Numerically Modeling the First Peak of the Type IIb SN 2016gkg

Many Type IIb supernovae (SNe) show a prominent additional early peak in their light curves, which is generally thought to be due to the shock cooling of extended hydrogen-rich material surrounding the helium core of the exploding star. The recent SN 2016gkg was a nearby Type IIb SN discovered shortly after explosion, which makes it an excellent candidate for studying this first peak. We numerically explode a large grid of extended envelope models and compare these to SN 2016gkg to investigate what constraints can be derived from its light curve. This includes exploring density profiles for both a convective envelope and an optically thick steady-state wind, the latter of which has not typically been considered for Type IIb SNe models. We find that roughly $\sim0.02\,M_\odot$ of extended material with a radius of $\approx180-260\,R_\odot$ reproduces the photometric light curve data, consistent with pre-explosion imaging. These values are independent of the assumed density profile of this material, although a convective profile provides a somewhat better fit. We infer from our modeling that the explosion must have occurred within $\approx2-3\,{\rm hrs}$ of the first observed data point, demonstrating that this event was caught very close to the moment of explosion. Nevertheless, our best-fitting one-dimensional models overpredict the earliest velocity measurements, which suggests that the hydrogen-rich material is not distributed in a spherically symmetric manner. We compare this to the asymmetries seen in the SN IIb remnant Cas A, and we discuss the implications of this for Type IIb SN progenitors and explosion models.Comment: 8 pages, 8 figures, updated version accepted for publication in The Astrophysical Journa

The genetic architecture of the human cerebral cortex

The cerebral cortex underlies our complex cognitive capabilities, yet little is known about the specific genetic loci that influence human cortical structure. To identify genetic variants that affect cortical structure, we conducted a genome-wide association meta-analysis of brain magnetic resonance imaging data from 51,665 individuals. We analyzed the surface area and average thickness of the whole cortex and 34 regions with known functional specializations. We identified 199 significant loci and found significant enrichment for loci influencing total surface area within regulatory elements that are active during prenatal cortical development, supporting the radial unit hypothesis. Loci that affect regional surface area cluster near genes in Wnt signaling pathways, which influence progenitor expansion and areal identity. Variation in cortical structure is genetically correlated with cognitive function, Parkinson's disease, insomnia, depression, neuroticism, and attention deficit hyperactivity disorder

Anarchists and anarchisms in France since 1945: introduction and sources

This is an Accepted Manuscript of an article published by Taylor & Francis in Modern and Contemporary France on 19 Apr 2016, available online: http://dx.doi.org/10.1080/09639489.2016.115430