2022A&A...660A..32M

We present the first Chandra detection of a single X-ray cavity within the interstellar medium of the small Fanaroff-Riley type I radio galaxy NGC 5141. The X-ray surface brightness depression, located ≃4 kpc away from the galaxy center, is projected on the northern radio lobe, which is completely contained within the galaxy. The thermal gas surrounding the cavity, which extends to ≃20 kpc, has a bolometric X-ray luminosity (0.1-100 keV) of L_X ≃ 2 x 10⁴⁰ erg s^–1 and a temperature of kT ≃ 0.8 keV. We calculated the total energy (E_cav = 4PV ≃ 10⁵⁵ erg) required to inflate the cavity and its age (t_cav ≃ 9 Myrs), assuming that it is filled with relativistic particles and rises buoyantly. The inferred total cavity power is as low as P_cav = E_cav/t_cav ≃ 6 x 10⁴⁰ erg s^–1, which is the lowest one among the radio-filled systems. Comparing P_cav to the bolometric X-ray luminosity (i.e., the cooling luminosity), we conclude that NGC 5141's central active galactic nucleus can heat the interstellar medium and balance its cooling luminosity, confirming that the P_cav-L_cool relation, mainly tested on groups and clusters, also works for such a low-power system.