J/MNRAS/485/5573 Gaia-DR2 100pc white dwarf population (Torres+, 2019)
Random Forest identification of the thin disc, thick disc, and halo Gaia-DR2
white dwarf population.
Torres S., Cantero C., Rebassa-Mansergas A., Skorobogatov G.,
Jimenez-Esteban F.M., Solano E.
<Mon. Not. R. Astron. Soc., 485, 5573-5589 (2019)>
=2019MNRAS.485.5573T 2019MNRAS.485.5573T (SIMBAD/NED BibCode)
ADC_Keywords: Stars, white dwarf ; Populations, stellar ; Milky Way ; Models ;
Optical
Keywords: stars: luminosity function - mass function - white dwarfs -
Galaxy: stellar content
Abstract:
Gaia-DR2 has provided an unprecedented number of white dwarf
candidates of our Galaxy. In particular, it is estimated that Gaia-DR2
has observed nearly 400000 of these objects and close to 18000 up to
100pc from the Sun. This large quantity of data requires a thorough
analysis in order to uncover their main Galactic population
properties, in particular the thin and thick disc and halo components.
Taking advantage of recent developments in artificial intelligence
techniques, we make use of a detailed Random Forest algorithm to
analyse an 8D space (equatorial coordinates, parallax, proper motion
components, and photometric magnitudes) of accurate data provided by
Gaia-DR2 within 100pc from the Sun. With the aid of a thorough and
robust population synthesis code, we simulated the different
components of the Galactic white dwarf population to optimize the
information extracted from the algorithm for disentangling the
different population components. The algorithm is first tested in a
known simulated sample achieving an accuracy of 85.3 per cent. Our
methodology is thoroughly compared to standard methods based on
kinematic criteria demonstrating that our algorithm substantially
improves previous approaches. Once trained, the algorithm is then
applied to the Gaia-DR2 100pc white dwarf sample, identifying 12227
thin disc, 1410 thick disc, and 95 halo white dwarf candidates, which
represent a proportion of 74:25:1, respectively. Hence, the numerical
spatial densities are (3.6±0.4)x10-3pc-3,
(1.2±0.4)x10-3pc-3, and (4.8±0.4)x10-5pc-3 for the thin
disc, thick disc, and halo components, respectively. The populations
thus obtained represent the most complete and volume-limited samples
to date of the different components of the Galactic white dwarf
population.
Description:
We have identified 12227 thin disc, 1410 thick disc, and 95 halo white
dwarf candidates belonging to the Gaia 100pc sample (Jimenez-Esteban
et al. 2018MNRAS.480.4505J 2018MNRAS.480.4505J, Cat. J/MNRAS/480/4505) by means of an
accurate Random Forest algorithm (Breiman 2001MachL..45....5B 2001MachL..45....5B). The
unprecedented wealth of valuable information provided to the
scientific community by the Gaia-DR2 (Gaia Collaboration
2018A&A...616A...1G 2018A&A...616A...1G, Cat. I/345) and, in particular, the quantity and
quality of their data related to the white dwarf population requires
the application of novel artificial intelligence matching learning
algorithms in order to extract the maximum information. To this aim we
used a supervised Random Forest algorithm to disentangle the different
white dwarf Galactic populations given its flexibility and low number
of input parameters. The algorithm has been applied to an 8D space
that includes astrometric as well as photometric values for each
object. With the aid of a thorough population synthesis model, we
accurately reproduce the characteristics of a standard three-component
Galactic model. The synthetic population is used for the training of
the classification algorithm as well as a testbed for assessing its
accuracy.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 98 95 Halo white dwarf candidates within 100 pc
identified by our Random Forest algorithm
g100pcwd.dat 270 13732 Gaia 100 pc White Dwarf sample
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See also:
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 I19 --- GaiaDR2 Gaia DR2 source identifier
21- 39 A19 --- Name Star name in equatorial coordinate format
41- 48 F8.2 mas/yr pmRA Gaia DR2 proper motion in right ascension
(pmRA*cosDE)
50- 57 F8.2 mas/yr pmDE Gaia DR2 proper motion in declination
59- 63 F5.2 pc Dist Distance
65- 69 F5.2 mag Gmag Gaia DR2 g-bang magnitude
71- 75 F5.2 mag GMAG Absolute G-band magnitude
77- 81 F5.2 mag BP-RP Gaia DR2 BP-RP colour index
83- 88 F6.2 km/s Vtan Tangential velocity
90- 98 A9 --- Ref References where the source has already
been identified as a halo member (1)
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Note (1): References as follows:
a = Liebert, Dahn & Monet (1989LNP...328...15L 1989LNP...328...15L)
b = Torres et al. (1998ApJ...508L..71T 1998ApJ...508L..71T)
c = Harris et al. (2006AJ....131..571H 2006AJ....131..571H)
d = Rowell & Hambly (2011MNRAS.417...93R 2011MNRAS.417...93R)
e = Pauli et al. (2006A&A...447..173P 2006A&A...447..173P, Cat. J/A+A/447/173)
f = Kawka & Vennes (2012MNRAS.425.1394K 2012MNRAS.425.1394K, Cat. J/MNRAS/425/1394)
g = Gianninas et al. (2015MNRAS.449.3966G 2015MNRAS.449.3966G, Cat. J/MNRAS/449/3966)
h = Si et al. (2017MNRAS.468.4374S 2017MNRAS.468.4374S)
i = Kilic et al. (2019MNRAS.482..965K 2019MNRAS.482..965K, Cat. J/MNRAS/482/965)
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Byte-by-byte Description of file: g100pcwd.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 A8 --- --- [Gaia DR2]
10- 28 I19 --- GaiaDR2 Gaia DR2 source identifier
30- 48 A19 --- Name Star name in equatorial coordinate format
50- 59 I10 --- RN Random number
61- 74 F14.10 deg RAdeg Right ascension (ICRS) at Ep=2015.5
76- 89 F14.10 deg DEdeg Declination (ICRS) at Ep=2015.5
91-104 F14.10 mas plx Parallax
106-130 F25.19 mas/yr pmRA Gaia DR2 proper motion in right ascension
(pmRA*cosDE)
132-147 F16.10 mas/yr pmDE Gaia DR2 proper motion in declination
149-158 F10.7 mag Gmag Gaia DR2 g-band magnitude
160-169 F10.7 mag BPmag Gaia DR2 BP-band magnitude
171-180 F10.7 mag RPmag Gaia DR2 RP-band magnitude
182-196 F15.12 mag BP-RP Gaia DR2 BP-RP colour index
198-211 F14.11 mag BP-G Gaia DR2 BP-G colour index
213-227 F15.12 mag G-RP Gaia DR2 G-RP colour index
229-241 F13.10 mag GMAG Absolute G-band magnitude
243-250 F8.3 km/s U U component of space velocity
252-259 F8.3 km/s V V component of space velocity
261-268 F8.3 k/s W W component of space velocity
270 I1 --- Pop Galactic component classification (1)
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Note (1): Population as follows:
0 = Thin disk (12227/13732, 89 per cent)
1 = Thick disk (1410/13732, 10 per cent)
2 = Halo (95/13732, 1 per cent)
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History:
From electronic version of the journal
(End) Ana Fiallos [CDS] 11-Oct-2022