2024-01-02 17:45:16
Some galaxies stand out for the violent activity that exists in their centers. As a general rule, this activity is generated by a quasar, an astronomical object whose engine is a black hole of enormous mass, devouring swirling material in its environment and causing the emission of jets of radiation and particles moving at speeds so close to that of light. that relativistic effects occur. Recent observations have revealed a spectacular increase in power in the quasar at the center of a distant galaxy.
On December 15, 2023, the LST (Large-Sized Telescope) Collaboration officially announced the detection of the OP 313 source at very high energies with LST-1. Although OP 313 was known at lower energies, it had never been detected above 100 GeV (gigaelectronvolts). With this observation, OP 313 becomes the most distant active galactic nucleus (AGN) detected so far by a Cherenkov-type telescope, also demonstrating the great scrutiny power of LST-1, installed at the CTAO-North, on the island from La Palma, in the Spanish archipelago of the Canary Islands.
OP 313 is what is known as a flat-spectrum radioquasar (FSRQ), a type of AGN.
LST-1 observed this source between December 10 and 14, after receiving an alert from the Fermi-LAT satellite that showed unusually high activity in the low-energy gamma ray regime, also confirmed in the optical range with different instruments. . With just four days of data, the LST Collaboration was able to detect the source above 100 gigaelectronvolts (GeV), an energy level one billion times higher than the light detectable by the human eye.
LST-1 during an observation at CTAO-North, La Palma, Spain. (Photo: CTAO gGmbH. CC BY-NC-ND)
Until now, there were only nine known very high energy quasars. OP 313 has become the tenth. In general, quasars are more difficult to detect at very high energies than when they make up other types of AGNs. This is not only because the brightness of their accretion disk weakens the emission of gamma rays, but also because they tend to be further away (and date from an older time in the universe). In this case, OP 313 is about 8 billion light-years away, which means we are capturing it as it was about 8 billion years ago. This makes it the most distant AGN and the second most distant emitter, among all those detected at very high energies. (Source: NCYT from Amazings)
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