| Could the Galactic disk heating be due to Globular Cluster impacts? (2009) | |||||||||
Abstract | |||||||||
| So far, six mechanisms have been proposed to account for the Galactic disk heating. Of these, the most important appear to be a combination of scattering of stars by molecular clouds and by spiral arms. We study a further mechanism, namely, the repeated disk impact of the original Galactic Globular Cluster population up to the present. We find that Globular Clusters could have contributed at most a small fraction of the current vertical energy of the disk, as they could heat the whole disk to {$\sigma $}$_{z}$ = 5.5kms$^{{\rm -} {\rm 1}}$ (c.f. the observed 18 and 39 kms$^{{\rm -} {\rm 1}}$ for the thick and thin disks respectively). We find that the rate of rise of disk heat ($\alpha$=0.22 in \textit{$\sigma $}$_{z}$ $\sim t^{\alpha}$ with \textit t being time), is close to that found for scattering by molecular clouds.. Comment: 4 pages, 1 figure, accepted for publication in MNRAS on 2009/May/14 | |||||||||
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