Study of Gamma-Ray Emitting Compact Symmetric Object DA 362 Reveals New Insights
Study of Gamma-Ray Emitting Compact Symmetric Object DA 362 Reveals New Insights
Indian astronomers have conducted a multiwavelength study of DA 362, a gamma-ray emitting compact symmetric object (CSO), shedding light on the nature of this enigmatic source. The findings, published on December 17 on the pre-print server arXiv, provide a deeper understanding of the object and its characteristics.
CSOs are young jetted active galactic nuclei (AGN) with a projected size smaller than 3,300 light years. Despite limited research, observations indicate that CSOs typically feature symmetric radio morphologies and are in the early stages of their evolution, with kinematic ages under a few thousand years. Only four CSOs have been identified as gamma-ray emitters so far.
DA 362, also known as B2 1413+34, is the most recent addition to the list of gamma-ray emitting CSOs. Initially classified as a blazar candidate, it was associated with the gamma-ray source 4FGL J1416.0+3443.
A team of astronomers led by Subhashree Swain from the Inter-University Center for Astronomy and Astrophysics in Pune, India, analyzed long-term multiwavelength data from NASA's Fermi gamma-ray space telescope (Large Area Telescope, LAT) and the Swift satellite to investigate the nature of DA 362. The study confirmed DA 362 as a gamma-ray emitter, making it the fourth such object in this class of AGN.
LAT data revealed that the gamma-ray source 4FGL J1416.0+3443 is indeed associated with DA 362. The optimized gamma-ray position matched the radio source within the 95 percent uncertainty region. Over 12 years of LAT observations (2008–2020), DA 362 remained mostly in a quiescent state. However, the data also revealed flaring activity, suggesting that the gamma-ray emission originates from the object’s core or jet, rather than its radio lobes.
Additionally, the study found small, parsec-scale, bi-polar radio emission from DA 362 and confirmed that its jet separation velocity is subluminal, validating its classification as a compact symmetric object. Comparing the gamma-ray spectral properties of DA 362 with other gamma-ray emitting CSOs, the astronomers found DA 362 to be the brightest of the four and exhibiting a spectrum steeper than the others. However, the object was faint in the optical band, indicating possible dust obscuration. The researchers suggest that more sensitive observations are needed to explore the broadband physical properties of DA 362 and better understand the origin of its gamma-ray emission.
