9 thoughts on “Magneto’s star”

1. This seminar discusses the life cycle of black holes:

   Alan Weinstein, Professor of Physics (Physics, Mathematics and Astronomy)

   LISTENING TO THE DANCE OF BLACK HOLES

   Black holes are the sites of the strongest gravitational fields in the universe. In pairs, they orbit each other, and the rapidly changing gravity produces vibrations of space itself, which travel to us as gravitational waves. As the pair loses all of its orbital energy, the two black holes merge into one, emitting an incredible burst of gravitational waves. LIGO (the Laser Interferometer Gravitational-Wave Observatory), operated by Caltech and MIT, have designed, built, and operated two huge detectors that can now “hear” these vibrations from the warped parts of the universe. Come listen! — Caltech | Alumni Reunion Weekend 2017 (80th Annual Seminar Day) Program

2. This August 2, 2017, Space.com article “Rebel Supernova Formed in ‘Heavy Metal’ Galaxy” discusses research on superluminous supernovas.

   The researchers also investigated what makes SN 2017egm so bright. They concluded that the supernova may be powered by a rapidly spinning dead star called a magnetar. Such ultradense, spinning neutron stars created by supernovas could continue to generate magnetic power that would heat up the expanding gas left over from the supernova.

3. Today (October 25, 2017), this Space.com article “Magnetic Fields Are the Unsung Workhorses of Astrophysics” caught my attention. It reminded me of how the Voyager space probes monitored magnetic fields in order to mark interstellar space.

   Galaxy clusters’ magnetic fields are particularly intriguing. For one, they completely fill up the volume of their host cluster. For those keeping score, that’s somewhere around 10^20 cubic light-years of nearly empty space. Despite their gargantuan size, those enormous magnetic fields are not perfectly smooth. They’re tangled and bent on the scale of tens of thousands of light-years. That means that, if you had a sufficiently sensitive compass, you could follow a single magnetic-field line for about the width of a galaxy before it would branch off into a new direction.

   … The answer might lie in the dynamos themselves, particularly the ones around supermassive black holes. These monstrous engines power active galactic nuclei. We see the intense radiation jetting away from these objects, and we know those jets are highly magnetized. Is it enough to completely fill up the enormous volume of galaxy clusters?

4. Phys.org > “Researchers theorize origins of magnetars, the strongest magnets in the universe” by Heidelberg University (October 9, 2019)

   How do some neutron stars become the strongest magnets in the universe? A German-British team of astrophysicists has found a possible answer to the question of how magnetars form. They used large computer simulations to demonstrate how the merger of two stars creates strong magnetic fields. If such stars explode in supernovae, magnetars can result. Scientists from Heidelberg University, the Max Planck Society, the Heidelberg Institute for Theoretical Studies, and the University of Oxford were involved in the research. The results were published in Nature.

5. Compare the strength of a magnetar’s field to that of the best man-made accelerator > Phys.org > “Fermilab achieves world-record field strength for accelerator magnet” by Leah Hesla, Fermi National Accelerator Laboratory (September 9, 2019)

   Scientists at the Department of Energy’s Fermilab have announced that they achieved the highest magnetic field strength ever recorded for an accelerator steering magnet, setting a world record of 14.1 teslas, with the magnet cooled to 4.5 kelvins or minus 450 degrees Fahrenheit. The previous record of 13.8 teslas, achieved at the same temperature, was held for 11 years by Lawrence Berkeley National Laboratory.

   That’s more than a thousand times stronger magnet than the refrigerator magnet that’s holding your grocery list to your refrigerator.

   The project is supported by the Department of Energy Office of Science. It is a key part of the U.S. Magnet Development Program, which includes Fermilab, Brookhaven National Laboratory, Lawrence Berkeley National Laboratory and the National High Magnetic Field Laboratory.

6. The fastest spinning magnetar known …

   Phys.org > “Mysterious spinning neutron star detected in the Milky Way proves to be an extremely rare discovery” by ARC Centre of Excellence for Gravitational Wave Discovery (July 7, 2020).

   On March 12th 2020 a space telescope called Swift detected a burst of radiation from halfway across the Milky Way. Within a week, the newly discovered X-ray source, named Swift J1818.0–1607, was found to be a magnetar, a rare type of slowly rotating neutron star with one of the most powerful magnetic fields in the universe.

   Spinning once every 1.4 seconds, it’s the fastest spinning magnetar known, and possibly one of the youngest neutron stars in the Milky Way. It also emits radio pulses like those seen from pulsars—another type of rotating neutron star. At the time of this detection, only four other radio-pulse-emitting magnetars were known, making Swift J1818.0–1607 an extremely rare discovery.

   These observations were made using the ultra wideband-low (UWL) receiver system installed on the Parkes radio telescope, also known as The Dish. Whereas most telescopes are limited to observing radio waves across very narrow frequency strips, the Parkes UWL receiver can detect radio waves across an extremely wide range of frequencies all at the same time.

   The spin-down rates of magnetars are highly variable on year-long timescales, particularly after outbursts, and can lead to incorrect age estimates.

