Messier 77, also known as NGC 1068, LEDA 10266 and Cetus A, is a barred spiral galaxy in the constellation of Cetus.
This image shows the barred spiral galaxy Messier 77, which lies in the constellation Cetus, about 47 million light-years away. Image credit: ESO.
Messier 77 has an apparent magnitude of 9.6 and lies at a distance of 47 million light-years.
The galaxy was discovered by the French astronomer Pierre Méchain in 1780, who originally identified it as a nebula.
Méchain then communicated the discovery to his colleague, French astronomer Charles Messier.
Messier believed that the highly luminous object he saw was a cluster of stars, but as technology progressed its true status as a galaxy was realized.
At 100,000 light-years across, Messier 77 is one of largest galaxies in the Messier catalogue — so massive that its gravity causes other nearby galaxies to twist and become warped.
Messier 77 is also one of the closest galaxies with an active galactic nucleus. Such active galaxies are among the brightest objects in the Universe and emit light at most, if not all, wavelengths, from gamma rays and X-rays all the way to microwaves and radiowaves.
It is also a Type II Seyfert galaxy, characterized by being particularly bright at infrared wavelengths.
“A supermassive black hole, obscured by cosmic dust, powers the nearby active galaxy Messier 77,” said Dr. Gary Hill, an astrophysicist in the Department of Physics at the University of Adelaide and a member of the IceCube Collaboration.
“Neutrinos, which rarely interact with matter, could provide information on the galaxy’s active core.”
“We searched for neutrino emission from astrophysical objects using data recorded with the IceCube neutrino detector between 2011 and 2020.”
In 2018, IceCube found the first ever source of neutrinos emitted by TXS 0506+056 — a blazar located off the left shoulder of the Orion constellation and 4 billion light-years away — from which super-massive black hole-powered particle jets, pointing straight at Earth, emit neutrinos.
This led to the joint observations over a short time period of neutrinos and gamma-rays.
Messier 77 is about 100 times closer and around 80 neutrino events have so far been identified from the active galaxy.
In contrast to the TXS 0506+056 blazar, Messier 77 is oriented relative to Earth in such a way that a direct view of the central emitting region is obscured by dust. Gamma-rays are absorbed but the neutrinos can escape uninhibited from these regions.
“After the excitement in 2018 of the discovery of neutrinos from TXS 0506+056, it’s even more thrilling to find a source producing a steady stream of neutrinos that we can see with IceCube,” Dr. Hill said.
“The fact that neutrinos can escape from within these otherwise-obscured regions of the Universe means they are also hard to detect.”
“This requires large detectors like IceCube, which is the current leader in the field with an instrumented volume of a cubic kilometer of deep South Pole ice.”
Many neutrinos pass clear through the Earth, but some interact in the ice near the detector and create muons, which emit flashes of light that are picked up by IceCube’s more than 5,000 basketball-sized optical sensors spread over 86 strings, deployed into holes drilled to nearly 2,500 m depth and now permanently frozen into the deep ice.
The patterns of light are used to infer the arrival directions and energies of the particles.
“One of the best aspects of my research journey so far has been the time I have spent at the South Pole over many summer seasons working on the installation teams deploying the detector strings into the ice,” Dr. Hill said.
“The enormous size of IceCube required many years of effort from hundreds of people around the world to complete construction and understand the response to high energy particles.”
“In a few years we’ll be back to the South Pole to put more instruments into the ice, as part of an effort to further improve the detector.”
The discovery is reported in a paper in the journal Science.
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R. Abbasi et al. (IceCube Collaboration). 2022. Evidence for neutrino emission from the nearby active galaxy NGC 1068. Science 378 (6619): 538-543; doi: 10.1126/science.abg3395
