The hottest place in the universe is likely the quasar 3C273, with an estimated temperature of about 10 trillion degrees Celsius.
Although the Sun is the hottest object in our solar system, its temperature is relatively low compared to some other celestial bodies. According to Daniel Palumbo, a postdoctoral researcher at the Black Hole Initiative at Harvard University, the hottest places in the universe are very close to supermassive black holes, particularly those that are actively consuming gas. These black holes have relativistic jets, which are colossal streams of matter propelled to nearly the speed of light and are notably hot, as reported by Live Science.
Quasar 3C273 captured by the Hubble Space Telescope. (Photo: NASA).
The hottest place in the universe known to researchers is quasar 3C273, an extremely bright region surrounding a supermassive black hole located 2.4 billion light-years away from Earth. This region has a core temperature of over 10 trillion degrees Celsius, according to the Greenbank Observatory in West Virginia. However, this temperature estimate is still uncertain.
Supermassive black holes are incredibly powerful and sit at the centers of most galaxies. True to their name, they are colossal in size. For example, Sagittarius A*, the supermassive black hole at the center of the Milky Way, has a mass millions of times that of the Sun. Like any other black hole, quasar 3C273 has such strong gravitational pull that not even light can escape it. In contrast to this pull, there is a rotating gas cloud surrounding the black hole known as an accretion disk.
As molecules are drawn into the black hole at high speeds, the friction generated by collisions can produce temperatures in the trillions of degrees Celsius. In comparison, the surface of the Sun has a temperature of about 5,500 degrees Celsius. This temperature only increases as the black hole’s extreme gravitational force compresses nearby matter into the relativistic jets ejected into space, Palumbo notes.
However, the answer to where the hottest place in the universe could be might depend on when you ask the question, according to Koushik Chatterjee, a researcher at the Black Hole Initiative. When two massive celestial bodies collide, the explosion they create can generate extremely high temperatures. For example, two neutron stars, the collapsed cores of massive stars, colliding can produce temperatures reaching up to 800 billion degrees Celsius, according to a study published in 2019 in the journal Nature Physics. A black hole colliding with a neutron star can also emit particularly high temperatures.
It is very challenging to determine the exact hottest place in the universe because studying the temperature of distant objects is a complex task. Researchers are still uncertain about the actual temperatures of black holes. Instead, scientists measure the energy emitted from supermassive black holes in the form of visible light, radio waves, and X-rays. They can estimate the temperature based on the wavelength spectrum of the electromagnetic radiation produced by these sources.
A future X-ray observatory called the X-ray Imaging and Spectroscopy Mission (XRISM) will help scientists measure high-temperature gas in the universe more accurately. With advanced tools, they may discover areas that are even hotter than quasar 3C273.
