The supernova remnant 3C 58 contains at its center a rotating neutron star known as PSR J0205+6449. Astronomers have studied this neutron star and others like it to investigate the nature of the matter inside these very dense objects. A new study using NASA’s Chandra X-ray Observatory and ESA’s XMM-Newton reveals that the interiors of neutron stars may contain a type of ultradense matter found nowhere else in the universe.
In this image of 3C 58, low-energy X-rays are colored red, intermediate-energy X-rays are green, and the high-energy X-ray band is shown in blue. The X-ray data were combined with an optical image in yellow from the Digitized Sky Survey. The Chandra data show that the rapidly rotating neutron star (also known as a “pulsar”) at the center is surrounded by a torus of X-ray emission and a jet that stretches several light years. The optical data shows the stars in the field.
In this new study, the team analyzed previously published data from neutron stars to determine the so-called equation of state. This refers to the basic properties of neutron stars, including the pressures and temperatures in different parts of their interior.
The authors used machine learning, a type of artificial intelligence, to compare the data with different equations of state. Their results suggest that a significant fraction of the equations of state—those that do not include the ability to rapidly cool at higher masses—can be ruled out.
The researchers took advantage of the fact that some of the neutron stars in the study are found in supernova remnants, including 3C 58. Since astronomers have estimates of the ages of supernova remnants, they also have the ages of neutron stars that formed during the explosions that created both remnants. and neutron stars. The astronomers found that the neutron star in 3C 58 and two others were much cooler than the rest of the neutron stars in the study.
The team thinks that part of the explanation for the rapid cooling is that these neutron stars are more massive than most. Because more massive neutron stars have more particles, special processes can be triggered that cause neutron stars to cool faster.
One possibility is that what’s inside these neutron stars is a type of radioactive decay near their centers, where neutrinos — light-mass particles that move easily through matter — carry away much of the energy and heat, causing rapid cooling.
Another possibility is that species of exotic matter reside in the centers of these faster-cooling neutron stars.
A Nature Astronomy paper describing these results is available here. The authors of the paper are Alessio Marino (Institute of Space Sciences (ICE) in Barcelona, ​​Spain), Clara Dehman (ICE), Konstantinos Kovlakas (ICE), Nanda Rea (ICE), JA Pons (University of Alicante, Spain), and Daniele Viganò ( ICE).
NASA’s Marshall Space Flight Center manages the Chandra program. The Smithsonian Astrophysical Observatory’s Chandra X-ray Center manages science from Cambridge Massachusetts and flight operations from Burlington, Massachusetts.
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This is an image of debris from an exploded star called 3C 58, shown in X-ray and optical light. At the center of the remnant is a rapidly rotating neutron star called a pulsar, which presents itself as a bright white object that has a somewhat elongated shape.
Loops and swirls of material in shades of blue and purple extend from the neutron star in many directions, resembling the shape of an octopus and its arms.
Surrounding the octopus-like structure is a cloud of red-hued material that is wider horizontally than vertically. A ribbon of purple material stretches to the left edge of the red cloud, curling upwards at the end. Another purple ribbon stretches to the right edge of the red cloud, although it is less prominent than the one on the other side. Stars of many shapes and sizes flow throughout the image.
Megan Watzke
Chandra X-ray Centre
Cambridge, Mass.
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Jonathan Deal
Marshall Space Flight Center
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