A statistical approach to identify superluminous supernovae and probe their diversity

We investigate the identification of hydrogen-poor superluminous supernovae (SLSNe I) using a photometric analysis, without including an arbitrary magnitude threshold. We assemble a homogeneous sample of previously classified SLSNe I from the literature, and fit their light curves using Gaussian processes. From the fits, we identify four photometric parameters that have a high statistical significance when correlated, and combine them in a parameter space that conveys information on their luminosity and color evolution. This parameter space presents a new definition for SLSNe I, which can be used to analyse existing and future transient datasets. We find that 90% of previously classified SLSNe I meet our new definition. We also examine the evidence for two subclasses of SLSNe I, combining their photometric evolution with spectroscopic information, namely the photospheric velocity and its gradient. A cluster analysis reveals the presence of two distinct groups. `Fast' SLSNe show fast light curves and color evolution, large velocities, and a large velocity gradient. `Slow' SLSNe show slow light curve and color evolution, small expansion velocities, and an almost non-existent velocity gradient. Finally, we discuss the impact of our analyses in the understanding of the powering engine of SLSNe, and their implementation as cosmological probes in current and future surveys.Comment: 16 pages, 9 figures, accepted by ApJ on 23/01/201

Can filamentary accretion explain the orbital poles of the Milky Way satellites?

Several scenarios have been suggested to explain the phase-space distribution of the Milky Way (MW) satellite galaxies in a disc of satellites (DoS). To quantitatively compare these different possibilities, a new method analysing angular momentum directions in modelled data is presented. It determines how likely it is to find sets of angular momenta as concentrated and as close to a polar orientation as is observed for the MW satellite orbital poles. The method can be easily applied to orbital pole data from different models. The observed distribution of satellite orbital poles is compared to published angular momentum directions of subhalos derived from six cosmological state-of-the-art simulations in the Aquarius project. This tests the possibility that filamentary accretion might be able to naturally explain the satellite orbits within the DoS. For the most likely alignment of main halo and MW disc spin, the probability to reproduce the MW satellite orbital pole properties turns out to be less than 0.5 per cent in Aquarius models. Even an isotropic distribution of angular momenta has a higher likelihood to produce the observed distribution. The two Via Lactea cosmological simulations give results similar to the Aquarius simulations. Comparing instead with numerical models of galaxy-interactions gives a probability of up to 90 per cent for some models to draw the observed distribution of orbital poles from the angular momenta of tidal debris. This indicates that the formation as tidal dwarf galaxies in a single encounter is a viable, if not the only, process to explain the phase-space distribution of the MW satellite galaxies.Comment: 14 pages, 4 figures, 3 tables. Accepted for publication in MNRA

The Determinants of Mortality

Mortality rates have fallen dramatically over time, starting in a few countries in the 18th century, and continuing to fall today. In just the past century, life expectancy has increased by over 30 years. At the same time, mortality rates remain much higher in poor countries, with a difference in life expectancy between rich and poor countries of also about 30 years. This difference persists despite the remarkable progress in health improvement in the last half century, at least until the HIV/AIDS pandemic. In both the time-series and the cross-section data, there is a strong correlation between income per capita and mortality rates, a correlation that also exists within countries, where richer, better-educated people live longer. We review the determinants of these patterns: over history, over countries, and across groups within countries. While there is no consensus about the causal mechanisms, we tentatively identify the application of scientific advance and technical progress (some of which is induced by income and facilitated by education) as the ultimate determinant of health. Such an explanation allows a consistent interpretation of the historical, cross-country, and within-country evidence. We downplay direct causal mechanisms running from income to health.

Analogue Cosmological Particle Creation: Quantum Correlations in Expanding Bose Einstein Condensates

We investigate the structure of quantum correlations in an expanding Bose Einstein Condensate (BEC) through the analogue gravity framework. We consider both a 3+1 isotropically expanding BEC as well as the experimentally relevant case of an elongated, effectively 1+1 dimensional, expanding condensate. In this case we include the effects of inhomogeneities in the condensate, a feature rarely included in the analogue gravity literature. In both cases we link the BEC expansion to a simple model for an expanding spacetime and then study the correlation structure numerically and analytically (in suitable approximations). We also discuss the expected strength of such correlation patterns and experimentally feasible BEC systems in which these effects might be detected in the near future.Comment: Reference adde

On the Proof of Dark Matter, the Law of Gravity and the Mass of Neutrinos

We develop a new method to predict the density associated with weak lensing maps of (un)relaxed clusters in a range of theories interpolating between GR and MOND (General Relativity and Modified Newtonian Dynamics). We apply it to fit the lensing map of the bullet merging cluster 1E0657-56, in order to constrain more robustly the nature and amount of collisionless matter in clusters {\it beyond} the usual assumption of spherical equilibrium (Pointecouteau & Silk 2005) and the validity of GR on cluster scales (Clowe et al. 2006). Strengthening the proposal of previous authors we show that the bullet cluster is dominated by a collisionless -- most probably non-baryonic -- component in GR as well as in MOND, a result consistent with the dynamics of many X-ray clusters. Our findings add to the number of known pathologies for a purely baryonic MOND, including its inability to fit the latest data from the Wilkinson Microwave Anisotropy Probe. A plausible resolution of all these issues and standard issues of Cold Dark Matter with galaxy rotation curves is the "marriage" of MOND with ordinary hot neutrinos of 2eV. This prediction is just within the GR-independent maximum of neutrino mass from current $\beta$-decay experiments, and is falsifiable by the Karlsruhe Tritium Neutrino (KATRIN) experiment by 2009. Issues of consistency with strong lensing arcs and the large relative velocity of the two clusters comprising the bullet cluster are also addressed.Comment: 4 pages, 1 figure, accepted for publication in ApJL. Added a simple model of the bullet cluster's high velocity in TeVeS, and discussions of sterile neutrinos and of non-uniqueness of the lensing deprojectio

