The OGLE-II event sc5_2859 -- An example of disk-disk microlensing

Abstract

We present a new long-duration parallax event from the OGLE-II database, sc5_2859, which has the second longest time-scale ever identified (tE = 547.6{+22.6}{-7.8} days). We argue that both the lens and source reside in the Galactic disk, making event sc5_2859 one of the first confirmed examples of so-called disk-disk microlensing. We find that the source star is most probably located at a distance of D_S ~ 2 kpc, and from this we conclude that the lens is unlikely to be a main-sequence star due to the strict limits that can be placed on the lens brightness. A simple likelihood analysis is carried out on the lens mass, which indicates that the lens could be another candidate stellar mass black hole. We recommend that spectroscopic observations of the source be carried out in order to constrain the source distance, since this is the main source of uncertainty in our analysis. In addition, we briefly discuss whether there appears to be an excess of long duration microlensing events in the OGLE-II catalogue.

arXiv comment21 pages, 4 figures. Accepted for publication in MNRAS. Note Added in Proof: The nature of this event has become unclear, since archival EROS data have been found that may contradict the model presented in this paper

References in corpus (26)

• A method for optimal image subtraction
• Local stellar kinematics from Hipparcos data
• LCDM-based models for the Milky Way and M31 I: Dynamical Models
• Three Dimensional Structure of the Milky Way Disk
• Gravitational Microlensing in the Local Group
• The MACHO project: Microlensing Optical Depth towards the Galactic Bulge from Difference Image Analysis
• Detection of Rotation in a Binary Microlens: PLANET Photometry of MACHO 97-BLG-41
• Finite Source Sizes and the Information Content of MACHO-Type Lens Search Light Curves
• Predicting Stellar Angular Sizes
• Gravitational Microlensing Events Due to Stellar Mass Black Holes
• Acceleration and Parallax Effects in Gravitational Microlensing
• Optical Gravitational Lensing Experiment. OGLE-1999-BUL-32: the Longest Ever Microlensing Event -- Evidence for a Stellar Mass Black Hole?
• Observations of the Binary Microlens Event MACHO-98-SMC-1 by the Microlensing Planet Search Collaboration
• Statistical Determination of the MACHO Mass Spectrum
• Bulge Microlensing Optical Depth from EROS 2 observations
• Astrometric Microlensing with the GAIA satellite
• Mass Determination With Gravitational Microlensing
• Clump Distance to the Magellanic Clouds and Anomalous Colors in the Galactic Bulge
• Resolving gravitational microlensing events with long-baseline optical interferometry. Prospects for the ESO Very Large Telescope Interferometer
• A Consistent Microlensing Model for the Galactic Bar
• Finding Black Holes with Microlensing
• Optical Gravitational Lensing Experiment. OGLE 2000-BUL-43: A Spectacular Ongoing Parallax Microlensing Event. Difference Image Analysis
• Microlensing Maps for the Milky Way Galaxy
• Is Galactic Structure Compatible with Microlensing Data?
• Optical Gravitational Lensing Experiment. OGLE-1999-BUL-19: The First Multi-Peak Parallax Event
• On Microlensing Event Rates and Optical Depth toward the Galactic Center

Cited by in corpus (6)

• The Optical Gravitational Lensing Experiment. Catalog of stellar proper motions in the OGLE-II Galactic bulge fields
• Characterizing Lenses and Lensed Stars of High-Magnification Single-lens Gravitational Microlensing Events With Lenses Passing Over Source Stars
• Discovery of a Very Bright, Nearby Gravitational Microlensing Event
• The Nature of Parallax Microlensing Events Towards the Galactic Bulge
• The OGLE-II event sc5_2859 : a Classical Nova outburst?
• Casting Light on Degeneracies: A Comprehensive Study of Lightcurve Variations in Microlensing Events OGLE-2017-BLG-0103 and OGLE-2017-BLG-0192