Annihilating Dark Matter May Lurk in Milky Way’s Center

Ripped from the headlines. Literally. I ran across this dire warning while checking terms for an editing project. So, what gives, you may ask? Pause. Pause. Pause. Okay, if you won’t ask, I will. What gives? As you may or may not know, we are constantly being bombarded by electromagnetic radiation (EMR) thanks to the sun, the stars, that powerline right outside your front door, and even the laptop, tablet, TV, or phone you may be staring at right this moment.

So, what is EMR? I’m going to try to give a dumb answer here, mainly because it’s the only one I will understand.* Simply put, EMR is a form of energy that’s basically everywhere. It comes in various types such as radio waves, microwaves (yes, the cooking kind), x-rays, and gamma rays (more on g-rays in a moment). These types fall at various places onto the electromagnetic spectrum, an enormous range of wavelengths and frequencies. Some Scottish guy named James Clerk Maxwell figured all this out back in the late 1800s and put it down on paper as the classical theory of electromagnetic radiation, which brought together, for the first time, that fabulous threesome electricity, magnetism, and light as different manifestations of the same phenomenon.

The radio waves tend bar at the lowest end of the EMR spectrum. The g-rays hang their hats at the other end. Radio waves are our friends, bringing us information and entertainment such as the news, music, podcasts, and Howard Stern. G-rays are not our friends. While they can be used to kill cancer cells if applied carefully in small doses, in general, they just kill us, most dramatically in places like Chernobyl and Hiroshima.

Despite being deadly, gamma rays are of great interest to one particular group of people: astrophysicists. Smartly, they study these rays from a long way away, say, about 25,000 light years, which is the distance from our Solar System to the center of the Milky Way, the “barred spiral galaxy” in which we reside. (On an interesting side note, our Sun circles the MW center just as the Earth circles the Sun, taking about 250 million years to make the roundtrip.) The center of the MW glows thanks to our not-friends the g-rays, and this glow is known as the Galactic center gamma-ray excess, or GCE. The astrophysics gang once surmised that the GCE came from one of two things. One, “a population of pulsars” (pulsars, if this helps at all, are “highly magnetized, rapidly rotating neutron starts.” Still clueless? Me, too.) Or two, “a cloud of dark matter, colliding with itself to produce a glut of gamma rays.” Hence, the “annihilating dark matter.”

If you’re thinking, “How sad. There should be a help hotline for g-rays intent on self-destruction,” you rate extra high on the empathy meter and kudos for that. But you needn’t worry. Things just tend to randomly bang into one another. For dark matter, this results in annihilation. For me, it’s usually bruises from encountering door frames or parking meters unexpectedly.

The main question niggling at me, though, is not all this scientifiky stuff. It’s that “may lurk” in the headline. The word “lurk” has very sinister connotations. Merriam-Webster defines it as “to lie in ambush.” While the scientists were probably thinking of the “to be hidden but capable of being discovered” meaning, how can something called “annihilating dark matter” have anything but bad intent? I’m thinking it’s just biding its time, the gigamungous monster in the Galactic closet, waiting patiently for just the right moment to unleash its GCE, which I’m sure really stands for “gruesome cosmic exterminator.” Fortunately, my wife Kalo has had the foresight to lay in a stock of tinfoil hats and other protective devices. I advise you to do the same.

Asterisk: For those you who want that not-so-dumb answer, EMR is “created when an atomic particle, such as an electron, is accelerated by an electric field, causing it to move.” And if you really want to jump down this rabbit hole, see this Live Science article by Jim Lucas: “What Is Electromagnetic Radiation?”

Image: The Milky Way in visible light and a gamma-ray map from NASA’s Fermi Gamma-ray Space Telescope. NASA’s Goddard Space Flight Center / A. Mellinger, Central Michigan University / T. Linden, University of Chicago. Public Domain.

(Published originally on RatBlurt, September 11, 2020.)