Demyelination and axonal preservation in a transgenic mouse model of Pelizaeus-Merzbacher disease

It is widely thought that demyelination contributes to the degeneration of axons and, in combination with acute inflammatory injury, is responsible for progressive axonal loss and persistent clinical disability in inflammatory demyelinating disease. In this study we sought to characterize the relationship between demyelination, inflammation and axonal transport changes using a Plp1-transgenic mouse model of Pelizaeus-Merzbacher disease. In the optic pathway of this non-immune mediated model of demyelination, myelin loss progresses from the optic nerve head towards the brain, over a period of months. Axonal transport is functionally perturbed at sites associated with local inflammation and 'damaged' myelin. Surprisingly, where demyelination is complete, naked axons appear well preserved despite a significant reduction of axonal transport. Our results suggest that neuroinflammation and/or oligodendrocyte dysfunction are more deleterious for axonal health than demyelination per se, at least in the short ter

The spacetime structure of MOND with Tully-Fisher relation and Lorentz invariance violation

It is believed that the modification of Newtonian dynamics (MOND) is possible alternate for dark matter hypothesis. Although Bekenstein's TeVeS supplies a relativistic version of MOND, one may still wish a more concise covariant formulism of MOND. In this paper, within covariant geometrical framwork, we present another version of MOND. We show the spacetime structure of MOND with properties of Tully-Fisher relation and Lorentz invariance violation.Comment: 6 pages. arXiv admin note: substantial text overlap with arXiv:1111.1383 and arXiv:1108.344

Thermally Induced Fluctuations Below the Onset of Rayleigh-B\'enard Convection

We report quantitative experimental results for the intensity of noise-induced fluctuations below the critical temperature difference $\Delta T_c$ for Rayleigh-B\'enard convection. The structure factor of the fluctuating convection rolls is consistent with the expected rotational invariance of the system. In agreement with predictions based on stochastic hydrodynamic equations, the fluctuation intensity is found to be proportional to $1/\sqrt{-\epsilon}$ where $\epsilon \equiv \Delta T / \Delta T_c -1$. The noise power necessary to explain the measurements agrees with the prediction for thermal noise. (WAC95-1)Comment: 13 pages of text and 4 Figures in a tar-compressed and uuencoded file (using uufiles package). Detailed instructions of unpacking are include

Functional network changes and cognitive control in schizophrenia

Cognitive control is a cognitive and neural mechanism that contributes to managing the complex demands of day-to-day life. Studies have suggested that functional impairments in cognitive control associated brain circuitry contribute to a broad range of higher cognitive deficits in schizophrenia. To examine this issue, we assessed functional connectivity networks in healthy adults and individuals with schizophrenia performing tasks from two distinct cognitive domains that varied in demands for cognitive control, the RiSE episodic memory task and DPX goal maintenance task. We characterized general and cognitive control-specific effects of schizophrenia on functional connectivity within an expanded frontal parietal network (FPN) and quantified network topology properties using graph analysis. Using the network based statistic (NBS), we observed greater network functional connectivity in cognitive control demanding conditions during both tasks in both groups in the FPN, and demonstrated cognitive control FPN specificity against a task independent auditory network. NBS analyses also revealed widespread connectivity deficits in schizophrenia patients across all tasks. Furthermore, quantitative changes in network topology associated with diagnostic status and task demand were observed. The present findings, in an analysis that was limited to correct trials only, ensuring that subjects are on task, provide critical insights into network connections crucial for cognitive control and the manner in which brain networks reorganize to support such control. Impairments in this mechanism are present in schizophrenia and these results highlight how cognitive control deficits contribute to the pathophysiology of this illness

G10/COSMOS : 38 band (far-UV to far-IR) panchromatic photometry using LAMBDAR

We present a consistent total flux catalogue for a ∼1 deg2 subset of the Cosmic Evolution Survey (COSMOS) region (RA ∈ [149∘.55, 150∘.65], Dec. ∈ [1∘.80, 2∘.73]) with near-complete coverage in 38 bands from the far-ultraviolet to the far-infrared. We produce aperture matched photometry for 128 304 objects with i < 24.5 in a manner that is equivalent to the Wright et al. catalogue from the low-redshift (z < 0.4) Galaxy and Mass Assembly (GAMA) survey. This catalogue is based on publicly available imaging from GALEX, Canada–France–Hawaii Telescope, Subaru, Visible and Infrared Survey Telescope for Astronomy, Spitzer and Herschel, contains a robust total flux measurement or upper limit for every object in every waveband and complements our re-reduction of publicly available spectra in the same region. We perform a number of consistency checks, demonstrating that our catalogue is comparable to existing data sets, including the recent COSMOS2015 catalogue. We also release an updated Davies et al. spectroscopic catalogue that folds in new spectroscopic and photometric redshift data sets. The catalogues are available for download at http://cutout.icrar.org/G10/dataRelease.php. Our analysis is optimised for both panchromatic analysis over the full wavelength range and for direct comparison to GAMA, thus permitting measurements of galaxy evolution for 0 < z < 1 while minimizing the systematic error resulting from disparate data reduction methods.Publisher PDFPeer reviewe