We try to constrain the nuclear Equation-of-State (EoS) and supernova ejecta models by observations of young neutron stars in our galactic neighbourhood. There are seven thermally emitting isolated neutron stars known from X-ray and optical observati
ons, the so-called Magnificent Seven, which are young (few Myrs), nearby (few hundred pc), and radio-quiet with blackbody-like X-ray spectra, so that - by observing their surface - we can determine their luminosity, distance, and temperature, hence, their radius. We also see the possibility to determine their current neutron star masses and the masses of their progenitor stars by studying their origin. It is even feasible to find the neutron star which was born in the supernova, from which those Fe60 atoms were ejected, which were recently found in the Earth crust.
Neutron stars (NS) and black holes (BH) are sources of gravitational waves (GW) and the investigation of young isolated radio-quiet NS can in principle lead to constraints of the equation of state (EoS). The GW signal of merging NSs critically depend
s on the EoS. However, unlike radio pulsars young isolated radio-quiet neutron stars are hard to detect and only seven of them are known so far. Furthermore, for GW projects it is necessary to confine regions in the sky where and of which quantity sources of GW can be expected. We suggest strategies for the search for young isolated radio-quiet NSs. One of the strategies is to look for radioactivities which are formed during a supernova (SN) event and are detectable due to their decay. Radioactivities with half lives of ~1 Myr can indicate such an event while other remnants like nebulae only remain observable for a few kyrs. Here we give a brief overview of our strategies and discuss advantages and disadvantages
