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Microlensing Effect in Radioastronomy

#2495


The Weak Microlensing Effect and Its Influence on Very Long Baseline Radiointerferometry Observation

Tech Area / Field

  • SAT-AST/Astronomy/Space, Aircraft and Surface Transportation

Status
3 Approved without Funding

Registration date
15.04.2002

Leading Institute
Moscow State University / Sternberg State Institute of Astronomy, Russia, Moscow

Supporting institutes

  • VNIIEF, Russia, N. Novgorod reg., Sarov

Collaborators

  • Observatoire de Paris / International Earth Rotation Service, France, Paris\nNASA / Goddard Space Flight Center, USA, MD, Greenbelt

Project summary

In this project it is proposed to use unique opportunity to join scientist’s efforts from Russia, the USA and France to develop the theory of the weak microlensing. This theory will be used to develop all relevant very long baseline interferometry (VLBI) data available from 1979 to 2000, obtained by different observing programs. This project will provide us with a new point of view on realization of the inertial reference frame in astronomy of the XXI century and opportunity of separation of internal processes in distant sources (for example plasma jets) from the gravitational refraction of light in our Galaxy.

Both galactic stars and non-uniformly distributed dark matter which are situated in interstellar space, create non-stationary disturbances of the space-time curvature and bend the trajectory of a photon’s path of the light beam from rectilinear trajectory. This effect is known as weak microlensing. During this project the theory of the weak microlensing effect applied to very long baseline interferometry (VLBI) observations will be developed. Modern VLBI observations have high accuracy which allow to test the weak microlensing effect and to investigate both the non-stationary space-time curvature in Galaxy and long period instability of the celestial reference frame. The results of a general solution from all relevant VLBI data available from 1979 to 2000, obtained by the Goddard Space Flight Center (GSFC), the U.S. Naval Observatory (USNO) and International VLBI Service (IVS) will be used to search for apparent motions of extragalactic radio sources caused by weak microlensing. The VLBI data together with results of analysis of the HIPPARCOS catalog will be used to predict the distribution of the invisible (dark) bodies in the vicinity of the Sun and to estimate the instability of the International Celestial Reference Frame (ICRF) and to get the natural limits of accuracy with which inertial reference frame can be realized.

We will also propose to apply the developed microlensing theory to high-accuracy optical observations. We suppose that positions of a significant portion of stars in future high-accuracy catalogs like GAIA, SIM, FAME, DIVA (the titles of the international space missions for creation of the optical realization of the celestial reference frame) and others will be distorted by the weak microlensing produced by foreground stars and dark bodies. We intend to carry out the computer simulation of this effect to estimate the instability of the future celestial frames based on the positions of millions of stars that will be observed during space missions. It gives an opportunity to estimate the physical limit of accuracy of the realization of the inertial coordinate system in astronomy. Besides the computer simulation of future observations and application of results of realized HIPPARCOS project gives us opportunity to estimate the distribution of the dark matter in the vicinity of the Sun. Further detailed analysis of the weak microlensing effects may be allow us to establish existence of the non-barion objects that would be constituted fundamental interest for question about nature of the dark matter.


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