Wednesday, 8 June 2016

Independent Learning Log 4 by Saffron Lim



What I did:
I read a BBC article on radio waves coming from deep space.

What I learnt:
  1. Fast radio bursts “shine” for only a few milliseconds, and in that moment, they release about a million times more energy than the Sun. They were discovered in 2007, and since then, astronomers have found fewer than 20 from outside our own galaxy. However, telescopes typically observe small patches of space at a time. If they could extrapolate (meaning: Extend the application of a method or conclusion to an unknown situation by assuming that existing trends will continue or similar methods will be applicable) to the entire sky, they estimate as many as 10 000 bursts everyday.
  2. Astronomers have no idea what radio waves are. Some ideas are neutron stars, exploding black holes, snapping cosmic strings, and even aliens.
  3. These bursts capture information about intergalactic space since they are like lasers that shoot across the universe, encountering magnetic fields and other things along the way.
  4. Pulsars are rapidly-spinning neutron stars. These city-sized stars are as dense as an atomic nucleus and spin more than a thousand times per second. As they spin, they swing a beam of radiation around, producing radio signals that appear as pulsating blips. The signal was so bright that it saturated the electronics in the telescope. The signal was dubbed the Lorimer Burst.
  5. When radio waves travel through the Universe, they interact with electrons in plasma along the way. These interactions cause a delay, the length of which depends on the radio signal's frequency. Higher-frequency radio waves arrive a hair faster than low-frequency ones. By measuring this delay, astronomers can calculate how much plasma the signals had to go through, which gives an estimate for the distance travelled.
  6. Black-hole- powered objects called quasars produce prodigious (meaning: remarkably or impressively great in extent, size, or degree.) amounts of energy, including radio waves.
  7. “Cosmic strings” are defects in the fabric of space and time that stretch across the universe. According to the hypothesis suggested in 2014, these strings might snap occasionally, exploding in a burst of electromagnetic radiation.
  8. Young pulsars are neutron stars that can spin as fast as once every millisecond. Over time, pulsars lose rotational energy and slow down.
  9. Highly magnetic neutron stars, called magnetars, produce bursts through a process similar to the one that generates solar flares. As the magnetar rotates, the magnetic fields in its corona, the wispy outermost layer of its atmosphere, rearrange themselves and become unstable. Eventually, the field lines snap like a whip, unleashing a torrent of energy that accelerates charged particles, which then emit radio bursts.

This article is about what fast radio bursts are, and how they could be created.

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