Astronomers trace a ghostly cosmic particle to distant ‘Shadow Blaster’ galaxy

A distant star-forming galaxy nicknamed the “Shadow Blaster” may have sent a ghostly cosmic particle toward Earth.

Astronomers believe they can trace the particle’s origin back to 11 billion years ago light year It takes a step forward in understanding mysterious neutrinos.

Neutrinos are abundant in the universe and have a reputation as ghost particles because they have no electric charge, very little mass, and do not interact with other types of matter.

Supernovae, stellar nuclear reactions, and the disintegration of heavy particles can create neutrinos. But tracking exactly where neutrinos were coming from became more difficult for astronomers when detectors such as the IceCube Neutrino Observatory in Antarctica alerted to their presence.

Taiwan-based astronomy research company MITOS Science Co. Ltd. researcher Dr. “They rarely interact with matter, so they can travel through the universe almost undisturbed,” Yuji Urata said. “Even when IceCube detects a high-energy neutrino, the location in the sky often has a region of uncertainty much larger than the size of a galaxy.”

If the source is an object whose brightness remains constant and does not brighten due to activity, it seems impossible to focus on the origin of the neutrino.

But lead author Urata and his team had a chance encounter, according to the study published June 17 in the journal. Nature Astronomy.

A cosmic coincidence illuminated the Shadow Blaster galaxy shortly after a high-energy neutrino was detected on Earth; This indicates a burst of activity that is leading researchers directly into the galaxy and may point to a new way to investigate the origins of ghost particles.

How did the Shadow Blaster galaxy get its nickname?

Erik Blaufuss, a research scientist in the physics department at the University of Maryland, said that the IceCube detector, which has sensors placed deep in the Antarctic ice, detected the presence of a high-energy neutrino in 2021. Scientists detect this type every two to three years. Blaufuss was not included in the study.

The event that created the neutrino called IC 210922A was seen to have occurred in the direction of the Eridanus constellation, and the observatory issued a warning to the astronomy community. To find the particle’s starting point, scientists performed fast-tracking observations at different wavelengths of light.

But they failed to detect exploding stars, gamma-ray bursts, X-rays, or visible light components that might be associated with the neutrino.

“Neutrinos alone tell us that something energetic is happening somewhere in the sky, but they usually don’t tell us exactly what the source is, how far away it is, or what kind of object is producing them,” Urata wrote in an email. “To answer these questions, we need light: radio, submillimeter, infrared, optical, X-ray and gamma-ray observations.”

Days after the warning was issued, Urata and colleagues conducted observations with the East Asian Observatory’s James Clerk Maxwell Telescope and the submillimeter Array, both located near the summit of Mauna Kea in Hawaii. They discovered a galaxy rich in star formation called JCMT0402−0424.

The galaxy was trillions of times brighter than our sun in infrared light and was potentially in the right position to bind to the neutrino.

The team named the galaxy Shadow Blaster because it is filled with dust, making it nearly invisible in optical light, X-rays or gamma rays, Urata said. Blaster touched on the idea that, despite its secretive nature, the galaxy could be a powerful source of high-energy particles and neutrinos.

When researchers conducted additional follow-up observations using the Atacama Large Millimeter/submillimeter Array in Chile, they realized Shadow Blaster was located behind a gravitational lens.

Gravitational lensing occurs when a large galaxy in the foreground of an observation acts like a cosmic magnifying glass, magnifying a distant galaxy behind it.

“This lensing effect magnified the galaxy and allowed us to examine a hidden, compact star-forming region that would otherwise be much more difficult to detect,” Urata said.

Possibly an important source of high-energy neutrinos

He added that dense stellar nurseries in galaxies like the one in Shadow Blaster, which form new stars at a powerful rate, could provide gas, radiation and magnetic environments that act like particle accelerators to produce neutrinos.

“Star-forming galaxies are galaxies that produce large numbers of stars, some of which are very massive and rapidly blinking, exploding into supernovae, possibly accelerating cosmic rays in the process,” said Justin Vandenbroucke, a professor at the Wisconsin IceCube Center for Particle Astrophysics and the department of physics at the University of Wisconsin-Madison. He did not participate in the research.

In the early days of the universe, 10 billion years ago, there was an intense burst of star formation in galaxies like Shadow Blaster. Galaxies also created cosmic rays, which are the most energetic particles in the universe and can create neutrinos.

But making the connection between neutrinos and star-forming galaxies has been a difficult task, given that most galaxies are distant and faint due to the amount of dust they contain (a key ingredient in the formation of stars). Being able to look inside the Shadow Blaster through a gravitational lens makes this challenge easier, Urata said.

Star-forming galaxies like Shadow Blaster can be an important source of high-energy neutrinos.

“Our analysis suggests that this population may contribute up to roughly 20% of the observed scattered neutrino background measured by IceCube,” Urata said.

Vandenbroucke noted that finding the right galaxy near where the neutrino came from may have been a serendipitous coincidence.

“Researchers estimate there is about a 1% chance of this being a random coincidence,” he said. “Detecting more such relationships between such galaxies and high-energy neutrinos is necessary to determine whether they are truly neutrino sources.”

Scientists also want to know what conditions in a star-forming galaxy contribute to neutrino formation.

Observatories like ALMA and the James Webb Space Telescope are changing the way astronomers study distant, dusty, massive galaxies, Urata said.

“If some of these galaxies are also sources of neutrinos, then neutrinos could provide a completely new way to study how galaxies formed stars, generated magnetic fields, and accelerated cosmic rays when the universe was young,” he added.

Blaufuss noted that the study will motivate the search for deeper relationships between neutrinos and potential sources going forward.

Finding neutrinos using gravitational lenses could also enable deeper study of ghost particles that remain mysterious despite being detected for decades.

“Neutrinos provide a type of super X-ray vision, allowing us to study phenomena that our telescopes normally cannot see, in the same way that X-ray machines allow us to see inside people and objects,” Vandenbroucke said.

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