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arXiv · 0707.2382

Evidence for a Long-Standing Top-Heavy IMF in the Central Parsec of the Galaxy

H. Maness·F. Martins·S. Trippe·R. Genzel·J. R. Graham·C. Sheehy·M. Salaris·S. Gillessen·T. Alexander·T. Paumard·T. Ott·R. Abuter·F. Eisenhauer
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Abstract

We classify 329 late-type giants within 1 parsec of Sgr A*, using the adaptive optics integral field spectrometer SINFONI on the VLT. These observations represent the deepest spectroscopic data set so far obtained for the Galactic Center, reaching a 50% completeness threshold at the approximate magnitude of the helium-burning red clump (Ks ~ 15.5 mag.). Combining our spectroscopic results with NaCo H and Ks photometry, we construct an observed Hertzsprung-Russell diagram, which we quantitatively compare to theoretical distributions of various star formation histories of the inner Galaxy, using a chi-squared analysis. Our best-fit model corresponds to continuous star formation over the last 12 Gyr with a top-heavy initial mass function (IMF). The similarity of this IMF to the IMF observed for the most recent epoch of star formation is intriguing and perhaps suggests a connection between recent star formation and the stars formed throughout the history of the Galactic Center.

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H. Maness, F. Martins, S. Trippe, R. Genzel, J. R. Graham, C. Sheehy, M. Salaris, S. Gillessen, T. Alexander, T. Paumard, T. Ott, R. Abuter, F. Eisenhauer. 2007-07-16. Evidence for a Long-Standing Top-Heavy IMF in the Central Parsec of the Galaxy. https://doi.org/10.1086/521669

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