An international research team has discovered with a new method, the brightest known extragalactic pulsar. The new observation technique similar to the astronomical version of “sunglasses” was used with the Australian Square Kilometer Array Pathfinder (ASKAP) radio telescope, and thanks to it they have found a new pulsar 10 times brighter than any other detected outside our Milky Way.
A new astronomical landmark
This could be the brightest pulsar in the sky. Pulsars are a type of neutron star that emit beams of radiation from their poles , creating pulses of light as these beams flood the Earth. These bright pulses flicker rapidly, with just seconds or milliseconds between them, making them relatively easy for astronomers to spot.
As bright as it is, as intense as the light from this pulsar, named PSR J0523−7125, has largely eluded detection. How is it possible? As the rays pass through space, they create a unique signature of timing and polarization, but traditional methods can miss rays that are too fast or too slow. Looking instead for polarized light, pulsars outside the standard time range can be found. In fact, it has been possible because this telescope has been equipped with cosmic “sunglasses”.
How is the pulsar?
The newly discovered, steep-spectrum, variable and highly polarized pulsar blinks three times a second and is located in the Large Magellanic Cloud, a dwarf galaxy orbiting our own Milky Way. According to experts, it is the brightest known extragalactic pulsar, and could even be the brightest ever found.
“This was an incredible surprise. I did not expect to find a new, brighter pulsar. But with the new telescopes that we now have access to, such as ASKAP and its sunglasses, it is possible”, explains Yuanming Wang, leader of the work published in The Astrophysical Journal.
After seeing hints of the pulsar in the ASKAP data, the team confirmed its existence with the South African Radio Astronomy Observatory’s MeerKAT radio telescope .
And these cosmic ‘sunglasses’?
As part of the Australian Square Kilometer Array Pathfinder (ASKAP) Variables and Slow Transients (VAST) survey, CSIRO researcher Yuanming Wang and colleagues used the ASKAP radio telescope to apply their new method of searching for pulsars. By using astronomical’s version of ‘sunglasses’ to capture polarized light, they detected this pristine pulsar.
Thanks to their extreme magnetic fields, pulsars produce highly polarized light, which is indistinguishable from normal light for most instruments. ASKAP, however, can see it.
“We should expect to find more pulsars using this technique. This is the first time we have been able to systematically and routinely search for the polarization of a pulsar. Due to its unusual properties , previous studies did not detect this pulsar, despite how bright it is,” says study co-author Tara Murphy of the Institute for Astronomy at the University of Sydney.
“It’s amazing that the first pulsar to be found using this technique is extreme,” adds Elaine Sadler, chief scientist at CSIRO’s Australian National Telescope Facility. “This speaks to all the great things we can expect from our telescopes and researchers as they constantly find new ways to answer some of our biggest questions.”
Referencia: Yuanming Wang et al. 2022. Discovery of PSR J0523-7125 as a Circularly Polarized Variable Radio Source in the Large Magellanic Cloud. The Astrophysical Journal, 930, 38; doi: 10.3847/1538-4357/ac61dc
