Astronomers have confirmed that the neutron star M82 Este compact object, with a brightness equivalent to about 10 million suns, defies conventional understanding about the accretion of matter.
Exceeding this theoretical ceiling, which normally prevents the continued attraction of gas to the star, has been explained by recent research. Elas point to the existence of extremely intense magnetic fields and an exceptionally high rate of mass transfer as the main factors behind the observed phenomenon. Essa discovery reinforces the idea that certain ultraluminous X-ray sources are, in fact, highly magnetized neutron stars, redefining concepts in astrophysics.
Neutron star defies theories
The neutron star M82 X-2 has a mass that exceeds that of our Sol, concentrated in a diameter of just 20 kilometers. Esta extreme density results in a surface gravity that reaches an impressive 100 trillion times that of Terra, creating a cosmic environment of unparalleled conditions.
This binary system is composed of the neutron star and a companion star that is progressively losing material. The rate of mass loss from the donor star is equivalent to 1.5 Earth masses per year, fueling the accretion process that generates the extraordinary luminosity observed.
The phenomenon of superluminosity
The limit of Eddington represents a delicate balance point where external radiation pressure counteracts the internal gravitational force of a stellar object. Teoricamente, upon exceeding this limit, the intense radiation would expel the surrounding gas before it could reach the star’s surface.
In the specific case of M82 X-2, the observed luminosity reaches around 10³⁹ erg per second, a value that is 100 to 500 times greater than expected for a typical neutron star. Anteriormente, studies tried to explain this anomaly by suggesting the presence of intermediate-mass black holes, but new evidence points in another direction.
The influence of magnetic fields
Magnetic fields with intensities greater than 10¹³ gauss play a crucial role in channeling matter toward the neutron star. Esse process occurs through narrow funnels that form along the lines of magnetic force, directing the gas flow efficiently.
This advanced magnetic configuration is fundamental because it significantly reduces the scattering of photons, allowing the accretion of matter to continue uninterrupted, even in the face of extraordinarily high luminosity. Tal behavior brings the characteristics of M82 X-2 closer to the class of objects known as magnetars, which are neutron stars with even more powerful magnetic fields.
Theoretical models indicate that the accretion disk, the structure of gas and dust that orbits the neutron star, ends in a region where magnetic forces become dominant over gravitational and pressure forces. Essa structural particularity is essential for maintaining the high accretion rate and the consequent emission of X-rays at such high levels. Understanding these mechanisms is vital to unraveling the mysteries of ultraluminous X-ray sources.
Observations confirm mass transfer
Data collected by NASA’s NuSTAR X-ray telescope over an eight-year period revealed a gradual shortening in M82 X-2’s orbital period. Essa progressive reduction is a direct indication of the intense transfer of mass and angular momentum between the companion star and the neutron star.
The mass transfer rate measured in this binary system exceeds the classical Eddington limit for accretion by 150 times. Essas Detailed and consistent observations are crucial as they conclusively eliminate previous hypotheses that based the object’s superluminosity solely on directional beam effects, as if the radiation was being focused in our direction.
Implications for astrophysics
M82 X-2 functions as a unique natural laboratory, allowing scientists to study extreme physical conditions that are unattainable in any terrestrial environment. Understanding their behavior offers valuable insights into several areas of astrophysics.
Distant future of the binary system
M82 X-2’s orbit will continue to shrink over millions of years, driven by ceaseless mass transfer. The donor star, in turn, will progressively lose its mass, altering the dynamics of the system.
This ongoing process will lead to the pair forming an even more compact configuration in the future. The gradual transformation will alter M82 X-2’s current appearance as an ultraluminous X-ray source, marking a new phase in its cosmic evolution.
The environment of the galaxy M82
The galaxy Messier 82, known as the “Charuto Galaxy”, is notable for its high rate of star formation, making it a cosmic nursery. The regions of intense star birth in M82 concentrate a diversity of ultraluminous X-ray sources, making it a privileged location for these studies.
M82 X-2 is located at a considerable distance from the galactic center, in an area that favors the formation and evolution of binary systems characterized by high mass transfer. The study on M82 X-2, led by Matteo Bachetti, Observatório of Cagliari of Instituto Nacional of Astrofísica of
