J/A+A/662/A59 Gaia18cbf Gi light curves (Kruszynska+, 2022)
Lens parameters for Gaia18cbf - a long gravitational microlensingevent in the
Galactic Plane.
Kruszynska K., Wyrzykowski L., Rybicki M., Maskoliunas K.A., Bachelet E.,
Rattenbury N., Mroz P., Zielinski P., Howil K., Kaczmarek Z., Hodgkin S.T.,
Ihanec N., Gezer I., Gromadzki M., Mikolajczyk P., Stankeviciute A.,
Cepas V., Pakstiene E., Siskauskaite K., Zdanavicius J., Bozza V.,
Dominik M., Figuera Jaimes R., Fukui A., Hundertmark M., Narita N.,
Street R., Tsapras Y., Bronikowski M., Jablonska M., Jablonowska A.,
Ziolkowska O.
<Astron. Astrophys. 662, A59 (2022)>
=2022A&A...662A..59K 2022A&A...662A..59K (SIMBAD/NED BibCode)
ADC_Keywords: Gravitational lensing ; Photometry ; Optical
Keywords: gravitational lensing: micro - Galaxy: stellar content -
stars: black holes - stars: neutron -
Abstract:
The timescale of a microlensing event scales as a square root of a
lens mass. Therefore, long-lasting events are important candidates for
massive lenses, including black holes.
Here we present the analysis of the Gaia18cbf microlensing event
reported by the Gaia Science Alerts system. It has exhibited a long
timescale and features characteristic to the annual microlensing
parallax effect. We deduce the parameters of the lens based on the
derived best fitting model.
We used photometric data collected by the Gaia satellite as well as
the follow-up data gathered by the ground-based observatories. We
investigate the range of microlensing models and use them to derive
the most probable mass and distance to the lens using a Galactic model
as a prior. Using known mass-brightness relation we determined how
likely it is that the lens is a main sequence star.
This event is one of the longest ever detected, with the Einstein
timescale of tE=491.41+128.31-84.94 days for the best solution
and tE=453.74+178.69-105.74 days for the second-best. Assuming
Galaxy priors, this translates to the most probable lens mass of
ML=2.65+509-1.48M☉ and ML=1.71+3.78-1.06M☉,
respectively. The limits on the blended light suggest that this event
was most likely not caused by a main sequence star, but rather by a
dark remnant of stellar evolution.
Description:
Photometric data for the microlensing event Gaia18cbf. We present two
tables which were used for modelling, one with Gaia data with
simulated errors and second with the follow-up data.
Objects:
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RA (2000) DE Designation(s)
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16 04 38.86 -41 06 17.39 Gaia18cbf
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
follow_i.dat 26 34 Photometry of i-band follow-up data
gaia.dat 26 76 Photometric measurements from Gaia
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Byte-by-byte Description of file: follow_i.dat
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Bytes Format Units Label Explanations
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1- 13 F13.5 d JD Julian Date
15- 20 F6.3 mag imag Apparent magnitude in i filter
22- 26 F5.3 mag e_imag Uncertainty in mag
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Byte-by-byte Description of file: gaia.dat
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Bytes Format Units Label Explanations
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1- 13 F13.5 d JD Julian Date
15- 20 F6.3 mag Gmag Apparent Gaia G magnitude
22- 26 F5.3 mag e_Gmag Uncertainty in mag
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Acknowledgements:
Katarzyna Kruszynska, kkruszynska(at)astrouw.edu.pl
(End) K. Kruszynska [Astron. Obs., Warsaw Univ.], P. Vannier [CDS] 15-Mar-2022