首次測量到 Sgr A* 對伴星的引力紅移

mca

最近天文學家利用歐洲南天文台 VLT 甚大望遠鏡的干涉儀組合，觀測銀河中心的特大質量黑洞 Sgr A* 及其伴繞星 S2，證實 S2 的星光被 Sgr A* 的引力紅移，表現一如廣義相對論預測，詳見 https://www.eso.org/public/news/eso1825/ 。S2 繞 Sgr A* 運行一周約要 16 年，兩者距離地球約 27000 光年。

短片 https://www.eso.org/public/videos/eso1825a/ (英文字幕)

原論文     https://www.aanda.org/articles/aa/abs/2018/07/aa33718-18/aa33718-18.html

Abstract:  The highly elliptical, 16-year-period orbit of the star S2 around the massive black hole candidate Sgr A✻ is a sensitive probe of the gravitational field in the Galactic centre. Near pericentre at 120 AU ≈ 1400 Schwarzschild radii, the star has an orbital speed of ≈7650 km s−1, such that the first-order effects of Special and General Relativity have now become detectable with current capabilities. Over the past 26 years, we have monitored the radial velocity and motion on the sky of S2, mainly with the SINFONI and NACO adaptive optics instruments on the ESO Very Large Telescope, and since 2016 and leading up to the pericentre approach in May 2018, with the four-telescope interferometric beam-combiner instrument GRAVITY. From data up to and including pericentre, we robustly detect the combined gravitational redshift and relativistic transverse Doppler effect for S2 of z = Δλ / λ ≈ 200 km s−1/c with different statistical analysis methods.