In the early Universe, things were quite different. The first stars were much more massive than stars today, and contained mostly Hydrogen. Astronomers have good ideas about how they formed, but other objects from around this time, namely black holes, are much tougher to account for. Early black holes were huge, with no explanation for how they grew so large. “Early” means “first Billion years after the Big Bang,” but even in that time, it’s hard to determine how observed black holes could grow as large as 100,000 solar masses. I say 100,000 solar masses, because that is the mass of two ‘seed’ black holes, discovered...
As I’ve said before, the most powerful, most energetic, most intense processes happen in the center. The gravitational center of the Earth, the Sun, and the galaxy are all places where temperature, pressure, and interactions of matter and energy are pushed to their limits. When you look up to the sky it’s easy to see the Milky Way (unless you live in an urban center). Do you ever wonder where the middle of it is? Where that supermassive black hole lies? Astronomers know where it is, but you need infrared cameras to see it past the thick dust that blocks...
We know that galaxies like our Milky Way are far more massive than we can see. The dark matter in the Milky Way makes up 90% of it’s total mass. Another way of saying this is the Mass to Light ratio, comparing the total mass inferred by the rotation speed of the galaxy to the total mass of stars in the galaxy. This ratio, M/L, for the Milky Way, is about 10. But for a galaxy cluster, the M/L ratio is more like 100. Galaxy clusters are not just dense collections of stars and massive galaxies, they are also immense...
There are multiple types of Supernovae that have been observed throughout the Universe. Classifying them is difficult because the conditions of each one are not always similar. There are now seven different classifications of these stellar explosions, that are divided (and subdivided) by their spectral characteristics. By studying the light from supernovae, we can determine what type it is, and identify what kind of stellar environment led to its destruction. The supernova remnant 3C 397, shown above in the constellation Aquilla at a distance of 33,000 light years, has thought to have been expanding for 1-2 millennia. Originally thought to have...
We call it dark matter because it doesn’t give off light, right? Well there is a lot of matter than doesn’t radiate, but the difference is that whatever the stuff is that we call dark matter doesn’t interact with anything through the small-scale fundamental forces. The only way we have been able to detect it’s presence is through large-scale gravitational interaction. Dark matter is ‘dark’ because it doesn’t interact with anything in a way that lets us figure out what it’s made of. Well now that we’ve got that out of the way, we can look at the new...
