The quasar found fluctuations in the brightness of an unknown nature

(ORDO NEWS) — Chinese astronomers from the University of Yunnan have discovered that the distant blazar PKS 0405-385 produces quasi-periodic fluctuations in gamma rays, while the cause of this phenomenon remains unknown.

The discovery, which should help unravel the nature of changes in the brightness of many such objects, is reported in a preprint available from the arXiv repository.

PKS 0405-385 has a redshift of 1.285, which, given the expansion of the universe, corresponds to a radial distance of about 13 billion light years. It is a blazar, that is, a compact quasar with relativistic jets directed towards the observer.

Scientists attribute it to the type of flat-spectrum radio quasars (FSRQ), whose characteristic feature is very fast and significant changes in optical radiation.

It is believed that FSRQs are quasars in a period of violent activity, while another type of quasars – lacertides – is in a state of relative rest.

Astronomers have analyzed the light curve of PKS 0405-385 taken by NASA’s Fermi spacecraft and covering the time period from 2008 to 2021.

They found quasi-periodic oscillations (QPO) in the gamma-ray curve, which take about 2.8 years. Quasi-periodic oscillations are in an intermediate position between chaotic and periodic oscillations and can be the result of the superposition of two or more oscillatory processes.

For example, X-ray QPOs from a black hole or neutron star can be generated by hot gas swirling in an accretion disk.

To date, QPOs have been observed in over 20 blazars. Scientists suggest that the cause may be the spiral flow of matter inside a relativistic jet escaping at great speed from one of the poles of a single supermassive black hole, or the presence of a pair of supermassive black holes.

Quasars are the active nuclei of elliptical galaxies that are fueled by the energy of supermassive black holes that devour interstellar matter.

Relativistic jets or jets erupt from both sides of the core, with the exhaust velocity being a significant fraction of the speed of light.

A black hole is a source of very powerful radiation, which exceeds the total radiation of all stars in ordinary galaxies like the Milky Way.

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