A Systematic Gaia–ZTF Search for Short-period Blue Compact-binary Candidates
- 1Sun Yat-sen University
- 2Anhui Science and Technology University
- 3Shenzhen Campus of Sun Yat-sen University
Abstract
Short-period binaries containing white dwarfs or hot subdwarfs are among the strongest Galactic sources for millihertz gravitational-wave (GW) observatories, but the confirmed sample remains small. Combining Gaia DR3 astrometry and photometry with ZTF DR23 light curves—through a Gaia selection calibrated against known systems, ZTF period searches, and machine learning morphology ranking—we assemble a catalog of 147 short-period (10.34–106.46 minutes) blue compact-binary candidates, 111 of them without a previous compact-binary classification. DESI DR1, GALEX, and AllWISE data reveal an intrinsically heterogeneous sample: on the Gaia color–magnitude diagram it comprises 52 white-dwarf-locus, 69 hot-subdwarf-region, and 26 intermediate sources, and among the 26 members with DESI spectra only about one-third lie on the white-dwarf cooling sequence, the rest being more luminous blue stars whose low-resolution spectra resemble white dwarfs. We identify a prioritized set of new short-period white-dwarf-locus candidates for time-resolved follow-up, including 10 with periods below 40 minutes and none with an existing radial-velocity series. Under fiducial binary assumptions, 17 newly identified white-dwarf-locus candidates would exceed the adopted LISA threshold, led by a 37 pc white dwarf; no candidate has a measured chirp mass, and with the signal-to-noise ratio scaling as M c 5 / 3 the count is 9 for M c = 0.15 M ⊙ , 17 for the adopted 0.3 M ⊙ , and 21 for 0.6 M ⊙ , in each case assuming the modulation is orbital. We show, however, that for the compact majority of the white-dwarf-locus sample the observed modulation amplitudes exceed any possible ellipsoidal signal by 3 to 5 orders of magnitude, so a rotating magnetic or chemically inhomogeneous single white dwarf is a competing interpretation that ZTF photometry alone cannot exclude; the catalog contains at least one confirmed case. We release the full 147-source catalog with periods, Gaia and spectroscopic classifications, harmonic and ellipsoidal diagnostics, and supplementary tables of fiducial GW estimates and ultraviolet–infrared photometry.
Related
- A Sample of Long-Period Binaries with Dormant Compact-Object Candidates from LAMOST DR13 MRS and Gaia DR3
- A Sample of Long-period Binaries with Dormant Compact-object Candidates from LAMOST DR13 MRS and Gaia DR3
- Gaia DR3 Compact Binary Candidates Constrained by Radial Velocity Measurements
- Spectroscopic follow-up of compact object binary candidates from Gaia DR3: White dwarfs, neutron stars, black holes, and the parallax zeropoint
- Spectroscopic follow-up of compact object binary candidates from Gaia DR3: White dwarfs, neutron stars, black holes, and the parallax zeropoint
BibTeX
@article{lin2026systematic,
title = {{A Systematic Gaia–ZTF Search for Short-period Blue Compact-binary Candidates}},
author = {Jiamao Lin and Liangliang Ren and Yilong Li and Bo Ma and Di-Chang Chen and Zi-Heng Yu and Sen Yang and Shun-Jia Huang and Yi-Ming Hu and Chengyuan Li},
journal = {The Astrophysical Journal},
year = {2026},
month = oct,
doi = {10.3847/1538-4357/ae9d7d},
url = {https://iopscience.iop.org/article/10.3847/1538-4357/ae9d7d},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - A Systematic Gaia–ZTF Search for Short-period Blue Compact-binary Candidates
AU - Jiamao Lin
AU - Liangliang Ren
AU - Yilong Li
AU - Bo Ma
AU - Di-Chang Chen
AU - Zi-Heng Yu
AU - Sen Yang
AU - Shun-Jia Huang
AU - Yi-Ming Hu
AU - Chengyuan Li
PY - 2026
DA - 2026/10/12
JO - The Astrophysical Journal
DO - 10.3847/1538-4357/ae9d7d
UR - https://iopscience.iop.org/article/10.3847/1538-4357/ae9d7d
AB - Short-period binaries containing white dwarfs or hot subdwarfs are among the strongest Galactic sources for millihertz gravitational-wave (GW) observatories, but the confirmed sample remains small. Combining Gaia DR3 astrometry and photometry with ZTF DR23 light curves—through a Gaia selection calibrated against known systems, ZTF period searches, and machine learning morphology ranking—we assemble a catalog of 147 short-period (10.34–106.46 minutes) blue compact-binary candidates, 111 of them without a previous compact-binary classification. DESI DR1, GALEX, and AllWISE data reveal an intrinsically heterogeneous sample: on the Gaia color–magnitude diagram it comprises 52 white-dwarf-locus, 69 hot-subdwarf-region, and 26 intermediate sources, and among the 26 members with DESI spectra only about one-third lie on the white-dwarf cooling sequence, the rest being more luminous blue stars whose low-resolution spectra resemble white dwarfs. We identify a prioritized set of new short-period white-dwarf-locus candidates for time-resolved follow-up, including 10 with periods below 40 minutes and none with an existing radial-velocity series. Under fiducial binary assumptions, 17 newly identified white-dwarf-locus candidates would exceed the adopted LISA threshold, led by a 37 pc white dwarf; no candidate has a measured chirp mass, and with the signal-to-noise ratio scaling as M c 5 / 3 the count is 9 for M c = 0.15 M ⊙ , 17 for the adopted 0.3 M ⊙ , and 21 for 0.6 M ⊙ , in each case assuming the modulation is orbital. We show, however, that for the compact majority of the white-dwarf-locus sample the observed modulation amplitudes exceed any possible ellipsoidal signal by 3 to 5 orders of magnitude, so a rotating magnetic or chemically inhomogeneous single white dwarf is a competing interpretation that ZTF photometry alone cannot exclude; the catalog contains at least one confirmed case. We release the full 147-source catalog with periods, Gaia and spectroscopic classifications, harmonic and ellipsoidal diagnostics, and supplementary tables of fiducial GW estimates and ultraviolet–infrared photometry.
SN - 0004-637X
SN - 1538-4357
ER -