7. Another benchmark in the cosmic distance ladder.

   • Phys.org > “VLBA makes first direct distance measurement to magnetar” by National Radio Astronomy Observatory (Sept 18, 2020)

   A team of astronomers used the [National Science Foundation’s Very Long Baseline Array] VLBA to regularly observe XTE J1810-197 from January to November of 2019, then again during March and April of 2020. By viewing the magnetar from opposite sides of the Earth’s orbit around the Sun, they were able to detect a slight shift in its apparent position with respect to background objects much more distant. This effect, called parallax, allows astronomers to use geometry to directly calculate the object’s distance.

   “This is the first parallax measurement for a magnetar, and shows that it is among the closest magnetars known – at about 8100 light-years – making it a prime target for future study,” said Hao Ding, a graduate student at the Swinburne University of Technology in Australia.

   “Having a precise distance to this magnetar means that we can accurately calculate the strength of the radio pulses coming from it. If it emits something similar to an FRB, we will know how strong that pulse is,” said Adam Deller, also of Swinburne University. “FRBs vary in their strength, so we would like to know if a magnetar pulse comes close or overlaps with the strength of known FRBs,” he added.

8. Neutron star magnetic fields and X-ray binaries.

   • Phys.org > “Strongest magnetic field in universe directly detected by X-ray space observatory” by Liu Jia, Chinese Academy of Sciences (Sept 10, 2020)

   The Insight-HXMT [the first Chinese X-ray astronomical satellite] team has performed extensive observations of the accreting X-ray pulsar GRO J1008-57 and has discovered a magnetic field of ~1 billion Tesla [“which is tens of millions of times stronger than what can be generated in Earth laboratories”] on the surface of the neutron star. This is the strongest magnetic field conclusively detected in the universe. This work, published in the Astrophysical Journal, was primarily conducted by scientists from the Institute of High Energy Physics (IHEP) of the Chinese Academy of Sciences and Eberhard Karls University of Tübingen, Germany.

   Neutron stars have the strongest magnetic fields in the universe. Neutron star X-ray binaries are systems consisting of a neutron star and a normal stellar companion. The neutron star accretes matter and forms a surrounding accretion disk. If the magnetic field is strong, the accreted matter is channeled by magnetic lines onto the surface of the neutron star, resulting in X-ray radiations.

9. Magnetars … Milky Way fast radio bursts …

   • Caltech Weekly > “A Magnificent Burst from Within Our Galaxy” (November 4, 2020) – Caltech’s STARE2 project helps pinpoint cause of mysterious fast radio bursts

   A suite of radio antennas, including those making up Caltech’s STARE2 (Survey for Transient Astronomical Radio Emission 2) project, together with other ground- and space-based observatories, have captured overwhelming evidence to help unlock the mysterious cause of cosmic blasts known as fast radio bursts, or FRBs.

   The FRB was first detected on April 28, 2020, by the Canadian Hydrogen Intensity Mapping Experiment, or CHIME, located in southwestern Canada. Though CHIME caught the blast in its peripheral vision, outside where the telescope is most sensitive, it was clear that the signal was coming from our own Milky Way galaxy (before now, all observed FRBs had originated from outside our galaxy).

   … this event amounts to the most energetic radio blast ever recorded from our galaxy, shooting out as much energy as the sun produces in about 30 seconds, assuming the magnetar’s estimated distance of about 30,000 light-years.

   STARE2, a Caltech-led project with funding from NASA’s Jet Propulsion Laboratory (JPL) and Caltech, consists of three radio receivers, each about the size of a large bucket. They are located at Caltech’s Owens Valley Radio Observatory; the Goldstone Deep Space Communications Complex operated by JPL; and near the town of Delta, Utah. STARE2 is not nearly as sensitive as CHIME but has a wider field of view that covers basically the whole visible sky, and it observes at radio frequencies that are twice as high as those seen by CHIME.

   • YouTube > NASA > “NASA Missions Team Up to Study Unique Magnetar Outburst” (Nov 4, 2020)

   On April 28, a supermagnetized stellar remnant known as a magnetar blasted out a simultaneous mix of X-ray and radio signals never observed before. The flare-up included the first fast radio burst (FRB) ever seen from within our Milky Way galaxy and shows that magnetars can produce these mysterious and powerful radio blasts previously only seen in other galaxies.

   • CNET > “Mysterious fast radio burst spotted in the Milky Way traced to extreme, rare star” by Jackson Ryan (Nov 4, 2020) – The first detection of a fast radio burst inside the Milky Way leads astronomers back to a magnetar, partially solving a long-standing mystery.

   “Magnetars occasionally produce bursts of bright X-ray emission,” says Adam Deller, an astrophysicist at Swinburne University in Melbourne, Australia, “but most magnetars have never been seen to emit any radio emission.”

   All in all, there’s still some uncertainty. “We cannot say for certain if magnetars are the sources of all of the FRBs observed to date,” Weltman [astrophysicist at the University of Cape Town] notes.

   Another question: How did Mag-1 generate the FRB? Two different mechanisms have been proposed.

   The investigation will, ultimately, change the way we see the universe. Duncan Lorimer notes that if FRBs can be definitively linked to neutron stars, it would provide a way to take a census of those extreme cosmic entities. Current methods can’t identify neutron star types with great specificity …

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