2020/10/15 by Yoon-Hyun Ryu, Przemek Mróz, Andrew Gould +28 · 1 citation
Physics and Astronomy · #astro-ph.EP #astro-ph.GA
paper · pdf · doi:10.3847/1538-3881/abd55f
35 pages, 7 figures, 1 Table
arxiv created 2020/10/15 · arxiv updated 2021/03/03
We report a new free-floating planet (FFP) candidate, KMT-2017-BLG-2820, with Einstein radius θ_\e≃ 6 \muas, lens-source relative proper motion μ_\rel ≃ 8 \masyr, and Einstein timescale t_\e=6.5 hr. It is the third FFP candidate found in an ongoing study of giant-source finite-source point-lens (FSPL) events in the KMTNet data base, and the sixth FSPL FFP candidate overall. We find no significant evidence for a host. Based on their timescale distributions and detection rates, we argue that five of these six FSPL FFP candidates are drawn from the same population as the six point-source point-lens (PSPL) FFP candidates found by \citetmroz17 in the OGLE-IV data base. The θ_\e distribution of the FSPL FFPs implies that they are either sub-Jovian planets in the bulge or super-Earths in the disk. However, the apparent "Einstein Desert" (10\laθ_\e/\muas\la 30) would argue for the latter. Whether each of the 12 (6 FSPL and 6 PSPL) FFP candidates is truly an FFP, or simply a very wide-separation planet, can be determined at first adaptive optics (AO) light on 30m telescopes, and earlier for some. If the latter, a second epoch of AO observations could measure the projected planet-host separation with a precision \cal O(10 \au). At the present time, the balance of evidence favors the unbound-planet hypothesis.