Galactic angular momentum in the IllustrisTNG simulation — I. Connection to morphology, halo spin, and black hole mass

Kavli Affiliate: Mark Vogelsberger

| First 5 Authors: Vicente Rodriguez-Gomez, Shy Genel, S. Michael Fall, Annalisa Pillepich, Marc Huertas-Company

| Summary:

We use the TNG100 simulation of the IllustrisTNG project to investigate the
stellar specific angular momenta ($j_{ast}$) of $sim$12~000 central galaxies
at $z=0$ in a full cosmological context, with stellar masses ($M_{ast}$)
ranging from $10^{9}$ to $10^{12} , {rm M}_{odot}$. We find that the
$j_{ast}$–$M_{ast}$ relations for early-type and late-type galaxies in
IllustrisTNG are in good overall agreement with observations, and that these
galaxy types typically `retain’ $sim$10–20 and $sim$50–60 per cent of their
host haloes’ specific angular momenta, respectively, with some dependence on
the methodology used to measure galaxy morphology. We present results for
textit{kinematic} as well as textit{visual-like} morphological measurements
of the simulated galaxies. Next, we explore the scatter in the
$j_{ast}$–$M_{ast}$ relation with respect to the spin of the dark matter
halo and the mass of the supermassive black hole (BH) at the galactic centre.
We find that galaxies residing in faster-spinning haloes, as well as those
hosting less massive BHs, tend to have a higher specific angular momentum. We
also find that, at fixed galaxy or halo mass, halo spin and BH mass are
anticorrelated with each other, probably as a consequence of more efficient gas
flow toward the galactic centre in slowly rotating systems. Finally, we show
that halo spin plays an important role in determining galaxy sizes — larger
discs form at the centres of faster-rotating haloes — although the trend
breaks down for massive galaxies with $M_{ast} gtrsim 10^{11} , {rm
M}_{odot}$, roughly the mass scale at which a galaxy’s stellar mass becomes
dominated by accreted stars.

| Search Query: ArXiv Query: search_query=au:”Mark Vogelsberger”&id_list=&start=0&max_results=10

Read More