Universe Guide

What are Quasars and Blazars and whats the difference?

Quasar and Blazar Facts

What is a Quasar - QUAsi-StellAr Radio Source?

A Quasar is just one of a number of different Active Galactic Nuclei which also include Blazars, Radio Galaxies and Seyfert Galaxy. Quasars full name is QUASi-StAllar Radio object. The centre of the Milky Way is reputed to be just a supermassive black hole and not a quasar. It is now thought that at one time, the Milky Way was a Quasar before become inactive like it is today.

There are also Quasi-Stellar Objects (QSO) which are similar to Radio (QSR) sources except that Objects have a large redshift in their optical spectrum. Radio Sources on the other hand will also have a strong radio source. An object may or may not have a radio source. Both are starlike in appearance and both are outside our galaxy. Stargazing.

Quasars are large supermassive black holes at the centre of galaxy that is so active, that it tends to outshine the stars in the galaxy. Quasars tend to have accretion discs surrounding them like Saturn but on a grander scale. Quasars tend to be at the centres of galaxies far far away.

All the Quasars we can see are billions of light years away which leads to scientists to believe that they are young galaxies. If we were to travel to those galaxies and see how they look today, they would probably be calm and like any other galaxy, their streams would not be active.

One of the nearest Quasar is 3C273, it is 2.5 Billion light years away in the constellation of Virgo. Ref: N.A.S.A. . Some Quasars that have been studied were formed not long after The Big Bang and are many years older than 3C273. The picture below is a N.A.S.A. artist's impression of what a Quasar looks like. A Quasar will have a stream of particles being ejected out of the galaxy, if it didn't, it'd be a normal galaxy

N.A.S.A. Impression of a Quasar Galaxy

You're probably wonder, if a quasar is a supermassive black hole and they only suck in everything, how can they emit streams? The short answer is that it is believed that the electromagnetic field inside a black hole are so powerful that they cause the particles to head towards the poles and then out in a stream. If this is too simplestic, have a read of what Cornell University has to say on the matter.

To look at a Quasar from Earth, they would appear as red stars. When I mean look, I mean through a telescope, they are too distant and from here, too small to be seen with a naked eye. The redness is because they are so far away and also because they appear in the redshift of the spectrum, that they are moving away from us.

Quasars are similar to pulsars (Pulsating Stars) in that they have streams of x-rays shooting from their middles. They don't rotate as often if ever. A quasar is approximately about 1 Kiloparsec in width which is 1000 parsecs which is 1 parsec = 3.26 Light years. Ref: Starchild

As Quasars are so far away, their light has been travelling for billions of years. Quasar ULAS J1120+0641, which has a size of over 2 billion times the mass of the Sun. It is believed to have formed only about several hundred million years after the Big Bang.Ref: Space

How and When were Quasars discovered?

Marteen Schmidt, a Dutch astronomer is credited with discovering Quasars in 1963. Although before that the ground work was already in place for it. The first Quasar to be discovered was 3C 273. The object in question was very bright and also too far away to be a star. His research helped nail a coffin in the Steady State Theory which said that the Universe was not born in a Big Bang and has and always will be around for eternity. Carnegie

Special mention should also go to other astronomers who had helped directly and indirectly with Quasar discovery. 3C 273 had been examined the previous year by scientists at the Parkes Radio Telescope in Australia but it was not until the year later that the objects mystery was solved. Wired

The object is thought to have shined with a power of trillion Sun like stars and yet only be a light year across. For comparison, our galaxy is believed to be 100,000 light years across. EarthSky

Quasar Luminosity / Temperature

If we use 1LMW as the luminosity of the Milky Way Galaxy, a quasar could have the luminosity power of 10 to 100,000 LMW. Luminosity is the amount of energy that a star or galaxy produces. The Luminosity of the Sun is described as 1Lsun. The Luminosity of the Milky Way is equivalent to 25 Billion Lsun. You get the idea of how powerful the Luminosity of a quasar can be. Our galaxy would be outshone by even the dimmest of Quasars. The luminosity of a quasar is anything from 250,000,000,000 Sun to 2,500,000,000,000,000 times more power than the Sun. Ohio State.

