Magnetars And Gamma Ray Bursts
How magnetic fields and photons synergistically produce the highest-energy flashes in the universe
Almost a year ago, on April 15th 2020, a wave of gamma rays blasted through our solar system, having traveled 11.42 million light-years across space from a source in the Sculptor galaxy. In other words, an event that actually occurred 11.42 million years ago, hundreds of trillions of kilometers away, finally reached us. Fortunately, by the time the gamma rays got here they were sufficiently diffused that they didn’t cause us any harm. But if we’d been up close and personal, we’d have been destroyed because gamma rays are the most powerful emissions in the universe.
Let’s start with the basics: what’s a gamma ray?
Gamma rays are highly energetic photons. Photons are what we commonly call light. When we open our eyes we see the world around us because photons created in the heart of the sun reach the Earth and then bounce off objects around us. Some of those photons end up going into our eyes where they hit the cells in our retinae and this triggers nerves to send messages that our brains then interpret as shapes and colors. Our color vision goes from violet to red as the cells in our eyes react to different frequencies of light. But we see only a tiny sliver of the photons our sun emits. If we imagine, by way of analogy, an old-fashioned 12-inch ruler then photons can be as small as the smallest 1/16th mark at the very beginning, and can stretch out as long as the entire ruler. Our eyes see a spread of only about 0.0035% across that imaginary ruler, or about four-hundredths of an inch. Nearly all the photons in the universe are invisible to the human eye.
When thinking about photons, which travel at the speed of light and which have no mass, it’s important to realize that they carry energy. The shorter the wavelength of the photon, the greater the energy. Very short wavelength photons can carry a huge amount of energy. The shortest-wavelength photons of all are called gamma rays. These are highly energetic photons whose energy can be so great that single photons can damage human cells.
So now, what’s a magnetar?