In the 1960s century satellite detected bursts which were in gamma ray Bursts. We did not know the nature what are these gamma ray bursts but we only knew they are coming not from the Earth but from space from someplace in the universe. 30 years to find out its nature, and today we know these gamma ray bursts are the results of the biggest explosions of the universe.
Mystery of Gamma Ray Bursts
In 1963s century when the Cold War between America and the Soviet Union was at its height, America, and the Soviet Union signed the nuclear test ban treaty at that time, which is a good thing. I think there should be no nuclear bombs. When this treaty was signed the question was how to check whether someone was violating it. So in 1967, America sent some spy satellite name Vela
It’s aim was to check whether Soviet Union was secretly carrying out tests or not. These spy satellites had that ability to detect gamma ray bursts so if there was a nuclear test its gamma ray could be detected.
Detected Bursts of Gamma Ray
So these Vela satellites did not discovered any gamma ray bursts on earth but the surprising thing is they detected bursts of gamma ray which were coming not from earth but from space, from the universe. And 50 years before in June 1973 a paper was published of the gamma ray bursts of the Vela satellite in which it was revealed that since 1967 they had detected 60, 70 gamma ray bursts and they do not know what it is.
Now these gamma ray bursts was a very big mystery of astronomy, gamma rays are just like light.
Normally our eyes see in visible light but if you go to small wavelengths or towards high energy, you have ultraviolet x-ray and then gamma rays. So according to light gamma rays are mostly of energy. The special thing about gamma rays bursts was,
- The first thing is there no optical counterparts at the beginning meaning they were only being detected in gamma rays.
- The second is there bursts (as the name signifies bursts) their direction was very brief.
Gamma Rays Bursts Types
In fact astronomers saw these gamma rays bursts were of two types
One long duration gamma ray burst, the long duration was from 2 seconds to 10, 15 second or up-to 1 minute
Second short duration gamma ray burst from milliseconds to two seconds.
If you are talking about timeframe, the satellite which detected them, they detected these bursts very quickly and only in gamma rays. In the 1990’s an observatory Compton gamma rays Observatory was launched. Whose major aim was to understand these very gamma rays bursts.
This Compton gamma rays Observatory, is from the family of NASA big telescope,s which includes the hubble space telescope, Spitzer infrared space telescope, and chandra X-ray telescope. So Compton gamma rays space telescope.
Now we know there are two types of gamma ray bursts short duration and long duration, all of which of few seconds but there was another thing in it.
Where are they? Now gamma ray telescope could not isolate it minutely but it could tell over all from which directions the gamma ray bursts are coming and this information can be obtained what type of object is it.
For example, If these gamma ray bursts are being produced in our Milky Way than the distribution of it then the distribution of the gamma ray bursts will be according to the distribution of the Milky Way galaxy.
If you see Milky Way galaxy in the night sky in summer, you see the concentration of stars in a band called Milky Way. If the gamma rays bursts are in our Milky Way than their concentration will be seen more in this band. But the Compton gamma rays Observatory, specially, which detected many hundreds of gamma rays bursts, observed that its distribution is isotropic as astronomers call it.
Meaning it is distribution equally in the whole sky so the Milky Way is ruled out. Now the question is which sort of objects can create this type of isotopic distribution.
Gamma Rays Bursts Ideas
These were two ideas. One was that these gamma ray bursts are near our solar system, meaning as the distribution of comets in oat clouds is spherical. So it is possible the gamma ray bursts may have some connection with these comets. If this is true, the power of these gamma rays bursts, bursts is not actually very much because it is either a part of our solar system or near it.
Or they are very very very far away from us billion of light years away. If they are so far, this can be a spherical or isotropic distribution called cosmological distribution but then it means if we are detecting it from so far it must be very powerful. Now this question, that they are near us, are a part of our solar system and do not have much energy or are very very very far away and very powerful.
How to find answer to this.
Now Compton gamma rays bursts Observatory detected many hundreds gamma rays bursts but could not catch it is whose counterpart could be found. The breakthrough came in 1997. This was an Italian telescope BeppoSax.
