MG11 
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MICROLENSING WITH THE RADIOASTRON SPACE TELESCOPE

The space 10-meter radio telescope Radioastron will be launched in 2007. It is well-known that gravitational lensing is a powerful tool to investigate matter distributions including DM. Typical angular distances between images and typical time scales depend on gravitational lens masses. For microlensing case angular distances between images or typical astrometric shifts due to microlensing are about $10^{-5}-10^{-6}~as$. Such an angular resolution will be reached with the space space--ground interferometer Radioastron. The basic targets for microlensing searches should be bright point-like radio sources at cosmological distances and gravitationally lens systems where people discovered features of microlensing. We discuss a possibility to study microlensing in the objects with the interferometer.

Fe K_\alpha line profiles and shadows shapes as evidences of a gravitational lensing in a strong gravitational field near BHs

Based on ray-shooting method we simulate Fe $K_\alpha$ line profiles discovered in microquasars and Seyfert galaxies. Using narrow disk model for the emission line we describe transformations of characteristic two-peak profiles into one-peak profiles. We discuss also features at high inclination angles ($> 85^0$) since two addititional peaks arise in this case. In 2007 Radioastron 10 m telescope will be launched and it will be a generalization of VLBI technique using space base. This interferometer will have extraordinary angular resolution (~ 10^{-6} as). We discuss a procedure to measure masses, charges and spins analyzing these forms of mirages (glories or shadows). Actually, that is a manifestation of gravitational lens effect in the strong gravitational field near black hole horizon.

Signatures of black holes

A number of X-ray space missions like, ASCA, XMM-Newton, Chandra got a lot of information about Fe $K_\alpha$ lines and other X-ray lines. We discuss Fe $K_\alpha$ line profile formation using the simple narrow ring model and explain transformation of two-peak profiles into one-peak profiles. We propose also a procedure to measure spins, inclination angles and charge of black holes analysing shapes of shadows around BHs, for example with forthcoming VLBI. In 2007 Radioastron telescope will be launched and that will be a generalization of VLBI technique using space-ground base. We discuss a possibility to use the facilities for the measurements, since roughly speaking a charge is responsible for the shadow size but a spin is responsible for its shape.

Model of Radiating Annuli near Black Holes for Fe K_\alpha Line Profile Interpretations

X-ray observations of microquasars and Seyfert galaxies reveal the broad emission lines in their spectra, which can arise in the innermost parts of accretion disks. We consider a radiating annulus model to simulate spectral line shapes. That is a natural approximation for narrow emitting circular rings without extra astrophysical assumptions about emissivity laws. Recently Muller & Camenzind (2004) presented results of their calculations and classified different types of spectral line shapes and described their origin. We clarified their results and showed that triangular spectral lines could arise for nearest annuli and high inclination angles. We discussed a possibility of appearance of narrow spectral line shapes as a result of spiralling evolution of matter along quasi-circular orbits.

Astrometrical microlensing with Radioastron

For microlensing case angular distances between images or typical astrometric shifts due to microlensing are about $10^{-5}-10^{-6}~as$. Such an angular resolution will be reached with the space space--ground interferometer Radioastron (which should be launched in 2007). The basic targets for astrometrical microlensing searches should be bright point-like radio sources at cosmological distances and gravitational lenses systems. We discuss a possibility to observe the astrometrical microlensing with the Radioastron for different locations of microlenses. Astrometric microlensing due Galactic Macho's actions is not very important because of low optical depths and long typical time scales.

Shadow shape measuremens as a space test of GR in the strong gravitational field limit

In 2007 Radioastron 10-m telecope will be launched and that will be a generalization of VLBI technique using space -- ground base. We discuss shadows (glories, mirages) formed near rapidly rotating Kerr black hole horizons and propose a procedure to measure position angles of a distant observer and spins for supermassive BHs analyzing these forms of mirages with the interferometer. A similar approach could be used to measure the charge of black hole. Thus these facilities could be used as a test of GR in strong gravitational field limit and for determination of parameters of supermassive BHs in centers of our own and nearby galaxies.

Astrometrical microlensing with Radioastron

For microlensing case angular distances between images or typical astrometric shifts due to microlensing are about $10^{-5}-10^{-6}~as$. Such an angular resolution will be reached with the space space--ground interferometer Radioastron (which should be launched in 2007). The basic targets for astrometrical microlensing searches should be bright point-like radio sources at cosmological distances and gravitational lenses systems. We discuss a possibility to observe the astrometrical microlensing with the Radioastron for different locations of microlenses. Astrometric microlensing due Galactic Macho's actions is not very important because of low optical depths and long typical time scales.