Quartet-metric gravity and scalar graviton dark holes: supplements

This note includes results of a study of stationary spherically symmetric ``dark holes'', objects merging central black holes and peripheral scalar graviton dark haloes arising in the framework of the modified gravity -- the quartet-metric, or more appropriately, multiscalar-metric gravity with spontaneously broken relativity as a gauge symmetry [1]. An exact solution to be considered as a basic one for the dark holes is presented. This solution may, in principle, be used for a qualitative description of the effect of asymptotically flat rotation curves in galaxies. To convert the basic solution into a more realistic one suitable for astrophysical applications, a family of modified solutions is considered. These solutions are studied numerically for representative set of free parameters. These results were reported in the talk [2] but not included into the proceedings [3] due to article length limitations. The note can be considered as a supplement to this reference.