X-ray cavities in the hot corona of the lenticular galaxy NGC 4477

NGC 4477 is a low-mass lenticular galaxy in the Virgo Cluster, residing at 100 kpc to the north of M87. Using a total of 116 ks Chandra observations, we study the interplay between its hot (∼0.3 keV) gas halo and the central supermassive black hole. A possible cool core is indicated by the short cooling time of the gas at the galaxy centre. We identify a pair of symmetric cavities lying 1.1 kpc south-east and 0.9 kpc north-west of the galaxy centre with diameters of 1.3 and 0.9 kpc, respectively. We estimate that these cavities are newly formed with an age of ∼4 Myr. No radio emission is detected at the positions of the cavities with the existing Very Large Array data. The total energy required to produce the two cavities is ∼10⁵⁴ erg, at least two orders of magnitude smaller than that of typical X-ray cavities. NGC 4477 is arguably far the smallest system and the only lenticular galaxy in which active galactic nuclei (AGN) X-ray cavities have been found. It falls on the scaling relation between the cavity power and the AGN radio luminosity, calibrated for groups and clusters. Our findings suggest that AGN feedback is universal among all cool-core systems. Finally, we note the presence of molecular gas in NGC 4477 in the shape of a regular disc with ordered rotation, which may not be related to the feedback loop.