Search

Hidden within the Gaia satellite’s multiple data releases lies a valuable cache of dark companions. To facilitate the efficient and reliable detection of these companions via combined analyses involving the Gaia, Hipparcos, and Tycho-2 catalogs, we introduce an astrometric modeling framework. This method incorporates analytical least-square minimization and nonlinear parameter optimization techniques to a set of common calibration sources across the different space-based astrometric catalogs. This enables us to discern the error inflation, astrometric jitter, differential parallax zero-points, and frame rotation of various catalogs relative to Gaia Data Release 3 (DR3). Our findings yield the most precise Gaia DR2 calibration parameters to date, revealing notable dependencies on magnitude and color. Intriguingly, we identify submilliarcsecond frame rotation between Gaia DR1 and DR3, along with an estimated astrometric jitter of 2.16 mas for the revised Hipparcos catalog. In a thorough comparative analysis with previous studies, we offer recommendations on calibrating and utilizing different catalogs for companion detection. Furthermore, we provide a user-friendly pipeline ( https://github.com/ruiyicheng/Download_HIP_Gaia_GOST ) for catalog download and bias correction, enhancing accessibility and usability within the scientific community.

A large number of candidate binary stars with apparent acceleration on the sky has emerged from analysis of astrometric data collected by the Hipparcos, Tycho-2, and Gaia space missions. Although the apparent acceleration can serve as a relatively reliable indicator of binarity, it provides scarce information about the orbital and physical parameters of the components. With an emphasis on the search for stellar-mass black holes and neutron stars hidden in binary systems, we start a broader effort to characterize the most promising candidates using follow-up ground-based observations. Accurate quantification of orbital and physical parameters of systems with dim or invisible companions requires combination of Hipparcos, Gaia, and precision spectroscopic measurements. In this paper, we review the necessary steps in this implementation and describe the improved Hipparcos–Gaia sample of long-term astrometric accelerations, which includes correction of sky-correlated systematic errors using the vector spherical decomposition method. As an example, we study one Hipparcos star with a large acceleration, HIP 44842, where the companion is revealed to be a normal main-sequence star.

Soon after Gaia Data Release 3 (DR3) in 2022 June, some candidates (and one confirmed) of detached black hole (BH)–luminous companion (LC) binaries have been reported. Existing and future detections of astrometric BH–LC binaries will shed light on the spatial distribution of these systems, which can deepen our understanding of the natal kicks and the underlying formation mechanism of BHs. By tracking Galactic orbits of BH–LC binaries obtained from BSE, we find that distributions of BH mass and the height from the Galactic plane ∣ z ∣ would help us give a constraint on the supernova model. We also indicate that the correlations of (i) orbital periods and eccentricities, and (ii) BH mass and ∣ z ∣ could be clues for the strength of the natal kick, and that the correlations of ( P , Z / Z _⊙ ) may give us a clue for the common-envelope (CE) efficiency. We also discuss the possibility of forming BH–LC binaries like the BH binary candidates reported in Gaia DR3 and Gaia BH 1, finding that if the candidates as well as the confirmed binary originate from isolated binaries, they favor models that produce low-mass BHs and have high CE efficiencies exceeding unity.