SAO researchers have discovered that supercritical accretion disks eject hot gas with a velocity of a few thousand kilometers per second. The supercritical regime of accretion onto black holes is very important for astrophysics. In the first half-billion years just after our Universe was born, supermassive black holes (quasars) began to appear and grow in centers of young galaxies. In such a "short" period they accumulated a huge mass of a few billion masses of the Sun. This is possible only in the supercritical accretion regime. So far, nobody was able to observe the process of fast quasar growth, because it ejects such a huge mass of gas and dust that it is not possible to see the quasar itself. However, there is a micro-copy of those young quasars in our Milky Way Galaxy - SS433. That is why it is very important to study this unique object.
    Gas falling onto a black hole (accretion) is not a frequent phenomenon in our Galaxy. Gas falling onto a black hole in the supercritical regime is even rarer. A supercritical accretion disk appears. SS433 is the only object of this kind in the Galaxy, and therefore it is unique. It is a binary system consisting of two close stars; the first one is a black hole of about 10 solar masses, the second is a donor-star, which literally drowns the black hole in its material.
    Many groups all over the world have studied SS433. Recently in SAO we have succeeded in discovering a new property of SS433 - the super-broad lines in its spectrum (Fig. 1). The gas falls onto the black hole, but the black hole can not accept all this gas (the supercritical regime), and most of the matter is thrown back with a velocity of about 4000 kilometers per second. We developed for the first time a computer model of the supercritical-disk wind (Fig. 2), which explains all the main observational data. The supercritical disk in SS433 possesses the most powerful wind in the Galaxy.
Published:
P.S.Medvedev, S.N.Fabrika, V.V.Vasiliev, V.P.Goranskij, E.A.Barsukova
Astronomy Letters, v.39, p.826 (2013)