quasar

History

The first quasars were noticed in the 1950s as point-like radio sources. In 1963, Dutch astronomer Martin Schmidt measured the redshift of 3C 273 and realized: the object is incredibly distant and therefore monstrously bright. Calculations were based on Hubble's law, discovered by Edwin Hubble.

How it works

Gravity accelerates infalling matter to near-light speeds. When particles collide, kinetic energy turns into heat — the accretion disk glows white-hot. Excess energy escapes as narrow jets shooting from the poles of the rotating hole.

History

The first quasars were noticed in the 1950s as point-like radio sources. In 1963, Dutch astronomer Martin Schmidt measured the redshift of 3C 273 and realized: the object is incredibly distant and therefore monstrously bright. Calculations were based on Hubble's law, discovered by Edwin Hubble.

How it works

Gravity accelerates infalling matter to near-light speeds. When particles collide, kinetic energy turns into heat — the accretion disk glows white-hot. Excess energy escapes as narrow jets shooting from the poles of the rotating hole.

History

In the 1950s, radio telescopes recorded compact sources similar to stars but with anomalous spectra. In 1963, Martin Schmidt identified hydrogen lines in the spectrum of 3C 273, redshifted by 16%, which, within the framework of Hubble's law, implied a distance of about 750 Mpc. The conclusion of monstrous luminosity forced a search for the energy source — it turned out to be accretion onto a supermassive black hole, predicted by the Schwarzschild and Kerr solutions in general relativity. By the end of the 20th century, it became clear that most large galaxies had gone through a quasar phase in the past.

How it works

Within Einstein's equations, the gravitational field of the black hole accelerates gas-dust material to relativistic speeds. Energy release obeys the virial theorem: gravitational potential energy transforms into thermal energy, radiated according to the Stefan–Boltzmann law (L = σT⁴A). Simultaneously, magnetic fields amplified by differential rotation form collimated jets via the Blandford–Znajek effect. The redshift of radiation is determined by the Doppler effect for cosmological expansion.

Open problems & fun facts

Nature of the Blandford–Znajek mechanism and spin energy of the black hole; Formation and acceleration of jets to γ-factors >10; AGN feedback and galaxy evolution; Causes of active nucleus type changes (Seyfert, LINER, Blazar); Measuring black hole masses in near-IR/optics at high redshift

💡 The nearest quasar to us, 3C 273, is 2.4 billion light-years away, but through an amateur telescope it appears as a modest 13th-magnitude star.