Four phases of angular-momentum buildup in high-z galaxies: from cosmic-web streams through an extended ring to disc and bulge

By M. Danovich, A. Dekel, Oliver Hahn, D. Ceverino, Joel R. Primack. 2014

222 citations recorded by the source corpus.

We study the angular-momentum (AM) buildup in high-$z$ massive galaxies using high-resolution cosmological simulations. The AM originates in co-planar streams of cold gas and merging galaxies tracing cosmic-web filaments, and it undergoes four phases of evolution. (I) Outside the halo virial radius ($R_{\rm v}\!\sim\!100\,{\rm kpc}$), the elongated streams gain AM by tidal torques with a specific AM (sAM) $\sim\!1.7$ times the dark-matter (DM) spin due to the gas' higher quadrupole moment. This AM is expressed as stream impact parameters, from $\sim\!0.3R_{\rm v}$ to counter rotation. (II) In the outer halo, while the incoming DM mixes with the existing halo of lower sAM to a spin $\lambda_{\rm dm}\!\sim\!0.04$, the cold streams transport the AM to the inner halo such that their spin in the halo is $\sim\!3\lambda_{\rm dm}$. (III) Near pericenter, the streams dissipate into an irregular rotating ring extending to $\sim\!0.3R_{\rm v}$ and tilted relative to the inner disc. Torques exerted partly by the disc make the ring gas lose AM, spiral in, and settle into the disc within one orbit. The ring is observable with 30\% probability as a damped Lyman-$\alpha$ absorber. (IV) Within the disc, $<\!0.1R_{\rm v}$, torques associated with violent disc instability drive AM out and baryons into a central bulge, while outflows remove low-spin gas, introducing certain sensitivity to feedback strength. Despite the different AM histories of gas and DM, the disc spin is comparable to the DM-halo spin. Counter rotation can strongly affect disc evolution.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/05a084b6a385e3830e8717c397dbef9c07c0ee2d

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Citations in the corpus

A unified model for galactic discs: star formation, turbulence driving, and mass transport (2017, background): “…and, at least at high redshift, cold accretion tends to join the disc at radii of ∼0.1–0.3 virial radii, which is ∼10 times the stellar scale length (Danovich et al. 2015), though there are exceptions associated with loss of angular momentum by counter-rotating streams and major mergers, which…”
Tracing the cosmic web (2017, background): “Indeed, the direct impact of the structure and connectivity of filamentary web on the star formation activity of forming galaxies has been convincingly demonstrated by Dekel et al. (2009a, see also Dekel et al. 2009b; Danovich et al. 2015; Goerdt et al. 2015; Aragón-Calvo et al. 2016).”
CONNECTING ANGULAR MOMENTUM AND GALACTIC DYNAMICS: THE COMPLEX INTERPLAY BETWEEN SPIN, MASS, AND MORPHOLOGY (2015, methodology): “…shifted toward larger values, in agreement with more recent studies by Sharma & Steinmetz (2005), Kimm et al. (2011), Sharma et al. (2012), and Danovich et al. (2015), but in contrast to previous studies by van den Bosch et al. (2002) and Chen et al. (2003), who found nearly the same spin…”
Evolution of density profiles in high-z galaxies: compaction and quenching inside-out (2015, background): “…galaxies are continuously fed by streams from the cosmic web, consisting of smooth gas and a whole spectrum of merging clumps and galaxies (Birnboim & Dekel 2003; Kereš et al. 2005; Dekel & Birnboim 2006; Ocvirk et al. 2008; Kereš et al. 2009; Dekel et al. 2009a; Danovich et al. 2012, 2015).”
The Horizon-AGN Simulation: Morphological Diversity of Galaxies ,Promoted by AGN Feedback (2016, background): “…gas towards the center of dark matter (DM) halos (Binney 1977; Kereš et al. 2005; Dekel & Birnboim 2006; Ocvirk, Pichon & Teyssier 2008; Dekel et al. 2009), and contribute to the rapid disc builtup at high redshift (Pichon et al. 2011; Kimm et al. 2011; Stewart et al. 2013; Danovich et al. 2015).”