J/MNRAS/518/2991 Study of Gaia binaries with compact companions (Shahaf+, 2023)
Triage of the Gaia DR3 astrometric orbits.
I. A sample of binaries with probable compact companions.
Shahaf S., Bashi D., Mazeh T., Faigler S., Arenou F., El-Badry K., Rix H.W.
<Mon. Not. R. Astron. Soc. 518, 2991-3003 (2023)>
=2023MNRAS.518.2991S 2023MNRAS.518.2991S (SIMBAD/NED BibCode)
ADC_Keywords: Photometry ; Optical ; Stars, double and multiple ;
Stars, masses ; Stars, normal ; Stars, neutron ;
Stars, white dwarf ; Black holes ; Binaries, orbits
Keywords: astrometry - binaries: general - stars: black holes - stars: neutron -
(stars:) white dwarfs
Abstract:
In preparation for the release of the astrometric orbits of Gaia,
Shahaf et al. (2019MNRAS.487.5610S 2019MNRAS.487.5610S) proposed a triage technique to
identify astrometric binaries with compact companions based on their
astrometric semimajor axis, parallax, and primary mass. The technique
requires the knowledge of the appropriate mass-luminosity relation to
rule out single or close-binary main-sequence companions. The recent
publication of the Gaia DR3 astrometric orbits used a schematic
version of this approach, identifying 735 astrometric binaries that
might have compact companions. In this communication, we return to the
triage of the DR3 astrometric binaries with more careful analysis,
estimating the probability for its astrometric secondary to be a
compact object or a main-sequence close binary. We compile a sample of
177 systems with highly probable non-luminous massive companions,
which is smaller but cleaner than the sample reported in Gaia DR3. The
new sample includes eight candidates to be black-hole systems with
compact-object masses larger than 2.4 M☉. The
orbital-eccentricity-secondary-mass diagram of the other 169 systems
suggests a tentative separation between the white-dwarf and the
neutron-star binaries. Most white-dwarf binaries are characterized by
small eccentricities of about 0.1 and masses of 0.6 M☉, while
the neutron star binaries display typical eccentricities of 0.4 and
masses of 1.3 M☉.
Description:
In preparation for the release of the astrometric orbits of Gaia,
Shahaf et al. (2019MNRAS.487.5610S 2019MNRAS.487.5610S) proposed a triage technique to
identify astrometric binaries that have compact companions based on
their derived semimajor axis, parallax, orbital period, and the
estimated primary mass. The technique requires the knowledge of the
proper mass-luminosity relation (MLR) to rule out a single or a
close-binary MS companion. We return to the triage of the DR3
astrometric binaries with a more careful analysis that uses a more
conservative MLR to identify compact-secondary binaries based on a
suit of MIST isochrone grids. We derive a less contaminated catalogue
of compact companions, identifying astrometric binaries with WD, NS,
or BH companions.
