Abstract
Astrometric observations of microlensing events can be used to obtain important information about lenses. During these events, the shift of the position of the multiple image centroid with respect to the source star location can be measured. This effect, which is expected to occur on scales from micro-arcseconds to milli-arcseconds, depends on the lens-source-observer system physical parameters. Here, we consider the astrometric and photometric observations by space and ground-based telescopes of microlensing events towards the Galactic bulge caused by free floating planets (FFPs). We show that the efficiency of astrometric signal on photometrically detected microlensing events tends to increase for higher FFP masses in our Galaxy. In addition, we estimate that during five years of the Gaia observations, about a dozen of microlensing events caused by FFPs are expected to be detectable.
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References
Alcock, C., et al.: Astrophys. J. 454, 125 (1995)
Bisnovatyi-Kogan, G.S., Yu, T.O.: Mem. Soc. Astron. Ital. 83, 54B (2012)
Boden, A.F., Shao, M., Van Buren, D.: Astrophys. J. 502, 538 (1998)
Choi, J.Y., et al.: Astrophys. J. 751, 41 (2012)
De Paolis, F., et al.: Astron. Astrophys. 366, 1065 (2001)
Dominik, M., Sahu, K.C.: Astrophys. J. 534, 213 (2000)
Dominik, M.: Astron. Astrophys. 329, 361 (1998)
Eisenhauer, F., et al.: ASSP 9, 361 (2009)
Er, X., Mao, S.H.: Mon. Not. R. Astron. Soc. 437, 2180 (2014)
Gilmore, G., et al.: Astron. Astrophys. 27, 555 (1989)
Hafizi, M., et al.: Int. J. Mod. Phys. D 13, 1831 (2004)
Hamolli, L., et al.: Int. J. Mod. Phys. D 22, 1350072 (2013)
Hamolli, L., et al.: Adv. Astron. (2015). ID 402303
Hamolli, L., et al.: Astrophys. Space Sci. 361, 274 (2016)
Han, Ch., Gould, A.: Astrophys. J. 447, 53 (1995)
Hog, E.: (2017). arXiv:1707.01020
Hog, E., Novikov, I.D., Polnarev, A.G.: Astron. Astrophys. 294, L287 (1995)
Miyamoto, M., Yoshii, Y.: Astron. J. 110, 1427 (1995)
Mróz, P., et al.: Astron. J. 155, 121 (2018)
Nemiroff, R.J., Wickramasinghe, W.A.D.T.: Astrophys. J. 424, 21 (1994)
Nucita, A.A., et al.: Astrophys. J. 823, 120 (2016)
Nucita, A.A., et al.: Int. J. Mod. Phys. D 26, 1741015 (2017)
Paczyński, B.: Astrophys. J. 384, 1 (1986)
Paczyński, B.: Annu. Rev. Astron. Astrophys. 34, 419 (1996)
Schneider, P., Ehlers, J., Falco, E.E.: Gravitational Lenses. Springer, New York (1992)
Spergel, D., et al.: (2015). arXiv:1503.03757
Strigari, L.E., et al.: Mon. Not. R. Astron. Soc. 423, 1856 (2012)
Sumi, T., et al.: Nature 473, 349 (2011)
Walker, M.A.: Astrophys. J. 453, 37 (1995)
Witt, H.J., Mao, S.: Astrophys. J. 430, 505–510 (1994)
Witt, H.J.: Astrophys. J. 449, 42 (1995)
Zurlo, A., et al.: Astron. Astrophys. 572, 85 (2014)
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FDP and AN acknowledge the support by the INFN projects TAsP and Euclid, respectively.
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Hamolli, L., Hafizi, M., De Paolis, F. et al. The astrometric signal of microlensing events caused by free floating planets. Astrophys Space Sci 363, 153 (2018). https://doi.org/10.1007/s10509-018-3374-2
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DOI: https://doi.org/10.1007/s10509-018-3374-2