Here is the WP image for the centre of the Milky Way where we can see depicted 6 orbits around what is beleived to be a central SMBH (Super Massive Black Hole). Here is a paper about the orbital parameters.
I dont find any reference to any effect in the reddening of the light when the stars are in the nearby of the central region where a deep potential well is expected to be. Lets go ahead.
Here is the WP article about Keplerian orbital motion that constrains every body in a central force where we see that all the ellipses must have a commom focus.
The orbits are 3D curves and we see a 2D projection in the figure.
If it was a central force then the projection of the commom focus is a single point, depicted in the image by the cross of the vertical axis with the horizontal axis.
What we conclude from the image is that several of orbits are out of focus.
(elsewhere in this site I've already explained the origin of the gravitational vortex that subjects the motion of the galaxies)
Here is the above image after I've located, with two big black dots two aditional candidate focus that are completelly off centre.
Central force is the main cause of the orbits? No, it is impossible, and other effect (also a gravitational force field) is much more important.
Am I wrong ? Show me why!
There are not much physical simulations, that I'm aware, of the motion and light effects due to a BH. Almost always they are only "Artistic images" .
One is the light++ software package, freely accessible in the past, and the image bellow from European Southern Observatory
We can see that the simulated motions are almost keplerian and the motions of the stars are far from that. The curvature of the space is flat in the simulation.
I've never saw any reference in the paper that presents the orbital parameters (whatsoever in any other that concerns the Milky Way) any reference to a spatial curvature. THey only apply Newtonian mechanics, and never reported any light reddening even when the light was emmited in the vicinity of SgrA*.
If there is a deep potential well than some of the orbits can not be represented by ellipses. If they are represented always by ellipses then there is no chance to assign any curvature to the space.
One problem less known is the impossible youngness of the stars near the centre of the MilkyWay.
quoting Gezh and several
are unlikely solutions for the Sgr A* cluster stars. Unfortunately,
alternative theories for producing young stars, or old stars that look
young, in close proximity to a central supermassive black hole are all
also somewhat problematic. Understanding the apparent youth of stars
in the Sgr A* cluster, as well as the more distant He I emission line
stars, has now become one of the major outstanding issues in the study
of the Galactic center.
In the vortex approximation (as I explained elsewhere in this site there is no need of a SMBH) the stars are obviously, young.