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The effect of models of the interstellar media on the central mass distribution of galaxies | | Charlotte Christensen
; Fabio Governato
; Thomas Quinn
; Alyson M. Brooks
; David B. Fisher
; Sijing Shen
; Jacqueline McCleary
; James Wadsley
; | | Date: |
1 Nov 2012 | | Abstract: | We compare the central mass distribution of galaxies simulated with three
different models of the interstellar medium (ISM) with increasing complexity:
primordial (H+He) cooling down to 10^4 K, additional cooling via metal lines
and to lower temperatures, and molecular hydrogen (H_2) with shielding of
atomic and molecular hydrogen in addition to metal line cooling. In order to
analyze the effect of these models, we follow the evolution of four field
galaxies with V_peak < 120 km/s to a redshift of zero using high-resolution
Smoothed Particle Hydrodynamic simulations in a fully cosmological LCDM
context. The spiral galaxies produced in simulations with either primordial
cooling or H_2 physics have bulge magnitudes and scale lengths very similar to
observed galaxies and realistic, rising rotation curves. In contrast, the metal
line cooling simulation produced galaxies with more massive and concentrated
bulges and with the peaked rotation curves typical of most previous LCDM
simulations of spiral galaxies. The less-massive bulges and non-peaked rotation
curves in the galaxies simulated with primordial cooling or H_2 are linked to
changes in the angular momentum distribution of the baryons. These galaxies had
smaller amounts of low-angular momentum baryons because of increased gas loss
from stellar feedback. When there is only primordial cooling, the star forming
gas is hotter and the feedback-heated gas cools more slowly than when metal
line cooling is included and so requires less energy to be expelled. When H_2
is included, the accompanying shielding produces large amounts of clumpy, cold
gas where H_2 forms. Star formation in clumpy gas results in more concentrated
supernova feedback and greater efficiency of mass loss. The higher feedback
efficiency causes a decrease of low-angular momentum material and formation of
realistic bulges. (abridged) | | Source: | arXiv, 1211.0326 | | Services: | Forum | Review | PDF | Favorites | |
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