Xtronomy (or Xtrophysics) is the physics or EXTREME astronomy/astrophysics and, if you want Cosmology (Xosmology could be used for the latters). It includes the following:
- X-ray astronomy.
- Gamma ray astronomy.
- Cosmic ray astronomy.
- Neutrino astronomy.
- Gravitational wave astronomy.
- Possible X-particle astronomy (like axions, monopoles, dark matter particles, gravitons, etcetera).