Spatially resolved microlensing time-scale distributions across the Galactic bulge with the VVV survey

• Verfasst von: Kaczmarek, Zofia [VerfasserIn]
• Verfasst von: McGill, Peter [VerfasserIn]
• Verfasst von: Evans, N Wyn [VerfasserIn]
• Verfasst von: Smith, Leigh C [VerfasserIn]
• Verfasst von: Golovich, Nathan [VerfasserIn]
• Verfasst von: Kerins, Eamonn [VerfasserIn]
• Verfasst von: Specht, David [VerfasserIn]
• Verfasst von: Dawson, William A [VerfasserIn]
• Titel: Spatially resolved microlensing time-scale distributions across the Galactic bulge with the VVV survey
• Verf.angabe: Zofia Kaczmarek, Peter McGill, N. Wyn Evans, Leigh C. Smith, Nathan Golovich, Eamonn Kerins, David Specht and William A. Dawson
• E-Jahr: 2024
• Jahr: April 2024
• Umfang: 13 S.
• Illustrationen: Illustrationen
• Fussnoten: Veröffentlicht: 14 February 2024 ; Gesehen am 26.06.2024
• Titel Quelle: Enthalten in: Royal Astronomical SocietyMonthly notices of the Royal Astronomical Society
• Ort Quelle: Oxford : Oxford Univ. Press, 1827
• Jahr Quelle: 2024
• Band/Heft Quelle: 529(2024), 2 vom: Apr., Seite 1308-1320
• ISSN Quelle: 1365-2966
• DOI: doi:10.1093/mnras/stae445
• Datenträger: Online-Ressource
• Sprache: eng
• K10plus-PPN: 1892254433

Abstract

We analyse 1602 microlensing events found in the VISTA Variables in the Via Lactea (VVV) near-infrared (NIR) survey data. We obtain spatially resolved, efficiency-corrected time-scale distributions across the Galactic bulge (|ℓ| < 10°, |b| < 5°), using a Bayesian hierarchical model. Spatially resolved peaks and means of the time-scale distributions, along with their marginal distributions in strips of longitude and latitude, are in agreement at a 1σ level with predictions based on the Besançon model of the Galaxy. We find that the event time-scales in the central bulge fields (|ℓ| < 5°) are on average shorter than the non-central (|ℓ| > 5°) fields, with the average peak of the lognormal time-scale distribution at 23.6 ± 1.9 d for the central fields and 29.0 ± 3.0 d for the non-central fields. Our ability to probe the structure of the bulge with this sample of NIR microlensing events is limited by the VVV survey’s sparse cadence and relatively small number of detected microlensing events compared to dedicated optical surveys. Looking forward to future surveys, we investigate the capability of the Roman telescope to detect spatially resolved asymmetries in the time-scale distributions. We propose two pairs of Roman fields, centred on (ℓ = ±9, 5°, b = −0.125°) and (ℓ = −5°, b = ±1.375°) as good targets to measure the asymmetry in longitude and latitude, respectively.