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Potential Direct Single-Star Mass Measurement

journal contribution
posted on 2023-05-16, 15:18 authored by Ghosh, H, DePoy, DL, Gal-Yam, A, Gaudi, BS, Gould, A, Han, C, Lipkin, Y, Maoz, D, Ofek, EO, Park, BG, Pogge, RW, Salim, S, Abe, F, Bennett, DP, Bond, IA, Eguchi, S, Furuta, Y, Hearnshaw, JB, Kamiya, K, Kilmartin, PM, Kurata, Y, Masuda, K, Matsubara, Y, Muraki, Y, Noda, S, Okajima, K, Rattenbury, NJ, Sako, T, Sekiguchi, T, Sullivan, DJ, Sumi, T, Tristram, PJ, Yanagisawa, T, Yock, PCM, Udalski, A, Soszynski, I, Wyrzykowski, L, Kubiak, M, Szymanski, MK, Pietrzynski, G, Szewczyk, O, Zebrun, K, Albrow, MD, Beaulieu, JP, Caldwell, JAR, Cassan, A, Coutures, C, Dominik, M, Donatowicz, J, Fouque, P, Greenhill, JG, Kym HillKym Hill, Horne, K, Jorgensen, UG, Kane, S, Kubas, D, Martin, R, Menzies, J, Pollard, KR, Sahu, KC, Wambsganss, J, Watson, RD, Williams, A
We analyze the light curve of the microlensing event OGLE-2003-BLG-175/MOA- 2003-BLG-45 and show that it has two properties that, when combined with future high-resolution astrometry, could lead to a direct, accurate measurement of the lens mass. First, the light curve shows clear signs of distortion due to the Earth's accelerated motion, which yields a measurement of the projected Einstein radius r̃ E. Second, from precise astrometric measurements, we show that the blended light in the event is coincident with the microlensed source to within about 15 mas. This argues strongly that this blended light is the lens and hence opens the possibility of directly measuring the lens-source relative proper motion μ rel and so the mass M = (c 2/4G)μ relt Er̃ E, where t E is the measured Einstein timescale. While the light-curve-based measurement of r̃ E is, by itself, severely degenerate, we show that this degeneracy can be completely resolved by measuring the direction of proper motion μ rel.


Publication title

The Astrophysical Journal








School of Natural Sciences


The University of Chicago Press

Place of publication

Chicago, USA

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  • Restricted

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Expanding knowledge in the physical sciences

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