Day 987

Tuesday.


1510.02796
Advanced data visualization in astrophysics: the X3D pathway
Vogt, et al

Introduce the concept of the "X3D pathway" as a mean of simplifying and easing the access to data visualization and publication via 3D diagrams.  Argue that X3D standard is an ideal vector for sharing multi-dimensional datasets, as it provides direct access to a range of different data visualization techniques, is fully-open source, and is a well defined ISO standard.  Is compatible wit ha range of open-source software already in use by the community.  Detailed set of practical astrophysical examples given.


1510.02985
Shocks in the early universe
Pen, Turok

A consequence of the usually assumed ICs for cosmological perturbations: a scale invariant spectrum of Gaussian, linear, adiabatic, scalar, growing mode perturbations not only creates acoustic oscillations, of the kind observed in great detail on large scales today, it also leads to the production of shock waves in the radiation fluid of the very early universe.  At very early epochs, 1 GeV<T<1e7 GeV, assuming standard model physics, viscous damping is negligible and NL effects turn acoustic waves into shocks after ~1e4 oscillations.  The resulting scale-invariant network of shocks provides a natural mechanism for creating significant departures from local thermal equilibrium as well as primordial vorticity and gravitational waves.


1510.03171
Model-independent characterization of strong gravitational lenses
Wagner, Bartelmann

Develop a new approach to extracting model-independent information from observations of strong gravitational lenses.  The approach is based on the generic properties of images near the fold and cusp catastrophes in caustics and critical curves.  Observables used are the relative image positions, the magnification ratios and ellipticities of extended images, and time delays between images with temporally varying intensity.  Show how these observables constrain derivatives and ratios of derivatives of the lensing potential near a critical curve.  Based on these measured properties of the lensing potential, classes of parametric lens models can then easily be restricted to such parameter values compatible with the measurements, thus allowing fast scans of large varieties of models.  Applying the approach to a representative galaxy and a galaxy cluster lens, show which model-independent information can be extracted in those cases and demonstrate that the parameters obtained by the approach for known parametric lens models agree well with those found by detailed model fitting.