X-ray Observations of the Chemical Abundances in the Intra-Cluster Medium

Clusters of galaxies as the largest clearly defined objects in our Universe are ideal laboratories to study the distribution of the most abundant chemical elements heavier than hydrogen and helium and the history of their production. The cluster environment allows us to study the element abundances not only inside the galaxies, but also in the intergalactic space, the intracluster medium. Since the intracluster medium is heated to temperatures of several ten Million degrees, we can study the chemical composition of this medium through X-ray spectroscopy. Up to 13 heavy elements have been detected by X-ray spectroscopy so far. The element most easily detected in the X-ray spectra is iron. In massive galaxy clusters we find a larger mass of heavy elements in the intracluster medium than in the galaxies. The consideration of the intracluster medium is therefore vital for an understanding of the complete history of nucleosynthesis of the heavy elements. The observed abundances for all elements heavier than nitrogen can roughly be modeled by using two types of sources: core collapse supernovae and supernovae type Ia. So called cool-core galaxy clusters show a larger heavy element abundance in the cluster center which seems to be enriched primarily by products of supernovae of type Ia. The evidence for observations of an evolution of the heavy element abundance with redshift has still a moderate significance.Comment: To be published by Mem. S.A.It., Conference Proceedings of the Rencontre de l'Observatoire 2013 ESO Workshop on Metal Production in a Hierachical Universe, 8 pages, 9 figure

Climate politics from Kyoto to Bonn: from little to nothing?!?

We investigate how the U.S. withdrawal and the amendments of the Bonn climate policy conference in 2001 will change the economic and environmental impacts of the Kyoto Protocol in its original form. Based on simulations with a large-scale computable general equilibrium model, we find that U.S. withdrawal together with the new provisions of Bonn are likely to reduce environmental effectiveness to zero. U.S. compliance under the new Bonn amendments would accommodate a substantial cut in global emissions at small compliance costs for OECD countries rising some hopes that the U.S. might rejoin the Kyoto Protocol during the next years. --climate policy,emission trading,computable general equilibrium

Environmental tax differentiation between industries and households - implications for efficiency and employment: a multi-sector intertemporal CGE analysis for Germany

This paper investigates the economic impacts of environmental tax reforms designed to reach given emission reduction targets for the German economy. Our focus is on the efficiency and employment implications of alternative schemes for emission tax differentiation between the production sector and the household sector. We point out that strong tax discrimination in favor of the production sector may cause substantial excess costs. Differences in the emission tax base and the respective ease of emission mitigation across the production sector and the household sector are shown to play a crucial role for explaining our results. --environmental taxes,taxing production vs. taxing consumption,environmental tax reforms,computable general equilibrium

The Kyoto Protocol: A Review and Perspectives

International concern about climate change has led to the Kyoto Protocol, negotiated in 1997, which contains legally binding emission targets for industrialized countries to be achieved during the commitment period 2008-2012. While proponents of the Protocol celebrate it as a breakthrough in international climate policy, opponents criticize that its approach, namely setting targets and timetables for emission reductions, is seriously flawed. This paper provides a critical assessment of the Protocol?s potential performance and discusses amendments to foster its effectiveness and efficiency. It concludes that, even without any effective emission reductions in the initial commitment period, the ratification of Kyoto is important for the further policy process of climate protection. The Kyoto Protocol has established a flexible broad-based international mechanism that provides a valuable starting point for shaping efficient climate policies in the future. --climate policy,cost-benefit analysis,Kyoto Protocol

Cooling down hot air: a global CGE analysis of post-Kyoto carbon abatement strategies

The Kyoto Protocol marks a break-through in global warming mitigation policies as it sets legally binding emissions targets for major emitting regions. However, realisation of the Protocol depends on the clarification of several issues one of which is the permissible scope of international emissions trading between signatory countries. Unrestricted trade produces hot air when signatory countries whose Kyoto targets are well above their business as usual emissions trade in larger amounts of ?abundant? emission rights. Concerns on hot air motivated proposals for caps on emissions trading by the EU. These caps are strictly refused by the USA and other non-European industrialized countries who want to exploit the full efficiency gains from trade. In this paper we show that there are cooling down strategies which can reconcile both positions. International permit trade provides enough efficiency gains to make all signatory countries better off than without permit trade while mitigating hot air. In other words, part of the efficiency gains from free trade could be used to pay for higher abatement targets of signatory countries which assure the same environmental effectiveness as compared to strictly domestic action or restricted permit trade. --

