The First Simultaneous Microlensing Observations by Two Space telescopes: Spitzer and Swift Reveal a Brown Dwarf in Event OGLE-2015-BLG-1319
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Simultaneous observations of microlensing events from multiple locations
allow for the breaking of degeneracies between the physical properties
of the lensing system, specifically by exploring different regions of
the lens plane and by directly measuring the “microlens
parallax.” We report the discovery of a 30-65M J
brown dwarf orbiting a K dwarf in the microlensing event
OGLE-2015-BLG-1319. The system is located at a distance of ˜5 kpc
toward the Galactic Bulge. The event was observed by several
ground-based groups as well as by Spitzer and Swift, allowing a
measurement of the physical properties. However, the event is still
subject to an eight-fold degeneracy, in particular the well-known
close-wide degeneracy, and thus the projected separation between the two
lens components is either ˜0.25 au or ˜45 au. This is the first
microlensing event observed by Swift, with the UVOT camera. We study the
region of microlensing parameter space to which Swift is sensitive,
finding that though Swift could not measure the microlens parallax with
respect to ground-based observations for this event, it can be important
for other events. Specifically, it is important for detecting nearby
brown dwarfs and free-floating planets in high magnification events.
Originalsprog | Engelsk |
---|---|
Artikelnummer | 183 |
Tidsskrift | Astrophysical Journal |
Vol/bind | 831 |
Udgave nummer | 2 |
ISSN | 0004-637X |
DOI | |
Status | Udgivet - 1 nov. 2016 |
ID: 170455206