New accreting millisecond X-ray pulsar discovered

Astronomers report the invention of a brand new pulsar utilizing the Spektr-RG space observatory. The newfound object, designated SRGA J144459.2−604207 (or SRGA J1444 for brief), seems to be a bursting accreting millisecond X-ray pulsar. The discovering was detailed in a paper printed April 30 on the pre-print server arXiv.

X-ray pulsars exhibit strict periodic variations in X-ray depth, which might be as brief as a fraction of a second. Accreting millisecond X-ray pulsars (AMXPs) are a peculiar kind of X-ray pulsars during which brief spin intervals are brought on by long-lasting mass switch from a low-mass companion star by way of an accretion disk onto a slow-rotating neutron star. Astronomers understand AMXPs as astrophysical laboratories that may very well be essential in advancing our data about thermonuclear burst processes.

Now, a group of astronomers led by Sergey V. Molkov of House Analysis Institute in Moscow, Russia, has discovered a brand new AMXP primarily based on the observations carried out with Spektr-RG’s Astronomical Roentgen Telescope X-ray Concentrator (ART-XC). The pulsar was detected on February 21, 2024, on the place near the galactic aircraft.

“The extraordinary follow-up marketing campaign carried out instantly after the invention revealed that SRGA J1444 is a brand new accreting millisecond pulsar with a spin interval of 447.8 Hz, exhibiting common Kind-I X-ray bursts,” the researchers wrote within the paper.

Assuming that the mass of the neutron star in SRGA J1444 is 1.4 solar lots, the mass of the companion star is no less than 0.25 solar masses. The system has a circular orbit with a interval of roughly 5.2 hours and is estimated to be situated some 27,000–35,000 light years away from the Earth.

The examine discovered that the heartbeat profiles of the persistent emission of SRGA J1444 have fascinating shapes showcasing a sine-like half throughout half a interval with a plateau in between. The astronomers defined that these pulse profiles might be modeled by emission from two round spots partially eclipsed by the accretion disk.

Throughout ART-XC observations, 19 thermonuclear X-ray bursts had been detected from SRGA J1444. It was famous that each one the detected bursts have comparable shapes and energetics and don’t present any indicators of photospheric radius growth.

Based on the paper, the burst fee decreases linearly from about one per 1.6 hours initially of observations to about one per 2.2 hours on the finish, whereas the vitality launch throughout the bursts stays roughly on the identical stage. Spectral evolution of SRGA J1444 throughout the burst means that the neutron star has a radius of about 11–12 kilometers.

The observations additionally detected pulsations throughout the bursts of SRGA J1444. Nevertheless, the authors of the paper couldn’t discover a easy bodily mannequin explaining the heartbeat profiles detected throughout the bursts.

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