# Spectroscopy of NGC 4258 globular cluster candidates: membership confirmation and kinematics

## TL;DR

This study confirms globular cluster candidates in NGC 4258 using spectroscopy, validating a new selection method and revealing their kinematic association with the galaxy’s HI disk, which enhances understanding of galaxy-GC relationships.

## Contribution

It introduces and validates the uiks-method for selecting globular clusters in spiral galaxies, improving accuracy and understanding of their kinematics.

## Key findings

- 70% of candidates confirmed as GCs
- GCs are mostly metal-poor
- GCs co-rotate with the HI disk

## Abstract

We present multi-object spectroscopic observations of 23 globular cluster candidates (GCCs) in the prototypical megamaser galaxy NGC 4258, carried out with the OSIRIS instrument at the 10.4 m Gran Telescopio Canarias. The candidates have been selected based on the ($u^*\ -\ i^\prime$) versus ($i^\prime\ -\ K_s$) diagram, in the first application of the uiks-method to a spiral galaxy. In the spectroscopy presented here, 70% of the candidates are confirmed as globular clusters. Our results validate the efficiency of the uiks-method in the sparser GC systems of spirals, and given the downward correction to the total number of GCs, the agreement of the galaxy with the correlations between black hole mass, and total number and mass of GCs is actually improved. We find that the GCs, mostly metal-poor, co-rotate with the HI disk, even at large galactocentric distances.