144 citations · 419 across the 18 of their papers we have counts for
7 papers · 1 filter
The extremes of AGN variability: outbursts, deep fades, changing looks, exceptional spectral states, and semi-periodicities
S. Komossa, D. Grupe, P. Marziani +16
The extremes of Active Galactic Nuclei (AGN) variability offer valuable new insights into the drivers and physics of AGN. We discuss some of the most extreme cases of AGN variabili…
First deep X-ray observations of the Fermi-detected steep-spectrum source and radio-loud NLS1 galaxy 3C 286
Su Yao, S. Komossa, A. Kraus +1
A well-known calibrator source in radio astronomy, 3C 286 (), is a compact steep-spectrum (CSS) radio source and spectroscopically classified as a narrow-line Seyfert 1 (NL…
On the nature of the radio calibrator and gamma-ray emitting NLS1 galaxy 3C 286 and its multiwavelength variability
S. Komossa, S. Yao, D. Grupe +1
The quasar 3C 286, a well-known calibrator source in radio astronomy, was found to exhibit exceptional multiwavelength properties. Its rich and complex optical emission-line spectr…
A Hot Mess: The Rich and Complex Soft Emitting Regions Surrounding the Reflection Dominated Flaring Central Engine of Mrk 1239
Margaret Z. Buhariwalla, L. C. Gallo, J. Mao +5
Previous X-ray works on Mrk 1239 have revealed a complex Narrow Line Seyfert 1 (NLS1) that exhibits substantial absorption and strong emission from both collisional (CIE) and photo…
The calm before the (next) storm: no third outburst in 2019--2020, and ongoing monitoring of the transient AGN IC 3599
Dirk Grupe, S. Komossa, Salem Wolsing
We report on follow-up observations of the Seyfert 1.9 galaxy IC 3599 with the NASA Neil Gehrels Swift mission. The detection of a second X-ray outburst in 2010 by Swift after the…
The transient event in NGC 1566 from 2017 to 2019 -- I. An eccentric accretion disk and a turbulent, disk-dominated broad-line region unveiled by double-peaked Ca II and O I lines
M. W. Ochmann, W. Kollatschny, M. A. Probst +12
NGC 1566 is known for exhibiting recurrent outbursts, which are accompanied by changes in spectral type. The most recent transient event occurred from 2017 to 2019 and was reported…
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…