1. Columbia University, Department of Physics, New York City, 116th str. Broadway, New York, NY 10027, USA
2. Moscow Institute of Physics and Technology, Dolgoprudny, Institutsky per. 9, Moscow Region 141700, Russia
3. P.N. Lebedev Physical Institute, Leninsky prosp. 53, Moscow 119991, Russia
4. Department of Astrophysical Sciences, Peyton Hall, Princeton University, Princeton, NJ 08544, USA
5. The Raymond and Beverly Sackler School of Physics and Astronomy, Tel Aviv University, Tel Aviv 69978, Israel
6. Sternberg Astronomy Institute, Moscow State University, Universitetsky prosp. 13, Moscow 119234, Russia
7. Kazan Federal University, Institute of Physics, Kremlyovskaya str. 18, Kazan 420008, Russia