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Microlensing Optical Depth and Event Rate in the OGLE-IV Galactic Plane Fields

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dc.abstract.enSearches for gravitational microlensing events are traditionally concentrated on the central regions of the Galactic bulge but many microlensing events are expected to occur in the Galactic plane, far from the Galactic Center. Owing to the difficuy in conducting high-cadence observations of the Galactic plane over its vast area, which are necessary for the detection of microlensing events, their global properties were hitherto unknown. Here, we present resus of the first comprehensive search for microlensing events in the Galactic plane. We searched an area of almost 3000 square degrees along the Galactic plane ( $| b| \ 7^\circ $ , 0° &; l &; 50°, 190° &; l &; 360°) observed by the Optical Gravitational Lensing Experiment (OGLE) during 2013-2019 and detected 630 events. We demonstrate that the mean Einstein timescales of Galactic plane microlensing events are on average three times longer than those of Galactic bulge events, with little dependence on the Galactic longitude. We also measure the microlensing optical depth and event rate as a function of Galactic longitude and demonstrate that they exponentially decrease with the angular distance from the Galactic Center (with the characteristic angular scale length of 32°). The average optical depth decreases from 0.5 × 10<SUP>‑6</SUP> at l = 10° to 1.5 × 10<SUP>‑8</SUP> in the Galactic anticenter. We also find that the optical depth in the longitude range 240° &; l &; 330° is asymmetric about the Galactic equator, which we interpret as a signature of the Galactic warp.
dc.affiliationUniwersytet Warszawski
dc.contributor.authorMróz, Przemysław
dc.contributor.authorUdalski, Andrzej
dc.contributor.authorSzymański, Michał
dc.contributor.authorSoszyński, Igor
dc.contributor.authorPietrukowicz, Paweł
dc.contributor.authorKozłowski, Szymon
dc.contributor.authorSkowron, Jan
dc.contributor.authorPoleski, Radosław
dc.contributor.authorUlaczyk, Krzysztof
dc.contributor.authorGromadzki, Mariusz
dc.contributor.authorRybicki, Krzysztof
dc.contributor.authorIwanek, Patryk
dc.contributor.authorWrona, Marcin
dc.date.accessioned2024-01-25T11:29:02Z
dc.date.available2024-01-25T11:29:02Z
dc.date.copyright2020-04-16
dc.date.issued2020
dc.description.accesstimeBEFORE_PUBLICATION
dc.description.financeŚrodki finansowe przyznane na realizację projektu w zakresie badań naukowych lub prac rozwojowych
dc.description.number1
dc.description.versionORIGINAL_AUTHOR
dc.description.volume249
dc.identifier.doi10.3847/1538-4365/AB9366
dc.identifier.issn0067-0049
dc.identifier.urihttps://repozytorium.uw.edu.pl//handle/item/112426
dc.identifier.weblinkhttp://adsabs.harvard.edu/abs/2020ApJS..249...16M
dc.languageeng
dc.pbn.affiliationastronomy
dc.relation.ispartofAstrophysical Journal, Supplement Series
dc.relation.pages16
dc.rightsOther
dc.sciencecloudnosend
dc.titleMicrolensing Optical Depth and Event Rate in the OGLE-IV Galactic Plane Fields
dc.typeJournalArticle
dspace.entity.typePublication