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#20 by jbenton on 27 Nov, 2022 00:55
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This from Nov. 10...
https://www.nasa.gov/mission_pages/ixpe/news/2022/nasa-s-ixpe-finds-powerful-magnetic-fields-and-solid-crust-at-neutron-star.htmlQuoteLess than a year after launching, NASA’s Imaging X-ray Polarimetry Explorer’s (IXPE) observations of a neutron star have led to confirmation of what scientists have only previously theorized: magnetars have ultra-strong magnetic fields and are highly polarized.
Scientists used IXPE to observe the magnetar 4U 0142+61, a neutron star located in the Cassiopeia constellation, about 13,000 light-years away from Earth. This is the first-ever observation X-ray polarization from a magnetar, a neutron star with the most powerful magnetic fields in the universe.
Astronomers found that the neutron star likely has a solid surface and no atmosphere. This is the first time that scientists have been able to reliably conclude that a neutron star has a bare solid crust, a finding enabled by IXPE’s X-ray polarization measurements.
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Scientists were surprised to learn energy levels can affect polarization.
“Based on current theories for the magnetars, we expected to detect polarization, but no one predicted polarization would depend on energy, as we are seeing in this magnetar,” said Martin Weisskopf, a NASA emeritus scientist who led the IXPE team from the mission’s inception until spring 2022.
Additionally, the polarization at low energies indicates that the magnetic field is so unimaginably powerful that it could have turned the atmosphere around the neutron star into a solid or a liquid.
“This is a phenomenon known as magnetic condensation,” said chairman of the IXPE’s magnetar topical working group, Roberto Turolla, with the University of Padova and University College London.
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For Weisskopf, it’s clear that IXPE’s observations have been critical.
“In my mind, there can be no question that IXPE has shown that X-ray polarimetry is important and relevant to furthering our understanding of how these fascinating X-ray systems work,” he said. “Future missions will have to be cognizant of this fact.”
... and this from Nov. 24
https://scitechdaily.com/astrophysicists-solve-40-year-old-black-hole-jet-mystery-with-nasas-ixpe/QuoteBlazars are some of the brightest objects in the cosmos. They are composed of a supermassive black hole feeding off material swirling around it in a disk, which can create two powerful jets perpendicular to the disk on each side. A blazar appears especially bright from the perspective of our telescopes because one of its powerful jets of high-speed particles points straight at Earth. For decades, scientists have wondered: How do particles in these jets get accelerated to such high energies?
NASA’s Imaging X-Ray Polarimetry Explorer, or IXPE, has helped astronomers get closer to an answer. In a new study that was published on November 23 in the journal Nature, authored by a large international collaboration, astronomers find that the best explanation for the particle acceleration is a shock wave within the jet.
“This is a 40-year-old mystery that we’ve solved,” said Yannis Liodakis, lead author of the study and astronomer at FINCA, the Finnish Centre for Astronomy with ESO. “We finally had all of the pieces of the puzzle, and the picture they made was clear.”
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The new study used IXPE to point at Markarian 501, a blazar located aproximately 450 million light years away from Earth in the constellation Hercules. This active black hole system sits at the center of a large elliptical galaxy.
IXPE watched Markarian 501 for three days in early March of 2022, and then again two weeks later. During these observations, astronomers used other telescopes in space and on the ground to gather information about the blazar in a wide range of wavelengths of light including radio, optical, and X-ray. While other studies have looked at the polarization of lower-energy light from blazars in the past, this was the first time scientists could get this perspective on a blazar’s X-rays, which are emitted closer to the source of particle acceleration.
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Scientists found that X-ray light is more polarized than optical, which is more polarized than radio. But the direction of the polarized light was the same for all the wavelengths of light observed and was also aligned with the jet’s direction.
After comparing their information with theoretical models, the team of astronomers realized that the data most closely matched a scenario in which a shock wave accelerates the jet particles. A shock wave is generated when something moves faster than the speed of sound of the surrounding material, such as when a supersonic jet flies by in our Earth’s atmosphere.
Emphasis in those two quotes are mine, not in the original.
The discovery in the first article really drives home just how insanely powerful magnetars are.
I'd say that the study mentioned in the second article might've been something for black hole scientists to be thankful for this Thanksgiving.
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#21 by Rondaz on 09 Dec, 2022 21:38
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IXPE Celebrates 1 Year of Exploring the Cosmos
Beth Ridgeway Posted on December 9, 2022
One year ago, NASA’s Imaging X-ray Polarimetry Explorer (IXPE) lit up the early morning sky as it started its journey into space. The satellite was launched on a Falcon 9 rocket from NASA’s Kennedy Space Center in Florida on Dec. 9, 2021.
IXPE is the first satellite dedicated to measuring the polarization of X-rays from a variety of cosmic sources, such as black holes and neutron stars. Polarization is a property of light that gives scientists important information about cosmic objects. Before IXPE, X-ray polarization was rarely measured in space. In just one year, IXPE has conducted measurements no telescope has ever been able to make before.
Here’s a look at some of IXPE’s accomplishments in the first year of its mission:
IXPE unlocked the secrets of Cassiopeia A, a famous exploded star.
Findings from IXPE’s observation of neutron star Hercules X-1 surprised scientists.
IXPE revealed the shape and orientation of hot matter around a black hole.
Thanks to IXPE, scientists confirmed magnetars are highly polarized.
NASA’s IXPE helped solve a 40-year mystery around particle acceleration in a blazar, an active black hole that has a jet pointed toward Earth.
IXPE is just getting started. Its baseline mission duration is two years, so with at least one more year of exploration to go, the satellite is poised to make more exciting discoveries about the intricacies of X-ray polarization. Happy first anniversary, IXPE!
https://blogs.nasa.gov/ixpe/2022/12/09/ixpe-celebrates-1-year-of-exploring-the-cosmos/
