2025ApJ...984..120R

We present new MeerKAT L-band (continuum and H I) and upgraded Giant Metrewave Radio Telescope (300-850 MHz) observations of the archetypal cool-core group-dominant early-type galaxy NGC 5044. Our new continuum images reveal diffuse, steep spectrum (${\alpha }_{0.99\,{\rm{GHz}}}^{1.56\,{\rm{GHz}}}=-1.53\pm 0.6$) radio emission extending about 25 kpc around the unresolved radio core. The observed radio emission overlaps the known X-ray cavities but is not confined to them. We also find the first direct evidence of neutral atomic gas in NGC 5044, in the form of a 3.8σ significant two-component H I absorption line seen against the emission of the active nucleus. The peak velocities are well correlated with the previously reported CO(2-1) absorption, but the H I lines are moderately broader, spanning velocities from 265 to 305 km s^–1. We do not detect H I emission but place an upper limit of M_H i_< 5.4 × 10⁷M_⊙in the central 15″ (2.2 kpc) of the galaxy. This is significantly less than the estimated molecular gas content and implies a molecular-to-atomic mass ratio of >∼1.7:1, consistent with these gas phases forming through cooling from the hot intra-group medium. We also constrain the spin temperature to T_spin ≤ 950 K, indicating that the detected H I is in the cold neutral phase.