Moscow State University
Sternberg Astronomical Institute
Moscow Union "Optic"
Astronomers in Lomonosov Moscow State University (MASTER project) have proved that gamma ray bursts (the most powerful explosions in the Universe) arise from the formation of fast rotating black holes possessing ergosphere. So, the nature of the gamma ray bursts is discovered, a new evidence in favour of black holes existence in the Universe is obtained.
Black holes are among the most mysterious object in the Universe predicted by Einsteins theory. Ninety years ago German physicist Karl Schwartaschield showed that the bodies describable by dint of only one parameter (their mass) can exist in the nature. Such black hole should be the product of the evolution of massive, non-rotating star. These objects are the holes in the space, their shape is sphere, their radii are about ten kilometers, and the radius (Schwartaschield radius) of the object is the minimum possible radius of the packed material of the definite mass. Any body inside this sphere (event horizon) is not able to return to the Universe. Therefore the black hole (outside the object) is the simplest (this is a paradox) object in the nature. Namely such black holes (Schwartaschield black holes) are usually described in popular scientific literature. Nevertheless, forty years ago physicist-theorists understood that black holes can be more complicated objects. If the hole rotates, it has a structure: the event horizon shrinks and becomes less due to influence of the centrifugal force. Ellipsoidal envelope (ergosphere) forms around the hole, any body is not able to stay in rest inside this envelope.
Although reports about the discovery of black holes appear in the press at times, the Nobel committee does not hurry to give a Nobel Prize for such discovery. Why? The point is that these publications concern candidates in black holes, but not black holes. Evidently, it is necessary to find a peculiar property of the black hole to prove its existence, and no other object to show the same feature in the whole Universe. It seems that group of Russian astronomers (this group had constructed the first Russian robotic telescope MASTER) proved that gamma ray bursts are the black holes surrounded by ergospheres. The group observed the process and made theoretical model of the process. This model directly shows that the energy of the gamma ray burst comes from the ergosphere of the black hole during the latest stages of its life.
Gamma ray bursts are the most powerful explosions in the Universe. Scientists from the leading countries in the world register them during forty years. In September, 2006 the MASTER robotic telescope observed one of such bursts and found a rare event: optical emission (the emission usually fades) after 400-th second began to increase.
This event was analyzed by the MASTERs group. A new theoretical model was created. When the star located at the edge of the Universe (at the distance about 10 billion light years) depletes its nuclear energy sources, its core began to collapse into the black hole. If the star does not rotate, everything should come to the end during some millisecond, so it is impossible to understand why the activity of the event (gamma ray burst) was resumed. Therefore we must conclude that something does not allow forming a black hole. Evidently the dying star rotates. During collapse two forces increase: gravitational and centrifugal forces. The star, like figure skater squeezing hands, spins up, and the collapse stops, a fast rotating object forms (a spinar). Its formation is accompanied by a huge energy release in the form of a gamma ray burst. The matter of the star resists to its irretrievable disappearance from the Universe. But this fight is vain. Fast rotation and strong magnetic field lead to a new energy release, and after 400-th second all become over, the stars size drops to the event horizon.
The MASTERs group did not hurry to publish this discovery, because described hypothesis is beautiful, but there are some different suggestions. On 10 January 2007 American gamma observatory Swift obtained a wonderful phenomenon: luminosity of the gamma ray burst remained unchanged during 10000 seconds. After this event we have no doubt that we are eye-witness of super long fight between gravitational and centrifugal forces. The paper of Russian scientists will appear in the leading American astrophysical journal. According to estimations of Russian scientists, the stars radius is less than Schwartaschield radius during about an hour, in other words, it is situated in the ergosphere of the future black hole.
1). in the upper Figure: The structure of the limit rotating black hole. Inner sphere (the red ball) is the event of horizon of the rotating black hole (a half of the Schwartaschield radius). Grey is the ergosphere.
.gif)
Film: theoretical calculations of the power of the collapsing star inside and outside the ergosphere. The real time collapsing star is shown; its size is in units of Schwartaschield radius (upper box). In the bottom box we show a diagram of the power radiated during collapse (vertical axis is the power of the spinar in logarithmic scale, ergs per second). Reload the page to start the film again.
Fig. 3. Figure 3a Combined Swift (BAT and XRT) light curves of GRB 050904 (z=6.29)
and GRB 070110 (z=2.35) in the source rest frame (Troja, E., et al 2007) Figures 3b-
c show the result of the computation of the spinar luminosity, radius and effective Kerr
parameter, respectively. The mean magnetic field evolution (Figure 3e) is calculated under
the approximated general relativistic model
Vladimir M. Lipunov -
MASTER Team Leader
Professor of the Moscow State University
MASTER - Mobile Astronomical System of the TElescope-Robots - First Russian Robotic Telescope disigned by Moscow State University Scientis and Moscow Union "OPTIC".
References:
Lipunov, V. & Gorbovskoy, E., 2007, ApJ.Letters, v.665., L97-L100
Lipunov, V. & Gorbovskoy, E., 2008, Monthly Notices of the Royal Astronomical Society, Volume 383, Issue 4, pp. 1397-1412
