147 research outputs found
Constraining slow-roll inflation with WMAP and 2dF
We constrain slow-roll inflationary models using the recent WMAP data
combined with data from the VSA, CBI, ACBAR and 2dF experiments. We find the
slow-roll parameters to be and . For inflation models
we find that at the 2 and levels,
indicating that the model is under very strong pressure from
observations. We define a convergence criterion to judge the necessity of
introducing further power spectrum parameters such as the spectral index and
running of the spectral index. This criterion is typically violated by models
with large negative running that fit the data, indicating that the running
cannot be reliably measured with present data.Comment: 8 pages RevTeX4 file with six figures incorporate
WMAP constraints on inflationary models with global defects
We use the cosmic microwave background angular power spectra to place upper
limits on the degree to which global defects may have aided cosmic structure
formation. We explore this under the inflationary paradigm, but with the
addition of textures resulting from the breaking of a global O(4) symmetry
during the early stages of the Universe. As a measure of their contribution, we
use the fraction of the temperature power spectrum that is attributed to the
defects at a multipole of 10. However, we find a parameter degeneracy enabling
a fit to the first-year WMAP data to be made even with a significant defect
fraction. This degeneracy involves the baryon fraction and the Hubble constant,
plus the normalization and tilt of the primordial power spectrum. Hence,
constraints on these cosmological parameters are weakened. Combining the WMAP
data with a constraint on the physical baryon fraction from big bang
nucleosynthesis calculations and high-redshift deuterium abundance, limits the
extent of the degeneracy and gives an upper bound on the defect fraction of
0.13 (95% confidence).Comment: 10pp LaTeX/RevTeX, 6 eps figs; matches accepted versio
Towards a synthesized critique of neoliberal biodiversity conservation
During the last three decades, the arena of biodiversity conservation has largely aligned itself with the globally dominant political ideology of neoliberalism and associated governmentalities. Schemes such as payments for ecological services are promoted to reach the multiple ‘wins’ so desired: improved biodiversity conservation, economic development, (international) cooperation and poverty alleviation, amongst others. While critical scholarship with respect to understanding the linkages between neoliberalism, capitalism and the environment has a long tradition, a synthesized critique of neoliberal conservation - the ideology (and related practices) that the salvation of nature requires capitalist expansion - remains lacking. This paper aims to provide such a critique. We commence with the assertion that there has been a conflation between ‘economics’ and neoliberal ideology in conservation thinking and implementation. As a result, we argue, it becomes easier to distinguish the main problems that neoliberal win-win models pose for biodiversity conservation. These are framed around three points: the stimulation of contradictions; appropriation and misrepresentation and the disciplining of dissent. Inspired by Bruno Latour’s recent ‘compositionist manifesto’, the conclusion outlines some ideas for moving beyond critique
Planck intermediate results: III. the relation between galaxy cluster mass and Sunyaev-Zeldovich signal
We examine the relation between the galaxy cluster mass M and Sunyaev-Zeldovich (SZ) effect signal DA2 Y500 for a sample of 19 objects for which weak lensing (WL) mass measurements obtained from Subaru Telescope data are available in the literature. Hydrostatic X-ray masses are derived from XMM-Newton archive data, and the SZ effect signal is measured from Planck all-sky survey data. We find an MWL-D A2 Y500 relation that is consistent in slope and normalisation with previous determinations using weak lensing masses; however, there is a normalisation offset with respect to previous measures based on hydrostatic X-ray mass-proxy relations. We verify that our SZ effect measurements are in excellent agreement with previous determinations from Planck data. For the present sample, the hydrostatic X-ray masses at R500 are on average ~ 20 percent larger than the corresponding weak lensing masses, which is contrary to expectations. We show that the mass discrepancy is driven by a difference in mass concentration as measured by the two methods and, for the present sample, that the mass discrepancy and difference in mass concentration are especially large for disturbed systems. The mass discrepancy is also linked to the offset in centres used by the X-ray and weak lensing analyses, which again is most important in disturbed systems. We outline several approaches that are needed to help achieve convergence in cluster mass measurement with X-ray and weak lensing observations. © ESO, 2013
- …