Gamma Ray Burst Detected
It finally detected a gamma ray bursts and identified where it happened and in the follow up observation
Its optical counterpart was discovered which faded in about 20 hours. And astronomers saw it was linked to a galaxy, a galaxy in which innumerable stars were forming. Astronomers measured its distance the found the gamma ray burst was approximately 6 billion light years away from earth.
It finally solved the case weather gamma ray bursts are near us part of our solar system or very very very fun and very powerful. It confirmed the second option. Imagine the mystery began in the 60’s through Vela satellite in 1967 and up-till 1997 we did not know what are gamma ray bursts and then we find out that these are the biggest explosions of our universe.
Hyper-Nova or long duration gamma ray bursts
Now what sort of event can produce this huge gamma ray burst? Astronomers call it Hyper Nova meaning this is more powerful than the supernova explosion that regular explosion of the big stars. In Hyper Nova a stars at least 30 times more than our sun mass wise, when it collapses in the black hole before that collapse this explosion takes place in which a lot of gamma ray bursts are produced.
This Hyper nova can be 50 times more powerful than the supernova. The idea of the astronomers is when star collapses, this big star in its dying moments collapses the world forming a black hole, the material before forming of the black hole, swirl makes an accretion disc
And a lot of material ejects via to jets made on either side of the disc. And a lot of energy when it interacts with the material of the stars and the nearby material produce gamma ray bursts and it from the jets one is pointing towards the Earth we detect it as gamma ray bursts. And these are ling duration gamma bursts meaning from a few seconds to 10, 15 seconds or 1 minute, gamma ray bursts.
Kilo-Nova or Short Duration gamma ray bursts
These shorts duration ones whose duration is some milliseconds to two seconds are actually because of the collision of two neutral stars or the merger of neutron star and the black hole.
Astronomers know the binary pulsars or binary neutron stars do exist and there are pairs of black hole, neutron stars. In fact when the gravitational waves were detected in 2015 to 2016 which was a big information of these type of mergers these short term duration gamma rays bursts or a result of that.
We know when neutron star and neutron star or the black hole neutron star pair merge gamma ray bursts emit for a very short duration and these are called kilo nova by astronomers.
GRB 080319B Burst Detected
In 2008 gamma rays bursts was detected whose name is GRB 080319B. This basically tells its date. This gamma ray bursts was so bright that to some extent it blinded the gamma ray detectors we have in space meaning it was very bright.
Not only this, this gamma ray bursts was also visible in optical light (naked eye). This gamma ray bursts for 30 second directly with your eyes. At a distance of 7.5 billion light years. This gamma ray bursts at a distance of 7.5 billion light years and was visible to the naked eye for 30 seconds.
BOAT Gamma Ray Burst detect
Last year there was another big burst which astronomers have named BOAT bright of all time. This is a gamma ray bursts which is at a distance of 2.5 billion light years. This is also a hyper nova. Astronomers are trying to understand this BOAT because no gamma ray bursts brighter than this one has been found yet.
Last month some papers have come which say it has a special thing. It has a het which is embedded in more material. This was so bright because of the outflow of the jet and the outflow of the material. BOAT brightest of all time.
If This Type of bursts in out Milky Way
If this type of hyper nova happens in our Milky Way, what will become of our earth? The guess is if such a hyper nova happens at a distance of 6 to 7 thousand light, years away, and if its direction is towards us the gamma ray bursts will impact the ozone layer of earth.
Probably 30% to 40% of the ozone layer will be destroyed because of this gamma rays bursts and because of that (ozone reduction) some organisms, specially microorganisms may start to die and that they impact other life forms included humans.
Extinction on Earth due to GRB?
We know there have been mass extinctions on Earth, was some extinction due to the gamma ray bursts? It is not easy to find out. We know the extension of dinosaurs which was the last major mass extinction 65 million years ago was probably due to the collision of a comet or an asteroid. But there have been mass extinction before and in one suspicious extension 450 million years ago, some species which survived were trilobites which used to eat plankton from the ocean. It is possible and it is very very speculative.
People think that maybe that mass extinction may have happened due to gamma ray bursts. The rest of things were wiped out but things below water survived such a trilobites.
