the NLS1 galaxy RX J2317.8-4422 in an extreme X-ray low flux state
Dirk Grupe, S. Komossa., Luigi Gallo +6
We report the discovery of RX J2317.8-4422 in an extremely low X-ray flux state by the Neil Gehrels Swift observatory in 2014 April/May. In total, the low-energy X-ray emission dro…