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

**Authors:** Sioree Ansar, Sandeep Kumar Kataria, Mousumi Das  
**arXiv:** [2304.00724](https://arxiv.org/abs/2304.00724)  
**Date:** 2023-04-03  
**Summary page:** https://www.summarizepaper.com/en/paper/2304.00724v1/

## Key points

- Dark matter (DM) halo properties are studied in cosmological simulations, but estimating them from observations is challenging.
- The authors investigate a method for estimating the halo spin and concentration of low surface brightness (LSB), gas-rich dwarf barred galaxy UGC 5288 by forward modeling disk properties derived from observations.
- The team combines 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.
- The best match with observations is a pseudo-isothermal halo model with a core radius of $r_{c} = 0.23$ kpc and halo spin of $\lambda$= 0.08 at the virial radius.
- Inner halo spin ($ r<10$ kpc) in barred galaxies differs from unbarred ones, and there are weak correlations between bar properties and halo spin.
- Combining observations and simulations can help estimate DM halos' properties in observed galaxies while also providing insights into their formation histories.

## Summary

Dark matter (DM) halo properties are extensively studied in cosmological simulations, but estimating them from observations remains challenging. In this study, the authors investigate a method for estimating the halo spin and concentration of low surface brightness (LSB), gas-rich dwarf barred galaxy UGC 5288 by forward modeling disk properties derived from observations. The team combines 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. They find that the best match with observations is a pseudo-isothermal halo model with a core radius of $r_{c} = 0.23$ kpc and halo spin of $\lambda$= 0.08 at the virial radius. The study's 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 in the high-resolution cosmological-magneto-hydrodynamical simulation TNG50. Furthermore, uncertainties remain due to limited knowledge about the formation history of the galaxy. Additionally, this research reveals that inner halo spin ($ r<10$ kpc) in barred galaxies differs from unbarred ones, and there are weak correlations between bar properties and halo spin. This study highlights how combining observations and simulations can help estimate DM halos' properties in observed galaxies while also providing insights into their formation histories.