The Growth of Black Holes and Bulges at the Cores of Cooling Flows

Central cluster galaxies (cDs) in cooling flows are growing rapidly through gas accretion and star formation. At the same time, AGN outbursts fueled by accretion onto supermassive black holes are generating X-ray cavity systems and driving outflows that exceed those in powerful quasars. We show that the resulting bulge and black hole growth follows a trend that is roughly consistent with the slope of the local (Magorrian) relation between bulge and black hole mass for nearby quiescent ellipticals. However, a large scatter suggests that cD bulges and black holes do not always grow in lock-step. New measurements made with XMM, Chandra, and FUSE of the condensation rates in cooling flows are now approaching or are comparable to the star formation rates, alleviating the need for an invisible sink of cold matter. We show that the remaining radiation losses can be offset by AGN outbursts in more than half of the systems in our sample, indicating that the level of cooling and star formation is regulated by AGN feedback.Comment: 3 pages, 4 figures, to appear in the proceedings of "Heating vs. Cooling in Galaxies and Clusters of Galaxies," edited by H. Boehringer, P. Schuecker, G. W. Pratt, and A. Finogueno

Benefits of Organic Farming for Society

Recent food scares have lead to a boom in demand for organic products and an increasing awareness of policy makers of the potential benefits of organic farming. However, policies specifically targeting organic farming support do not remain beyond dispute and a sound justification of these is in great demand. The potential specific contribution of organic farming to the achievement of some of the key objectives of the European Common Agricultural Policy, e.g. competitiveness of agriculture, farming income, food supply, food quality and minimisation of negative environmental impacts of agricultural production are discussed. It is argued that organic farming can contribute to the objectives of the CAP, however, addressing the various objectives to different degrees. The environmental effects of organic farming seem to be largely positive in comparison to conventional farming on a per hectare basis in all categories, be it biodiversity, input-output balances or soil and water resources, although other farming systems might perform better with respect to single indicators or when results are related to the amount of produced output. The quality of organically produced food seems to be higher than that of conventionally produced food for several indicators, for example, the risk of food contamination with pesticides and or nitrate tends to be lower. Income levels from organic farming are on average comparable to income generated on conventional farms, and organic farming is clearly a profitable alternative for quite a few farms in Europe. With respect to rural development organic farming is expected to have little direct effects, e.g. on unemployment rates, although small scale marketing and processing initiatives may contribute directly to rural employment. However, indirect effects such as increased employment in tourism due to a positive “ecological” image of a region can be of importance. Conclusively, organic farming can contribute to several of the declared policy objectives of the CAP. However, the information available to date does not permit a clear conclusion if organic farming achieves desirable effects at lower costs than other farming systems. Nevertheless, the positive effects on a broad range of objectives clearly justifies the support of organic farming and is therefore recommended

Produktionsverfahren des Ökologischen Landbaus in Baden-Württemberg

Diese Datensammlung ist als Hilfsmittel für die Betriebsplanung gedacht. Es stellt standardisierte Produktionsverfahren des Ökolandbaus in Baden-Württemberg dar, wobei die wichtigsten Verfahren des Ackerbaus, der Rindviehhaltung, des Feldfutterbaus und des Grünlandes aufgeführt sind. Die Ausgleichszahlungen und Prämien sind bis zum Jahr 2002/2003 aufgeführt: Für die Deckungsbeitragsrechnung wurde das Jahr 2002/2003 berücksichtigt. Als Maßnahme des MEKA (Marktentlastungs- und Kulturlandschaftsausgleichsprogramm) ist die Beibehaltung des ökologischen Landbaus in die Berechnung mit einbezogen

Entwicklung eines regionalen Ausbildungsmodells „Ökolandbau und Vermarktung“ an der Fachhochschule Eberswalde im Rahmen des Bundesförderprogramms Regionen Aktiv

In September 2004 a new B. Sc. study course for Organic Farming and Marketing started at the University of Applied Sciences Eberswalde. Supported by the Federal Ministry of Consumer Protection, Food and Agriculture program “Regionen Aktiv” an innovative education model was established. Focussing on rural development farmers, processors and trading partners were involved in the development of topics for the study programme

Tanniferous forage plants: Agronomic performance, palatability and efficacy against parasitic nematodes in sheep

Tanniferous forage plants can have beneficial effects on ruminant productivity and health (improved protein supply, bloat safety and antiparasitic properties). However, condensed tannins can also lower palatability, voluntary feed intake and digestibility. The aim of our interdisciplinary project was to generate basic knowledge on plant management, feed palatability and the antiparasitic properties of tanniferous forage plants for their practical application in agronomy, focusing on their usefulness in controlling gastrointestinal nematodes in organic farming. We found that Onobrychis viciifolia (sainfoin), Lotus corniculatus (birdsfoot trefoil) and Cichorium intybus (chicory) were suitable for cultivation under the given temperate climatic conditions, whereas Lotus pedunculatus (big trefoil) was soon outcompeted by unsown species. Growing the tanniferous plant species in a mixture with Festuca pratensis (meadow fescue) rather than in a monoculture had the advantage of increasing total dry matter (DM) yield (especially in the case of tanniferous legumes) and of reducing the DM proportions of unsown species. However, due to dilution by non-tanniferous F. pratensis, the tannin concentrations of mixtures were clearly lower and the seasonal fluctuations in tannin concentrations greater than that of monocultures. Across species, tannin concentrations were highest for O. viciifolia, followed by L. corniculatus and very low for C. intybus. Palatability of all tanniferous forages was comparable to that of a ryegrass/clover mixture when fed as dried forage and, when offered as silage, palatability of O. viciifolia was clearly superior to that of the respective ryegrass/clover control. Administration of dried or ensiled O. viciifolia reduced parasite egg counts in feces of lambs co-infected with the gastrointestinal nematode species Haemonchus contortus and Cooperia curticei. We conclude that O. viciifolia is the most promising among the tested tanniferous forage plant species due to its suitability for cultivation, its high tannin concentration, its high palatability and its antiparasitic activity even in dried or ensiled for