Industry-level emission trading between power producers in the EU

In this paper we investigate how restrictions for emission trading to the energy-intensive power sector will affect the magnitude and distribution of abatement costs across EU countries vis-?-vis a comprehensive EU emission trading regime. We find that emission trading between European power sectors allows the harvest of a major part of the efficiency gains provided by full trade as compared to strictly domestic action. However, trade restrictions may create a more unequal distribution of abatement costs across member states than is the case for a comprehensive trade regime. The reason for this is that restricted permit trade enhances the secondary terms-of-trade benefits to EU member countries with low marginal abatement costs at the expense of the other EU member states. --emission trading,computable general equilibrium

The ROSAT-ESO Flux Limited X-ray Galaxy Cluster Survey (REFLEX II) I. Newly identified X-ray luminous clusters at z>=0.2

We report 19 intermediate redshift clusters newly detected in the ROSAT All-Sky survey that are spectroscopically confirmed. They form a part of 911 objects in the REFLEX II cluster catalogue with a limiting flux of 1.8\times10^12 erg/s/cm2 in the 0.1-2.4 keV ROSAT band at redshift z >= 0.2. In addition we report three clusters from the REFLEX III supplementary catalogue, which contains objects below the REFLEX II flux limit but satisfies the redshift constraint above. These clusters are spectroscopically followed-up by our ESO NTT-EFOSC2 campaigns for the redshift measurement. We describe our observing and data reduction methods. We show how X-ray properties such as spectral hardness ratio and source extent can be used as important diagnostics in selecting galaxy cluster candidates. Physical properties of the clusters are subsequently calculated from the X-ray observations. This sample contains the high mass and intermediate-redshift galaxy clusters for astrophysical and cosmological applications.Comment: Astronomy and Astrophysics (in press

The ROSAT-ESO Flux-Limited X-Ray (REFLEX) Galaxy Cluster Survey VI: Constraints on the cosmic matter density from the KL power spectrum

The Karhunen-Lo\'{e}ve (KL) eigenvectors and eigenvalues of the sample correlation matrix are used to analyse the spatial fluctuations of the REFLEX clusters of galaxies. The method avoids the disturbing effects of correlated power spectral densities which affects all previous cluster measurements on Gpc scales. Comprehensive tests use a large set of independent REFLEX-like mock cluster samples extracted from the Hubble Volume Simulation. It is found that unbiased measurements on Gpc scales are possible with the REFLEX data. The distribution of the KL eigenvalues are consistent with a Gaussian random field on the 93.4% confidence level. Assuming spatially flat cold dark matter models, the marginalization of the likelihood contours over different sample volumes, fiducial cosmologies, mass/X-ray luminosity relations and baryon densities, yields the 95.4% confidence interval for the matter density of $0.03<\Omega_mh^2<0.19$. The N-body simulations show that cosmic variance, although difficult to estimate, is expected to increase the confidence intervals by about 50%.Comment: 11 pages, 7 figures, accepted for publication in MNRA

Detection of X-ray Clusters of Galaxies by Matching RASS Photons and SDSS Galaxies within GAVO

A new method for a simultaneous search for clusters of galaxies in X-ray photon maps and optical galaxy maps is described. The merging of X-ray and optical data improves the source identification so that a large amount of telescope time for spectroscopic follow-up can be saved. The method appears thus ideally suited for the analysis of the recently proposed wide-angle X-ray missions like DUO and ROSITA. As a first application, clusters are extracted from the 3rd version of the ROSAT All-Sky Survey and the Early Date Release of the Sloan Digital Sky Survey (SDSS). The time-consuming computations are performed within the German Astrophysical Virtual Observatory (GAVO). On a test area of 140 square degrees, 75 X-ray clusters are detected down to an X-ray flux limit of $3-5\times 10^{-13} {\rm erg} {\rm s}^{-1} {\rm cm}^{-2}$ in the ROSAT energy band 0.1-2.4 keV. The clusters have redshifts $z\le 0.5$. The survey thus fills the gap between traditional large-area X-ray surveys and serendipitous X-ray cluster searches based on pointed observations, and has the potential to yield about 4,000 X-ray clusters after completion of SDSS.Comment: 19 pages, low-resolution figures, accepted for publication in Astronomy and Astrophysic