# Mass content of UGC 6446 and UGC 7524 through HI rotation curves: deriving the stellar discs from stellar population synthesis models

## TL;DR

This study analyzes the mass distribution of two irregular galaxies using HI rotation curves and stellar population models, demonstrating that certain dark matter halo profiles fit the observed data well.

## Contribution

It introduces a method combining HI rotation curves with stellar population synthesis to constrain galaxy mass components and compares multiple dark matter halo models.

## Key findings

- Dark matter is necessary to explain rotation curves.
- Burkert, Einasto, and Stadel halos fit the data well.
- Einasto and Stadel models are viable alternatives to Burkert.

## Abstract

In this work we study the mass distribution of two irregular galaxies, UGC 6446 and UGC 7524, by means of HI rotation curves derived from high resolution HI velocity fields obtained through the Westerbork Synthesis Radio Telescope data archive. We constrain the stellar and gas content of both galaxies with stellar population synthesis models and by deriving the HI+He+metals rotation curves from the total HI surface density maps, respectively. The discrepancy between the circular velocity maxima of the stellar plus the HI+He+metals rotation curves and the observed HI rotation curves of both galaxies requires the inclusion of a substantial amount of dark matter. We explore the Navarro Frenk and White, Burkert, Di Cintio, Einasto and Stadel dark matter halo models. We obtain acceptable fits to the observed HI rotation curves of UGC 6446 and UGC 7524 with the cored Burkert, Einasto and Stadel dark matter halos. In particular, Einasto and Stadel models prove to be an appropriate alternative to the Burkert dark matter halo. This result should increase the empirical basis that justify the usage of dark matter exponential models to adjust the observed rotation curves of real galaxies.