https://phys.org/news/2020-06-cosmic-baby-brilliant.html A cosmic baby is discovered, and it's brilliant: Please Register or Log in to view the hidden image! This illustration shows magnetic field lines protruding from a highly magnetic neutron star, or a dense nugget left over after a star goes supernova and explodes. Known as magnetars, these objects generate bright bursts of light that might be powered by their strong magnetic fields. Credit: ESA Astronomers tend to have a slightly different sense of time than the rest of us. They regularly study events that happened millions or billions of years ago, and objects that have been around for just as long. That's partly why the recently discovered neutron star known as Swift J1818.0-1607 is remarkable: A new study in the journal Astrophysical Journal Letters estimates that it is only about 240 years old—a veritable newborn by cosmic standards. NASA's Neil Gehrels Swift Observatory spotted the young object on March 12, when it released a massive burst of X-rays. Follow-up studies by the European Space Agency's XMM-Newton observatory and NASA's NuSTAR telescope, which is led by Caltech and managed by the agency's Jet Propulsion Laboratory, revealed more of the neutron star's physical characteristics, including those used to estimate its age. A neutron star is an incredibly dense nugget of stellar material left over after a massive star goes supernova and explodes. In fact, they're some of the densest objects in the universe (second only to black holes): A teaspoon of neutron star material would weigh 4 billion tons on Earth. The atoms inside a neutron star are smashed together so tightly, they behave in ways not found anywhere else. Swift J1818.0-1607 packs twice the mass of our Sun into a volume more than one trillion times smaller. With a magnetic field up to 1,000 times stronger than a typical neutron star—and about 100 million times stronger than the most powerful magnets made by humans—Swift J1818.0-1607 belongs to a special class of objects called magnetars, which are the most magnetic objects in the universe. And it appears to be the youngest magnetar ever discovered. If its age is confirmed, that means light from the stellar explosion that formed it would have reached Earth around the time that George Washington became the first president of the United States. "This object is showing us an earlier time in a magnetar's life than we've ever seen before, very shortly after its formation," said Nanda Rea, a researcher at the Institute of Space Sciences in Barcelona and principal investigator on the observation campaigns by XMM Newton and NuSTAR (short for Nuclear Spectroscopic Telescope Array). While there are over 3,000 known neutron stars, scientists have identified just 31 confirmed magnetars—including this newest entry. Because their physical properties can't be re-created on Earth, neutron stars (including magnetars) are natural laboratories for testing our understanding of the physical world. more at link.... the paper: https://iopscience.iop.org/article/10.3847/2041-8213/ab9742 A Very Young Radio-loud Magnetar: Abstract The magnetar Swift J1818.0–1607 was discovered in 2020 March when Swift detected a 9 ms hard X-ray burst and a long-lived outburst. Prompt X-ray observations revealed a spin period of 1.36 s, soon confirmed by the discovery of radio pulsations. We report here on the analysis of the Swift burst and follow-up X-ray and radio observations. The burst average luminosity was L burst ~ 2 × 1039 erg s−1 (at 4.8 kpc). Simultaneous observations with XMM-Newton and NuSTAR three days after the burst provided a source spectrum well fit by an absorbed blackbody (Please Register or Log in to view the hidden image! = (1.13 ± 0.03) × 1023 cm−2 and kT = 1.16 ± 0.03 keV) plus a power law (Γ = 0.0 ± 1.3) in the 1–20 keV band, with a luminosity of ~8 × 1034 erg s−1, dominated by the blackbody emission. From our timing analysis, we derive a dipolar magnetic field B ~ 7 × 1014 G, spin-down luminosity Please Register or Log in to view the hidden image! erg s−1, and characteristic age of 240 yr, the shortest currently known. Archival observations led to an upper limit on the quiescent luminosity <5.5 × 1033 erg s−1, lower than the value expected from magnetar cooling models at the source characteristic age. A 1 hr radio observation with the Sardinia Radio Telescope taken about 1 week after the X-ray burst detected a number of strong and short radio pulses at 1.5 GHz, in addition to regular pulsed emission; they were emitted at an average rate 0.9 min−1 and accounted for ~50% of the total pulsed radio fluence. We conclude that Swift J1818.0–1607 is a peculiar magnetar belonging to the small, diverse group of young neutron stars with properties straddling those of rotationally and magnetically powered pulsars. Future observations will make a better estimation of the age possible by measuring the spin-down rate in quiescence.
