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February 21, 2024

NuSTAR program finds data in black holes

By MARK STUCZYNSKI | September 21, 2013

The celestial bodies found on the beaches of southern California have only a secondary priority for researchers at Caltech’s NuSTAR program. The Nuclear Spectroscopic Telescope Array, or NuSTAR, is an X-ray telescope designed to focus X-rays from the universe to survey for black holes.

Black holes are physical objects with an incredible amount of mass found throughout space, typically at the core of galaxies. While black holes are a known phenomenon throughout the universe, there remain many questions about the physical nature of the dense objects and their relationship to the universe.

NuSTAR seeks to answer some of these questions by using mirrors to focus X-ray light into usable data. In the cosmos, a wide dispersion of light wavelengths can be used to determine the location, characteristics, and features of both physical objects and cosmic events that have occurred over the universe’s life span. Two such wavelengths of note are X-rays and microwaves, which lie outside of the visible spectrum of light but nonetheless inform astrophysicists about the nature of the cosmos.

David Alexander, a researcher at Durham University in the United Kingdom, posits that unlike the cosmic microwave background radiation — leftover thermal radiation from the Big Bang — present in the universe, which is relatively diffuse, the cosmic X-ray background results from distant, focused points. In a paper published on August 20th, Alexander found ten separate, high energy points that seem to indicate that the X-ray background stems from active galactic nuclei. Active galactic nuclei are locations of supermassive black hole formation and activity at the center of active galaxies.

Unlike our galaxy, which is “inactive,” active galaxies, such as the ones containing black holes found by Alexander’s team at NuSTAR, are sites of intense cosmological effects and galaxies in the throes of formation. Were our own Milky Way galaxy in a similar state, the intense radiation and scale of physical changes would deem our planet to be incapable of supporting human life. These findings allow for a greater understanding of the formation of galaxies and the physical universe by comparing the new data from NuSTAR to previous knowledge.

By fitting the data from NuSTAR’s X-ray spectrum over a wide range of energy spectra, Alexander has discovered and confirmed the presence of ten supermassive black holes acting as active galactic nuclei by making a one hundred fold increase in sensitivity over previous observations, and that despite the distant X-ray sources being far more luminous and massive, there seems to be indication that the supermassive black holes that comprise distant active galactic nuclei should follow the same rules of nearby active galactic nuclei, and that with further samplings using NuSTAR, it will be possible to map the development of active galactic nuclei, and garner more in-depth information about how the universe came to be.


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