The Effects of X-Ray Feedback from AGN on Host Galaxy Evolution

Hydrodynamic simulations of galaxies with active galactic nuclei (AGN) have typically employed feedback that is purely local: i.e., an injection of energy to the immediate neighborhood of the black hole. We perform GADGET-2 simulations of massive elliptical galaxies with an additional feedback component: an observationally calibrated X-ray radiation field which emanates from the black hole and heats gas out to large radii from the galaxy center. We find that including the heating and radiation pressure associated with this X-ray flux in our simulations enhances the effects which are commonly reported from AGN feedback. This new feedback model is twice as effective as traditional feedback at suppressing star formation, produces 3 times less star formation in the last 6 Gyr, and modestly lowers the final BH mass (30%). It is also significantly more effective than an X-ray background in reducing the number of satellite galaxies.Comment: 9 emulateapj pages, 8 figures; accepted to Ap

The evolution of Black Hole scaling relations in galaxy mergers

We study the evolution of black holes (BHs) on the M_BH-sigma and M_BH-M_bulge planes as a function of time in disk galaxies undergoing mergers. We begin the simulations with the progenitor black hole masses being initially below (Delta log M_BH=-2), on (Delta log M_BH=0) and above (Delta log M_BH=0.5) the observed local relations. The final relations are rapidly established after the final coalescense of the galaxies and their BHs. Progenitors with low initial gas fractions (f_gas=0.2) starting below the relations evolve onto the relations (Delta log M_BH=-0.18), progenitors on the relations stay there (Delta log M_BH=0) and finally progenitors above the relations evolve towards the relations, but still remaining above them (Delta log M_BH=0.35). Mergers in which the progenitors have high initial gas fractions (f_gas=0.8) evolve above the relations in all cases (Delta log M_BH=0.5). We find that the initial gas fraction is the prime source of scatter in the observed relations, dominating over the scatter arising from the evolutionary stage of the merger remnants. The fact that BHs starting above the relations do not evolve onto the relations, indicates that our simulations rule out the scenario in which overmassive BHs evolve onto the relations through gas-rich mergers. By implication our simulations thus disfavor the picture in which supermassive BHs develop significantly before their parent bulges.Comment: 6 pages, 4 figures, accepted to ApJL (minor revisions to match accepted version

A Virtual Sky with Extragalactic HI and CO Lines for the SKA and ALMA

We present a sky simulation of the atomic HI emission line and the first ten CO rotational emission lines of molecular gas in galaxies beyond the Milky Way. The simulated sky field has a comoving diameter of 500/h Mpc, hence the actual field-of-view depends on the (user-defined) maximal redshift zmax; e.g. for zmax=10, the field of view yields ~4x4 sqdeg. For all galaxies, we estimate the line fluxes, line profiles, and angular sizes of the HI and CO emission lines. The galaxy sample is complete for galaxies with cold hydrogen masses above 10^8 Msun. This sky simulation builds on a semi-analytic model of the cosmic evolution of galaxies in a Lambda-cold dark matter (LCDM) cosmology. The evolving CDM-distribution was adopted from the Millennium Simulation, an N-body CDM-simulation in a cubic box with a side length of 500/h Mpc. This side length limits the coherence scale of our sky simulation: it is long enough to allow the extraction of the baryon acoustic oscillations (BAOs) in the galaxy power spectrum, yet the position and amplitude of the first acoustic peak will be imperfectly defined. This sky simulation is a tangible aid to the design and operation of future telescopes, such the SKA, the LMT, and ALMA. The results presented in this paper have been restricted to a graphical representation of the simulated sky and fundamental dN/dz-analyzes for peak flux density limited and total flux limited surveys of HI and CO. A key prediction is that HI will be harder to detect at redshifts z>2 than predicted by a no-evolution model. The future verification or falsification of this prediction will allow us to qualify the semi-analytic models.Comment: 16 pages, 9 figures, 1 tabl

Discovery of an active supermassive black hole in the bulge-less galaxy NGC 4561

We present XMM-Newton observations of the Chandra-detected nuclear X-ray source in NGC 4561. The hard X-ray spectrum can be described by a model composed of an absorbed power-law with Gamma= 2.5^{+0.4}_{-0.3}, and column density N_H=1.9^{+0.1}_{-0.2} times 10^{22} atoms cm^{-2}. The absorption corrected luminosity of the source is L(0.2 - 10.0 keV) = 2.5 times 10^{41} ergs s^{-1}, with bolometric luminosity over 3 \times 10^{42} ergs s^{-1}. Based on the spectrum and the luminosity, we identify the nuclear X-ray source in NGC 4561 to be an AGN, with a black hole of mass M_BH > 20,000 solar masses. The presence of a supermassive black hole at the center of this bulge-less galaxy shows that black hole masses are not necessarily related to bulge properties, contrary to the general belief. Observations such as these call into question several theoretical models of BH--galaxy co-evolution that are based on merger-driven BH growth; secular processes clearly play an important role. Several emission lines are detected in the soft X-ray spectrum of the source which can be well parametrized by an absorbed diffuse thermal plasma with non-solar abundances of some heavy elements. Similar soft X-ray emission is observed in spectra of Seyfert 2 galaxies and low luminosity AGNs, suggesting an origin in the circumnuclear plasma.Comment: To appear in Ap