Aims. This paper addresses the global molecular gas properties of a representative sample of galaxies hosting low-luminosity quasistellar objects. An abundant supply of gas is necessary to fuel both the active galactic nucleus and any circum-nuclear starburst activity of QSOs. The connection between ultraluminous infrared galaxies and the host properties of QSOs is still subject to a controversial debate. Nearby low-luminosity QSOs are ideally suited to study the properties of their host galaxies because of their higher frequency of occurrence compared to high-luminosity QSOs in the same comoving volume and because of their small cosmological distance. Methods. We selected a sample of nearby low-luminosity QSO host galaxies that is free of infrared excess biases. All objects are drawn from the Hamburg-ESO survey for bright UV-excess QSOs, have δ > −30• and redshifts that do not exceed z = 0.06. The IRAM 30 m telescope was used to measure the 12 CO(1−0) and 12 CO(2−1) transition in parallel. Results. 27 out of 39 galaxies in the sample have been detected. The molecular gas masses of the detected sources range from 0.4 × 10 9 M to 9.7 × 10 9 M . The upper limits of the non-detected sources correspond to molecular gas masses between 0.3 × 10 9 M and 1.2 × 10 9 M . We can confirm that the majority of galaxies hosting low-luminosity QSOs are rich in molecular gas. The properties of galaxies hosting brighter type I AGN and circumnuclear starformation regions differ from the properties of galaxies with fainter central regions. The overall supply of molecular gas and the spread of the line width distribution is larger. When comparing the farinfrared with the CO luminosities, the distribution can be separated into two different power-laws: one describing the lower activity Seyfert I population and the second describing the luminous QSO population. The separation in the L FIR /L CO behavior may be explainable with differing degrees of compactness of the emission regions. We provide a simple model to describe the two power-laws. The sample studied in this paper is located in a transition region between the two populations.

Context. We report on a successful, simultaneous observation and modeling of the sub-millimeter to near-infrared flare emission of the Sgr A* counterpart associated with the super-massive (4 × 10 6 M ) black hole at the Galactic center. Aims. We study and model the physical processes giving rise to the variable emission of Sgr A*. Methods. Our non-relativistic modeling is based on simultaneous observations that have been carried out on 03 June, 2008. We used the NACO adaptive optics (AO) instrument at the European Southern Observatory's Very Large Telescope and the LABOCA bolometer at the Atacama Pathfinder Experiment (APEX). We emphasize the importance of a multi-wavelength simultaneous fitting as a tool for imposing adequate constraints on the flare modeling. Results. The observations reveal strong flare activity in the 0.87 mm (345 GHz) sub-mm domain and in the 3.8 μ/2.2 μm NIR. Inspection and modeling of the light curves show that the sub-mm follows the NIR emission with a delay of 1.5 ± 0.5 h. We explain the flare emission delay by an adiabatic expansion of the source components. The derived physical quantities that describe the flare emission give a source component expansion speed of v exp ∼ 0.005c, source sizes around one Schwarzschild radius with flux densities of a few Janskys, and spectral indices of α = 0.8 to 1.8, corresponding to particle spectral indices ∼2.6 to 4.6. At the start of the flare the spectra of these components peak at frequencies of a few THz. Conclusions. These parameters suggest that the adiabatically expanding source components either have a bulk motion greater than v exp or the expanding material contributes to a corona or disk, confined to the immediate surroundings of Sgr A*.

We present near infrared ISAAC VLT observations of nine nearby (0.01 ≤ z ≤ 0.06) Active Galactic Nuclei selected from the Hamburg/ESO Survey and the Véron-Cetty & Véron catalog. Hydrogen recombination lines Paα and Brγ are observed in seven of the nine sources of which five show a broad component. In three sources, extended 1-0S(1) rotational-vibrational molecular hydrogen emission is detected. Stellar CO absorption is seen in four sources. In one of these objects, an upper limit of the central mass can be determined from the stellar velocity field. H-and Ks-band imaging allow us to determine the morphology class of the host galaxies. Colors (with supplementary J-band 2MASS images) show that the four galaxies with detected CO absorption are characterized by an overall strong stellar contribution. One galaxy shows an increased extinction towards the nucleus. After removal of the nuclear point source, the host galaxies show colors typical for non-active spiral galaxies.

Aims. We present first results of near-infrared (NIR) J and H + K ESO-SINFONI integral field spectroscopy of the composite starburst/Seyfert 1.8 galaxy Mrk 609. The data were taken during the science verification period of SINFONI. We aim to investigate the morphology and excitation conditions within the central 2 kpc. Additional Nobeyama 45 m CO(1−0) data are presented, which we used to estimate the molecular gas mass. The source was selected from a sample of SDSS/ROSAT-based, X-ray bright AGN with redshifts of 0.03 < z < 1 that are suitable for adaptive optics observations. This sample allows for a detailed study of the NIR properties of the nuclear and host environments with high spectral and spatial resolution. Methods. Integral field spectroscopy with SINFONI delivers simultaneous spatial and spectral coverage of the circumnuclear environment. The NIR light is influenced less by dust extinction than by optical light and is sensitive to mass-dominating stellar populations. Furthermore, several NIR emission lines allow us to distinguish between Seyfert and starburst activities. Results. Our NIR data reveal a complex emission-line morphology that is possibly associated with a nuclear bar seen in the recon- Conclusions. High angular resolution imaging spectroscopy provides an ideal tool for resolving the nuclear and starburst contributions in active galaxies. We show that Mrk 609 exhibits LINER features that appear to be hidden in visible/NIR spectra with larger apertures.

We present CO(1-0) and CO(2-1) line emission maps of the barred spiral active galaxy HE 1029-1831 (z = 0.0403) obtained with the IRAM Plateau de Bure Interferometer (PdBI) and in part by the Berkeley-Illinois-Maryland Association (BIMA) observatory. The CO emission is well associated with the optical bar and extended along it. The FWHM of the CO emission is estimated to be ∼(6 ± 2) kpc. The CO emission shows a strong velocity gradient along the minor axis of the bar (PA = 90• ). The molecular gas mass is estimated to be ∼1.2 × 10 10 M which indicates a very gas rich host galaxy. Most of the molecular gas appears to be subthermally excited and cold but we also find weak evidence for a warmer and/or denser gas component at the southern part of the bar emission, about ∼4 kpc from the galactic nucleus.