The S-Star Cluster at the Center of the Milky Way: On the nature of diffuse NIR emission in the inner tenth of a parsec

Abstract

Sagittarius A*, the super-massive black hole at the center of the Milky Way, is surrounded by a small cluster of high velocity stars, known as the S-stars. We aim to constrain the amount and nature of stellar and dark mass associated with the cluster in the immediate vicinity of Sagittarius A*. We use near-infrared imaging to determine the $K_{\mathrm{s}}$-band luminosity function of the S-star cluster members, and the distribution of the diffuse background emission and the stellar number density counts around the central black hole. This allows us to determine the stellar light and mass contribution expected from the faint members of the cluster. We then use post-Newtonian N-body techniques to investigate the effect of stellar perturbations on the motion of S2, as a means of detecting the number and masses of the perturbers. We find that the stellar mass derived from the $K_{\mathrm{s}}$-band luminosity extrapolation is much smaller than the amount of mass that might be present considering the uncertainties in the orbital motion of the star S2. Also the amount of light from the fainter S-cluster members is below the amount of residual light at the position of the S-star cluster after removing the bright cluster members. If the distribution of stars and stellar remnants is strongly enough peaked near Sagittarius A*, observed changes in the orbital elements of S2 can be used to constrain both their masses and numbers. Based on simulations of the cluster of high velocity stars we find that at a wavelength of 2.2 $\mu$m close to the confusion level for 8 m class telescopes blend stars will occur (preferentially near the position of Sagittarius A*) that last for typically 3 years before they dissolve due to proper motions.

14 pages, 11 figures, minor changes to match the published version in Astronomy & Astrophysics

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• The Two Young Star Disks in the Central Parsec of the Galaxy: Properties, Dynamics and Formation
• The structure of the nuclear stellar cluster of the Milky Way
• Stellar remnants in galactic nuclei: mass segregation
• Dynamical evolution of the young stars in the Galactic center: N-body simulations of the S-stars
• On the nature of the fast moving star S2 in the Galactic Center
• Red giant stellar collisions in the Galactic Centre
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Cited by in corpus (26)

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• Investigating the Relativistic Motion of the Stars Near the Supermassive Black Hole in the Galactic Center
• A numerical study of vector resonant relaxation
• S62 and S4711: Indications of a population of faint fast moving stars inside the S2 orbit -- S4711 on a 7.6 year orbit around Sgr~A*
• S62 on a 9.9 yr Orbit around SgrA*
• Monitoring the Dusty S-Cluster Object (DSO/G2) on its Orbit towards the Galactic Center Black Hole
• Polarized light from Sgr A* in the near-infrared $K_s$-band
• Kinematic Structure of the Galactic Center S-cluster
• Observation of S4716 -- a Star with a 4 yr Orbit around Sgr A*
• Using the motion of S2 to constrain scalar clouds around SgrA*
• Monitoring dusty sources in the vicinity of Sgr A*
• Polarized near-infrared light of the Dusty S-cluster Object (DSO/G2) at the Galactic Center
• A Stability Timescale for Non-Hierarchical Three-Body Systems
• A binary system in the S cluster close to the supermassive black hole Sagittarius A*
• Constraining the accretion flow density profile near Sgr A* using the $L^{\prime }$-band emission of the S2 star
• The apparent tail of the Galactic center object G2/DSO
• First observed interaction of the circumstellar envelope of an S-star with the environment of Sgr A*
• Observation of the apoapsis of S62 in 2019 with NIRC2 and SINFONI
• X3: a high-mass Young Stellar Object close to the supermassive black hole Sgr~A*
• Exploring the presence of a fifth force at the Galactic Center
• The Evaporating Massive Embedded Stellar Cluster IRS 13 Close to Sgr A*. II. Kinematic structure
• Electromagnetic signatures of strong-field gravity from accreting black holes
• Candidate Young Stellar Objects in the S-cluster: The Kinematic Analysis of a Sub-population of the Low-mass G-objects close to Sgr A*
• Detecting Black Hole Occultations by Stars with Space Interferometric Telescopes
• Impact of a granular mass distribution on the orbit of S2 in the Galactic center
• Closing the gap: Follow-up observations of peculiar dusty objects close to Sgr A* using ERIS