J/A+A/699/A212 DA DWD candidates based on DESI EDR (Jiang+, 2025)
The survey of DA double white dwarf candidates based on DESI EDR.
Jiang Z., Yuan H., Bai Z., Yang M., Yang X., Liu Q., He Y., Li G., Dong Y.,
Wang M., Zhou M., Zhang H.
<Astron. Astrophys. 699, A212 (2025)>
=2025A&A...699A.212J 2025A&A...699A.212J (SIMBAD/NED BibCode)
ADC_Keywords: Binaries, spectroscopic ; Stars, white dwarf ; Radial velocities ;
Optical
Keywords: techniques: radial velocities - binaries: spectroscopic - white dwarfs
Abstract:
Mergers of double white dwarfs (DWDs) are considered significant
potential progenitors of type Ia supernovae (SNe Ia), which serve as
"standard candles" in cosmology to measure the expansion rate of
the Universe and explore the nature of dark energy. Although there is
no direct observational evidence to definitively determine the
formation pathways of SNe Ia, studying the physical properties of DWDs
provides valuable insights into their evolutionary processes,
interaction modes, and merger mechanisms, which are essential for
understanding the explosion mechanisms of SNe Ia. This study aims to
identify DWD candidates through spectroscopic radial velocity (RV)
measurements and analyze their physical properties based on DESI EDR.
We crossmatched DESI EDR with Gaia EDR3 WD catalog to select DA
spectra. Spectroscopic RV was measured using the cross-correlation
function (CCF), with RV variability assessed via a chi-squared method.
We derived spectroscopic Teff and log g by fitting hydrogen Balmer
lines, applying 3D convection corrections. Orbital periods and
semi-amplitudes came from Lomb-Scargle analysis of RV time series. WD
cooling models and Monte Carlo simulations were used to calculate
masses, cooling ages, radii, and uncertainties. We also analyzed
photometric and SED properties to derive temperatures and radii,
comparing them with spectroscopic parameters.
We identified 33 DA DWD candidates with significant RV variability,
including 28 new discoveries. Among them, an extremely low mass (ELM)
DWD candidate and a potential triple system were found. We measured
key parameters like Teff, logg, mass, and radius for these candidates
and estimated their orbital periods from the data. Of these, 17 showed
clear periodic RV variability, and we reported their best-fitting
periods and RV semi-amplitudes.
Description:
In this study, we have searched for DA DWD candidates by measuring
spectroscopic RV and selecting sources with significant RV
variability. We crossmatched DESI EDR spectra with Gaia WD catalog to
select DA samples with S/N greater than 10.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tableb2.dat 228 33 Parameters for 33 DWD candidates
tableb1.dat 53 381 Radial velocities of single-exposure spectra
tableb3.dat 54 165 Orbital parameters for 33 DWD candidates
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See also:
I/350 : Gaia EDR3 (Gaia Collaboration, 2020)
J/MNRAS/508/3877 : Catalogue of white dwarfs in Gaia EDR3 (Gentile+, 2021)
J/ApJ/970/181 : Categorizing WDs with Gaia XP spectra and UMAP (Kao+, 2024)
Byte-by-byte Description of file: tableb2.dat
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Bytes Format Units Label Explanations
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1- 22 A22 --- WDJname WDJ name (WDJHHMMSS.ssDDMMSS.ss,
equinox and epoch 2000)
24- 35 F12.8 deg RAdeg Right ascension (J2000)
37- 47 F11.8 deg DEdeg Declination (J2000)
49- 52 F4.1 mag Gmag Gaia EDR3 G-band mean magnitude
54- 60 F7.4 mas plx Gaia EDR3 Absolute stellar parallax
at Ep=2016.0
62- 70 F9.6 mag BP-RP Gaia EDR3 BP-RP colour
72- 75 F4.1 mag GMAG Gaia EDR3 Absolute G magnitude
77- 88 F12.10 mag E(B-V) 3D extinction obtained from dustmaps (1)
90- 91 I2 --- N Number of observations
