In 2007 the RADIOASTRON space telescope will be launched and it will be a generalization of VLBI technique using the space -- ground base This interferometer will have the extraordinary angular resolution namely 10 -5 as - 10 -6 as at 1 3 and 6 cm wavelenghts We analyze the case of a Kerr black hole rotating at arbitrary speed for some selected positions of a distant observer with respect to the equatorial plane of a Kerr black hole We propose to use future radio interferometer RADIOASTRON facilities to measure shapes of mirages glories and to evaluate the black hole spin as a function of the position angle of a distant observer A similar approach which uses the characteristic properties of gravitational retro-lensing images can be followed to measure the charge of a Reissner-Nordstr o m black hole or magnetic monopole of black hole Indeed in spite of the fact that their formation might be problematic charged black holes are objects of intensive investigations From a theoretical point of view it is well-known that a black hole is described by only three parameters namely its mass M angular momentum J and charge Q Therefore it would be important to have a method for measuring all these parameters preferably by independent model of any In this paper we propose a procedure to measure the black hole charge by using the size of the retro-lensing images that can be revealed by future astrometrical missions A discussion of the Kerr-Newmann black hole case is also offered
The Radioastron as a tool with the highest angular resolution in radio band: Astrophysical applications
DE PAOLIS, Francesco;INGROSSO, Gabriele;NUCITA, Achille
2006-01-01
Abstract
In 2007 the RADIOASTRON space telescope will be launched and it will be a generalization of VLBI technique using the space -- ground base This interferometer will have the extraordinary angular resolution namely 10 -5 as - 10 -6 as at 1 3 and 6 cm wavelenghts We analyze the case of a Kerr black hole rotating at arbitrary speed for some selected positions of a distant observer with respect to the equatorial plane of a Kerr black hole We propose to use future radio interferometer RADIOASTRON facilities to measure shapes of mirages glories and to evaluate the black hole spin as a function of the position angle of a distant observer A similar approach which uses the characteristic properties of gravitational retro-lensing images can be followed to measure the charge of a Reissner-Nordstr o m black hole or magnetic monopole of black hole Indeed in spite of the fact that their formation might be problematic charged black holes are objects of intensive investigations From a theoretical point of view it is well-known that a black hole is described by only three parameters namely its mass M angular momentum J and charge Q Therefore it would be important to have a method for measuring all these parameters preferably by independent model of any In this paper we propose a procedure to measure the black hole charge by using the size of the retro-lensing images that can be revealed by future astrometrical missions A discussion of the Kerr-Newmann black hole case is also offeredI documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
