If you’ve been following developments in astronomy over the last few years, you may have heard about the so-called “crisis in cosmology,” which has astronomers wondering whether there might be something wrong with our current understanding of the Universe. This crisis revolves around the rate at which the Universe expands: measurements of the expansion rate in the present Universe don’t line up with measurements of the expansion rate during the early Universe. With no indication for why these measurements might disagree, astronomers are at a loss to explain the disparity.
The first step in solving this mystery is to try out new methods of measuring the expansion rate. In a paper published last week, researchers at University College London (UCL) suggested that we might be able to create a new, independent measure of the expansion rate of the Universe by observing black hole-neutron star collisions.
Dark matter continues to resist our best efforts to pin it down. While dark matter remains a dominant theory of cosmology, and there is lots of evidence to support a universe filled with cold dark matter, every search for dark matter particles yields nothing. A new study continues that tradition, ruling out a range of dark matter candidates.
One of the strangest predictions of general relativity is that gravity can deflect the path of light. The effect was first observed by Arthur Eddington in 1919. While the bending effect of the Sun is small, near a black hole light deflection can be significant. So significant that you need a powerful supercomputer to calculate how light will behave.
Imagine trying to study an object light-years away that is less than 20 kilometers in diameter. The object is so dense that it’s made of material that can’t exist naturally on Earth. This is the challenge astronomers face when studying neutron stars, so they have to devise ingenious ways to do it. Recently a team figured out how to study them by using the power of resonance.
It’s hard to make a black hole in the lab. You have to gather up a bunch of mass, squeeze it until it gravitationally collapses on itself, work, work, work. It’s so hard to do that we’ve never done it. We can, however, make a simulated black hole using a tank of water, and it can tell us interesting things about how black holes work.
Gravitational wave detectors are limited by fundamental quantum noise – an incessant “hum” that they cannot ever remove. But now physicists have recently improved a technique, called “squeezing”, that can allow the next generation of detectors to double their sensitivity.
Few events in the astronomy community were received with more fanfare than the first detection of gravitational waves, which took place on September 14th, 2015. Since then, different events have been recorded using the same techniques. Many include data from other observational platforms, as the events that normally create gravitational waves are of interest to almost everyone in the astronomical community. Black hole and neutron star mergers and the like provide a plethora of data to understand the physics that happen under such extreme conditions.
To distribute that data equitably, researchers at LIGO, one of the main observatories for gravitational waves, have released a data set that contains information about all 50 confirmed gravitational wave events that have taken place since observations began. What’s more, a team from the Cardiff University made a tool that makes it much easier to navigate the data.
The successful detection of gravitational waves has been a game-changer for astronomy. And now the new frontier is in space, with satellite-based detection systems currently in development that will uncover some of the universe’s biggest mysteries. And while the team behind LISA is now developing that observatory in space, it just may be outclassed by a rival, TianQin, developed by the Chinese.
Lately there has been a flood of interest in gravitational waves. After the first official detection at LIGO / Virgo in 2015, data has been coming in showing how common these once theoretical phenomena actually are. Usually they are caused by unimaginably violent events, such as a merging pair of black holes. Such events also have a tendency to emit another type of phenomena – light. So far it has been difficult to observe any optical associated with these gravitational-wave emitting events. But a team of researchers hope to change that with the full implementation of the Gravitation-wave Optical Transient Observer (GOTO) telescope.
Gravitational waves are produced by all moving masses, from the Earth’s wobble around the Sun to your motion as you go about your daily life. But at the moment, those gravitational waves are too small to be observed. Gravitational observatories such as LIGO and VIRGO can only see the strong gravitational waves produced by merging stellar-mass black holes.