What is a Blazar?

The difference between Quasar, Radio Galaxy and a Blazar is the angle of the stream. If the stream is straight up, it is a radio galaxy and we are not in the firing line. If the stream is angled slightly towards us, then its a Quasar and if the stream is angle directly towards us, its a Blazar.

In the beginning when they were first discovered, they were thought to be different objects in space but as we learned more, we discovered they were the same. There is a video on Youtube which gives a good explanation into Quasars and Blazars if you'd rather see a video.

Was The Milky Way Galaxy A Quasar Once?

Researching trying to find the missing mass of our galaxy believe they might have found the missing mass. According to the report, the Milky Way was active some six million years ago. This would have been at a time when the first human like creatures were walking on the Earth. This would be more recent than the dinosaurs.

This timeline is corroborated by the presence of 6-million-year-old stars near the galactic center, Sagittarius A*. Those stars formed from some of the same material that once flowed toward the black hole. Activity ended when the centre ran out of food to keep it going. Harvard

When the Andromeda Galaxy eventually collides with our galaxy, there is nothing to say, the resulting supergalaxy won't become an Active Galactic Nuclei galaxy. As the collision won't be around for a few billion years, we won't be around to see it.

Scientists have discovered six normal galaxies turning into Quasar. These galaxies are LINER (low-ionization nuclear emission-line region) galaxies such as the Sombrero Galaxy. At the time of the news, the scientists don't know why yet. Astronomy Now

Quasars and Hubble's Law

The Big Bang Theory, the actual theory, not the television series is based on Hubble's Law. Hubble's Law was developed by Edwin Hubble in the early part of the twentieth century. He stated that when a galaxies light is spectrograph, split into colours of the rainbow, if the light is more heavily red, the item is moving away from the observer. If the light is more blue, the object is moving closer to the observer.

When observing Quasar light, the items are more red than they should be. Using Hubbles Law, they are calculated at being at the edge of the known Universe and that they are moving at the speed of light.

Where is the nearest Quasar to Earth

As of August 2015, the nearest Quasar to Earth is Markarian 231 according to NASA Hubble space observatory. It is estimated to be about 600 million light years away in the constellation of Ursa Major in the northern hemisphere. It is believed that the galaxy has two black holes that are orbiting around one another.

The light that we are seeing now is how it was 600 million years ago, that is even before the dinosaurs roamed the earth over 250 million years ago. The central black hole is believed to be 150 million times the mass of the Sun and weigh over 4 million times the mass of the Sun.

Even though the quasar is so far away and old, it is believed that the two black holes orbit round each other 1.2 years. The reason why they are believed to be in orbit round one another is the result of two galaxies colliding. The two black holes will have already collided by now but we would not see the effect of the collision here on Earth for another few hundred thousand years. ref:N.A.S.A.

Difference between Quasar and Pulsar

A Quasar is a galaxy, they are billions of light years away and very young. If you were to travel to a Quasar now, they probably wouldn't be active, they'd just be a normal galaxy. Quasars won't be active forever, only active long enough for them to excrete all the material they need to.

A Pulsar is a rotating neutron star, they exist within a galaxy such as ours. A Pulsar is created in the aftermath of a star having gone supernova and it is remnants. A pulsar can rotate many times a second, known as millisecond pulsar.

Is a Quasar a White Hole?

No, they are two different things. A white hole is an unproven theoretical exit point of a black hole which no one has yet discovered. It seems strange that all the black holes are pointing towards us, if white holes existed, surely there would be some pointing towards us.

The equivalent of a white hole in a quasar would be the stream. The stream from a quasar is the ejected matter that the centre of the galaxy has accumulated and is ejecting because it no longer needs or requires it.

Can you see a Quasar in the Night Sky?

Even though a Quasar is an extremely bright and powerful object, it is not possible to see one just by looking up to the sky. The furthest thing we can see with our naked eye is the Andromeda Galaxy which is a mere 2.4 million light years away. Quasars are billions of light years away. You would need a telescope of at least 8 inches in order to see the brightest quasar in the sky.

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