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Main Authors: Zhao, Yue, Gandhi, Poshak, Knigge, Christian, Charles, Phil, Stern, Daniel, Boorman, Peter, Nuchvanichakul, Pornisara, Brown, Cordelia Dashwood, Buckley, David A. H.
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2601.02287
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author Zhao, Yue
Gandhi, Poshak
Knigge, Christian
Charles, Phil
Stern, Daniel
Boorman, Peter
Nuchvanichakul, Pornisara
Brown, Cordelia Dashwood
Buckley, David A. H.
author_facet Zhao, Yue
Gandhi, Poshak
Knigge, Christian
Charles, Phil
Stern, Daniel
Boorman, Peter
Nuchvanichakul, Pornisara
Brown, Cordelia Dashwood
Buckley, David A. H.
contents We perform a comprehensive search for high-velocity X-ray sources with large X-ray/optical flux ratios ($F_\mathrm{X}/F_\mathrm{G}$), identifying candidates for interacting black hole or neutron star binaries potentially accelerated by supernova natal kicks. We cross-match X-ray points sources from a variety of catalogues (Chandra, XMM-Newton, Swift and eROSITA) with Gaia DR3. Using Gaia coordinates, parallaxes, and proper motions, we compute peculiar velocities ($\upsilon_\mathrm{pec}$) relative to Galactic disc rotation. Remaining agnostic about radial velocities (RVs), we vary RVs to find the minimum possible $\upsilon_\mathrm{pec}$ values ($\upsilon_\mathrm{pec, min}$). Uncertainties on $\upsilon_\mathrm{pec, min}$ are estimated via Monte Carlo resampling, and we select X-ray sources that have $1\,σ$ lower limits on $\upsilon_\mathrm{pec, min}\geq 200\,\mathrm{km~s^{-1}}$ and high $F_\mathrm{X}/F_\mathrm{G}$ values. We show that this velocity threshold excludes most contaminants (e.g., cataclysmic variables and active binaries) while retaining a sensible fraction of compact object binaries, demonstrating that $\upsilon_\mathrm{pec}$ could serve as an effective indicator for the presence of a neutron star or black hole companion. Our selection yields a sample of 2372 sources, from which we construct a gold sample of 7 sources that have relatively well-constrained astrometry and confident optical counterparts. Follow-up is necessary to confirm and characterise their high-energy emission, as well as a Galactic disc vs. halo origin.
format Preprint
id arxiv_https___arxiv_org_abs_2601_02287
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle A comprehensive search for high-velocity X-ray sources: New compact object binary candidates in the Gaia era
Zhao, Yue
Gandhi, Poshak
Knigge, Christian
Charles, Phil
Stern, Daniel
Boorman, Peter
Nuchvanichakul, Pornisara
Brown, Cordelia Dashwood
Buckley, David A. H.
High Energy Astrophysical Phenomena
We perform a comprehensive search for high-velocity X-ray sources with large X-ray/optical flux ratios ($F_\mathrm{X}/F_\mathrm{G}$), identifying candidates for interacting black hole or neutron star binaries potentially accelerated by supernova natal kicks. We cross-match X-ray points sources from a variety of catalogues (Chandra, XMM-Newton, Swift and eROSITA) with Gaia DR3. Using Gaia coordinates, parallaxes, and proper motions, we compute peculiar velocities ($\upsilon_\mathrm{pec}$) relative to Galactic disc rotation. Remaining agnostic about radial velocities (RVs), we vary RVs to find the minimum possible $\upsilon_\mathrm{pec}$ values ($\upsilon_\mathrm{pec, min}$). Uncertainties on $\upsilon_\mathrm{pec, min}$ are estimated via Monte Carlo resampling, and we select X-ray sources that have $1\,σ$ lower limits on $\upsilon_\mathrm{pec, min}\geq 200\,\mathrm{km~s^{-1}}$ and high $F_\mathrm{X}/F_\mathrm{G}$ values. We show that this velocity threshold excludes most contaminants (e.g., cataclysmic variables and active binaries) while retaining a sensible fraction of compact object binaries, demonstrating that $\upsilon_\mathrm{pec}$ could serve as an effective indicator for the presence of a neutron star or black hole companion. Our selection yields a sample of 2372 sources, from which we construct a gold sample of 7 sources that have relatively well-constrained astrometry and confident optical counterparts. Follow-up is necessary to confirm and characterise their high-energy emission, as well as a Galactic disc vs. halo origin.
title A comprehensive search for high-velocity X-ray sources: New compact object binary candidates in the Gaia era
topic High Energy Astrophysical Phenomena
url https://arxiv.org/abs/2601.02287