학술논문
Where intermediate-mass black holes could hide in the Galactic Centre: A full parameter study with the S2 orbit
Document Type
Working Paper
Author
The GRAVITY Collaboration; Straub, O.; Bauböck, M.; Abuter, R.; Aimar, N.; Seoane, P. Amaro; Amorim, A.; Berger, J. P.; Bonnet, H.; Bourdarot, G.; Brandner, W.; Cardoso, V.; Clénet, Y.; Dallilar, Y.; Davies, R.; de Zeeuw, P. T.; Dexter, J.; Drescher, A.; Eisenhauer, F.; Schreiber, N. M. Förster; Foschi, A.; Garcia, P.; Gao, F.; Gendron, E.; Genzel, R.; Gillessen, S.; Habibi, M.; Haubois, X.; Heißel, G.; Henning, T.; Hippler, S.; Horrobin, M.; Jochum, L.; Jocou, L.; Kaufer, A.; Kervella, P.; Lacour, S.; Lapeyrère, V.; Bouquin, J. -B. Le; Léna, P.; Lutz, D.; Ott, T.; Paumard, T.; Perraut, K.; Perrin, G.; Pfuhl, O.; Rabien, S.; Ribeiro, D. C.; Bordoni, M. Sadun; Scheithauer, S.; Shangguan, J.; Shimizu, T.; Stadler, J.; Straubmeier, C.; Sturm, E.; Tacconi, L. J.; Vincent, F.; von Fellenberg, S.; Widmann, F.; Wieprecht, E.; Wiezorrek, E.; Woillez, J.
Source
A&A 672, A63 (2023)
Subject
Language
Abstract
In the Milky Way the central massive black hole, SgrA*, coexists with a compact nuclear star cluster that contains a sub-parsec concentration of fast-moving young stars called S-stars. Their location and age are not easily explained by current star formation models, and in several scenarios the presence of an intermediate-mass black hole (IMBH) has been invoked. We use GRAVITY astrometric and SINFONI, KECK, and GNIRS spectroscopic data of S2 to investigate whether a second massive object could be present deep in the Galactic Centre (GC) in the form of an IMBH binary companion to SgrA*. To solve the three-body problem, we used a post-Newtonian framework and consider two types of settings: (i) a hierarchical set-up where the star S2 orbits the SgrA* - IMBH binary and (ii) a non-hierarchical set-up where the IMBH trajectory lies outside the S2 orbit. In both cases we explore the full 20-dimensional parameter space by employing a Bayesian dynamic nested sampling method. For the hierarchical case we find: IMBH masses > 2000 Msun on orbits with smaller semi-major axes than S2 are largely excluded. For the non-hierarchical case the parameter space contains several pockets of valid IMBH solutions. However, a closer analysis of their impact on the resident stars reveals that IMBHs on semi-major axes larger than S2 tend to disrupt the S-star cluster in less than a million years. This makes the existence of an IMBH among the S-stars highly unlikely. The current S2 data do not formally require the presence of an IMBH. If an IMBH hides in the GC, it has to be either a low-mass IMBH inside the S2 orbit that moves on a short and significantly inclined trajectory or an IMBH with a semi-major axis >1". We provide the parameter maps of valid IMBH solutions in the GC and discuss the general structure of our results. (abridged)
Comment: 11 pages, 6 figures, published in A $\&$ A
Comment: 11 pages, 6 figures, published in A $\&$ A