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Red giant stellar collisions in the Galactic Centre

Dale, James E.; Davies, Melvyn B LU ; Church, Ross P. and Freitag, Marc (2009) In Monthly Notices of the Royal Astronomical Society 393(3). p.1016-1033
Abstract
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,... (More)
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. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
stars: late-type, Galaxy: centre
in
Monthly Notices of the Royal Astronomical Society
volume
393
issue
3
pages
1016 - 1033
publisher
Wiley-Blackwell
external identifiers
  • wos:000263359300025
  • scopus:60349122937
ISSN
1365-2966
DOI
10.1111/j.1365-2966.2008.14254.x
language
English
LU publication?
yes
id
19729448-f155-43fd-b14a-a71d8fd44bf4 (old id 1372123)
date added to LUP
2009-05-08 16:21:55
date last changed
2017-09-03 03:48:48
@article{19729448-f155-43fd-b14a-a71d8fd44bf4,
  abstract     = {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 &lt; K &lt; 12 band. However, depleting the brighter (K &lt; 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 &lt; K &lt; 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.},
  author       = {Dale, James E. and Davies, Melvyn B and Church, Ross P. and Freitag, Marc},
  issn         = {1365-2966},
  keyword      = {stars: late-type,Galaxy: centre},
  language     = {eng},
  number       = {3},
  pages        = {1016--1033},
  publisher    = {Wiley-Blackwell},
  series       = {Monthly Notices of the Royal Astronomical Society},
  title        = {Red giant stellar collisions in the Galactic Centre},
  url          = {http://dx.doi.org/10.1111/j.1365-2966.2008.14254.x},
  volume       = {393},
  year         = {2009},
}