Red giant stellar collisions in the Galactic Centre
Författare
Summary, in English
We show that collisions with stellar-mass black holes can partially explain the absence of bright giant stars in the Galactic Centre, first noted by Genzel et al. We show that the missing objects are low-mass giants and asymptotic giant branch stars in the range 1-3 M-circle dot. Using detailed stellar evolution calculations, we find that to prevent these objects from evolving to become visible in the depleted K bands, we require that they suffer collisions on the red giant branch, and we calculate the fractional envelope mass losses required. Using a combination of smoothed particle hydrodynamic calculations, restricted three-body analysis and Monte Carlo simulations, we compute the expected collision rates between giants and black holes, and between giants and main-sequence stars in the Galactic Centre. We show that collisions can plausibly explain the missing giants in the 10.5 < K < 12 band. However, depleting the brighter (K < 10.5) objects out to the required radius would require a large population of black hole impactors which would in turn deplete the 10.5 < K < 12 giants in a region much larger than is observed. We conclude that collisions with stellar-mass black holes cannot account for the depletion of the very brightest giants, and we use our results to place limits on the population of stellar-mass black holes in the Galactic Centre.
Avdelning/ar
Publiceringsår
2009
Språk
Engelska
Sidor
1016-1033
Publikation/Tidskrift/Serie
Monthly Notices of the Royal Astronomical Society
Volym
393
Issue
3
Länkar
Dokumenttyp
Artikel i tidskrift
Förlag
Oxford University Press
Ämne
- Astronomy, Astrophysics and Cosmology
Nyckelord
- stars: late-type
- Galaxy: centre
Status
Published
Forskningsgrupp
- Observational and Theoretical Astrophysics
ISBN/ISSN/Övrigt
- ISSN: 1365-2966