Galactic Angular Momentum in Cosmological Zoom-in Simulations. I. Disk and Bulge Components and the Galaxy–Halo Connection

Journal Article · Wed Feb 01 04:00:00 EST 2017 · Astrophysical Journal

DOI:https://doi.org/10.3847/1538-4357/835/2/289· OSTI ID:22869504

Sokołowska, Aleksandra; Capelo, Pedro R.; Mayer, Lucio ^[1]; Fall, S. Michael ^[2]; Shen, Sijing ^[3]; Bonoli, Silvia ^[4]

---

1. Center for Theoretical Astrophysics and Cosmology, Institute for Computational Science, University of Zurich, Winterthurerstrasse 190, CH-8057 Zürich (Switzerland)
2. Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)
3. Kavli Institute for Cosmology, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom)
4. Centro de Estudios de Física del Cosmos de Aragón, Plaza San Juán 1, Planta 2, E-44001 Teruel (Spain)

We investigate the angular momentum evolution of four disk galaxies residing in Milky-Way–sized halos formed in cosmological zoom-in simulations with various sub-grid physics and merging histories. We decompose these galaxies, kinematically and photometrically, into their disk and bulge components. The simulated galaxies and their components lie on the observed sequences in the j {sub *}–M {sub *} diagram, relating the specific angular momentum and mass of the stellar component. We find that galaxies in low-density environments follow the relation j{sub ∗} ∝ M{sub ∗}{sup α} past major mergers, with α∼0.6 in the case of strong feedback, when bulge-to-disk ratios are relatively constant, and α∼1.4 in the other cases, when secular processes operate on shorter timescales. We compute the retention factors (i.e., the ratio of the specific angular momenta of stars and dark matter) for both disks and bulges and show that they vary relatively slowly after averaging over numerous but brief fluctuations. For disks, the retention factors are usually close to unity, while for bulges, they are a few times smaller. Our simulations therefore indicate that galaxies and their halos grow in a quasi-homologous way.

• OSTI ID: 22869504
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 835; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ANGULAR MOMENTUM
COMPUTERIZED SIMULATION
DENSITY
DIAGRAMS
FLUCTUATIONS
GALACTIC EVOLUTION
MASS
MILKY WAY
NONLUMINOUS MATTER
STARS