发表机构
University of California, Los Angeles; University of Nevada, Reno（加州大学洛杉矶分校; 内华达大学里诺分校）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
该研究在Gaia-CRF3中首次测得Sgr A*-IR的自行与加速度，排除了特定范围内的中等质量黑洞伴星，预计Gaia DR4将进一步提升相关限制精度。
AI 中文摘要
我们在盖亚天体参考框架3（Gaia-CRF3）中，首次测量了银河系中心超大质量黑洞（SMBH）射手座A*（Sgr A*）的红外对应体（Sgr A*-IR）的自行和加速度。Gaia-CRF3实现了由类星体定义的国际天球参考系（ICRS），是一个绝对参考坐标系。我们结合盖亚卫星和哈勃空间望远镜的数据，将凯克自适应光学（AO）观测数据转换至Gaia-CRF3。我们开发了一种参考恒星选择方法，可最小化天体测量转换误差（统计误差为0.10-0.63毫角秒）和坐标系漂移（系统误差约为0.01毫角秒/年）。我们测得Sgr A*-IR在Gaia-CRF3中的自行：赤经方向μ_α* = -3.093 ± 0.085毫角秒/年，赤纬方向μ_δ = -5.62 ± 0.13毫角秒/年，初始位置（t₀=2016.0）的赤经为266.41680848 ± 0.00000029度，赤纬为-29.00783947 ± 0.00000050度，对应赤经精度为1.05毫角秒，赤纬精度为1.79毫角秒，该结果与Xu等人2022年对Sgr A*射电对应体的天体测量测量结果一致。我们还对Sgr A*-IR在天球上的加速度施加了2σ上限约束，为0.061毫角秒/年²。这一加速度限制排除了质量≥4×10⁴倍太阳质量、距离约0.01秒差距内的任何中等质量黑洞伴星，与之前的研究结果一致。随着盖亚数据发布4（Gaia Data Release 4）的发布，我们预测这些限制将至少提高两倍。
英文摘要
We report the first proper motion and acceleration measurements of the infrared (IR) counterpart to Sagittarius A* (Sgr A*-IR), the supermassive black hole (SMBH) at the center of our Galaxy, in the Gaia-Celestial Reference Frame (Gaia-CRF3). This reference frame realizes the International Celestial Reference System (ICRS), which is an absolute reference coordinate system defined by quasars. A combination of Gaia and Hubble Space Telescope data was used to transform Keck adaptive optics (AO) observations into Gaia-CRF3. We developed a method for selecting reference stars that minimizes astrometric transformation errors (statistical error = $0.10-0.63$ mas) and drift of the coordinate system (systematic error $\sim 0.01$ mas/yr). We find the proper motion of Sgr A*-IR in Gaia-CRF3 to be $μ_{α^{*}} = -3.093 \pm 0.085$ mas yr$^{-1}$ and $μ_δ= -5.62 \pm 0.13$ mas yr$^{-1}$ with the initial position at $t_{0} = 2016.0$ of R.A. = 266.41680848 $\pm$ 0.00000029 deg and DEC = -29.00783947 $\pm$ 0.00000050 deg, which translates to a precision of 1.05 mas in R.A. and 1.79 mas DEC. This is consistent with the astrometric measurements of the radio counterpart to Sgr A* by \citet{Xu_2022}. We also place a $2σ$ upper constraint of the acceleration of Sgr A*-IR on the sky at 0.061 mas yr$^{-2}$. This acceleration limit on Sgr A*-IR excludes any intermediate-mass black hole companion with mass $\gtrsim 4\times 10^{4}$ $M_{\odot}$ within a distance of $\sim$0.01 pc, consistent with previous studies. With the release of Gaia Data Release 4, we predict these limits will be improved by at least a factor of two.
Comments22 pages, 10 figures, Accepted to ApJ
