Gerold Busch

The nuclear gas disk of NGC 1566 dissected by SINFONI and ALMA

We present the results of near-infrared (NIR) H- and K-band European Southern Observatory SINFONI integral field spectroscopy (IFS) of the Seyfert galaxy NGC 1566. We investigate the central kpc of this nearby galaxy, concentrating on excitation conditions, morphology, and stellar content. NGC 1566 was selected from our NUGA (-south) sample and is a ringed, spiral galaxy with a stellar bar in north-south direction (PA 5 ). The galaxy inhibits a very active Seyfert 1 nucleus but narrow line ratios from optical observations in the nuclear region are similar to Seyfert 2 galaxies. The recent strong activity phase, as inferred from strong variablity in X-ray to IR wavelengths, makes NGC 1566 an ideal candidate to look for feeding and feedback of a supermassive black hole. We present emission and absorption line measurements in the central kpc of NGC 1566. Broad and narrow Br lines were detected. The detection of a broad Br component is a clear sign of a supermassive black hole in the center. Blackbody emission temperatures of 1000 K are indicative of a hot dust component, the torus, in the nuclear region. The molecular hydrogen lines, hydrogen recombination lines, and [Feii] indicate that the excitation at the center is coming from an AGN. The central region is predominantly inhabited by molecular gas, dust, and an old K-M type giant stellar population. The molecular gas and stellar velocity maps both show a rotation pattern. The molecular gas velocity field shows a perturbation toward the center that is typical for bars or spiral density waves. The molecular gas species of warm H2(1 0)S(1) and cold 12 CO(3 2) gas trace a nuclear gas disk of about 3 00 in radius with a nuclear spiral reaching toward the nucleus. From the equivalent width of H2(1 0)S(1) a molecular ring with r . 3 00 can be inferred. This spiral seems to be an instrument that allows gas to fall toward the nucleus down to <50 pc scales. The excitation of molecular hydrogen in the nuclear gas disk is not clear, but diagnostic diagrams show a distinction between the nuclear region and a <9 Myr old star-forming region at the southwestern spiral arm. Gas that might be shocked is detected 2 00 from the center, which is visible in dispersion maps of H2(1 0)S(1) and 12 CO(3 2) and in the 0.87 mm continuum.

The Close AGN Reference Survey (CARS): What is causing Mrk 1018’s return to the shadows after 30 years?

We recently discovered that the active galactic nucleus (AGN) of Mrk 1018 has changed optical type again after 30 yr as a type 1 AGN. Here we combine Chandra, NuStar, Swift, Hubble Space Telescope and ground-based observations to explore the cause of this change. The 2–10 keV flux declines by a factor of ~8 between 2010 and 2016. We show with our X-ray observation that this is not caused by varying neutral hydrogen absorption along the line-of-sight up to the Compton-thick level. The optical-UV spectral energy distributions are well fit with a standard geometrically thin optically thick accretion disc model that seems to obey the expected L ~ T^4 relation. It confirms that a decline in accretion disc luminosity is the primary origin for the type change. We detect a new narrow-line absorber in Lyα blue-shifted by ~700 km s^(-1) with respect to the systemic velocity of the galaxy. This new Lyα absorber could be evidence for the onset of an outflow or a companion black hole with associated gas that could be related to the accretion rate change. However, the low column density of the absorber means that it is not the direct cause for Mrk 1018’s changing-look nature.

A low-luminosity type-1 QSO sample. V. Overluminous host spheroids and their excitation mechanisms

We present near-infrared (NIR)

A low-luminosity type-1 QSO sample - II. Tracing circumnuclear star formation in HE 1029-1831 with SINFONI

H+K

Star formation and gas flows in the centre of the NUGA galaxy NGC 1808 observed with SINFONI

-band longslit spectra of eleven galaxies which are obtained with SOFI at the NTT (ESO). The galaxies are chosen from the low-luminosity type-1 quasi-stellar object (LLQSO) sample which comprises the 99 closest (

High-resolution observations of SDSS J080800.99+483807.7 in the optical and radio domains - A possible example of jet-triggered star formation

z\leq 0.06

Nature of the Galactic centre NIR-excess sources - I. What can we learn from the continuum observations of the DSO/G2 source?

) QSOs from the Hamburg/ESO survey for bright UV-excess QSOs. These objects are ideal targets to study the gap between local Seyfert galaxies and high-redshift quasars, since they show much stronger AGN activity compared to local objects but are still close enough for a detailed structural analysis. We fit hydrogen recombination, molecular hydrogen, and [FeII] lines after carefully subtracting the continuum emission. From the broad Pa

A low-redshift low luminosity QSO sample: Comparison with NUGA galaxies and PG QSOs and first interferometric images of three sample members

\alpha

The Multifrequency Behavior of Sagittarius A

components, we estimate black hole masses and enlarge the sample of LLQSOs that show a deviation from the

Spatially Resolved Spectroscopy of Narrow-line Seyfert 1 Host Galaxies

M_\mathrm{BH}-L_\mathrm{bulge}