3 research outputs found
The stellar bar - dark matter halo connection in the TNG50 simulations
Stellar bars in disk galaxies grow by losing angular momentum to their
environments, including the Dark Matter (DM) halo, stellar and gas disks, and
interacting satellite galaxies. This exchange of angular momentum during galaxy
evolution hints at a connection between bar properties and the DM halo spin
-- the dimensionless form of DM angular momentum. We investigate the
connection of halo spin and galaxy properties in the presence/absence
of stellar bars, using the cosmological magneto-hydrodynamic TNG50 simulations
at three redshifts and 1. We estimate the halo spin for barred and
unbarred galaxies (bar strength: ) at the central regions of the
DM halo close to the galaxy disk and far from the disk, close to halo virial
radius. At , strongly barred galaxies () reside in DM halos
having low spin and low specific angular momentum, while unbarred and weakly
barred galaxies () are hosted in high spin and high specific
angular momentum halos. The inverse correlation between bar strength and halo
spin is surprising since previous studies show that bars transfer angular
momentum to DM halos. However, the bar strength-halo spin connection is more
complex at higher redshift () with higher halo spin for all galaxies
than that at . Using galaxy samples across various DM halo mass ranges,
we highlight the importance of sample selection in obtaining meaningful
results. Investigating the bar--halo connection in further detail is crucial
for understanding the impact of bars on galaxy evolution models.Comment: 20 pages (including Appendix), 12 figures; submitted to AAS Journals;
comments are welcome
Modelling Dark Matter Halo Spin using Observations and Simulations: application to UGC 5288
Dark matter (DM) halo properties are extensively studied in cosmological
simulations but are very challenging to estimate from observations. The DM halo
density profile of observed galaxies is modelled using multiple probes that
trace the dark matter potential. However, the angular momentum distribution of
DM halos is still a subject of debate. In this study we investigate a method
for estimating the halo spin and halo concentration of low surface brightness
(LSB), gas-rich dwarf barred galaxy UGC 5288, by forward modelling disk
properties derived from observations - stellar and gas surface densities, disk
scale length, HI rotation curve, bar length and bar ellipticity. We combine
semi-analytical techniques, N-body/SPH and cosmological simulations to model
the DM halo of UGC 5288 with both a cuspy Hernquist profile and a flat-core
pseudo-isothermal profile. We find that the best match with observations is a
pseudo-isothermal halo model with a core radius of kpc, and halo
spin of = 0.08 at the virial radius. Although our findings are
consistent with previous core radius estimates of the halo density profile of
UGC 5288, as well as with the halo spin profiles of similar mass analogues of
UGC5288 in the high-resolution cosmological-magneto-hydrodynamical simulation
TNG50, there still remain some uncertainties as we are limited in our knowledge
of the formation history of the galaxy. Additionally, we find that the inner
halo spin ( kpc) in barred galaxies is different from the unbarred
ones, and the halo spin shows weak correlations with bar properties.Comment: 29 pages including Appendix, 28 figures, accepted in MNRAS, comments
are welcome from the communit