Formation of late-type spiral galaxies: gas return from stellar populations regulates disk destruction and bulge growth - Astrophysics > Cosmology and Nongalactic AstrophysicsReport as inadecuate




Formation of late-type spiral galaxies: gas return from stellar populations regulates disk destruction and bulge growth - Astrophysics > Cosmology and Nongalactic Astrophysics - Download this document for free, or read online. Document in PDF available to download.

Abstract: Spiral galaxies have most of their stellar mass in a large rotating disk, andonly a modest fraction in a central spheroidal bulge. This poses a majorchallenge for cosmological models of galaxy formation. Galaxies form at thecentre of dark matter halos through a combination of hierarchical merging andgas accretion along cold streams, and should rapidly grow their bulge throughmergers and instabilities. Cosmological simulations predict galaxies to havemost of their mass in the central bulge, and therefore an angular momentum muchbelow the observed level, except in dwarf galaxies. We propose that thecontinuous return of fresh gas by stellar populations over cosmic times couldsolve this issue. A population of stars formed at a given instant typicallyreturns half of its initial mass in the form of gas over 10 billion years, andthe process is not dominated by rapid supernovae explosions but by thelong-term mass-loss from low- and intermediate-mass stars. Using simulations ofgalaxy formation, we show that this recycling of gas can strongly affect thestructural evolution of massive galaxies, potentially solving the bulgefraction issue: we find that the bulge-to-disk ratio of a massive galaxy can bedivided by a factor of 3. The continuous recycling of baryons through starformation and stellar mass loss helps the growth of disks and their survival tointeractions and mergers. Instead of forming only early-type,spheroid-dominated galaxies S0 and ellipticals, the standard cosmologicalmodel can then successfully account for massive late-type, disk-dominatedspiral galaxies Sb-Sc.



Author: Marie Martig, Frederic Bournaud CEA Saclay

Source: https://arxiv.org/







Related documents