During a survey of bright radio sources in the mid-20th century, astronomers found a very bright radio source in the constellation Hercules. The radio source is strongest in the middle range frequency and emitssynchrotron radiation,suggesting the source of radio emission may be gravitational interaction. In 1959, astronomers from the Radio Astronomy Group (later theCavendish Astrophysics Group) detected the radio source using the Cambridge Interferometer of the Cavendish Observatory inCambridge Universityin theUnited Kingdom,including it in theThird Cambridge Catalogue of Radio Sources(3C) as 3C 348, the 348th object detected by the survey.
The galaxy, 3C 348, is a supergiantelliptical galaxy.[3][4]It is located inside a poorgalaxy clusterwith anX-rayluminosity of Lbol= 4.8 × 1037W.[5]3C 348 is classified as type E3 to E4 of the updated Hubble–de Vaucouleurs extended galaxy morphological classification scheme. It has a companion galaxy, shown appearing as a secondary nucleus, indicating it ismerging.[6][7]
3C 348, the galaxy located in the center of the image, appears to be a relatively normal elliptical galaxy in visible light. When imaged inradio waves,however, plasma jets over one million light years long appear. Detailed analyses indicate that the galaxy is actually over 1,000 times more massive (approx. 1015solar masses) than ourMilky Way Galaxy,and the centralblack holeis nearly 1,000 times more massive (approx. 4 billionsolar masses) thanthe black hole at our Milky Way's center,one of thelargest known.The physics that creates the jets is poorly understood, with a likely energy source being matter ejected perpendicular to the accretion disc of the central black hole[8]which has grown more times than 1.7×108Msolar,enough to produce ashock frontin the cluster'sinterstellar medium.[9][10]
The radio source in 3C 348 is considered powerful.[11]It is double-lobed with striking bizarre features such as a double optical core and radio intensity rings clustered together inside one of the host galaxy's tworadio lobes.Despite not being aFanaroff-Riley ClassII neither an FR I source, it instead shows similarities to both types.[12][13]
^Hambrick, D. C.; Nulsen, P. E. J.; MacNamara, B. R.; Rafferty, D. A.; Birzan, L. (2004). "Cooling Flows and Heating Shocks in Hercules A".American Astronomical Society Meeting Abstracts.205.Bibcode:2004AAS...20514508H.
