Abstract

Warming up the Universe: JWST deep lensing field as a tool to constrain fundamental physics

Andrea Grazian (INAF-Osservatorio Astronomico di Roma)

Nicola Menci (INAF-OARoma) Marco Castellano (INAF-OARoma) Norma Sanchez (Observatoire de Paris)

Several critical issues affect Cold Dark Matter (CDM) galaxy formation models on small scales. A possible solution is the so called Warm Dark Matter (WDM) component, constituted by a particle mass of the order of few keV, possibly in the form of sterile neutrinos. A natural prediction of the WDM model is a sharp cut off in the halo mass function at small scales (Mhalo~10^8-10^9 Msun), due to the enhanced free streaming of the lighter and faster WDM particles wrt the heavier CDM ones. A sterile neutrino mass of 7 keV is consistent with the observations of a 3.5 keV emission line from the Perseus cluster, as a possible signature of the decay processes of this particle into two energetic photons. We have used deep HST observations of galaxies at z>6, magnified by strong lensing by two clusters of galaxies observed under the Hubble Frontier Field (HFF) program, to put one of the most stringent limit to the thermal relic WDM particle mass (mX>2.9 keV at 68\% c.l.), free from assumptions related to baryonic physics (Menci et al. 2016). We propose here a very deep JWST survey on a HFF cluster with high magnification in order to derive the galaxy number densities down to extremely faint intrinsic luminosities (Muv=-10) at z>6. The expected cumulative number densities correspond to a constraint of mX>4 keV, which is a critical regime to distinguish between the cold and warm dark matter scenarios. These observations will demonstrate that JWST can be used as a unique tool to constrain fundamental physics.

Talk