If you believe (or at least want to believe) that fast radio bursts (FRBs) are communications signals from intelligent extraterrestrials, then perhaps you can help astronomers interpret the meaning of a new discovery – measuring at the shortest timescales ever, they’ve found unusual variations in the brightness that allows them to precisely pinpoint not only their source but also the size of the source … and it’s small enough to move the needle for many a bit closer to “It’s aliens!” Is it?
“(These) short timescale brightness variations strongly constrain the size of the FRB emission region, which dictates what models can work for producing FRBs.”
In a Vice interview on a paper published in the journal Nature Astronomy that she co-authored, Kenzie Nimmo, a PhD student at the Anton Pannekoek Institute for Astronomy at the University of Amsterdam, describes how her team used data from the intercontinental European Very Long Baseline Interferometry Network to study FRB 180916, a repeating burst whose 16-day cycle consists of four days of bursts followed by 12 days of quiet. While FRB 180916 has been studied before, Nimmo and her team used a new technique that sliced them into 100 microsecond pieces, which gave them the "polarization position angle" (PPA) at which the polarized light swings back and forth. This data then helps reveal the rotation of the FRB source, how close the radio emission takes place to its source and the size of the emission region or area creating the pulses.
Think about that for a moment. This new data can measure the size of the source of fast radio bursts from a different galaxy 457 million light-years away. The size of the source of FRB 180916 was truly a shocker. Any guesses?
Try approximately one kilometer (0.62 miles) wide. Could that be a transmitter? Nimmo and the other researchers are leaning more towards a neutron star, which can contain more mass than the Sun, yet be only about 12 miles in diameter. The FRB discovered just 30,000 light years away in our own Milky Way galaxy was proven to be a form of neutron star called a magnetar. The repeating periodicity of FRB 180916 points more to a binary consisting of a precessing (wobbling) neutron and a massive star that orbit in other over a 16-day period. The 4-day bursts from FRB 180916 could then be explained by the two stars being closer together, with the dark 12 days when they are farther apart.
Not as exciting as aliens, but this makes more scientific sense. Since they’re not looking for aliens, Nimmo sees these microsecond measurements as a tool to identify repeating FRBs, take another look at one-off FRBs to see if they’re a new kind of repeater and better pinpoint the locations of all FRBs.
If you don’t want your discussion on FRBs to become highly polarized, stay away from bringing up aliens.