Physics Seminar : A smooth transition to the black hole: new resonances, particle capture and collapse of spectrum 
Other events...

We show that a quantum scalar particle in the gravitational field of a massive body of radius R which slightly exceeds the Schwarzschild radius rs, possesses a dense spectrum
of narrow resonances. In the limit R goes to rs their lifetimes tend to infinity, and one can interpret the capture of the free particle into these states as absorption. In this limit the spacing between the resonances tends to zero, which allows one to calculate the energyaveraged (optical) capture cross section. Surprisingly, for R goes to rs this cross section reproduces Unruh's black hole absorption cross section. Thus, a nonsingular static metric may have black hole properties without the actual formation of a black hole.
The boundstate energy levels of a scalar particle in the static gravitational field of a massive body of radius R which slightly exceeds the Schwarzschild radius rs, are found. Bound states with zero energy (where the binding energy is equal to the rest mass of the scalar particle) only exist when a singularity occurs in the metric. Therefore, in contrast to the Coulomb case, no pairs are produced in the nonsingular static metric. As pair
production is a necessary condition for Hawking radiation to occur, this suggests that these objects do not Hawking radiate.
For the Florides metric the singularity occurs in the black hole limit, while for the Schwarzschild interior metric it corresponds to infinite pressure at the centre. The energy
spectrum is shown to become quasicontinuous as the metric becomes singular. All levels with finite principal quantum number n collapse to zero energy.
1. Dense spectrum of resonances and particle capture in a nearblackhole metric, V. V. Flambaum, G. H. Gossel,
and G. F. Gribakin, arXiv:1012.2134 Submitted to Phys. Rev. Lett.
2. Energy levels of a scalar particle in a static gravitational field approaching the black hole field, G. H. Gossel, J. C. Berengut and V. V. Flambaum , Gen. Rel. Grav. 43, 2673 (2011)
Speaker(s) 
Graeme Gossel (School of Physics, University of New South Wales, Sydney)

Location 
Room 2:15, School of Physics, UWA


Contact 
Gay Hollister
<[email protected]>
: 08 6488 2738

Start 
Tue, 15 Nov 2011 15:45

End 
Tue, 15 Nov 2011 16:45

Submitted by 
Gay Hollister <[email protected]>

Last Updated 
Mon, 14 Nov 2011 09:40

Included in the following Calendars: 

 Locations of venues on the Crawley and Nedlands campuses are
available via the Campus Maps website.
 Download this event as:
Text 
iCalendar

Mail this event:
