# IAUS379: Dynamical Masses of Local Group Galaxies

20-24 March 2023
Haus H, Telegrafenberg
Europe/Berlin timezone

## Modeling Dark Matter Halo Spin using Observations and Simulations: application to UGC 5288

22 Mar 2023, 16:03
2m
Haus H, Telegrafenberg

#### Haus H, Telegrafenberg

Potsdam, Germany
Poster SESSION 5 : Near-field cosmology and galaxy masses beyond the Local Group

### Speaker

Ansar Sioree (Indian Institute of Astrophysics, Bengaluru)

### Description

Dark matter halo properties are well studied in cosmological simulations but are very challenging to estimate from observations. The dark matter halo density profile of galaxies from observations has been modeled previously using multiple probes that trace the dark matter potential, however, the angular momentum distribution of the dark matter halos is still a subject of debate. In this study, we demonstrate a method for estimating the halo spin and halo concentration of a low luminosity, gas-rich dwarf galaxy by forward modeling disk properties derived from observations of the stellar and gas surface densities, the disk scale length, the neutral hydrogen rotation curve, the bar length, and bar ellipticity. Our method is a combination of semi-analytical techniques and N-body/SPH simulations. Here, we apply our method to the low surface brightness (LSB) dwarf galaxy UGC 5288, and model its dark matter halo 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 core radius r$_{c}$ = 0.23 kpc and a high halo spin $\lambda$ = 0.08 at the virial radius. These findings are consistent with previous rotation curve estimates of the halo density profile of UGC 5288, as well as the theoretically predicted high spins of dwarf LSB galaxies. We finally compare our results with the halo spin distribution of barred galaxies in one of the high resolution cosmological magneto-hydrodynamical simulations TNG-50. We find that our model predicts halo spin distribution of UGC5288 up to a ballpark value, although, there remain significant uncertainties due to the formation history of the dark matter halos from the TNG50 simulations. We also find that the inner halo spin in barred galaxies is different from that of unbarred ones, and the halo spin shows weak correlations with bar properties.

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### Primary author

Ansar Sioree (Indian Institute of Astrophysics, Bengaluru)

### Co-authors

Dr Kataria Sandeep Kumar (School of Physics and Astronomy, Shanghai Jiao Tong University, No.800, Dongchuan Road, Minhang District, Shanghai, China.) Prof. Das Mousumi (Indian Institute of Astrophysics, Bengaluru)