盖亚DR3致密天体双星候选体的光谱后续观测：白矮星、中子星、黑洞及视差零点
Spectroscopic follow-up of compact object binary candidates from Gaia DR3: White dwarfs, neutron stars, black holes, and the parallax zeropoint
- California Institute of Technology（加州理工学院）
- Max-Planck-Institut für Astronomie（马克斯·普朗克天文学研究所）
- DTU Space, National Space Institute, Technical University of Denmark（丹麦技术大学国家空间研究所）
- Tel Aviv University（特拉维夫大学）
- Universität Heidelberg（海德堡大学）
- The Observatories of the Carnegie Institution for Science（卡内基科学学会天文台）
- University of California, Berkeley（加州大学伯克利分校）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
本研究对盖亚DR3的227个致密天体双星候选体开展光谱后续观测，联合天体测量与视向速度数据确认约60%候选体含致密天体，还测量了盖亚DR3的视差零点，结果将指导盖亚DR4的候选体筛选。
AI中文摘要：
盖亚DR3的天体测量与视向速度（RV）数据给出了数十万双星系统的轨道参数，其中包含多个被提议存在黑洞（BH）、中子星（NS）和白矮星（WD）的样本。本文呈现针对这些天体的系统光谱后续观测项目结果。我们从227个源的样本出发，结合存档数据与多历元光谱后续观测对超过200个源进行表征；利用TRES和FEROS光谱仪在四年间获取了1292个高质量视向速度测量值，典型精度达50 m/s，其中60个源的视向速度测量次数至少为10次。我们用这些数据检验盖亚轨道解并收紧轨道参数与子天体质量的约束；结合天体测量与视向速度的联合拟合可直接约束流量比，验证未被探测的伴星确实是暗天体。我们发现约60%的天体测量候选体确实拥有致密天体，包括两个已知的盖亚黑洞、27个中子星候选体和十余个大质量白矮星；本样本中紧密的白矮星+白矮星双星可能伪装成中子星。光谱候选体纯度较低：约50%存在虚假解，其余大部分为质量转移后双星或等级三重系统。对含暗伴星的双星进行天体测量+视向速度联合拟合可得到直接的、不依赖视差的距离测量值；利用40个此类系统，我们测量了盖亚DR3天体测量轨道解的视差零点，得到Z=-0.0362±0.0053 mas，与相似颜色和亮度源的单星视差零点一致。这些结果将指导从盖亚DR4中筛选更纯净的候选体样本，更长的观测基线将在DR4中发现更多致密天体双星，视向速度后续观测对确认单个系统仍至关重要，尤其是具有极端参数的系统。
英文摘要：
Astrometry and radial velocities (RVs) from Gaia DR3 yielded orbits for hundreds of thousands of binary systems, including several samples proposed to contain black holes (BHs), neutron stars (NSs), and white dwarfs (WDs). We present results of a systematic spectroscopic follow-up program targeting these objects. Beginning with a sample of 227 sources, we used a combination of archival data and many-epoch spectroscopic follow-up to characterize more than 200. We obtained 1292 high-quality RVs over a period of four years using the TRES and FEROS spectrographs, achieving a typical precision of 50 m/s and at least 10 RVs for 60 sources. We use these data to test the Gaia orbital solutions and tighten constraints on orbital parameters and component masses. Joint fitting of astrometry and RVs allows us to directly constrain flux ratios, verifying that undetected companions are genuinely dark. We find that ~60% of the astrometric candidates indeed host compact objects, including the two known Gaia BHs, 27 NS candidates, and a dozen massive WDs. We show that tight WD+WD binaries may masquerade as NSs within this sample. The spectroscopic candidates have lower purity: ~50% have spurious solutions, and a majority of the rest are post-mass-transfer binaries or hierarchical triples. Joint astrometry+RV fits of binaries with dark companions yield direct, parallax-independent distance measurements. Using 40 such systems, we measure the Gaia DR3 parallax zeropoint for astrometric orbital solutions. We find $Z=-0.0362\pm0.0053$ mas, consistent with the single-star zeropoint for sources of similar color and magnitude. These results will guide the selection of cleaner candidate samples from Gaia DR4, where a longer observing baseline will enable discovery of many more compact object binaries. RV follow-up will remain important for confirming individual systems, particularly those with extreme parameters.
