Day 1518

Friday.

1812.08169
Testing dark matter and modifications to gravity using local Milky Way Observables
Lisanti, et al

Galactic rotation curve are often considered the first robust evidence for the existence of dark matter.  However, even in the presence of a dark matter halo, other galactic scale observations, such as the Baryonic Tully-Fisher relation and the radial acceleration relation, remain challenging to explain.  This has motivated long-distance, IR modifications to gravity as an alternative to the DM hypothesis.  Present a framework to test a general classification of IR gravity modifications using local Milky Way observables, including the vertical acceleration field, the rotation curve, the baryonic surface density, and the stellar disk profile.  Focus on models that predict scalar amplifications of gravity, i.e., models that increase the magnitude but do not change the direction of the gravitational acceleration.  Modified Newtonian Dynamics (MOND) is one such example.  Find that an IR modification to gravity of this type is in tension with observations of the MW scale radius and bulge mass and that DM provides a better fit to the data.  Conclude that models like MOND struggle to simultaneously explain both the rotational velocity and vertical motion of nearby stars in the MW.


1812.08206
Constraining neutrino mass with weak lensing Minkowski Functionals
Marques, et al

The presence of massive neutrinos affects structure formation, leaving imprints on large-scale structure observables such as the weak lensing field.  The common lensing analysis with 2pt statistics are insensitive to the large amount of non-Gaussian information in the density field.  Investigate non-Gaussian tools, in particular the Minkowski Functionals (MFs)---morphological descriptors including area, perimeter, and genus---in an attempt to recover the higher-order information.  Use convergence maps from the Cosmological Massive Neutrino Simulations (MassiveNus) and assume galaxy noise, density and z distribution for an LSST-like survey.  Show that MFs are sensitive to the neutrino mass sum, and the sensitivity is z dependent and is non-Gaussian.  Find that redshift tomography significantly improves the constraints on neutrino mass for MFs, compared to the improvements for the PS.  Attribute this to the stronger z dependence of neutrino effects on small scales.  Then build an emulator to model the PS and MFs, and study the constraints on M_nu, Omega_m, A_s from the PS, MFs, and their cmbination.  Show that MFs significantly outperform the PS in constraining neutrino mass, by more than a factor of four.  However, a thorough study of the impact from systematics such as baryon physics and galaxy shape and redshift biases will be important to realize the full potential of MFs.