As explained in section 3.1 Sample selection, we applied criteria on
Gaia database archive for astrometric binaries with MS primary stars
that have mass estimate. We focus on class-II or class-III binaries
with 101380 systems in our cleaned sample. The table1.dat presents
their class probabilities computed in sections 3.2 and 3.3, AMRF
values and binary companion masses. Next, as mentionned in section 4
Highly-probable class-III systems, we define a sample of systems
likely to host compact companions FDR approach. The selection
criterion we used is equivalent to setting a minimal class-III
probability of 99.984% and α (i.e the upper limit on the
expectancy values of the false discovery rate) to 10% yielding 177
systems in this sub-sample presented in table2.dat. This table
contains binary companion masses, periods, eccentricities,
significances and object classes for compact companions.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 154 101380 Probabilistic AMRF classification of the clean
selected astrometric sample
table2.dat 168 177 The highly probable class-III systems sample
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See also:
J/A+A/692/A247 : Gaia orbital and accelerated sources (Bashi+, 2024)
J/A+A/682/A12 : ESMORGA, Gaia astrometric binaries masses
(Perez-Couto+, 2024)
J/PASP/136/H4202 : Wide Post-common Envelope Binaries from Gaia
(Yamaguchi+, 2024)
J/ApJS/262/21 : 3-D selection of 167 sub-stellar companions (Feng+, 2022)
I/357 : Gaia DR3 Part 3. Non-single stars (Gaia Collaboration, 2022)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 I19 --- GaiaDR3 Gaia DR3 source identifier (source_id)
21- 28 F8.5 mag Gmag G optical mean magnitude from Gaia DR3
(photgmean_mag)
30- 37 F8.6 Msun M1 Mass of the binary primary star (m1)
39- 55 F17.15 --- A Astrometric mass ratio function defined by
Shahaf et al. (2019MNRAS.487.5610S 2019MNRAS.487.5610S) (AMRF)
57- 73 F17.15 --- e_A Error of A (AMRF_error)
75- 92 F18.15 Msun M2min The corresponding minimal mass of the
companion as defined in section 2 (AMRF_m2)
94-110 F17.15 Msun e_M2min Error of M2min (AMRFm2error)
112-132 E21.15 % PII Estimated probability being in
Class-II-binaries as explained in section 3.3
(classII_prob) (1)
134-154 E21.15 % PIII Estimated probability being in
Class-III-binaries as explained in section 3.3
(classIII_prob) (2)
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Note (1): More, as defined in section 2.1 AMRF classification, for definition
of Class-II binaries: (Ams < A < Atr), where the companion cannot
be a single MS star, but can be either an MS close binary or a compact
object. The class-II parameter space is denoted with slanted lines in
figure 2 of section 2.1.
Note (2): More, as defined in section 2.1 AMRF classification, for definition
of Class-III binaries: (A > Atr), where the companion cannot be a
single MS star nor a close MS binary; these systems are likely to host
a compact object secondary. The class-III parameter space is
highlighted by small circles in figure 2 of section 2.1.
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Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 I19 --- GaiaDR3 Gaia DR3 source identifier (source_id)
21- 38 F18.15 Msun M2min The secondary mass of the compact object
candidate derived from the AMRF (AMRF_m2)
40- 56 F17.15 Msun e_M2min Uncertainty of M2min (AMRFm2error)
58- 65 F8.6 Msun M1 Mass of the binary primary star (m1)
67- 83 F17.13 d P The orbital period (period)
85- 94 F10.6 d e_P Uncertainty of P (period_error)
96-112 F17.15 --- e The orbital eccentricity (eccentricity)
114-121 F8.6 --- e_e Uncertainty of e (eccentricity_error)
123-131 F9.5 --- s Significance value from Gaia archive
(significance)
133-149 F17.15 --- sigTI The The quadratic mean of the relative error
on the Thiele-Innes coefficients denoted
σti as defined by eq 4 of sect. 3.1
(sigma_TI)
151-152 A2 --- Class Result of our tentative Gaussian-mixture based
classification (labels) (1)
154-168 A15 --- n_Class Comments on Label (comments) (2)
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Note (1): The Gaussian-mixture based classification labels are as follows:
BH = Black hole companion, 8 sources in our sample
NS = Neutron star companion, 68 sources in our sample
WD = White dwarf companion, 101 sources in our sample
Most of these systems, if their orbits are valid, contain compact
secondaries. Therefore, we can derive their masses and possibly
distinguish between the WD, NS, or BH companions (i.e see more in
section 5).
Note (2): For 5 BH cases, 1 is confirmed by AstroSpectroSB1, 3 are refuted by
El-Badry et al. (2023MNRAS.518.1057E 2023MNRAS.518.1057E), 1 is confirmed by El-Badry et
al. (2023MNRAS.518.1057E 2023MNRAS.518.1057E) and for 6 NS cases are confirmed by
AstroSpectroSB1.
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History:
From electronic version of the journal
References:
Shahaf et al., Paper II 2024MNRAS.529.3729S 2024MNRAS.529.3729S
(End) Luc Trabelsi [CDS] 19-Dec-2025