93- 97 F5.2 --- eta ? RV Variability parameter η
98 A1 --- n_eta [I] i means a very large eta
100-102 I3 km/s deltaRV Maximum difference in RV
104-108 I5 K Teff1d Effective temperature obtained
from wd-tools (2)
110-113 I4 K e_Teff1d Error of effective temperature obtained
from wdtools (2)
115-118 F4.2 [cm/s2] logg1d Surface gravity obtained from wdtools
120-123 F4.2 [cm/s2] e_logg1d Error of surface gravity obtained
from wdtools (2)
125-129 I5 K Teff Effective temperature after
3D corrections (3)
131-134 F4.2 [cm/s2] logg Surface gravity after 3D corrections (3)
136-139 I4 K e_Teff Error of Teff
141-144 F4.2 [cm/s2] e_logg Error of logg
146-151 F6.4 Msun Mass Mass obtained by interpolating Teff and
logg into WD evolutionary models
153-158 F6.4 Msun e_Mass ? Error of mass
160-165 F6.4 Gyr Agecool ? Cooling age obtained by interpolating
Teff and logg into WD evolutionary
models
167-172 F6.4 Gyr e_Agecool ? Error of Agecool
174-179 F6.4 Rsun Radsp Radius obtained by interpolating Teff and
logg into WD evolutionary models
181-186 F6.4 Rsun e_Radsp Error of Radsp
188-192 I5 K Teffsed ? Effective temperature obtained from the
single-DA SED fitting
194-199 F6.4 Rsun Radsed ? Radius obtained from the single-DA
SED fitting
201-205 I5 K TeffDESIsp1d ? Effective temperature from DESI
spectroscopic fitting (4)
207-210 F4.2 [cm/s2] loggDESIsp1d ? Surface gravity from DESI
spectroscopic fitting (4)
212-216 I5 K TeffDESIsp3d ? Effective temperature after 3D
corrections from DESI spectroscopic
fitting (4)
218-221 F4.2 [cm/s2] loggDESIsp3d ? Surface gravity after 3D corrections
from DESI spectroscopic fitting (4)
223-228 F6.4 Rsun RadDESI ? Radius obtained by interpolating
TeffDESIsp3d and loggDESIsp3d into
WD evolutionary models
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Note (1): Gree, 2018, The Journal of Open Source Software, 3, 695
Note (2): Chandra et al., 2020MNRAS.497.2688C 2020MNRAS.497.2688C; Chandra, 2020, wdtools:
Computational Tools for the Spectroscopic Analysis of White Dwarfs
Note (3): Tremblay et al., 2013A&A...559A.104T 2013A&A...559A.104T
Note (4): by Manser et al., 2024MNRAS.535..254M 2024MNRAS.535..254M
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Byte-by-byte Description of file: tableb1.dat
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Bytes Format Units Label Explanations
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1- 22 A22 --- WDJname WDJ name (WDJHHMMSS.ss+DDMMSS.ss)
24- 35 F12.6 d MJD MJD identifier for a unique DESI spectrum
37- 41 F5.1 --- MedS/N Median S/N for a unique DESI spectrum
43- 48 F6.1 km/s RV RV obtained from CCF of template-matching
50- 53 F4.1 km/s e_RV Error of RV obtained from Equation 2 of the paper
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Byte-by-byte Description of file: tableb3.dat
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Bytes Format Units Label Explanations
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1- 22 A22 --- WDJname WDJ name (WDJHHMMSS.ss+DDMMSS.ss)
24- 32 F9.6 d Per Period obtained from the Lomb-Scargle method
34 I1 --- Rank Power spectrum rank of the period
36- 47 F12.6 km/s K Semi-amplitude corresponding to the period
49- 54 F6.4 --- R2 R2 of the fitting curve
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Acknowledgements:
Ziyue Jiang, jiangziyue(at)bao.ac.cn
References:
Green, G. 2018, The Journal of Open Source Software, 3, 695
Chandra et al., 2020MNRAS.497.2688C 2020MNRAS.497.2688C
Chandra, V. 2020, wdtools: Computational Tools for the Spectroscopic Analysis
of White Dwarfs
Tremblay et al., 2013A&A...559A.104T 2013A&A...559A.104T
Manser et al., 2024MNRAS.535..254M 2024MNRAS.535..254M
(End) Ziyue Jiang [NAOC, CHINA], Patricia Vannier [CDS] 27-May-2025