By analyzing the images of the Sombrero Galaxy obtained with the Hubble Space Telescope (HST), Elio Quiroga Rodriguez of the Mid Atlantic University in Spain, has identified a peculiar object, which turned out to be a galaxy hosting an active galactic nucleus (AGN). The finding was reported in a paper published August 11 on the pre-print server arXiv.
An AGN is a compact region at the center of a galaxy, more luminous than the surrounding galaxy light. Studies show that AGNs are very energetic due either to the presence of a black hole or star formation activity at the core of the galaxy.
Astronomers generally divide AGNs into two groups based on emission line features. Type 1 AGNs show broad and narrow emission lines, while only narrow emission lines are present in Type 2 AGNs. However, observations revealed that some AGNs transition between different spectral types; therefore, they were dubbed changing-look (CL) AGNs.
Sombrero Galaxy (also known as Messier 104 or NGC 4594) is an unbarred spiral galaxy located between the borders of the Virgo and Corvus constellations, some 31 million light years away. With a mass of about 800 billion solar masses, it is one of the most massive objects in the Virgo galaxy cluster. It also hosts a rich system of globular clusters.
Rodriguez has recently investigated HST images of the Sombrero Galaxy, focusing one particular object in its halo. He found that this object, previously classified as a globular cluster candidate, may be a barred spiral galaxy of the SBc type, with an AGN at its center.
2023-08-22 00:00:04
Article from phys.org