Astronomers discover twin quasars merging

DeThree-color (HSC r, i, and z bands) composite image around the two central reddest sources, C1 and C2. The inset shows a close-up of C1 and C2. Bottom: Two-dimensional FOCAS spectra of C1 (top optical trace) and C2 (bottom optical trace), created by stacking all available data. Image credit: Astrophysical Journal Letters (2024). DOI: 10.3847/2041-8213/ad35c7 Astronomers have discovered a pair of merging high-redshift quasars using the Subaru Telescope in Hawaii as part of the Subaru Strategic Program’s (SPP) Hyper Suprimecam (HSC) survey. This serendipitous discovery is reported in the latest issue of Astrophysical Journal Letters. Quasars or quasi-stellar objects (QSOs) are extremely bright active galactic nuclei (AGNs) that emit electromagnetic radiation that can be observed in radio, infrared, visible, ultraviolet, and X-ray wavelengths. They are among the brightest and most distant objects in the known universe and serve as fundamental tools for numerous studies in astrophysics and cosmology. For example, quasars have been used to study the large-scale structure of the universe and the reionization era. They also improved our understanding of the dynamics of supermassive black holes and the intergalactic medium. Recently, a team of astronomers led by Yoshiki Matsuoka of Ehime University in Japan analyzed deep multiband imaging data collected by HSC-SPP. While searching for data, they happened to discover two merging quasars, named HSC J121503.42–014858.7 (C1) and HSC J121503.55–014859.3 (C2). The two quasars are about 39,000 light-years apart and are likely physically connected to each other, according to the study. This observation led to the discovery of extended Lyman-alpha emission bridging C1 and C2 and various extended structures of other emission lines. The astronomers emphasized that the bridging emission structure suggests that these two quasars are undergoing a merger. Therefore, given the redshift of C1 and C2 of 6.05, they are the most distant merging quasars discovered so far. The study found that the absolute UV magnitudes of C1 and C2 in still images are -23.1 and -22.6, respectively. The luminosity of C1 was measured at 6.2 quarter deciliters/s, while that of C2 was lower at 4.1 quarter deciliters/s. The study also found that the two quasars most likely have supermassive black holes (SMBHs) with similar masses. In summary, the authors of the paper stated that the newly discovered quasar merger is still under study and will publish more detailed results soon. “The attached paper presents the properties of the gas and dust captured by observations from the Atacama Large Millimeter/Submillimeter Array, providing additional evidence of merging and detailed measurements, and also confirms that the two sources are singular. It also shows that this is not a gravitational lens image of quasar activity.” ” the scientists wrote.

source: https://phys.org/journals/astrophysical-journal-letters/