CTA and Pulsars


Pulsars are observed to emit radiation across the entire electromagnetic spectrum- including gamma rays, which is why we are interested in them for the CTA.

This section has given an overview of the basics that we know for certain about pulsar physics. However, pulsar physics is very much a new area- a lot of it is not well understood, meaning that it is perfect for study by the CTA. One of the main science goals of the CTA is to find out more about particle acceleration, so pulsars are ideal candidates.

It was mentioned earlier that electrons are accelerated by electric fields to very high velocities. Astronomers are not certain about how exactly this happens- it involves high magnetic and electric fields, and the velocities are so high that general relativity is needed too. To make progress in understanding how the electrons are accelerated, and how the radiation is then produced, we need to be able to study the radiation they give off at the extreme ends of the electromagnetic spectrum.

CTA also has the opportunity to study a related object, Pulsar Wind Nebulae. When the pulsar starts to spin more slowly, it gives out a wind of charged particles and a magnetic field. This is just like the solar wind of our Sun. These particles interect with the strong magnetic fields which are hanging around, as well as any dust or gas which is also there. Eventually, a shock wave is produced, which accelerates these charged particles, which in turn give off our gamma-rays. Pulsar wind neubulae are actually the most common gamma-ray source we have found.

Source: NASA

The CTA has the sensitivity to be able to study these pulsars across the entire energy spectrum. The CTA has a huge detection area, so it only has to observe the pulsar over a very short time in order to get a measurement. The low energy threshold is important for observing pulsars- the CTA will be able to look in the lower energy gamma-rays. Measurements from the CTA are less affected by glitches in the pulsars (where the frequency of the pulse increases suddenly). So the measurements from the CTA will also be more reliable and accurate, which is important if we are going to be discovering new physics.

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