Fermi bubbles, their origin and possible connection to cosmic rays near the Earth

Discovery of two giant structures seen in gamma-rays and radio, located above and below the Galactic center, known as Fermi bubbles, can be considered as one of the most interesting phenomena observed by Fermi-LAT. Their position and total energy content suggest a very strong energy outburst happened in the Galactic center in the past. We point out some limitations of theoretical models of Fermi bubbles. We also discuss interconnection between Fermi bubbles and Galactic cosmic rays. In particular, we point out that gamma-ray emitting electrons in the bubbles are most likely originated from cosmic ray electrons. In addition we show that Fermi bubbles may be responsible for the formation of the spectrum of cosmic rays above the "knee".