Julian Merten


AstroFIt 2 – COFUND fellow since July 1, 2017

Project ended May 31, 2019

INAF Research Centre: Osservatorio Astronomico di Bologna

Email: julian.merten at inaf.it

Curriculum vitae



Project title: COSMORPH – From the luminous shapes of galaxies to the dark shape of structure


The cosmological standard model is very successful in describing key observations with only very few parameters but it makes no attempt to understand quantitatively its key components, dark matter and dark energy. At the intersection between Cosmology and Astrophysics, at the scales of individual haloes, tension between theoretical predictions and observations arise. This proposal aims to remedy these shortcomings of the standard model and to investigate potential inconsistencies via a thorough study of nonlinear structure formation. The main tool in this study is gravitational lensing and I propose a three branch research programme. The first branch will contribute to the main ingredient of a modern galaxy lensing survey, the weak lensing shear catalogue. New methods for PSF characterisation and shear calibration will be developed for the Euclid mission and applied to current surveys. The second branch shall produce optimal mass maps from multi-wavelength data. Derived mainly from lensing, but including information form gas tracers and spectroscopy these maps show the distribution of matter on many different length scales and over significant portions of the sky. Besides applications for studies of the high redshift Universe and lensed supernovae, these maps will be used for morphological studies of the cosmic web and the shape of haloes. This defines the third research branch which has the goal to go beyond the usual paradigm of two point statistics and spherically symmetric functional forms to characterise the cosmic web on large and the density profile of haloes on smaller scales. Characterising features, based on the full available morphological information shall be derived and compared to the results of numerical simulations within different structure formation scenarios. These scenarios include different theories of gravity, different dark matter and dark energy couplings and varying implementations of baryonic physics.

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