Milky Way's black hole could be a natural particle accelerator, study finds

Milky Way's black hole could be a natural particle accelerator, study finds

The supermassive black hole at the centre of the Milky Way may be accelerating protons to peta electron volt energies, according to a preprint posted to arXiv by Marina Cermeño and colleagues. If they are right, the signal is detectable, just not yet.

The mechanism is the Penrose process, proposed by Roger Penrose in 1969. A spinning black hole drags space around with it, and close in, inside a region called the ergosphere, nothing can resist that drag. Matter that splits in two there can leave one piece falling in with negative energy while the other escapes with more energy than the original had. The black hole pays for it with a little of its own mass.

The team applied the magnetic version of the process to neutrons near Sagittarius A*. A neutron decays into a proton, an electron and a neutrino. The charged proton and electron then interact with the magnetic field in the ergosphere, and the paper estimates the protons can leave at PeV energies, roughly a thousand times what the Large Hadron Collider reaches.

Those protons would slam into the gas around the black hole and produce gamma rays with a distinctive spectrum, while the decays would add high energy neutrinos. That pairing of light and neutrinos is a multimessenger signature.

Both signals are too faint for current instruments. The authors point to an upgraded High Altitude Water Cherenkov observatory and the next generation of the IceCube Neutrino Observatory in Antarctica as the facilities that could pick them up. A detection would be the first observed sign of the Penrose process at work, and evidence that a black hole can lose mass.

SourcearXiv: Cermeño et al.Universe Today

SpaceX calls off two attempts to launch 21 SDA satellites

SpaceX aborted the launch of 21 Space Development Agency satellites in the final minute of the 5 October countdown at Vandenberg Space Force Base, as the Falcon 9 was moving into its automated startup sequence. SpaceX then called off its next attempt, set for 6 October, as well. A new launch date has not been confirmed.

The mission, Tranche 1 Transport Layer A, is the fourth to carry production satellites for the agency. All 21 were built by Northrop Grumman and arrived at Vandenberg on 28 September. Booster B1103 is flying for the sixth time and is due to land at Landing Zone 4 about seven and a half minutes after liftoff.

The satellites join the Proliferated Warfighter Space Architecture, the military's low Earth orbit network for missile tracking and secure communications. Three earlier launches have put 63 Tranche 1 satellites in orbit. The full tranche calls for 126 Transport Layer satellites, 28 Tracking Layer satellites and four missile defence demonstrators, with operational capability expected from 2027.

SourceSpaceflight Now

Redwire wins solar array contract for Axiom Station's second module

Axiom Space has hired Redwire to build two Roll-Out Solar Array wings for the second module of Axiom Station, the commercial outpost it plans as a successor to the International Space Station. Redwire is already building the arrays for the first module.

That first module is in final assembly at Thales Alenia Space in Turin and is due to launch in 2028. The second is about to start final assembly and should launch less than a year later, waiting in orbit until it can dock. Together the two modules make a free flying station for four crew.

The same array design has powered the International Space Station. Redwire says it has more than 65 solar array wings delivered or in development.

SourceRedwire

SMILE starts science and returns its first view of the northern aurora

SMILE, the joint mission of the European Space Agency and the Chinese Academy of Sciences, has officially begun science operations. Its first ultraviolet images show a complete ring of aurora around Earth's north pole.

The spacecraft launched on a Vega C from Kourou on 19 May and spent the next month raising its orbit, reaching its working path on 20 June. That orbit is inclined 73 degrees and runs from 5,027 km to 120,920 km, which keeps SMILE high above the poles for about nine months of the year.

Four instruments, a soft X-ray imager, an ultraviolet imager, a light ion analyser and a magnetometer, will watch how the solar wind and solar storms push on Earth's magnetic field. "This is a very important milestone," said Carole Mundell, ESA's Director of Science.

SourceNASASpaceflight

Iron in cosmic rays can trigger cancer in cells it never touches

Galactic cosmic rays may do their worst damage to astronauts through the cells they miss, not the ones they hit. Researchers at Oklahoma State University and the University of Texas Health Science Center found that a cell struck by a heavy iron ion sends out chemical signals that push its unharmed neighbours toward cancer.

On a three year round trip to Mars, estimates based on Curiosity's flight data suggest only about 3 percent of an astronaut's cells would take a direct hit from an iron ion. The team bombarded human blood vessel lining cells with iron ion beams at the NASA Space Radiation Laboratory at Brookhaven. The struck cells triggered a long running inflammatory loop, releasing the signalling molecule TNF alpha for up to three days.

Lung lining cells that shared only liquid with the irradiated cells, without touching them, showed spikes in free radicals and double strand DNA breaks, and their normal safeguards against runaway growth were switched off. When those bystander cells were implanted in mice, they grew tumours.

Blocking the TNF alpha receptor broke the chain and spared the cells. The researchers suggest pairing drugs like that with shielding such as water walls and hydrogen rich plastics on deep space missions.

SourceUniverse TodayPhys.org