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Astronomers Detected a 'Ghost Particle' and Tracked It To Its Source (space.com)
An anonymous reader quotes a report from Space.com: Astronomers have traced a high-energy neutrino to its cosmic source for the first time ever, solving a century-old mystery in the process. Observations by the IceCube Neutrino Observatory at the South Pole and a host of other instruments allowed researchers to track one cosmic neutrino to a distant blazar, a huge elliptical galaxy with a fast-spinning supermassive black hole at its heart. And there's more. Cosmic neutrinos go hand in hand with cosmic rays, highly energetic charged particles that slam into our planet continuously. So, the new find pegs blazars as accelerators of at least some of the fastest-moving cosmic rays as well. Astronomers have wondered about this since cosmic rays were first discovered, way back in 1912. But they've been thwarted by the particles' charged nature, which dictates that cosmic rays get tugged this way and that by various objects as they zoom through space. Success finally came from using the straight-line journey of a fellow-traveler ghost particle.
On Sept. 22, 2017, [...] IceCube picked up another cosmic neutrino. It was extremely energetic, packing about 300 teraelectron volts -- nearly 50 times greater than the energy of the protons cycling through Earth's most powerful particle accelerator, the Large Hadron Collider. Within 1 minute of the detection, the facility sent out an automatic notification, alerting other astronomers to the find and relaying coordinates to the patch of sky that seemed to house the particle's source. The community responded: Nearly 20 telescopes on the ground and in space scoured that patch across the electromagnetic spectrum, from low-energy radio waves to high-energy gamma-rays. The combined observations traced the neutrino's origin to an already-known blazar called TXS 0506+056, which lies about 4 billion light-years from Earth. The IceCube team also went through its archival data and found more than a dozen other cosmic neutrinos that seemed to be coming from the same blazar. These additional particles were picked up by the detectors from late 2014 through early 2015. The findings are reported in two separate studies published in the journal Science.
On Sept. 22, 2017, [...] IceCube picked up another cosmic neutrino. It was extremely energetic, packing about 300 teraelectron volts -- nearly 50 times greater than the energy of the protons cycling through Earth's most powerful particle accelerator, the Large Hadron Collider. Within 1 minute of the detection, the facility sent out an automatic notification, alerting other astronomers to the find and relaying coordinates to the patch of sky that seemed to house the particle's source. The community responded: Nearly 20 telescopes on the ground and in space scoured that patch across the electromagnetic spectrum, from low-energy radio waves to high-energy gamma-rays. The combined observations traced the neutrino's origin to an already-known blazar called TXS 0506+056, which lies about 4 billion light-years from Earth. The IceCube team also went through its archival data and found more than a dozen other cosmic neutrinos that seemed to be coming from the same blazar. These additional particles were picked up by the detectors from late 2014 through early 2015. The findings are reported in two separate studies published in the journal Science.
I'm just glad IceCube is doing something useful with the rest of his life.
There was a link to it in the story: https://www.space.com/41147-co...
The hard bit is 'given the timings and intensities of flashes I detected in my detector, what was the direction of the primary neutrino?' That gives a direction relative to the detector array, then all you need to know is the sidereal time and location on Earth of the detector to turn it into a direction on the sky, with some simple addition of angles. The uncertainty in neutrino direction is on the order of a degree (I've commented elsewhere on this) so effects much smaller than a degree can be ignored.
I did calculations quite similar to this for a cosmic ray experiment in my MSc thesis in 1988/89. I used likelihood calculations to determine direction and uncertainty in direction. I expect this experiment does the same.
Quattuor res in hoc mundo sanctae sunt: libri, liberi, libertas et liberalitas.
But when they issued the alert, other telescopes started looking at that 1.6 by 0.8 degrees. Some telescopes detected high energy gamma rays in the area, and those telescopes had much better accuracy. And there was a previously detected gamma ray source, located with even higher spacial accuracy, within that error ellipse. And the galaxy in turn was within this smallest error ellipse.
Here is the picture.
Even the smallest error ellipse probably contains a bunch of galaxies. I presume that just one of them looked 'weird' in some way, and so was assumed to have interesting activity at its core. I haven't taken the time to drill down that far into their identification process.
Quattuor res in hoc mundo sanctae sunt: libri, liberi, libertas et liberalitas.