26-30 June 2023
Centro Congressi Federico II
Europe/Rome timezone

Optical/X-ray variations of the changing-look AGN IRAS23226-3843

29 Jun 2023, 10:45
Aula Magna (Centro Congressi Federico II)

Aula Magna

Centro Congressi Federico II

Via Partenope, 36, Napoli, Italy


W. Kollatschny


We present spectroscopic and photometric observations of the changing look AGN
IRAS23226-3843. This object has previously been classified as a
changing-look AGN based on observations taken in the 1990s in comparison to
X-ray data (Swift, XMM-Newton, and NuSTAR) and optical spectra taken after
a very strong X-ray decline in 2017. In 2019, Swift observations revealed
a strong rebrightening in X-ray and UV fluxes. We took follow-up X-ray
observations of IRAS23226-3843 together with optical spectra from 2019 until
2021. IRAS23226-3843 showed a strong X-ray and optical outburst in 2019. It
varied in the X-ray continuum by a factor of 5 and in the optical continuum by
a factor of 1.6 within two months. The Balmer and FeII emission-line
intensities showed comparable variability amplitudes during the outburst in
2019. The Halpha emission-line profiles of IRAS23226-3843 changed from a
blue-peaked profile in the years 1997 and 1999 to a broad double-peaked
profile in 2017 and 2019. However, there were no major profile variations in
the extremely broad double-peaked profiles despite the strong intensity
variations in 2019. One year after the outburst, IRAS23226-3843 changed its
optical spectral type and became a Seyfert type 2 object in 2020.
A deep broadband XMM/NuSTAR spectrum was taken during IRAS23226-3843 maximum
state in 2019. This spectrum is qualitatively very similar to a spectrum taken
in 2017, but by a factor of 10 higher. The soft X-ray band appears featureless.
The soft excess is well modeled with a Comptonization model.

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