19 quasars identified, including lensed, dual, and projected types
Observations conducted with P200/DBSP at Palomar Observatory
Findings advance studies of supermassive black holes and redshifts
The DBSP/P200 spectra and images of two dual quasars, with slit placement in yellow
Photo Credit: arXiv (2025)
A significant discovery has been made in the field of astronomy, with 19 new quasars, including strongly-lensed, dual, and projected types, identified through analysis of data from the DESI Legacy Surveys photometry catalog. This breakthrough highlights the potential of quasar observations in furthering our understanding of the universe. These objects, known for their extreme luminosity and powered by supermassive black holes, have long been pivotal for research into astrophysics and cosmology. Observations were conducted at the Palomar Observatory in California.
Findings of the DESI Legacy Surveys
According to the study led by Zizhao He of the Purple Mountain Observatory, the investigation confirmed two strongly-lensed quasars, six dual quasars, and 11 projected quasars. Observations were carried out on October 15–16, 2023, using the P200/DBSP instrument. The study noted that the lensed quasars, designated J0746+1344 and J2121-0826, were observed at redshifts of 3.1 and 2.39, respectively. J0746+1344 displayed a unique configuration, with the lensing galaxy positioned beside the brightest image—an anomaly compared to typical observations.
Dual and Projected Quasars
As reported by phys.org, the six dual quasars identified showed redshifts ranging from 0.59 to 3.28, with separations between their components varying from 50,300 to 73,500 light years. Among these, J1929+6009 stood out due to a remarkably small redshift difference of less than 0.0001 and a projected separation of 62,800 light years.
The 11 projected quasars demonstrated separations spanning 35,700 to 123,400 light years. One such system, J0422+0047, was previously thought to be a gravitationally-lensed quasar system, though further analysis indicated a chance alignment of projected quasars with an intervening galaxy, complicating its classification.
Implications of the Discovery
This research underscores the importance of advanced observational techniques in uncovering unique cosmic phenomena. By analysing the behaviour, redshifts, and configurations of these quasars, astronomers aim to expand their knowledge of the universe's structure and the dynamics of supermassive black holes.
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