From Gaia to GaiaNIR: I. Probing dark matter halos in globular clusters

The proposed GaiaNIR mission would extend Gaia's astrometric capabilities into the near-infrared, improving astrometric precision and enabling observations in heavily dust-obscured regions. In this work, we investigate the impact of GaiaNIR on the detectability of dark matter halos in globular clusters by comparing its performance with that of Gaia. Expected observations from future Gaia data releases and GaiaNIR are modeled for a globular cluster with properties similar to M4. The cluster is simulated with a range of dark matter halo sizes and varying levels of extinction, allowing a direct assessment of each mission's ability to detect and distinguish dark matter halos across different extinction conditions. To support this comparison, the relationship between the Gaia G band and several near-infrared bands is examined. We find that Gaia can resolve extended dark matter halos in low-extinction conditions, but its performance degrades significantly as extinction increases. In contrast, GaiaNIR reduces statistical uncertainties and retains sensitivity to extended halos even with strong extinction. These results indicate that GaiaNIR would both strengthen constraints on kinematic signatures accessible to Gaia and enable the study of clusters in heavily obscured regions that are currently beyond Gaia's reach.