The EDA2 radio telescope in the Australian outback is like a giant ear pressed against the sky. It listens to the cosmos at very low frequencies, from 50 to 250 megahertz, where ordinary telescopes can barely make out anything. This is exactly where pulsars, fast-spinning neutron stars, sound most intriguing: their pulses stretch, distort, and tell us what they encountered along the way.
In this new survey, that ear caught 120 pulsars. For 23 of them, the signal below 150 megahertz was recorded for the first time, and 5 were even heard below 100 megahertz, like spotting a distant lighthouse through thick fog for the first time. Each pulsar was recorded in full, with all the details of its pulse shape and polarization — the characteristics that reveal how the star spins and what its magnetic field is like.
But the real value isn't just the new pulsars. On their way to us, radio waves pass through interstellar gas and Earth's ionosphere, which leave their "fingerprints" on the signal. The team measured how much the signal was delayed (the dispersion measure) and how its polarization rotated under the influence of magnetic fields (the rotation measure). For 110 pulsars, they refined the delay; for 40, they measured the rotation. One pulsar, J1453-6413, showed that the rotation changes right during the pulse — something rarely caught.
These data are like a detailed map of road hazards for future observations. When the full SKA-Low antenna array comes online, it will listen to the sky at the same frequencies but be thousands of times more sensitive. For now, EDA2 is charting the course: where to look, what to tune into, and what surprises to expect from cosmic beacons.
as written by the authors arXiv:2603.11553
Low-frequency pulsar observations are crucial for understanding pulsar emission spectra and population physics, as well as for probing the interstellar medium (ISM) and Earth's ionosphere. We report the largest low-frequency pulsar census conducted in the southern hemisphere, covering 50-250 MHz, using the EDA2, an SKA-Low prototype station. In this survey, we detected 120 pulsars, including 23 first-time detections below 150 MHz and 5 below 100 MHz. For each source, we provide integrated pulse profiles and flux-density measurements across five sub-bands spanning 50-250 MHz. We also obtained improved dispersion measure (DM) values for 110 pulsars, with a median absolute DM correction of about 0.1 pc cm^-3. We measured significant Faraday rotation for 40 pulsars with improved rotation measure (RM) values for 4 pulsars, as well as phase-resolved RM variation in J1453-6413. Full-polarimetric pulse profiles are provided for all these pulsars, with multi-frequency polarimetric data for 20 of them. These results will enhance future SKA-Low science: refining pulsar population models, informing survey strategies, and advancing characterization of both the ISM and the ionosphere through low-frequency pulsar monitoring.
The fastest known pulsar spins 716 times per second — faster than a kitchen blender.
In Carl Sagan's novel "Contact," pulsars are used as natural navigation beacons for interstellar travel.