Maarten Schmidt solves the quasar riddle | The universe

Maarten Schmidt via Caltech.

Today in science: On February 5, 1963, Dutch astronomer and Caltech professor Maarten Schmidt had a moment of eureka while studying quasi-stellar radio source, or quasar, which had profound implications for how scientists would view space. Schmidt studied a quasar known as 3C273 that looked like stars, with the addition of a mysterious jet. But even stranger was his spectrum. Astronomers examine the spectrum or range of wavelengths of light emitted by a star to decipher the composition of an object. But emission lines spectrum 3C273 did not correspond to any known chemical element. Schmidt suddenly realized that 3C273 contained a very common hydrogen element. It was simply tricky to identify, as the spectral lines of hydrogen did not appear where expected; instead they were strongly shifted toward the red end of the spectrum. So big redshift it could happen if 3C273 was very distant, about three billion light-years away.

Dr. Schmidt recalled the excitement of his discovery at EarthSky. He said:

She realized it right away: my wife still remembers me walking up and down most of the evening.

The implications were just this: for a quasar to be so far away and still visible, 3C273 must essentially be very bright and very powerful. It is now thought that it will shine with the light of two trillion stars like our sun. That’s hundreds of times more than the light of our entire Milky Way galaxy. Still, 3C273 appears to be less than a light-year wide, as opposed to 100,000 light-years for our Milky Way.

Quasar 3C273 is not just remote. It is also extremely brilliant, implying powerful energy production processes unknown in 1963. Schmidt announced his discovery of quasars in the journal Nature March 16, 1963

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Portrait of the elderly Maarten Schmidt wearing a bow and patterned glasses.

Maarten Schmidt is a Dutch astronomer who recognized in 1963 that quasars are located in a very distant universe and must therefore be extremely powerful sources of energy.

A bright sun-like circle on top with a brightly colored ribbon shooting down from it.

X-ray image of 3C273 and its jet. Today, it is known that this quasar lies at the center of a giant elliptical galaxy. Image via Chandra X-ray Observatory.

Hundreds of thousands of quasars are known today, and many are both more distant and more powerful than 3C273. It is no exaggeration to say that they turned the science of astronomy to the ear. Why, for example, are these powerful quasars located so far away in space? Light travels at a finite speed (186,000 miles per second), and we see quasars only in the distant universe, and thus in the distant past. These strange objects existed only in the early universe and no longer exist in the present universe. Why?

In the 1960s, 3C273 and other similar quasars were strong evidence against Fred Hoyle’s theory of steady state, which suggested that matter is continuously created as the universe expands, leading to a universe that is the same everywhere. Quasars have shown that the universe is not the same everywhere, which helped establish the cosmology of the Big Bang.

But the steady-state theory was losing ground even before 1963. The biggest change caused by Maarten Schmidt’s discovery of quasar 3C273 was in the way we to think about our universe.

In other words, the idea that 3C273 was extremely luminous, and that it occupied such a relatively small space, suggested powerful energies that astronomers had not thought of before. 3C273 gave astronomers one of the first hints that we live in a universe of colossal explosive events – and extreme temperatures and glow – a place where mysterious black holes abound and play a major role.

According to a March 2013 Caltech email:

In 1963, Schmidt’s discovery gave us an unprecedented view of how the universe behaved at a much younger time in its history – billions of years before the birth of the sun and its planets. Later, Schmidt, along with his colleague Donald Lynden-Bell, discovered that quasars of a galaxy containing supermassive black holes are billions of light-years away — not stars in our own galaxy, as was once believed. His basic work has dramatically increased the scale of the visible universe and enhanced our present-day view of the violent nature of the universe in which massive black holes play a dominant role.

What are quasars? Astronomers today believe that a quasar is a compact area at the center of a galaxy in early space. The compact region is thought to surround a central supermassive black hole, much like a black hole is thought to reside at the center of our own Milky Way galaxy and many (or most) other galaxies. The strong illumination of quasars is thought to be the result of processes taking place in accretion diskor a disk of material surrounding a black hole, because these supermassive black holes are consumed by stars passing too close. Such activities occur during the merging of galaxies, an activity that peaked in the early universe.

ULAS J1120 + 0641 was the most distant quasar known in 2011. The quasar appears as a faint red dot near the center. Composite image created from Sloan Digital Survey and UKIRT Infrared Deep Sky Survey via Wikimedia Commons.

The American astrophysicist, born in China, Hong-Yee Chiu, coined that name quasar May 1964. in publication Physics today. He wrote:

So far, the awkwardly long name “quasi-stellar radio sources” has been used to describe these objects. Since the nature of these items is completely unknown, it is difficult to prepare a short, appropriate nomenclature for them so that their essential properties are apparent from their name. For convenience, the abbreviated form ‘quasar’ will be used in this paper.

Currently, the most famous quasar is ULAS J1342 + 0928, but it can be downloaded at any time. It has a redshift of z = 7.54 and existed when the universe was about 690 million years old, only 5 percent of its current age.

Conclusion: Today in science, on February 5, 1963, Maarten Schmidt revealed the mystery of quasars and moved away from the edges of our cosmos. His insight into the most distant and brightest known objects has changed the way scientists look at space.

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Deborah Byrd

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