Astronomers capture a pulsar ‘powering up’

Astronomers capture a pulsar ‘powering up’

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Melbourne: The Monash-University-led collaboration first observed the entire 12-day process of physical spiraling in a neutron star far from the outbreak of X-rays thousands of times faster than our Sun.
The research, led by PhD candidate Adele Goodwin from the Monash School of Physics and Astronomy, will be featured in the American Astronomical Society before being published in the Royal Astronomical Society’s monthly notice to be held this week.
Adele leads a team of international researchers, including her supervisor, Duncan Galloway, Associate Professor at Monash University, and Dr. David Russell of New York University Abu Dhabi.
Scientists observed an ‘accreting’ neutron star as it entered an abusive phase involving five groups of researchers, seven telescopes (five on the ground, two in space), and 15 collaborators in an international collaborative effort.
This is the first time such a phenomenon has been observed in this expansion — in many frequencies, including high sensitivity measurements in both optical and X-rays.
The physicists behind this ‘switching on’ process have sidelined physicists for decades, partly because there are few widespread observations of the phenomenon.
The researchers instigated one of these to enter the neutron star system. They observed the onset of the outbreak from the first sign of optical activity, all the way to the end of the outburst, until the beginning of X-ray emission.
Observations showed that the material took 12 days to rotate inward and the neutron collided with the star, which was much longer than previously thought.
“These observations allow us to study the structure of the accretion disk, and determine how quickly and easily the material can move inward toward the neutron star,” Adele said.
“Using multiple telescopes that are sensitive to light at different energies, we were able to detect that the initial activity occurred near the companion star, in the outer edges of the accretion disk, and it took 12 days to heat the disc. Went. The material for the spiral in the state and inward to the neutron star, and X-rays have to be produced, “she said.
In the ‘Acting’ neutron star system, a pulsar (a dense remnant of an old star) strips the material away from the nearby star, creating an attrition disk of the material spiraling toward the pulsar from where an extraordinary amount of energy Turns out – the total energy output of the Sun in about 10 years, over a period of a few weeks.
It is so energetic that most of the radiation is released in the highest energy part of the electromagnetic spectrum: in X-rays.
Some acting neutron stars are not always active and can spend years in a cool state, known as cultivars, where they emit absolutely no light and accumulate at very low rates. They can go into sudden outbreaks and be extremely bright in X-rays for about a month.
Pulsar’s observation is SAX J1808.4-3658 which rotates 400 times per second and is located 11,000 light years away in the constellation Sagittarius.
What the researchers saw was unexpected: it took 12 days before the first sign of increased optical activity to observe any high-energy X-ray emission.
While the neutron star orbits its partner every 2 hours, an X-ray appears 12 days after visible light increases – which is remarkably long, with most theories suggesting that there should only be a delay of two to three days .
“This work enables us to shed some light on the physics of neutron star systems, and to understand how these explosive outbreaks are triggered,” said a researcher from New York University in Abu Dhabi. Dr. David Russell, one of the study’s co-authors.
Alternating disks are usually made of hydrogen, but this particular object consists of a disk made up of 50 percent helium, more helium than most disks. Scientists think that this excess helium may slow down the heating of the disk because helium “burns” at high temperatures, taking 12 days to “power up”.
The telescopes involved include two space observatories: the Neil Gehrels Swift X-ray Observatory and the Neutron Star Interior Composition Explorer (NICER) at the International Space Station, as well as the geo-based Las Combs Observatory Network of Telescopes and South African Large. Telescope (SALT).


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