Similar to black holes, neutron stars with accretion disks form when they consume nearby matter. This process results in the creation of cosmic winds, which are distinct from the atmospheric winds experienced on Earth or solar winds generated by the Sun. The mechanisms behind accretion disk winds remain an enigma to scientists, but they are commonly observed in binary systems with black holes or neutron stars.
Studying the winds surrounding these celestial objects is challenging due to the typically flat nature of accretion disks. However, the Hercules X-1 system offers a unique opportunity, as its accretion disk oscillates every 35 days. This movement allows researchers to observe winds from various locations on the disk at different heights above it.
By producing a 2D map of the Hercules X-1 disk's winds, scientists have gained valuable insights that were previously unattainable with flat disks. They observed the disk's movement and detected signs of winds at varying heights relative to the disk. Examining the X-ray emissions from the disk also enabled them to measure properties like temperature and wind density at different altitudes.
The researchers discovered that the winds become colder, weaker, and more "grainy" as they move farther away from the disk. The team now plans to compare their findings with theoretical simulations of potential mechanisms behind the formation of accretion disk winds. The most accurate simulation will be supported by this observational evidence.
Despite these advancements, there is still much work to be done. Scientists must continue searching for more systems with warped disks to determine if these observations are typical or unusual. This research will help improve our understanding of how neutron star winds contribute to the formation of galaxies that host these celestial bodies.
Source: MIt
Illustration of a neutron star at the center of the accretion disk formed by matter sucked in from the larger star (Image: Reproduction/Jose-Luis Olivares/MIT/D. Klochkov/ESA)
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