Jan. 26 () –
Nine millisecond pulsars, most of them in rare and sometimes unusual binary systems, have been discovered in a conducted survey with the South African MeerKAT telescope array.
An international team of astronomers selected 79 unidentified pulsar sources from observations from NASA’s Fermi Gamma-ray Space Telescope and observed them at radio frequencies with MeerKAT.
The use of this proven method with a set of state-of-the-art telescopes presents significant advantages over previous studies, according to a statement from the Max Planck Institutewho participated in the study.
The team discovered nine rapidly rotating neutron stars, most of them with unusual properties. They also followed up on multiple wavelengths, finding gamma-ray pulsations in two of these objects, optical counterparts, as well as X-rays in another of the systems. The scientists also looked for gravitational waves continuous beams coming from one of the neutron stars.
These results highlight the value of targeted searches for radio pulsars in unidentified gamma-ray sources and hold promise for the future: the researchers are confident that future observations may discover several more millisecond pulsarsadds the statement.
“Our Trapum survey used MeerKAT, a relatively new and superbly sensitive radio telescope, together with specific analysis software to observe a selection of very promising pulsar sources,” says Colin Clark, group leader at the Max Planck Institute for Gravitational Physics (Albert Einstein Institut) in Hannover and lead author of the study.
The team used a tried and tested method to discover new millisecond pulsars. The Fermi Large Area Telescope catalog collects gamma ray sources from eight years of observations made with NASA’s Fermi Gamma-ray Space Telescope. This catalog contains information on the position of the sources in the sky, the energies of their gamma rays and the variations in their brightness over time.
One of the discovered pulsars, named PSR J1526-2744, was subsequently studied in detail. After detecting this radio pulsar in a binary system, the researchers also picked up the gamma-ray pulsations from the neutron star. Using all the available Fermi data, they were able to accurately study the orbital motion and determine the properties of the binary system. Most likely, the neutron star will orbit the common center of mass with a light white dwarf in just under five hours. This would be one of the shortest orbital periods of any known pulsar-white dwarf binary system.
The team also searched for so-called continuous gravitational waves coming from PSR J1526-2744. If the neutron star were warped, it would emit gravitational waves at twice its rotation frequency. The researchers used all publicly available advanced LIGO data from the O1, O2, and O3 series. Since they knew exactly the motion of the pulsar in the binary from gamma-ray observations, the research team reached the highest possible sensitivity in the search for gravitational waves.
Two other pulsars, called PSR J1036-4353 and PSR J1803-6707, are typical ‘redback’ pulsar systems made up of neutron stars with companion stars at least a quarter of the mass of our Sun. These pulsars evaporate and destroy their partners. mates over time, hence the reference to its arachnid namesake, the Australian ‘redback’ spiders, whose females consume the males after mating.
