Researchers investigate pulsations of the ultra-luminous X-ray pulsar M82 X-2

Utilizing NASA’s Chandra spacecraft and ESA’s XMM-Newton satellite, Chinese language astronomers have inspected the pulsations of an ultra-luminous X-ray pulsar often known as M82 X-2. Outcomes of the research point out that the pulsar showcases a long-term spin-down development. The research was detailed in a paper published December 28 on the pre-print server arXiv.

Extremely-luminous X-ray sources (ULXs) are level sources within the sky which are so brilliant in X-rays that every emits extra radiation than 1 million suns emit in any respect wavelengths. Though they’re much less luminous than active galactic nuclei, they’re extra constantly luminous than any recognized stellar course of.

Astronomers typically imagine that as a result of their brightness, most ULXs are black holes. Nonetheless, latest observations have discovered that some ULXs showcase coherent pulsations. These sources, often known as ultra-luminous X-ray pulsars (ULXPs), are neutron stars usually much less huge than black holes. The checklist of recognized ULPs continues to be comparatively brief; thus, learning objects of this class is important for researchers exploring the universe in X-rays.

M82 X-2 is the primary found ULXP. It’s situated within the Cigar Galaxy (often known as Messier 82), at a distance of about 12 million light years away. The system consists of a neutron star, with a spin period of roughly 1.37 seconds, and a way more huge companion.

Provided that many properties of M82 X-2 nonetheless stay unclear, a crew of astronomers led by Jiren Liu has analyzed archival Chandra and XMM-Newton knowledge to be able to higher perceive its nature, particularly its pulsation.

Liu’s crew managed to measure the pulsation conduct of M82 X-2 again to 2001. They decided spin frequencies of this ULXP, which allowed them to determine a transparent spin-down trend over a timescale of 20 years, with occasional spin-up occasions. Such spin conduct is normally noticed in Be-type X-ray binaries (BeXBs).

“BeXBs typically present a spin-up development throughout an outburst or big outburst state, and present a steady spin-down development when there’s a lot much less mass to be accreted,” the researchers defined.

In line with the research, the altering spin-down/spin-up conduct of M82 X-2 appears to recommend that its accretion torque, and subsequently its accretion price, should be various. Based mostly on these findings, the astronomers suppose that M82 X-2 might have a various accretion price, and for lengthy durations of time it’s in a comparatively quiet state and spins down.

In attempting to clarify the reason for the noticed spin-down development noticed in M82 X-2, the authors of the paper contemplate just a few prospects. They assume that essentially the most believable speculation is that such a development is because of magnetic threading. If this situation is true, they estimate that the dipolar magnetic subject of this pulsar is at a degree of 12 trillion Gauss.

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