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Mass measurement of a single unseen star and planetary detection efficiency for OGLE 2007-BLG-050

journal contribution
posted on 2023-05-17, 00:53 authored by Batista, V, Dong, S, Gould, A, Jean-Philippe BeaulieuJean-Philippe Beaulieu, Cassan, A, Christie, GW, Han, C, Udalski, A, Allen, W, DePoy, DL, Gal-Yam, A, Gaudi, BS, Johnson, B, Kaspi, S, Lee, CU, Maoz, D, McCormick, J, McGreer, I, Monard, B, Natusch, T, Ofek, E, Park, BG, Pogge, RW, Polishook, D, Shporer, A, Albrow, MD, Bennett, DP, Brilliant, S, Bode, M, Bramich, DM, Burgdorf, M, Caldwell, JAR, Calitz, H, Andrew ColeAndrew Cole, Cook, KH, Coutures, C, Dieters, S, Dominik, M, Prester, DD, Donatowicz, J, Fouque, P, Greenhill, JG, Hoffman, M, Horne, K, Jorgensen, UG, Kains, N, Kane, S, Kubas, D, Marquette, JB, Martin, R, Meintjes, P, Menzies, J, Pollard, KR, Sahu, KC, Snodgrass, C, Steele, I, Tsapras, Y, Wambsganss, J, Williams, A, Zub, M, Wyrzykowski, L, Kubiak, M, Szymanski, MK, Pietrzynski, G, Soszynski, I, Szewczyk, O, Ulaczyk, K, Abe, F, Bond, IA, Fukui, A, Furusawa, K, Hearnshaw, JB, Holderness, S, Itow, Y, Kamiya, K, Kilmartin, PM, Korpela, A, Lin, W, Ling, CH, Masuda, K, Matsubara, Y, Miyake, N, Muraki, Y, Nagaya, M, Ohnishi, K, Okumura, T, Perrott, YC, Rattenbury, N, Saito, T, Sako, T, Skuljan, L, Sullivan, D, Sumi, T, Sweatman, WL, Tristram, PJ, Yock, PCM
Aims. We analyze OGLE-2007-BLG-050, a high magnification microlensing event (A~ 432) whose peak occurred on 2 May, 2007, with pronounced finite-source and parallax effects. We compute planet detection efficiencies for this event in order to determine its sensitivity to the presence of planets around the lens star. Methods. Both finite-source and parallax effects permit a measurement of the angular Einstein radius $\theta_{\rm E}=0.48\pm 0.01$ mas and the parallax $\pi_{\rm E}=0.12\pm 0.03$, leading to an estimate of the lens mass $M=0.50\pm0.14\,M_{\odot}$ and its distance to the observer $D_L=5.5\pm0.4$ kpc. This is only the second determination of a reasonably precise (<$30\%$) mass estimate for an isolated unseen object, using any method. This allows us to calculate the planetary detection efficiency in physical units $(r_\perp,m_{\rm p})$, where $r_\perp$ is the projected planet-star separation and m_ p is the planet mass. Results. When computing planet detection efficiency, we did not find any planetary signature, i.e. none of the planetary configurations provides a $\Delta\chi^2$ improvement higher than 60, and our detection efficiency results reveal significant sensitivity to Neptune-mass planets, and to a lesser extent Earth-mass planets in some configurations. Indeed, Jupiter and Neptune-mass planets are excluded with a high confidence for a large projected separation range between the planet and the lens star, respectively [0.6–10] and [1.4–4] AU, and Earth-mass planets are excluded with a 10% confidence in the lensing zone, i.e. [1.8–3.1] AU.


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Astronomy and Astrophysics








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