Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Detection of the gravitational redshift in the orbit of the star S2 near
  the Galactic centre massive black hole   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, 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 ~ 200 km/s / c with different statistical analysis
methods. When parameterising the post-Newtonian contribution from these effects
by a factor f, with f = 0 and f = 1 corresponding to the Newtonian and general
relativistic limits, respectively, we find from posterior fitting with
different weighting schemes f = 0.90 +/- 0.09 (stat) +\- 0.15 (sys). The S2
data are inconsistent with pure Newtonian dynamics.

36
The categories of this paper are: cmp-lg
16
The categories of this paper are: stat
23
The categories of this paper are: solv-int
15
The categories of this paper are: nucl-ex
35
The categories of this paper are: mtrl-th
22
The categories of this paper are: chao-dyn
11
The categories of this paper are: hep-lat
13
The categories of this paper are: quant-ph
17
The categories of this paper are: q-fin
1
The categories of this paper are: cs
31
The categories of this paper are: ao-sci
19
The categories of this paper are: eess
28
The categories of this paper are: alg-geom
14
The categories of this paper are: math-ph
24
The categories of this paper are: dg-ga
12
The categories of this paper are: nucl-th