J/A+A/636/A20 OGLE-III parallax events with Gaia DR2 (Wyrzykowski+, 2020)
Constraining the masses of microlensing black holes and the mass gap with
Gaia DR2.
Wyrzykowski L., Mandel I.
<Astron. Astrophys., 636, A20 (2020)>
=2020A&A...636A..20W 2020A&A...636A..20W (SIMBAD/NED BibCode)
ADC_Keywords: Gravitational lensing ; Photometry
Keywords: gravitational lensing: micro - Galaxy: stellar content -
stars: neutron - stars: black holes
Abstract:
Context. Gravitational microlensing is sensitive to compact-object
lenses in the Milky Way, including white dwarfs, neutron stars, or
black holes, and could potentially probe a wide range of
stellar-remnant masses. However, the mass of the lens can be
determined only in very limited cases, due to missing information on
both source and lens distances and their proper motions. Aims. Our aim
is to improve the mass estimates in the annual parallax microlensing
events found in the eight years of OGLE-III observations towards the
Galactic Bulge with the use of Gaia Data Release 2 (DR2). Methods. We
use Gaia DR2 data on distances and proper motions of non-blended
sources and recompute the masses of lenses in parallax events. We also
identify new events in that sample which are likely to have dark
lenses; the total number of such events is now 18. Results. The
derived distribution of masses of dark lenses is consistent with a
continuous distribution of stellar-remnant masses. A mass gap between
neutron star and black hole masses in the range between 2 and 5 solar
masses is not favoured by our data, unless black holes receive natal
kicks above 20-80km/s. We present eight candidates for objects with
masses within the putative mass gap, including a spectacular
multi-peak parallax event with mass of 2.4-1.3+1.9M☉ located
just at 600pc. The absence of an observational mass gap between
neutron stars and black holes, or conversely the evidence of black
hole natal kicks if a mass gap is assumed, can inform future supernova
modelling efforts.
Description:
Wyrzykowski et al. (2016, Cat. J/MNRAS/458/3012) analysed light curves
of 150 million stars in the Galactic bulge monitored over 8 years by
the OGLE-III survey and found 59 long-lasting microlensing events with
a significant effect on the amplification due to the Earth orbital
motion.
We matched all OGLE-III parallax events with the Gaia Data Release 2
catalogue. There were 46 matches out of 59 events, with most of the
missed ones being fainter than 19mag in OGLE's I band, hence
indicating incompleteness of GDR2 in the bulge region at the faint end
of source magnitude distribution. Table 1 lists all 46 matched events.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 82 46 OGLE-III parallax events with Gaia Data Release 2
data and distances from CBJ18 (Cat. I/347)
table2.dat 41 91 *OGLE-III parallax events and an estimate of the
blending contribution
table4.dat 53 36 *Posterior medians and 1 uncertainty estimates on
masses, distances, and total blend magnitudes
for all events matched with Gaia DR2
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Note on table2.dat: Events with the blending parameter greater than 0.6 and
blend magnitude fainter than 18.5mag are assumed to have negligible
contribution to the light in the Gaia DR2 solution.
Note on table4.dat: Multiple entries are shown for different solutions found,
indicated in the last column. Blend magnitudes fainter than 21.9mag correspond
to solutions with negative blending, consistent with no blending.
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See also:
J/MNRAS/458/3012 : OGLE-III Parallax microlensing events (Wyrzykowski+, 2016)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 6 A6 --- Lens Lens name, PAR-NN, OGLE3-ULENS-
7 A1 --- Note [*] * for dark lens candidate
9- 27 I19 ---- GaiaDR2 Gaia DR2 source id
29- 33 F5.2 mas plx ? GaiaDR2 parallax
35- 38 F4.2 mas e_plx ? GaiaDR2 parallax error
40- 45 F6.2 mas/yr pmRA* ? GaiaDR2 proper motion along RA, pmRA*cosDE
47- 50 F4.2 mas/yr e_pmRA* ? GaiaDR2 proper motion along RA error
52- 56 F5.2 mas/yr pmDE ? GaiaDR2 proper motion along DE
58- 61 F4.2 mas/yr e_pmDE ? GaiaDR2 proper motion along DE error
63- 66 I4 pc rest ? Estimated distance
68- 71 I4 pc e_rest ? Error on estimated distance, lower value
73- 77 I5 pc E_rest ? Error on estimated distance, upper value
79- 82 I4 pc rlen ? Length of the Galactic prior from CBJ18
(I/347) used here to derive the posterior
distribution of the source distance
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 6 A6 --- Lens Lens name, PAR-NN, OGLE3-ULENS-
7 A1 --- Note [*] * for dark lens candidate
9- 10 I2 --- u0 [-1/+1] Impact parameter, u0, solution (G1)
12- 13 I2 --- piEE [-1/+1] Eastern component of microlensing
parallax, πEE, solution (G1)
15- 19 F5.2 mag I0mag Baseline magnitude in I band
21- 24 F4.2 --- fS Blending parameter
26- 30 F5.2 mag Ibmag ? Blended I magnitude
32- 41 A10 --- Com Comments
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 6 A6 --- Lens Lens name OGLE3-ULENS-
8- 11 F4.1 Msun Mass Mass
13- 15 F3.1 Msun E_Mass Error on Mass, upper value
17- 19 F3.1 Msun e_Mass Error on Mass, lower value
21- 23 F3.1 pc Dist Distance
25- 27 F3.1 pc E_Dist Error on distance, upper value
29- 31 F3.1 pc e_Dist Error on distance, lower value
33- 37 F5.2 mag Blend Blend magnitude
39- 42 F4.2 mag E_Blend Error on blend magnitude, upper value
44- 47 F4.2 mag e_Blend Error on blend magnitude, lower value
49- 50 I2 --- u0 [-1/+1] Impact parameter, u0, solution (G1)
52- 53 I2 --- piEN [-1/+1] Northen component of microlensing
parallax, πEN, solution (G1)
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Global notes:
Note (G1): Code as follows:
1 = u0, piEE or piEN > 0
-1 = u0, piEE or piEN < 0
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 16-Jun-2020