A quasar, short for "quasi-stellar radio source," is an extremely luminous and distant celestial object that emits enormous amounts of energy, particularly in the form of light and radio waves. Quasars are considered to be a type of active galactic nucleus (AGN), which means they are powered by accretion of matter onto a supermassive black hole at the center of a galaxy.
The X or Y-shaped structure of gas around a quasar is known as a "radio jet" or "radio lobes." These structures result from the powerful jets of high-energy particles that are ejected from the vicinity of the supermassive black hole at the center of the quasar. The particles in these jets travel at relativistic speeds and interact with the surrounding gas, creating shock waves and emitting radio waves. The radio lobes can extend thousands or even millions of light-years away from the central quasar.
The significance of these radio jets and lobes is that they provide important clues about the activity of the central supermassive black hole and its interaction with the surrounding galaxy. The jets are believed to be produced by the infalling matter that forms an accretion disk around the black hole. Magnetic fields associated with the black hole then accelerate charged particles along the jets, causing them to emit radiation.
The presence of radio jets and lobes in quasars is relatively common, but their exact occurrence rate is not precisely known. They are more commonly observed in radio-loud quasars, which are a subset of quasars that exhibit strong radio emissions. However, not all quasars show prominent radio jet structures, as their visibility can depend on factors such as the orientation of the jets with respect to our line of sight.
The formation of galaxies and the activity of supermassive black holes, including quasars, are indeed connected. It is believed that quasars represent an active phase in the life cycle of galaxies, particularly during early cosmic times. The accretion of matter onto supermassive black holes and the subsequent release of energy as quasars can influence the formation and evolution of galaxies. The energy released by quasars can affect the surrounding gas and star formation processes, regulating the growth of galaxies over cosmic timescales.
Studying quasars and their associated phenomena, including the X or Y-shaped structures, provides valuable insights into the processes that shape galaxies and the role of supermassive black holes in galactic evolution.