Category: mergers

Sorry Science Fans, Discovering A 70-Solar-Mass Black Hole Is Routine, Not Impossible

“Astronomers aren’t perplexed by this object (or similar ones to it) at all, but rather are fascinated with uncovering the details of how they formed and how common they truly are. The mystery isn’t why these objects exist at all, but rather how the Universe makes them in the abundances we observe. We don’t falsely generate excitement by spreading misinformation that diminishes our knowledge and ideas prior to this discovery.

In science, the ultimate rush comes from discovering something that furthers our understanding of the Universe within the context of everything else we know. May we never be tempted to pretend anything else is the case.”

Did you hear about this “impossible” black hole that “perplexes” astronomers and “defies” theory? If you followed the news cycle last week, that’s probably what you’ve heard. But the truth is far more interesting, and includes facts like:

-this is the fourth black hole we’ve found like it, not the first,
-there are two other ways to make black holes that would explain this object in addition to the one way that can’t,
-and that we’ve seen each and every one of the steps necessary to make a black hole like this,
-but that finding this black hole with this particular method really is revolutionary?

As always, the real science is far more interesting than the mangled hype you’ve seen before. This black hole doesn’t defy theory, but sure does teach us a lot. Come get the real story today.

What Happens When Planets, Stars, And Black Holes Collide?

Brown dwarf collisions. Want to make a star, but you didn’t accumulate enough mass to get there when the gas cloud that created you first collapsed? There’s a second chance available to you! Brown dwarfs are like very massive gas giants, more than a dozen times as massive as Jupiter, that experience strong enough temperatures (about 1,000,000 K) and pressures at their centers to ignite deuterium fusion, but not hydrogen fusion. They produce their own light, they remain relatively cool, and they aren’t quite true stars. Ranging in mass from about 1% to 7.5% of the Sun’s mass, they are the failed stars of the Universe.

But if you have two in a binary system, or two in disparate systems that collide by chance, all of that can change in a flash.”

Nothing in the Universe exists in total isolation. Planets and stars all have a common origin inside of star clusters; galaxies clump and cluster together and are the homes for the smaller masses in the Universe. In an environment such as this, collisions between objects are all but inevitable. We think of space as being extremely sparse, but gravity is always attractive and the Universe sticks around for a long time. Eventually, collisions will occur between planets, stars, stellar remnants, and black holes.

What happens when they run into one another? Unbelievably, we not only know, we have the evidence to back it up!

Black Hole Mergers Might Actually Make Gamma-Ray Bursts, After All

“If there is a gamma-ray signal associated with black hole-black hole mergers, it heralds a revolution in physics. Black holes may have accretion disks and may often have infalling matter surrounding them, being drawn in from the interstellar medium. In the case of binary black holes, there may also be the remnants of planets and the progenitor stars floating around, as well as the potential to be housed in a messy, star-forming region. But the central black holes themselves cannot emit any radiation. If something’s emitted from their location, it must be due to the accelerated matter surrounding them. In the absence of magnetic fields anywhere near the strength of neutron stars, it’s unclear how such an energetic burst could be generated.”

In 2015, the very first black hole-black hole merger was seen by the LIGO detectors. Interestingly, the NASA Fermi team claimed the detection of a transient event well above their noise floor, beginning just 0.4 seconds after the arrival of the gravitational wave signal. On the other hand, the other gamma-ray detector in space, ESA’s Integral, not only saw nothing, but claimed the Fermi analysis was flawed. Subsequent black hole-black hole mergers showed no such signal, but they were all of far lower masses than that very first signal from September 14, 2015. Now, however, a reanalysis of the data is available from the Fermi team themselves, validating their method and indicating that, indeed, a 3-sigma result was seen during that time. It doesn’t necessarily mean that there was something real there, but it’s suggestive enough that it’s mandatory we continue to look for electromagnetic counterparts to black hole-black hole mergers.

The Universe continues to be full of surprises, and the idea that black hole mergers may make gamma-rays, after all, would be a revolutionary one! Come get the full story today.