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Skywatching

Probing the youth of the universe through BlackHoles

Badly behaved Black Holes

We hoped the James Webb Space Telescope would revolutionize our ideas about the youth of the universe. It is certainly doing that.

Although it feels good for new observations to fit one's theories and preconceptions, it is more exciting when they don't, and we have to go away to do a lot more thinking. However, there were hints of trouble in observations made decades ago.

In the 1950s, radio telescopes detected an odd sort of radio source. Unlike all the other radio sources outside the Solar System that were known at the time, they varied in intensity over time, ranging from months to days.

That meant they had to have been around the size of the Solar System, or smaller. Optical telescopes were pointed at them and revealed the radio waves came from objects that looked like stars. That led to them being referred to as "quasi-stellar radio sources", which very rapidly became abbreviated to "quasars".

Moreover, these sources were carried away by the expansion of the universe very quickly, which meant quasars lie a long way away. For our radio telescopes to pick them up at distances of many millions to billions of light years, quasars have to be radiating prodigious amounts of energy.

The only objects we know that can be smaller than the Solar System yet radiate such enormous amounts of energy are black holes. These objects suck in any material in reach, such as gas, dust, stars and planets and convert them into energy with almost 100% efficiency.

Small black holes are the remains of supergiant stars that have run out of fuel and catastrophically collapsed. Most large galaxies, including ours, have supermassive black holes in their centres. These can have masses millions of times that of the Sun.

So far, our black hole is fairly well behaved, spending its time grazing on nearby stars and gas. However, if there is a lot of "food" available, supermassive black holes can be extremely disruptive. The galaxy M87, in the constellation of Virgo, is an example. It has a very active supermassive black hole in its core. Huge jets of material are being thrown out at a good fraction of the speed of light. The galaxy is a strong source of radio waves. We now believe quasars are distant galaxies with highly active supermassive black holes in their cores. Since the first discovery, many more quasars have been found. They mostly lie a long way away, which suggests they were more common in the youth of the universe than they are now. Recent observations made using the James Webb Space Telescope have rather complicated the picture.

The JWST was designed primarily for the study of the young universe. Even in the short time it has been in action, it has produced exciting results.

The telescope has detected full-grown galaxies that formed earlier in the history of the universe than we thought, just hundreds of million years after the Big Bang. It has found many of those galaxies are having their interiors churned up by active, supermassive black holes.

How mature galaxies can be present so early in the history of our 13.8 billion-year-old universe is a big question. Another is how those black holes managed to gorge themselves up to millions-of-solar-mass sizes in such a short time. Of course, one possibility is they were born big, along with or even before their host galaxies. These are important questions that could greatly impact out understanding of how the universe got started. They are attracting a lot of interest. It is easy to see why the line-up of astronomers wanting to use the JSWT is so big.

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There will be a partial eclipse of the Sun on Oct. 14. In B.C., it will start around 8 a.m. PDT. At 9:20 a.m. PDT, around three-quarters of the solar disc will be covered. It will be all over by 11:40 a.m.

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•Saturn rises just after sunset, with Jupiter following about an hour later. Venus, shining like a searchlight, rises around 3 am.

•The Moon will reach its first quarter Oct 21.

This article is written by or on behalf of an outsourced columnist and does not necessarily reflect the views of Castanet.



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About the Author

Ken Tapping is an astronomer born in the U.K. He has been with the National Research Council since 1975 and moved to the Okanagan in 1990.  

He plays guitar with a couple of local jazz bands and has written weekly astronomy articles since 1992. 

Tapping has a doctorate from the University of Utrecht in The Netherlands.

[email protected]



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The views expressed are strictly those of the author and not necessarily those of Castanet. Castanet does not warrant the contents.

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