CAA Talk – Gamma-ray Bursts

The monthly Cambridge Astronomy Association talk was entitled “Gamma-ray bursts at probes of the distant Universe” by Professor Nial Tanvir.

Nial gained his PhD on the extragalactic distance scale at the University of Durham in 1992, and then came to the Institute of Astronomy where he was a postdoc. He became a lecturer at the University of Hertfordshire in 1999, and he became a professor at the University of Leicester in 2006.

Gamma-ray bursts are the most luminous events known in the Universe and can be detected at great distances. Nial described how GRBs are being used to study the first generations of stars and galaxies, and to consider prospects for pushing these studies further in the future. He also give an update on the recent record-breaking GRB 080319B, which is by far the most distant “naked-eye” source ever found.

The talk was very in-depth, but very interesting as I had seen information on how the Gamma Ray bursts are recorded and people are notified via email or SMS text message that a Gamma Ray burst has occured.  I think there was a Sky at Night program about it.

We were told how Hubble in the 1920’s proved that spiral nebulae were external galaxies to the milky way at great distances. Hubble also discovered how the entire universe seems to be expanding.

I discovered that light travels at 300,000 km per second. We were also shown the different types of wavelengths in the electromagnetic wavelength.  These are radio waves, microwaves, infrared, visible light, ultraviolet light, x-rays and gamma rays.

We also learnt the basics of how the current universe was formed in this order:

  • Big Bang (0)
  • Inflation (10-32 seconds)
  • Quark Soup (1 second)
  • Big Freeze Out (300,000 years)
  • Parting Company (1 billion years)
  • First Galaxies (12-15 billion years)
  • Modern Universe

Gamma Ray Bursts (GRBs) are detected by satellites, the main one being the SWIFT satellite. 

080319B was an extremely intense GRB with the brightest visible afterglow ever (at 5th magnitude, bright enough to see with the naked eye). It is the most energetic event detected by the Swift satellite so far and the most luminous optical source ever seen.

Overall I learnt that the Gamma Ray bursts probably originate from distant galaxies, which are difficult to see via optical systems.  The main worry is that a nearby gamma ray burst could possibly cause mass extinctions on Earth.

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