2,928 research outputs found

    Observed parity-odd CMB temperature bispectrum

    Full text link
    Parity-odd non-Gaussianities create a variety of temperature bispectra in the cosmic microwave background (CMB), defined in the domain: 1+2+3=odd\ell_1 + \ell_2 + \ell_3 = {\rm odd}. These models are yet unconstrained in the literature, that so far focused exclusively on the more common parity-even scenarios. In this work, we provide the first experimental constraints on parity-odd bispectrum signals in WMAP 9-year temperature data, using a separable modal parity-odd estimator. Comparing theoretical bispectrum templates to the observed bispectrum, we place constraints on the so-called nonlineality parameters of parity-odd tensor non-Gaussianities predicted by several Early Universe models. Our technique also generates a model-independent, smoothed reconstruction of the bispectrum of the data for parity-odd configurations.Comment: 17 pages, 4 figures, 1 table. Accepted for publication in JCA

    Research Data Management at the University of Edinburgh: How is it done, what does it costs?

    Get PDF

    The shape of primordial non-Gaussianity and the CMB bispectrum

    Full text link
    We present a set of formalisms for comparing, evolving and constraining primordial non-Gaussian models through the CMB bispectrum. We describe improved methods for efficient computation of the full CMB bispectrum for any general (non-separable) primordial bispectrum, incorporating a flat sky approximation and a new cubic interpolation. We review all the primordial non-Gaussian models in the present literature and calculate the CMB bispectrum up to l <2000 for each different model. This allows us to determine the observational independence of these models by calculating the cross-correlation of their CMB bispectra. We are able to identify several distinct classes of primordial shapes - including equilateral, local, warm, flat and feature (non-scale invariant) - which should be distinguishable given a significant detection of CMB non-Gaussianity. We demonstrate that a simple shape correlator provides a fast and reliable method for determining whether or not CMB shapes are well correlated. We use an eigenmode decomposition of the primordial shape to characterise and understand model independence. Finally, we advocate a standardised normalisation method for fNLf_{NL} based on the shape autocorrelator, so that observational limits and errors can be consistently compared for different models.Comment: 32 pages, 20 figure

    Hearing new voices: re-viewing youth justice policy through practitioners’ relationships with young people

    Get PDF
    The relationship between young people and practitioners is the centre-piece of youth justice provision, yet little research-based knowledge has accumulated on its minutiae. After reviewing reforms affecting professional discretion, the paper draws on the concepts of dyadic relationships and praxis to reinvigorate a research agenda aimed at delineating a more nuanced understanding of practice relationships. Drawing on practice wisdom from across related social work fields, we argue that centralizing the practitioner-young person relationship remains the key to successful practice and thus needs greater, more detailed research attention. These claims are supported with a number of pilot interviews with youth justice workers about successful interventions that complement and extend related studies. The paper concludes with suggestions for research to enable joint activity between young people and practitioners to ‘rethink’ youth justice

    Primordial non-Gaussianity and the CMB bispectrum

    Get PDF
    We present a new formalism, together with efficient numerical methods, to directly calculate the CMB bispectrum today from a given primordial bispectrum using the full linear radiation transfer functions. Unlike previous analyses which have assumed simple separable ansatze for the bispectrum, this work applies to a primordial bispectrum of almost arbitrary functional form, for which there may have been both horizon-crossing and superhorizon contributions. We employ adaptive methods on a hierarchical triangular grid and we establish their accuracy by direct comparison with an exact analytic solution, valid on large angular scales. We demonstrate that we can calculate the full CMB bispectrum to greater than 1% precision out to multipoles l<1800 on reasonable computational timescales. We plot the bispectrum for both the superhorizon ('local') and horizon-crossing ('equilateral') asymptotic limits, illustrating its oscillatory nature which is analogous to the CMB power spectrum
    corecore