Svea Proft, Markus Demleitner, Joachim Wambsganss
We identify stars with large proper motions that are potential candidates for
the astrometric microlensing effect during the Gaia mission i.e. between 2012
and 2019. The effect allows a precise measurement of the mass of a single star
that is acting as a lens. We construct a candidate list by combining
information from several input catalogs including PPMXL, LSPM, PPMX, OGLEBG,
and UCAC3. The selection of the microlensing candidates includes the
verification of their proper motions as well as the calculation of the centroid
shift of the source resulting from the astrometric microlensing effect. The
assembled microlensing catalog comprises 1118 candidates for the years 2012 to
2019. Our analysis demonstrates that 96% of the (high) proper motions of these
candidates are erroneous. We are thus left with 43 confirmed candidates for
astrometric microlensing during the expected Gaia mission. For most of them the
light centroid shift is below ~100 microarcsec (assuming a dark lens) or the
astrometric deviation is considerably reduced by the brightness of the lens.
Due to this the astrometric microlensing effect can potentially be measured for
9 candidates that have a centroid shift between 100 and 4000 microarcsec. For 2
of these astrometric microlensing candidates we predict a strong centroid shift
of about 1000 and 4000 microarcsec, respectively, that should be observable
over a period of a few months up to a few years with the Gaia mission.
View original:
http://arxiv.org/abs/1201.4000
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