Recent structural evolution of forni glacier tongue (Ortles-Cevedale Group, Central Italian Alps)

Structural glaciology yields important details about the evolution of glacier dynamics in response to climate change. The maps provided here document the occurrence and evolution of brittle and ductile structures on the tongue of Forni Glacier, Ortles-Cevedale Group, Central Italian Alps, between 2003 and 2014. Through the remote sensing-based analysis of structures, we found evidence of brittle fractures such as crevasses, faults and ring faults, and ductile structures such as ogives at the base of the icefall in the eastern glacier tongue. Although each of the three glacier tongues have evolved differently, a reduction in flow-related dynamics and an increase in the number of collapse structures occurred over the study period. Analysis of the glacier structural evolution based on the numbers and the locations of different structures, suggest a slowdown of glacier flow on the eastern tongue. The recent evolution of the glacier also suggests that the occurrence of a disintegration scenario is likely to worsen over the next decades

Short GRBs at the dawn of the gravitational wave era

We derive the luminosity function and redshift distribution of short Gamma Ray Bursts (SGRBs) using (i) all the available observer-frame constraints (i.e. peak flux, fluence, peak energy and duration distributions) of the large population of Fermi SGRBs and (ii) the rest-frame properties of a complete sample of Swift SGRBs. We show that a steep $\phi(L)\propto L^{-a}$ with a>2.0 is excluded if the full set of constraints is considered. We implement a Monte Carlo Markov Chain method to derive the $\phi(L)$ and $\psi(z)$ functions assuming intrinsic Ep-Liso and Ep-Eiso correlations or independent distributions of intrinsic peak energy, luminosity and duration. To make our results independent from assumptions on the progenitor (NS-NS binary mergers or other channels) and from uncertainties on the star formation history, we assume a parametric form for the redshift distribution of SGRBs. We find that a relatively flat luminosity function with slope ~0.5 below a characteristic break luminosity ~3$\times10^{52}$ erg/s and a redshift distribution of SGRBs peaking at z~1.5-2 satisfy all our constraints. These results hold also if no Ep-Liso and Ep-Eiso correlations are assumed. We estimate that, within ~200 Mpc (i.e. the design aLIGO range for the detection of GW produced by NS-NS merger events), 0.007-0.03 SGRBs yr$^{-1}$ should be detectable as gamma-ray events. Assuming current estimates of NS-NS merger rates and that all NS-NS mergers lead to a SGRB event, we derive a conservative estimate of the average opening angle of SGRBs: $\theta_{jet}$~3-6 deg. Our luminosity function implies an average luminosity L~1.5$\times 10^{52}$ erg/s, nearly two orders of magnitude higher than previous findings, which greatly enhances the chance of observing SGRB "orphan" afterglows. Efforts should go in the direction of finding and identifying such orphan afterglows as counterparts of GW events.Comment: 13 pages, 5 figures, 2 tables. Accepted for publication in Astronomy & Astrophysics. Figure 5 and angle ranges corrected in revised versio

Technical Specification for the CLIC Two-Beam Module

A high-energy (0.5-3 TeV centre-of-mass), highluminosity Compact Linear Collider (CLIC) is being studied at CERN [1]. The CLIC main linacs, 21-km long each, are composed of 2-m long two beam modules. This paper presents their current layout, the main requirements for the different sub-systems (alignment, supporting, stabilization, cooling and vacuum) as well as the status of their integration

The cosmology dependence of the concentration-mass-redshift relation

The concentrations of dark matter haloes provide crucial information about their internal structure and how it depends on mass and redshift -- the so-called concentration-mass-redshift relation, denoted $c(M,z)$. We present here an extensive study of the cosmology-dependence of $c(M,z)$ that is based on a suite of 72 gravity-only, full N-body simulations in which the following cosmological parameters were varied: $\sigma_{8}$, $\Omega_{\mathrm{M}}$, $\Omega_{\mathrm{b}}$, $n_{\mathrm{s}}$, $h$, $M_{\nu}$, $w_{0}$ and $w_{\mathrm{a}}$. We characterize the impact of these parameters on concentrations for different halo masses and redshifts. In agreement with previous works, and for all cosmologies studied, we find that there exists a tight correlation between the characteristic densities of dark matter haloes within their scale radii, $r_{-2}$, and the critical density of the Universe at a suitably defined formation time. This finding, when combined with excursion set modelling of halo formation histories, allows us to accurately predict the concentrations of dark matter haloes as a function of mass, redshift, and cosmology. We use our simulations to test the reliability of a number of published models for predicting halo concentration and highlight when they succeed or fail to reproduce the cosmological $c(M,z)$ relation.Comment: 11 pages, 9 figure