While most of the radiation emitted from a "normal" galaxy is in the form of visible light, like that of the radiation of ordinary stars, AGNs are prominent across the entire electromagnetic spectrum. Thus, astronomers needed to look beyond the visual regime to see their full potential. Recent technological advancements, such as satellite deployment, have enabled astronomers to explore energies once unattainable. In addition to the showing in a wide range of energies, AGNs also change in brightness on time scales from minutes to decades. It's no wonder then that some stars once thought to be variable, such as W Comae, AP Librae, and BL Lacertae, were in fact AGN. Only decades in the making, the study of Active Galactic Nuclei (AGN) is a fairly
…show more content…
Alternatively, it is thought that perhaps every galaxy goes through an active phase. Seyfert galaxies are divided into two classes in the following manor: 1) those that have certain emission lines much broader suggesting gas with high velocities and 2) those that have similar width narrow emission lines, indicating slower moving gas (Hewitt & Poyner 1999). Astronomers found that Seyfert 1 type galaxies sometimes dim and flare by 50% or more in only a month or so. The variations imply that the size of the object could be no larger than a light-month in diameter (Finkbeiner 1992). The popularity of radio astronomy in the 1950s unveiled yet more astronomical puzzles. One of the first enigmas was the radio galaxy. While unassuming at optical wavelengths, these bodies, which consisted of a pair of extended radio lobes on either side of an elliptical galaxy, proved to be quite interesting in the radio band. Then in the 1960s, radio sources were found to be associated with objects assumed to be stellar in origin. First came the detection of 3C 48, which was initially referred to as a "radio star" later to be …show more content…
It was found that these faint "stars" were not stars and were not only beyond our own galaxy, but were the most distant galaxies known Quasars are bright and are seen to vary at all energies. Having derived from radio discoveries, many quasars found interestingly do not emit radio waves in a detectable amount. Such are called quasi-stellar objects (QSO), but are lumped together in the category of quasar. In general, quasars actually are best seen and surveyed at X-ray (Finkbeiner 1992). While quasars have spectra similar to Seyfert galaxies, they tend to be farther away than Seyferts and appear point-like to the optical astronomer. So what is the source of the energetic AGN? The powerhouse is said to come from the nucleus of the active galaxy where it is believed that a supermassive black hole resides. The super compact object may possess the mass and gravitational pull of a million to a few billion Suns, with a resulting diameter of less than one light-minute to several light-days. The geometry of the system continues, such that surrounding the massive central region is an
Alternatively, it is thought that perhaps every galaxy goes through an active phase. Seyfert galaxies are divided into two classes in the following manor: 1) those that have certain emission lines much broader suggesting gas with high velocities and 2) those that have similar width narrow emission lines, indicating slower moving gas (Hewitt & Poyner 1999). Astronomers found that Seyfert 1 type galaxies sometimes dim and flare by 50% or more in only a month or so. The variations imply that the size of the object could be no larger than a light-month in diameter (Finkbeiner 1992). The popularity of radio astronomy in the 1950s unveiled yet more astronomical puzzles. One of the first enigmas was the radio galaxy. While unassuming at optical wavelengths, these bodies, which consisted of a pair of extended radio lobes on either side of an elliptical galaxy, proved to be quite interesting in the radio band. Then in the 1960s, radio sources were found to be associated with objects assumed to be stellar in origin. First came the detection of 3C 48, which was initially referred to as a "radio star" later to be …show more content…
It was found that these faint "stars" were not stars and were not only beyond our own galaxy, but were the most distant galaxies known Quasars are bright and are seen to vary at all energies. Having derived from radio discoveries, many quasars found interestingly do not emit radio waves in a detectable amount. Such are called quasi-stellar objects (QSO), but are lumped together in the category of quasar. In general, quasars actually are best seen and surveyed at X-ray (Finkbeiner 1992). While quasars have spectra similar to Seyfert galaxies, they tend to be farther away than Seyferts and appear point-like to the optical astronomer. So what is the source of the energetic AGN? The powerhouse is said to come from the nucleus of the active galaxy where it is believed that a supermassive black hole resides. The super compact object may possess the mass and gravitational pull of a million to a few billion Suns, with a resulting diameter of less than one light-minute to several light-days. The geometry of the system continues, such that surrounding the massive central region is an