So many things happened during this bombshell month that I don’t know where to start.
– The Event Horizon Telescope, of first photo of a black hole fame, now released a photo of the jet coming out from another one.
– We might have finally found what causes fast radio bursts by seeing one in our own galaxy.
– Still in our galaxy and still at black holes, more specifically the black hole at the galaxy’s center: the orbit of a star around it has now been recorded.
– Leaving the skies and passing to elementary particles, the question of whether neutrinos and antineutrinos behave the same is half-way on its path to an answer. (This is actually written up separately at this post.)
– Meanwhile, time at a Tokyo tourist landmark passes more quickly. Also, this might be the start of using general relativity for predicting earthquakes.
Time, tourists, earthquakes … what?
Starting from this, the WTF news of the month, researchers from five japanese groups used super-precise clocks to prove that time passes more quickly at the top of Tokyo Skytree than on the ground. According to the theory of general relativity, which describes all things gravity, this is expected due to the earth’s pull being slightly less strong at the top of the iconic television tower than on the ground.
The fact that weaker gravity makes time pass more quickly has already been confirmed several times, typically by using satellites and atomic clocks. But now the team used optical lattice clocks (where lasers point against each other to form “nodes” of light that trap atoms) which they made both more precise and portable. Their experiment was a confirmation of relativity but, even more than this, a proof that such measurements can now be done in real-world conditions, even at places that are hard to reach.
Additionally, the precision achieved showed that we can rely on gravity for measuring even height differences of a few centimeters. So, for instance, an application that immediately popped in the researchers’ mind is monitoring the motion of the earth’s crust for the prediction of earthquakes… Do you have your own idea about other applications?
Capturing black holes
Usually general relativity is better known for other stuff though, like black holes. But in the era of Instagram these VIPs prefer the veil of mystery, as we now get one of only a few photos of them ever. With love from their official social media manager, the Event Horizon Telescope.
The network of telescopes of the project focused on a photogenic hole (other than that in last year’s mugshot) a few billion light years away. Then they combined their observations to create a picture of the jet gushing from it, as caught in the radiowave spectrum.
Going the rounds
A project has been running for almost 30 years now using various telescopes to track a single star; it’s been there before hipsters and even before you heard of Radiohead. And last month it graced us with its first results.
The star beautifully named S2 is close enough to Sgr A*, the black hole at the centre of the Milky Way, to orbit it without falling in and to complete an orbit every 16 years. Its track has been followed by a number of different devices at the Very Large Telescope in Chile, and now known with satisfactory precision.
On top of that, the observation confirmed yet one more prediction of general relativity: namely that the orbits are expected to stay on the same plane but move forward on it with time. Indeed during these three decades S2 was seen tracing a cosmic bloom in the sky.
Finally, April bowed out with some potentially big news. A fast radio burst (aka FRB) might have been found inside our own Milky Way and we might have begun understanding what this is about.
FRBs are one of the biggest current mysteries in astrophysics. They are inexplicable extremely powerful flashes of radio waves reaching us from other galaxies. And when we say powerful we talk millions of times the output of sun.
The new flash was caught by several telescopes after CHIME, a FRB-hunting radio telescope in Canada, announced it in an astronomy telegram (yes, this is a thing). Crucially, if viewed from another galaxy it’d look exactly like a FRB. Even more crucially, its source was pinpointed to a magnetar seen to be active the day before.
A magnetar is a weird form of dead star left behind after a supernova. It is actually a neutron star, one of those super-dense objects, only with magnetic fields several thousands of times larger than those of “ordinary” neutron stars. The gigantic battle between the magnetic force and gravity distorts the star’s shape; massive starquakes shake it and huge stellar flares are thrown into space. And now it looks as if FRBs might get added to those superlative events.