One Cosmic Mystery Illuminates Another, As Fast Radio Burst Intercepts A Galactic Halo
“Although scientists have studied [Fast Radio Bursts] intensely since their discovery, their origins remain mysterious. Meanwhile, an estimated 2 trillion galaxies populate our observable Universe. With incredibly large distances for FRBs to traverse, each one risks passing through an intervening galaxy. Giving off multiple pulses of under 40 microseconds apiece, FRB 181112 became the first burst to intercept a galactic halo.”
Where do fast radio bursts come from? Recent studies have demonstrated that they’re associated with host galaxies, but we don’t understand how they work, why some of them repeat, or why the pulse durations are so variable.
What about galactic halos: how much gas is in them? What is the gas temperature, density, magnetization, etc.? These are big questions about galaxies in general that we don’t have a general picture of. If only there were some way to learn more.
How about luck? We got lucky, in November of 2018, when for the first time a fast radio burst passed through a foreground galaxy’s halo. What did we learn? Come get (and see) the full story!
This Is How Astronomers Solved The ‘Zone Of Avoidance’ Mystery
“From the time of their very first discovery, the Universe’s grand spirals have puzzled astronomers.
While stars, star clusters and other nebulae were concentrated in the plane of our Milky Way, there were no spiral nebulae present. For some reason, they eschewed our galaxy’s plane, which became known as the Zone of Avoidance.”
On the largest scales of all, the one thing we’re certain we can say about the Universe is that it’s extremely uniform. On average, there are the same number of stars and galaxies, the same sized structure, and the same overall density of matter regardless of where we look. So why, then, would we see spiral and elliptical galaxies in roughly equal abundances, in all directions, except within about 10 degrees of the Milky Way’s plane? For some reason, the galaxies that ought to be there simply aren’t; they appear to avoid the plane of the Milky Way.
This was a mystery for generations, but infrared astronomy, pioneered in the 1960s, paved our path to the epic solution. Come get the incredible story today!
This Is How The Milky Way Is Eating Our Galactic Neighbors
“New star formation is triggered by mutual gravitational interactions combined with the Milky Way’s tug.
The gas within these galaxies gets shunted into new clusters, including the local group’s largest star-forming region: 30 Doradus.
But these gravitational interactions also strip the gas away from these dwarfs, where the Milky Way will devour it.
The largest gas stream seems to connect both galaxies, but which cloud it originated from was a mystery.
Until, that is, scientists led by Andrew Fox looked at the absorption effects of this gas from background quasar light.”
While the visible Universe extends for tens of billions of light years, our local group of galaxies extends for only a few million. Around our own Milky Way are a handful of dwarf galaxies, including two bright ones: the Large and Small Magellanic Clouds. These two galaxies contain large numbers of young stars, show evidence of hot, glowing gas, and are destined to be devoured by our Milky Way in cosmically short order. But until that happens, they’re engaged in a cosmic tug-of-war with one another, battling to expel the gas from each other and capture it for themselves. Because the Milky Way is nearby, the expelled gas is getting stretched and drawn into our own galaxy, but which cloud, the Large or the Small, did it arise from?
Owing to new work by a Hubble team led by Andrew Fox, we finally know it’s the Small Magellanic Cloud. Here’s how, and here’s what it means for science.