Astrophysics - Cosmology and Nongalactic Astrophysics
Beschreibung:
We study an inevitable cosmological consequence in PeV-scale SUSY-breaking scenarios. We focus on the SUSY-breaking scale corresponding to the gravitino mass m3 /2=100 eV - 1 keV . We argue that the presence of an early matter-dominated era and the resulting entropy production are requisite for the Universe with this gravitino mass. We infer the model-independent minimum amount of the entropy production Δ by requiring that the number of dwarf satellite galaxies Nsat in the Milky Way exceed the currently observed value, i.e., Nsat≳63 . This entropy production is inevitably imprinted on the primordial gravitational waves (PGWs) produced during the inflationary era. We study how the information on the value of Δ and the time of entropy production are encoded in the PGW spectrum ΩGW. If the future GW surveys observe a suppression feature in the PGW spectrum for the frequency range O (10-10) Hz ≲fGW≲O (10-5) Hz , it works as a smoking gun for PeV SUSY-breaking scenarios. Even if they do not, our study can be used to rule out all such scenarios.