Astronomy and Astrophysics – Astrophysics – Cosmology and Extragalactic Astrophysics
Scientific paper
2012-01-05
Astronomy and Astrophysics
Astrophysics
Cosmology and Extragalactic Astrophysics
Submitted to ApJ
Scientific paper
We analyze a suite of 33 cosmological simulations following the evolution of Milky Way-mass galaxies in low-density environments. Our sample at z = 0 comprises galaxies with a broad range of Hubble types, from nearly bulgeless disks to bulge-dominated galaxies. The bulges are typically pseudo-bulges, with a Sersic index lower than 2, and 70% of the galaxies have bars. Despite the fact that a large fraction of the bulge is typically in place by z = 1, we find no significant correlation between the morphology at z = 1 and at z = 0. The progenitors of disk galaxies span a whole range of morphologies at z = 1, including smooth disks, unstable disks, interacting galaxies and bulge-dominated systems. By z = 0.5, the progenitor morphology is correlated with the z = 0 morphology, with spiral arms and bars largely in place at z = 0.5. From this sample we analyze the formation histories of galaxies with a bulge-to-total ratio below 0.3 (typically Sb and later types). They do form in our simulations, but with a lower abundance than observed - a common failure of cosmological simulations. Amongst these galaxies, we find a correlation between the bulge fraction at z = 0 and the mass ratio of the largest merger undergone after z = 2, as well as a correlation with the gas accretion rate at z > 1. We find that the most disk-dominated galaxies have an extremely quiet baryon input history; there are typically no major mergers after z = 2, and gas is accreted at a low and constant rate, with the angular momentum stable at a fixed direction. By contrast, more violent merger or gas accretion histories give birth to galaxies with more prominent bulges. The galaxies with the highest bulge Sersic index at z = 0 are those with intense gas accretion and disk instabilities, including early bar formation, rather than the galaxies with the most active merger histories.
Bournaud Frederic
Croton Darren J.
Dekel Avishai
Martig Marie
Teyssier Romain
No associations
LandOfFree
A diversity of progenitors and histories for isolated spiral galaxies does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with A diversity of progenitors and histories for isolated spiral galaxies, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and A diversity of progenitors and histories for isolated spiral galaxies will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-609336