Curated by RSF Research Staff
Andromeda’s Bright X-Ray Mystery Solved by NuSTAR
Galaxies emit light across all wavelengths from radio to X-ray. However, until the late 1970’s - when X-ray satellites were first launched – they were traditionally observed in the optical range. The light in the optical range is predominantly from the ‘normal’ stars so with the advent of X-ray telescopes galaxies were revealed as spatially extended sources of X-ray emission.
Although some of the X-ray emission is from the ‘normal stars’ most is from the compact kind – like pulsars, neutron stars and black holes - specifically, those in binary systems that pull matter from the companion ‘normal’ star forming an accretion disk which is heated to millions of Kelvin and thus emits X-rays.
You would think that the most prevalent X-ray emitter would be black holes - and up until recently that is what most astronomers believed. However, with the use of NASA’s Nuclear Spectroscopic Telescope Array (NuSTAR), the culprit responsible for our neighbor’s X-ray emission has now been identified as non-other than Swift J0042.6+4112. This is a pulsar and accounts for a high percentage of the X-ray emission coming from our galactic neighbor Andromeda.
These results shed a whole new light on the source of X-ray emission inspiring scientists to delve deeper into our understanding of pulsars, black holes and the relationship with their home galaxy.