麻豆淫院

Using the Five-hundred-meter Aperture Spherical Radio Telescope (FAST), Chinese astronomers have discovered a new millisecond pulsar. The newfound pulsar, designated PSR J2129-1210O, was missed by previous searches as its spin period is close to the harmonics of the known pulsar PSR J2129+1210A.

The finding was reported in a published April 23 on the arXiv pre-print server.

Pulsars are highly magnetized, rotating neutron stars emitting a beam of electromagnetic radiation. The most rapidly rotating pulsars, with rotation periods below 30 milliseconds, are known as millisecond pulsars (MSPs).

Astronomers assume that they are formed in binary systems when the initially more massive component turns into a neutron star that is then spun up due to accretion of matter from the secondary star.

One of the globular clusters (GCs) abundant in pulsars is NGC 7078, also known as Messier 15 or M15. It is one of the oldest core-collapsed clusters at a distance of about 35,700 light years. Simulations indicate that M15 has the highest number of predicted pulsars among all the GCs in the region of sky covered by FAST.

Therefore, M15 is an excellent place to look for new pulsars and recently a team of astronomers led by Yinfeng Dai of the Guizhou University in China has conducted such a search with FAST. The observational campaign lasted from November 2019 to February 2024.

As a result, they detected a pulsar with a spin period of approximately 11.07 milliseconds, which received the designation PSR J2129-1210O (or M15O for short). It has remained undetected until now, given that its spin period is very close to the 10th harmonic of the bright and previously known pulsar PSR J2129+1210A (M15A).

"If the period of a new pulsar is similar to or overlaps with that of a known pulsar or its harmonics, and their DM [dispersion measure] values are also close (owing to the concentrated DM distribution within the cluster), conventional folding algorithms struggle to separate the signals due to phase鈥攁lignment ambiguities. The standard screening process may fail to effectively distinguish between them, potentially leading it to miss the new pulsar," the researchers explain.

According to the paper, M15O has a dispersion measure of around 67.44 pc/cm³. The pulsar is at a projected distance of 0.37 arcseconds from the cluster center and 0.81 arcseconds from M15A. Therefore, the projected distance of M15O from the optical center of M15 is the closest among all the known pulsars in this cluster.

The authors of the study add that in addition to M15O, their FAST observations have also identified two other pulsars, namely PSR J2129+1210M and PSR J2129+1210N (M15M and M15N). The astronomers will describe the discovery of these pulsars in a forthcoming research paper.

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