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Subject: Galaxies: Seyfert × WGL Institute: AIP ×

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Now showing 1 - 2 of 2
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    The close AGN reference survey (CARS) : Discovery of a global [C II] 158 µm line excess in AGN HE 1353−1917
    (Les Ulis : EDP Sciences, 2019) Smirnova-Pinchukova, I.; Husemann, B.; Busch, G.; Appleton, P.; Bethermin, M.; Combes, F.; Croom, S.; Davis, T.A.; Fischer, C.; Gaspari, M.; Groves, B.; Klein, R.; O’Dea, C.P.; Pérez-Torres, M.; Scharwächter, J.; Singha, M.; Tremblay, G.R.; Urrutia, T.
    The [C ii]λ158 µm line is one of the strongest far-infrared (FIR) lines and an important coolant in the interstellar medium of galaxies that is accessible out to high redshifts. The excitation of [C ii] is complex and can best be studied in detail at low redshifts. Here we report the discovery of the highest global [C ii] excess with respect to the FIR luminosity in the nearby AGN host galaxy HE 1353−1917. This galaxy is exceptional among a sample of five targets because the AGN ionization cone and radio jet directly intercept the cold galactic disk. As a consequence, a massive multiphase gas outflow on kiloparsec scales is embedded in an extended narrow-line region. Because HE 1353−1917 is distinguished by these special properties from our four bright AGN, we propose that a global [C ii] excess in AGN host galaxies could be a direct signature of a multiphase AGN-driven outflow with a high mass-loading factor.
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    Extreme ultra-soft X-ray variability in an eROSITA observation of the narrow-line Seyfert 1 galaxy 1H 0707-495
    (Les Ulis : EDP Sciences, 2021) Boller, Th.; Liu, T.; Weber, P.; Arcodia, R.; Dauser, T.; Wilms, J.; Nandra, K.; Buchner, J.; Merloni, A.; Freyberg, M. J.; Krumpe, M.; Waddell, S. G. H.
    The ultra-soft narrow-line Seyfert 1 galaxy 1H 0707-495 is a well-known and highly variable active galactic nucleus (AGN), with a complex, steep X-ray spectrum, and has been studied extensively with XMM-Newton. 1H 0707-495 was observed with the extended ROentgen Survey with an Imaging Telescope Array (eROSITA) aboard the Spectrum-Roentgen-Gamma (SRG) mission on October 11, 2019, for about 60 000 s as one of the first calibration and pointed verification phase (CalPV) observations. The eROSITA light curves show significant variability in the form of a flux decrease by a factor of 58 with a 1 σ error confidence interval between 31 and 235. This variability is primarily in the soft band, and is much less extreme in the hard band. No strong ultraviolet variability has been detected in simultaneous XMM-Newton Optical Monitor observations. The UV emission is LUV ≈ 1044 erg s-1, close to the Eddington limit. 1H 0707-495 entered the lowest hard flux state seen in 20 yr of XMM-Newton observations. In the eROSITA All-Sky Survey (eRASS) observations taken in April 2020, the X-ray light curve is still more variable in the ultra-soft band, but with increased soft and hard band count rates more similar to previously observed flux states. A model including relativistic reflection and a variable partial covering absorber is able to fit the spectra and provides a possible explanation for the extreme light-curve behaviour. The absorber is probably ionised and therefore more transparent to soft X-rays. This leaks soft X-rays in varying amounts, leading to large-Amplitude soft-X-ray variability.