We describe a complete volume limited sample of nearby active galaxies selected by their 14-195keV luminosity, and outline its rationale for studying the mechanisms regulating gas inflow and outflow. We describe also a complementary sample of inactiv
e galaxies, selected to match the AGN host galaxy properties. The active sample appears to have no bias in terms of AGN type, the only difference being the neutral absorbing column which is two orders of magnitude greater for the Seyfert 2s. In the luminosity range spanned by the sample, log L_{14-195keV} [erg/s] = 42.4-43.7, the optically obscured and X-ray absorbed fractions are 50-65%. The similarity of these fractions to more distant spectroscopic AGN samples, although over a limited luminosity range, suggests that the torus does not strongly evolve with redshift. Our sample confirms that X-ray unabsorbed Seyfert 2s are rare, comprising not more than a few percent of the Seyfert 2 population. At higher luminosities, the optically obscured fraction decreases (as expected for the increasing dust sublimation radius), but the X-ray absorbed fraction changes little. We argue that the cold X-ray absorption in these Seyfert 1s can be accounted for by neutral gas in clouds that also contribute to the broad line region (BLR) emission; and suggest that a geometrically thick neutral gas torus co-exists with the BLR and bridges the gap to the dusty torus.
The barred grand-design spiral M83 (NGC 5236) is one of the most studied galaxies given its proximity, orientation, and particular complexity. Nonetheless, many aspects of the central regions remain controversial conveying our limited understanding o
f the inner gas and stellar kinematics, and ultimately of the nucleus evolution. In this work, we present AO VLT-SINFONI data of its central ~235x140 pc with an unprecedented spatial resolution of ~0.2 arcsec, corresponding to ~4 pc. We have focused our study on the distribution and kinematics of the stars and the ionised and molecular gas by studying in detail the Pa_alpha and Br_gamma emission, the H_2 1-0S(1) line at 2.122 micron and the [FeII] line at 1.644 micron, together with the CO absorption bands at 2.293 micron and 2.323 micron. Our results reveal a complex situation where the gas and stellar kinematics are totally unrelated. Supernova explosions play an important role in shaping the gas kinematics, dominated by shocks and inflows at scales of tens of parsecs that make them unsuitable to derive general dynamical properties. We propose that the location of the nucleus of M83 is unlikely to be related to the off-centre optical nucleus. The study of the stellar kinematics reveals that the optical nucleus is a gravitationally bound massive star cluster with M_dyn = (1.1 pm 0.4)x10^7 M_sun, formed by a past starburst. The kinematic and photometric analysis of the cluster yield that the stellar content of the cluster is well described by an intermediate age population of log T(yr) = 8.0pm0.4, with a mass of M simeq (7.8pm2.4)x10^6 M_sun.
While the existence of a starburst-AGN connection is undisputed, there is no consensus on what the connection is. In this contribution, we begin by noting that the mechanisms which drive gas inwards in disk galaxies are generally inefficient at remov
ing angular momentum, leading to stalled inflows. Thus, a tiered series of such processes is required to bring gas to the smallest scales, each of which on its own may not correlate with the presence of an AGN. Similarly, each may be associated with a starburst event, making it important to discriminate between circumnuclear and nuclear star formation. In this contribution, we show that stellar feedback on scales of tens of parsecs plays a critical role in first hindering and then helping accretion. We argue that it is only after the initial turbulent phases of a starburst that gas from slow stellar winds can accrete efficiently to smaller scales. This would imply that the properties of the obscuring torus are directly coupled to star formation and that the torus must be a complex dynamical entity. We finish by remarking on other contexts where similar processes appear to be at work.
In this article we identify and discuss various statistical and systematic effects influencing the astrometric accuracy achievable with MICADO, the near-infrared imaging camera proposed for the 42-metre European Extremely Large Telescope (E-ELT). The
se effects are instrumental (e.g. geometric distortion), atmospheric (e.g. chromatic differential refraction), and astronomical (reference source selection). We find that there are several phenomena having impact on ~100 micro-arcsec scales, meaning they can be substantially larger than the theoretical statistical astrometric accuracy of an optical/NIR 42m-telescope. Depending on type, these effects need to be controlled via dedicated instrumental design properties or via dedicated calibration procedures. We conclude that if this is done properly, astrometric accuracies of 40 micro-arcsec or better - with 40 micro-arcsec/year in proper motions corresponding to ~20 km/s at 100 kpc distance - can be achieved in one epoch of actual observations
We present the first comparison of the dynamical properties of different samples of z~1.4-3.4 star forming galaxies from spatially resolved imaging spectroscopy from SINFONI/VLT integral field spectroscopy and IRAM CO millimeter interferometry. Our s
amples include 16 rest-frame UV-selected, 16 rest-frame optically-selected and 13 submillimeter galaxies (SMGs). We find that restframe UV- and optically bright (K<20) z~2 star forming galaxies are dynamically similar, and follow the same velocity-size relation as disk galaxies at z~0. In the theoretical framework of rotating disks forming from dissipative collapse in dark matter halos, the two samples require a spin parameter ranging from 0.06 to 0.2. In contrast bright SMGs have larger velocity widths and are much more compact. Hence, SMGs have lower angular momenta and higher matter densities than either of the UV- or optically selected populations. This indicates that dissipative major mergers may dominate the SMGs population, resulting in early spheroids, and that the majority of UV/optically bright galaxies have evolved less violently [...]. These early disks may later evolve into spheroids via disk instabilities or mergers. Because of their small sizes and large densities, SMGs lie at the high surface density end of a universal (out to z=2.5) Schmidt-Kennicutt relation between gas surface density and star formation rate surface density with a slope of ~1.7.
We analyse star formation in the nuclei of 9 Seyfert galaxies at spatial resolutions down to 0.085arcsec, corresponding to length scales of less than 10pc in some objects. Our data were taken mostly with the near infrared adaptive optics integral fie
ld spectrograph SINFONI. The stellar light profiles typically have size scales of a few tens of parsecs. In two cases there is unambiguous kinematic evidence for stellar disks on these scales. In the nuclear regions there appear to have been recent - but no longer active - starbursts in the last 10-300Myr. The stellar luminosity is less than a few percent of the AGN in the central 10pc, whereas on kiloparsec scales the luminosities are comparable. The surface stellar luminosity density follows a similar trend in all the objects, increasing steadily at smaller radii up to 10^{13}L_sun/kpc^2 in the central few parsecs, where the mass surface density exceeds 10^4M_sun/pc^2. The intense starbursts were probably Eddington limited and hence inevitably short-lived, implying that the starbursts occur in multiple short bursts. The data hint at a delay of 50--100Myr between the onset of star formation and subsequent fuelling of the black hole. We discuss whether this may be a consequence of the role that stellar ejecta could play in fuelling the black hole. While a significant mass is ejected by OB winds and supernovae, their high velocity means that very little of it can be accreted. On the other hand winds from AGB stars ultimately dominate the total mass loss, and they can also be accreted very efficiently because of their slow speeds.
