The origin and evolution of fast and slow rotators in the Illustris simulation

Penoyre, Zephyr; Moster, Benjamin P.; Sijacki, Debora und Genel, Shy (2017): The origin and evolution of fast and slow rotators in the Illustris simulation. In: Monthly Notices of the Royal Astronomical Society, Bd. 468, Nr. 4: S. 3883-3906

Abstract

Using the Illustris simulation, we follow thousands of elliptical galaxies back in time to identify how the dichotomy between fast-and slow-rotating ellipticals (FRs and SRs) develops. Comparing to the ATLAS(3D) survey, we show that Illustris reproduces similar elliptical galaxy rotation properties, quantified by the degree of ordered rotation, lambda(R). There is a clear segregation between low-mass (M-* < 10(11) M-circle dot) ellipticals, which form a smooth distribution of FRs, and high-mass galaxies (M-* > 10(11.5) M-circle dot), which are mostly SRs, in agreement with observations. We find that SRs are very gas poor, metal rich and red in colour, while FRs are generally more gas rich and still star forming. We suggest that ellipticals begin naturally as FRs and, as they grow in mass, lose their spin and become SRs. While at z = 1, the progenitors of SRs and FRs are nearly indistinguishable, their merger and star formation histories differ thereafter. We find that major mergers tend to disrupt galaxy spin, though in rare cases can lead to a spin-up. No major difference is found between the effects of gas-rich and gas-poor mergers, and the number of minor mergers seems to have little correlation with galaxy spin. In between major mergers, lower mass ellipticals, which are mostly gas rich, tend to recover their spin by accreting gas and stars. For galaxies with M* above similar to 10(11) M-circle dot, this trend reverses;galaxies only retain or steadily lose their spin. More frequent mergers, accompanied by an inability to regain spin, lead massive ellipticals to lose most of ordered rotation and transition from FRs to SRs.

• Dokumententyp: Zeitschriftenartikel
• Fakultät: Physik
• Themengebiete: 500 Naturwissenschaften und Mathematik > 530 Physik
• ISSN: 0035-8711
• Sprache: Englisch