The Star Formation History of the Milky Way's Nuclear Star Cluster

• DOI: 10.48550/arxiv.2212.01397
• Publication Date: 2022-01-01
• Authors: Zhuo Chen; Tuan Do; A. M. Ghez; Matthew W. Hosek; A. Feldmeier; Devin S. Chu; Rory O. Bentley; Jessica R. Lu; M. Morris
• Keywords: Stellar population; Stellar mass

We report the first star formation history study of Milky Way's nuclear cluster (NSC) that includes observational constraints from a large sample stellar metallicity measurements. These measurements were obtained recent surveys Gemini and VLT 770 late-type stars within central 1.5 pc. measurements, along with photometry spectroscopically derived temperatures, are forward modeled Bayesian inference approach. Including improves overall fit quality, as low-temperature red giants previously difficult to constrain now accounted for, best favors two-component model. The dominant component contains 93%$\pm$3% mass, is metal-rich ($\overline{[M/H]}\sim$0.45), has an age 5$^{+3}_{-2}$ Gyr, which $\sim$3 Gyr younger than earlier studies fixed (solar) metallicity; this challenges co-evolutionary models in NSC supermassive black holes formed simultaneously at early times. minor population low ($\overline{[M/H]}\sim$ -1.1) $\sim$7% mass. uncertain (0.1 - 5 old). Using estimated parameters, we infer following remnant (with $\sim$18% uncertainty): 1.5$\times$10$^5$ neutron stars, 2.5$\times$10$^5$ mass (BHs) 2.2$\times$10$^4$ BH-BH binaries. predictions result 2-4 times fewer compared assume solar metallicity, introducing possible new path understand so-called "missing pulsar problem". Finally, present updated for merger rates (0.01-3 Gpc$^{-3}$yr$^{-1}$).