Measuring Dark Energy Like a BOSS

When you start to think about the most massive and extreme ‘stuff’ in the universe, you inevitably go to Dark Matter and Dark Energy.  They exist as opposites, one with incredible gravity holding the universe together, and the other a mysterious vacuum energy tearing it apart.  Studying this cosmic tug of war gives astronomers a chance to determine the past and future of the entire universe. To study the immense scale of these two quantities, the Baryon Oscillation Spectroscopic Survey (BOSS) program of the Sloan Digital Sky Survey-III (SDSS) constructed a 3D map of the sky, amounting to a volume...

A Direct Black Hole

How did supermassive black holes form in the early epochs of the universe? More importantly, how did they have enough time to grow as large as they did? The answer requires a very different universe.  And back then, conditions were much different than they are now.  There was a lot of gas, little dust, no stars, and a plethora of dark matter. Astronomers have spent decades observing early quasars, massive active galaxies powered by huge black holes feeding on surrounding gas.  But these galaxies are seen so early in the universe’s history, one starts to wonder how a black hole finds sufficient...

Seeding The Supermassive

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...

Black Holes ARE Dark Matter?

Dark matter could be almost anything.  With little data other than how much total dark matter mass exists, we can’t decode much about what individual chunks of dark matter might be made of.  I’ve talked before about Massive Compact Halo Objects (MACHOs) and Weakly Interacting Massive Particles (WIMPs), but these are just two possibilities.  Other theorists have talked about Modified Newtonian Gravity (MNG), where gravity may work differently on the grand scale than it does on our small Earth scales.  Or perhaps it’s something I haven’t seen before.  Maybe what we call dark matter is just a large population of ancient black holes....

Narrowband Spaghetti

I’ve written many times about the power of looking at different wavelengths of light to study different properties of the universe.  From a visualization standpoint, there are other techniques that give you additional power when imaging.  More than just the wavelength of light you’re using to show the detail, you can choose the range of wavelengths to bring forward certain features while suppressing others. The aptly-named spaghetti nebula, shown above, is a great example of this.  A supernova remnant that covers the constellations Taurus and Auriga, the nebula is very large in the sky, covering three full moons worth (love that unit...

Dark Matter is Complicated

The fact that we have found gravitational waves tells us that we have come a long way in terms of science and technology.  We detected a perturbation in the fabric of space-time that was one one-thousandth the diameter of a proton.  It’s insane to think about that level of precision.  And yet we still can’t find Dark Matter, the stuff that is literally everywhere in the universe.  Is it our problem? Or is dark matter just on a whole different level? By now, we know that dark matter isn’t some clump of stuff sitting out there in space.  But that...

The Nearby Supernova Revealed

Remember last week when I was talking about the evidence for some ancient-but-astronomically-recent supernovae? It turns out there is other evidence! Evidence that has helped scientists narrow down the potential source locations. Data from the Cosmic Ray Isotope Spectrometer (CRIS), an instrument aboard NASA’s Advanced Composition Explorer (ACE) spacecraft, has helped us figure out where the recent supernovae might have come from.  CRIS measures what we call cosmic rays, atomic nuclei that have been accelerated across the galaxy at close to the speed of light.  CRIS has been around for a while, and through 17 years of cosmic ray observations,...

A Ring of Fire

A direct consequence of Einstein’s theory of general relativity, and an observational way to prove it, is gravitational lensing.  It requires a powerful gravitational source to work, such as a galaxy or cluster of galaxies.  It works in a similar way to a lens of glass, where rays of light are bent toward a single source, increasing the brightness.  In this case, instead of glass, the bending of the rays is due to the curvature of space. Light rays coming from the source would otherwise miss Earth, but instead are bent toward us when there is a massive object in front of it.  It’s...

Multiple Ancient Supernovae

If a supernova were to go off somewhere in our galaxy, the minimum safe distance for Earthbound life would be about 50 light years.  Any closer than that, and we would experience an intense blast of high energy radiation and an eventual shower of radioactive particles.  It would be like nuclear bombs were set off all around the Earth, causing little destruction but a lot of radioactive fallout.  Supernovae are incredibly powerful to be able to cause such damage at 50 light years, but even at larger distances, we can see evidence of their effects here on Earth. A team of...

The Largest Neutron Star in Existence

Neutron stars are the most extreme objects in the universe that have been proven to exist.  Black holes are very likely, but we’re still not 100% sure about them.  A black hole is like a giant squid in the ocean.  We’re pretty sure they exist, but nobody has caught one.  The neutron star on the other hand is like a blue whale, everybody knows they exist, and they are massive, rare, and beautiful.  Of course, once we know something exists, the next logical step is to figure out how it behaves, to characterize and generalize it, and to identify where it’s...