Pulsar with high circular polarization and variability discovered in the Large Magellanic Cloud

(ORDO NEWS) — An international team of astronomers announces the discovery of a new pulsar in the Large Magellanic Cloud (LMC) as part of the Variables and Slow Transients (VAST) study conducted by the Australian Square Kilometer Array Pathfinder (ASKAP).

The recently discovered pulsar, designated PSR J0523-7125, is a highly circularly polarized and variable radio source. The discovery is detailed in an article published May 3 on the arXiv website.

Pulsars are highly magnetized, spinning neutron stars that emit a beam of electromagnetic radiation. They are usually detected as short bursts of radio emission, but some of them are also observed with optical, X-ray and gamma-ray telescopes.

One of the methods for searching for new pulsars is their search in continuum observations and their identification by circularly polarized radiation.

Using this method, a team of astronomers led by Yuanming Wang of the University of Sydney (Australia) recently analyzed data from the Phase I ASCAP Pilot Survey for Variable and Slow Transients (VAST-P1), which found variable and transient sources in two ASCAP fields covering Magellanic clouds.

As a result, they discovered a highly variable, circularly polarized source with a steep spectrum, designated VAST J052348.6-712552. Subsequent observations of this source with the MeerKAT and Parkes telescopes confirmed that it is a pulsar located in the Large Magellanic Cloud (LMC), which was designated PSR J0523-7125.

“We discovered the highly variable, circularly polarized object VAST J052348.6-712552 while analyzing the variability of two fields containing the Magellanic Clouds observed in the VAST-P1 survey.

With about 20% fractional circular polarization and no optical/infrared counterpart, VAST J052348 .6-712552 was considered a strong pulsar candidate. Subsequent observations by MeerKAT found a pulsar, PSR J0523-7125, associated with a continuum source, which was confirmed by observations with the Parkes telescope,” the researchers explained.

According to the study, PSR J0523-7125 has a rotation period of 322.5 milliseconds. Its dispersion is about 157.5 pc/cm3, which is consistent with the origin of LMC. As for the rotation measure, it is calculated to be at +456 rad/m2 – about twice the most extreme rotation measure found in LMC pulsars.

The average flux density of PSR J0523-7125 is about 1 mJ at 1400 MHz and about 25 mJ at 400 MHz. This makes it one of the brightest radio pulsars known to date. Moreover, PSR J0523-7125 turned out to be brighter than all known pulsars in the Magellanic clouds both at frequencies of 400 MHz and 1400 MHz.

The astronomers stressed that despite its high luminosity, PSR J0523-7125 went unnoticed in several surveys of the LMC pulsars. They suspect that this is largely due to its broad momentum profile or steep spectral shape.

The researchers noted that the broad momentum profile of PSR J0523-7125 also suggests that it may be an aligned rotator. They added that the strong variability of this pulsar is most likely due to the effect of scintillation, but other explanations cannot be ruled out.

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