From NASA Chandra and From NASA NuSTAR: “Reclusive Neutron Star May Have Been Found in Famous Supernova”

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NASA Chandra X-ray Space Telescope

From NASA Chandra

February 23, 2021

Media contacts:
Megan Watzke
Chandra X-ray Center, Cambridge, Mass.
617-496-7998
mwatzke@cfa.harvard.edu

Molly Porter
Marshall Space Flight Center, Huntsville, Alabama
256-544-0034
molly.a.porter@nasa.gov

Astronomers now have evidence from two X-ray telescopes (Chandra and NuSTAR) for a key component of a famous supernova remnant.

NASA/DTU/ASI NuSTAR X-ray telescope.

Supernova 1987A was discovered on Earth on February 24, 1987, making it the first such event witnessed during the telescopic age.

SN 1987A remnant, imaged by ALMA. The inner region is contrasted with the outer shell, lacy white and blue circles, where the blast wave from the supernova is colliding with the envelope of gas ejected from the star prior to its powerful detonation. Image credit: ALMA / ESO / NAOJ / NRAO / Alexandra Angelich, NRAO / AUI / NSF.

SN1987A. Credit: NASA/ESA Hubble Space Telescope in January, 2017 using its Wide Field Camera 3 (WFC3).

NASA/ESA Hubble WFC3

NASA/ESA Hubble Telescope.

For decades, scientists have searched for a neutron star in SN 1987A, i.e. a dense collapsed core that should have been left behind by the explosion.

This latest study shows that a “pulsar wind nebula” created by such a neutron star may be present.
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Astronomers have found evidence for the existence of a neutron star at the center of Supernova 1987A (SN 1987A), which scientists have been seeking for over three decades. As reported in our latest press release, SN 1987A was discovered on February 24, 1987. The panel on the left contains a 3D computer simulation, based on Chandra data, of the supernova debris from SN 1987A crashing into a surrounding ring of material. The artist’s illustration (right panel) depicts a so-called pulsar wind nebula, a web of particles and energy blown away from a pulsar, which is a rotating, highly magnetized neutron star. Data collected from NASA’s Chandra X-ray Observatory and NuSTAR in a new study support the presence of a pulsar wind nebula at the center of the ring.

If this result is upheld by future observations, it would confirm the existence of a neutron star in SN 1987A, the collapsed core that astronomers expect would be present after the star exploded. The pulsar would also be the youngest one ever found.

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NuSTAR and Chandra images of Supernova 1987A. Credit: NASA.

When a star explodes, it collapses onto itself before the outer layers are blasted into space. The compression of the core turns it into an extraordinarily dense object, with the mass of the Sun squeezed into an object only about 10 miles across. Neutron stars, as they were dubbed because they are made nearly exclusively of densely packed neutrons, are laboratories of extreme physics that cannot be duplicated here on Earth. Some neutron stars have strong magnetic fields and rotate rapidly, producing a beam of light akin to a lighthouse. Astronomers call these objects “pulsars,” and they sometimes blow winds of charged particles that can create pulsar wind nebulas.

Dame Susan Jocelyn Bell Burnell, discovered pulsars with radio astronomy. Jocelyn Bell at the Mullard Radio Astronomy Observatory, Cambridge University, taken for the Daily Herald newspaper in 1968. Denied the Nobel.

With Chandra and NuSTAR, the team found relatively low-energy X-rays from the supernova debris crashing into surrounding material. The team also found evidence of high-energy particles, using NuSTAR’s ability to detect higher-energy X-rays.

There are two likely explanations for this energetic X-ray emission: either a pulsar wind nebula, or particles being accelerated to high energies by blast wave of the explosion. The latter effect doesn’t require the presence of a pulsar and occurs over much larger distances from the center of the explosion.

The latest X-ray study supports the case for the pulsar wind nebula on a couple of fronts. First, the brightness of the higher energy X-rays remained about the same between 2012 and 2014, while the radio emission increased. This goes against expectations in the scenario of energetic particles in the explosion debris. Next, authors estimate it would take almost 400 years to accelerate the electrons up to the highest energies seen in the NuSTAR data, which is over ten times older than the age of the remnant.

The Chandra and NuSTAR data also support a 2020 result from the Atacama Large Millimeter Array (ALMA) that provided possible evidence for the structure of a pulsar wind nebula in the radio band.

ESO/NRAO/NAOJ ALMA Array in Chile in the Atacama at Chajnantor plateau, at 5,000 metres.

While this “blob” had other potential explanations, its identification as a pulsar wind nebula could be substantiated with the new X-ray data.

The center of SN 1987A is surrounded by gas and dust. The authors used state-of-the-art simulations to understand how this material would absorb X-rays at different energies, enabling more accurate interpretation of the X-ray spectrum, that is, the spread of X-rays over wavelength. This enables them to estimate what the spectrum of the central regions of SN 1987A is without the obscuring material.

A paper describing these results is being published this week in The Astrophysical Journal Letters. The authors of the paper are Emanuele Greco and Marco Miceli (University of Palermo[Università degli Studi di Palermo](IT)), Salvatore Orlando, Barbara Olmi and Fabrizio Bocchino (Palermo Astronomical Observatory[Giuseppe S. Vaiana Astronomical Observatory](IT), an Italian National Institute for Astrophysics [Istituto Nazionale di Astrofisica](IT) research facility); Shigehiro Nagataki and Masaomi Ono (Astrophysical Big Bang Laboratory, RIKEN Institute of Physical and Chemical Research [Kokuritsu Kenkyū Kaihatsu Hōjin Rikagaku Kenkyūsho (国立研究開発法人理化学研究所](JP) ); Akira Dohi (Kyushu University[九州大学, Kyūshū Daigaku](JP), and Giovanni Peres (University of Palermo).

NuSTAR is a Small Explorer mission led by Caltech and managed by NASA’s Jet Propulsion Laboratory for the agency’s Science Mission Directorate in Washington. NuSTAR was developed in partnership with the Technical University of Denmark[Danmarks Tekniske Universitet](DK) and the ASI Italian Space Agency [Agenzia Spaziale Italiana](IT). The spacecraft was built by Orbital Sciences Corporation in Dulles, Virginia(US) (now part of Northrop Grumman). NuSTAR’s mission operations center is at UC Berkeley(US), and the official data archive is at NASA’s High Energy Astrophysics Science Archive Research Center(US). ASI provides the mission’s ground station and a mirror archive. JPL is a division of Caltech.


Quick Look: Supernova 1987A Pulsar Wind Nebula

See the full article here.


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NuSTAR is a Small Explorer mission led by Caltech and managed by NASA’s Jet Propulsion Laboratory for the agency’s Science Mission Directorate in Washington. NuSTAR was developed in partnership with the Technical University of Denmark[Danmarks Tekniske Universitet](DK) and the ASI Italian Space Agency [Agenzia Spaziale Italiana](IT). The spacecraft was built by Orbital Sciences Corporation in Dulles, Virginia(US) (now part of Northrop Grumman). NuSTAR’s mission operations center is at UC Berkeley(US), and the official data archive is at NASA’s High Energy Astrophysics Science Archive Research Center(US). ASI provides the mission’s ground station and a mirror archive. JPL is a division of Caltech.


NuSTAR’s mission operations center is at UC Berkeley, with the ASI providing its equatorial ground station located at Malindi, Kenya. The mission’s outreach program is based at Sonoma State University, Rohnert Park, Calif. NASA’s Explorer Program is managed by Goddard. JPL is managed by Caltech for NASA.

NASA’s Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program for NASA’s Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory controls Chandra’s science and flight operations from Cambridge, Mass.