Constraining Lens Masses in Moderately to Highly Magnified Microlensing Events from Gaia

Abstract

Microlensing events provide a unique way to detect and measure the masses of isolated, non-luminous objects, particularly dark stellar remnants. Under certain conditions, it is possible to measure the mass of these objects using photometry alone, specifically when a microlensing light curve displays a finite source (FS) effect. This effect generally occurs in highly magnified light curves, i.e. when the source and the lens are very well aligned. In this study, we analyse Gaia Alerts and Gaia Data Release 3 datasets, identifying four moderate-to-high-magnification microlensing events without a discernible FS effect. The absence of this effect suggests a large Einstein radius, implying substantial lens masses. In each event, we constrained the FS effect, and therefore established lower limits for the angular Einstein radius and lens mass. Additionally, we used the DarkLensCode software to obtain the mass, distance, and brightness distribution for the lens based on the Galactic model. Our analysis established lower mass limits of $\sim 0.7$ $M_{\odot }$ for one lens and $\sim 0.3-0.5$ $M_{\odot }$ for two others. A DarkLensCode analysis supports these findings, estimating lens masses in the range of $\sim 0.42-1.70$ $M_{\odot }$ and dark lens probabilities exceeding 80%. These results strongly indicate that the lenses are stellar remnants, such as white dwarfs or neutron stars. While further investigations are required to confirm the nature of these lenses, we demonstrate a straightforward yet effective approach to identifying stellar remnant candidates.

References in corpus (30)

• The Gaia mission
• Gaia Data Release 3: Summary of the content and survey properties
• A grid of MARCS model atmospheres for late-type stars I. Methods and general properties
• The Zwicky Transient Facility: System Overview, Performance, and First Results
• Estimating distances from parallaxes. V: Geometric and photogeometric distances to 1.47 billion stars in Gaia Early Data Release 3
• Trigonometric Parallaxes of Massive Star Forming Regions: VI. Galactic Structure, Fundamental Parameters and Non-Circular Motions
• Determining stellar atmospheric parameters and chemical abundances of FGK stars with iSpec
• Modern stellar spectroscopy caveats
• Gaia Data Release 3: External calibration of BP/RP low-resolution spectroscopic data
• PEPSI: The high-resolution echelle spectrograph and polarimeter for the Large Binocular Telescope
• An isolated mass gap black hole or neutron star detected with astrometric microlensing
• Gaia Photometric Science Alerts
• A Jovian analogue orbiting a white dwarf star
• First Space-based Microlens Parallax Measurement of an Isolated Star: Spitzer Observations of OGLE-2014-BLG-0939
• Predicting Stellar Angular Diameters from $V$, $I_C$, $H$, $K$ Photometry
• OGLE-2013-BLG-0102LA,B: Microlensing binary with components at star/brown-dwarf and brown-dwarf/planet boundaries
• Systematic errors as a source of mass discrepancy in black hole microlensing event OGLE-2011-BLG-0462
• First semi-empirical test of the white dwarf mass-radius relationship using a single white dwarf via astrometric microlensing
• Gaia Data Release 3: Microlensing Events from All Over the Sky
• MOA-2007-BLG-400 A Super-Jupiter Mass Planet Orbiting a Galactic BulgeK-dwarf Revealed by Keck Adaptive Optics Imaging
• Microlens Masses from 1-D Parallaxes and Heliocentric Proper Motions
• Single-lens mass measurement in the high-magnification microlensing event Gaia19bld located in the Galactic disc
• Lens parameters for Gaia18cbf -- a long gravitational microlensing event in the Galactic plane
• Is there a nearby microlensing stellar remnant hiding in Gaia DR3 astrometry?
• Uncovering the Invisible: A Study of Gaia18ajz, a Candidate Black Hole Revealed by Microlensing
• Dark lens candidates from Gaia Data Release 3
• MOA-2019-BLG-008Lb: a new microlensing detection of an object at the planet/brown dwarf boundary
• OGLE-2016-BLG-1093Lb: A Sub-Jupiter-mass Spitzer Planet Located in Galactic Bulge
• Observations of Microlensed Images with Dual-field Interferometry: On-sky Demonstration and Prospects
• Gaia21blx: Complete resolution of a binary microlensing event in the Galactic disk

Cited by in corpus (1)

• Gaia20fnr: A binary-lens microlensing event with full orbital motion revealed by four space telescopes