In astro-ph/0911.0891, Marie Martig and Frederic Bournaud report on the growth of bulges in disk like galaxies in a cosmological environment. The zoom in on a Milky-Way like halo in cosmological box that had a quiet merger history, to make it prone to disk formation. They include baryonic physics, including star formation, but excluding supernova feedback. In one simulation they add the mass loss of older stellar populations in a relatively simple way. They let the stars loose an amount of mass that is typical for a Salpeter IMF (~45% of the SSP mass is returned in total). This lost gas mass adds to the disk and makes disk survival (and a smaller bulge fraction) a lot easier. The disk becomes more stable to both internal instabilities and to minor mergers.
Showing posts with label galaxy evolution. Show all posts
Showing posts with label galaxy evolution. Show all posts
Friday, 6 November 2009
Formation of late-type spiral galaxies: Gas return from stellar populations regulates disk destruction and bulge growth.
In astro-ph/0911.0891, Marie Martig and Frederic Bournaud report on the growth of bulges in disk like galaxies in a cosmological environment. The zoom in on a Milky-Way like halo in cosmological box that had a quiet merger history, to make it prone to disk formation. They include baryonic physics, including star formation, but excluding supernova feedback. In one simulation they add the mass loss of older stellar populations in a relatively simple way. They let the stars loose an amount of mass that is typical for a Salpeter IMF (~45% of the SSP mass is returned in total). This lost gas mass adds to the disk and makes disk survival (and a smaller bulge fraction) a lot easier. The disk becomes more stable to both internal instabilities and to minor mergers.
In astro-ph/0911.0891, Marie Martig and Frederic Bournaud report on the growth of bulges in disk like galaxies in a cosmological environment. The zoom in on a Milky-Way like halo in cosmological box that had a quiet merger history, to make it prone to disk formation. They include baryonic physics, including star formation, but excluding supernova feedback. In one simulation they add the mass loss of older stellar populations in a relatively simple way. They let the stars loose an amount of mass that is typical for a Salpeter IMF (~45% of the SSP mass is returned in total). This lost gas mass adds to the disk and makes disk survival (and a smaller bulge fraction) a lot easier. The disk becomes more stable to both internal instabilities and to minor mergers.
Friday, 30 January 2009
mass build-up of red sequence
Fig 10. Ruhland et al. http://arxiv.org/abs/0901.4340
They present first measurements of the evolution of the scatter of the cosmic average early-type galaxy color-magnitude relation (CMR) from z=1 to the present day, finding that it is consistent with models in which galaxies are constantly being added to the red sequence through truncation of star formation in blue cloud galaxies.
This fig. shows comparison between observations and a model in which new red sequence galaxies are being constantly added at the rate required to match the observed number density evolution The model predicts the correct CMR scatter and its evolution.
Friday, 8 August 2008
The Millennium Simulation compared to z~2 galaxies
Genel et al.
0808.0194
The authors use the Millennium Simulation to extract merger fractions and
mass accretion rates. They find that the accretion rates are sufficient to
account for the high star formation rates observed in z~2 UV-optically selected disks.
(not in figure) When following the fate of these disks and submm galaxies, they find that subsequent mergers are not frequent enough to either convert all disks into elliptical galaxies at z~0, or transform all submm galaxies to massive cluster ellipticals at z~0. They conclude that secular and internal evolution must play an important role in the evolution of these z~2 galaxies
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