{"id":240941,"date":"2025-12-19T12:08:09","date_gmt":"2025-12-19T12:08:09","guid":{"rendered":"https:\/\/www.europesays.com\/ie\/240941\/"},"modified":"2025-12-19T12:08:09","modified_gmt":"2025-12-19T12:08:09","slug":"uah-researchers-use-new-x-ray-telescope-to-probe-dark-matter-decay","status":"publish","type":"post","link":"https:\/\/www.europesays.com\/ie\/240941\/","title":{"rendered":"UAH Researchers Use New X-ray Telescope To Probe Dark Matter Decay"},"content":{"rendered":"

Scientists search for \u201cdecaying\u201d dark matter (DDM) because it offers unique signatures like specific X-ray or gamma-ray lines or neutrino signals not seen in normal matter, potentially revealing dark matter\u2019s particle nature, mass and interactions, information that could illuminate the universe\u2019s structure. DDM is a theoretical model where dark matter particles aren\u2019t perfectly stable, but slowly decay over vast cosmic timescales into lighter dark matter particles and\/or massless particles, leaving behind gravitational or electromagnetic signals. Now a study published in the Astrophysical Journal Letters<\/a> demonstrates this form of dark matter can potentially be detected in unidentified X-ray emission lines in the spectra of galaxy clusters.\u00a0<\/p>\n

\u201cEighty-five percent of mass in galaxy clusters come from dark matter, and we can model the dark matter radial distribution well,\u201d notes Dr. Ming Sun, a professor in the College of Science at The University of Alabama in Huntsville (UAH), a part of The University of Alabama System, and the corresponding author on the project. \u201cThus, galaxy clusters are great targets for such a search as they are dark matter rich and we know the dark matter mass in clusters well.\u201d<\/p>\n

Dr. Sun\u2019s postdoctoral student, Prathamesh Tamhane, was also involved in the work, which follows-up on a 2014 study led by UAH alumna Dr. Esra Bulbul, who now serves as the lead scientist for cluster science and cosmology at the Max Planck Institute<\/a>.\u00a0<\/p>\n

X-ray emission lines are unique fingerprints of elements that appear as peaks in an X-ray spectrum when electrons drop from higher to lower energy shells in an atom, releasing energy as X-ray photons. These distinct spectral lines reveal the presence of heavy elements like iron, silicon and oxygen ejected from galaxies, allowing astronomers to map elemental abundances and measure gas temperatures and densities, all helping to understand the complex physics of these massive structures.\"\"<\/a>\u00a0<\/p>\n

An unidentified X-ray emission line found at approximately 3.5 kiloelectron volts (keV) in the spectra of galaxy clusters has been subject to intense scientific debate as a persistent astronomical anomaly. Scientists have traditionally used Charge-Coupled Devices (CCDs) \u2013 light-sensitive semiconductor chips \u2013 to detect the faint tracks of ionizing particles like heavy ions or neutrinos in these spectra, allowing them to observe particle paths in attempting to resolve this \u201cunidentified\u201d emission line.\u00a0<\/p>\n

Researchers for the new study relied instead on data collected from the X-ray Imaging and Spectroscopy Mission (XRISM)<\/a>, a collaborative space telescope developed by JAXA (Japan) and NASA, with European Space Agency (ESA) support.\u00a0<\/p>\n

\u201cNearly all the past studies used the CCD data, which lacks the required energy resolution to resolve the unidentified line,\u201d Sun explains. \u201cNow XRISM provides high-energy-resolution spectra that can resolve the line. As the line signals are very weak, we combined nearly three months of the XRISM data for such a search. There are many X-ray lines detected. They originate from known atoms, such as iron, silicon, sulfur and nickel. X-ray emission lines that appear that are not at the known position of atomic lines are then the candidates for DM decay lines, which is the focus of this work.\u201d<\/p>\n

The leading candidate for the mysterious emission line is a particle called a \u201csterile\u201d neutrino. Neutrinos are tiny, nearly massless, subatomic particles that travel near the speed of light and barely interact with normal matter, crucial to understanding the universe, despite being incredibly hard to detect.<\/p>\n

\u201cA sterile neutrino is a hypothetical type of neutrino that only interacts with other particles via gravity, unlike the three known \u2018active\u2019 neutrinos that also interact via the weak force,\u201d Sun notes. \u201cThe existence of the sterile neutrino is well-motivated theoretically and can explain the very small but non-zero mass of regular neutrinos. Sterile neutrinos can decay into two photons with the same energy. Models can predict the decay rate of sterile neutrinos, which is then constrained from the data.\u201d<\/p>\n

In considering the future of this type of research, Weakly Interacting Massive Particles, or WIMPS \u2013 hypothetical particles that are massive but only interact via gravity and the weak nuclear force \u2013 are still considered one of the most likely places where dark matter could be hiding. But Sun is quick to note that investigating alternate possibilities remains crucial to solving the mystery.<\/p>\n

\u201cWIMPs are still the leading candidate for dark matter, but billions of dollars of experiments have been done, only getting stronger and stronger upper limits, so alternative scenarios have to be considered. This study provides the strongest limits from high-energy-resolution data on the sterile neutrino at the 5 \u2013 30 keV band, subsequently limiting the models for dark matter,\u201d the UAH researcher concludes. \u201cWith more XRISM data in the next 5-10 years or so, we will be able to either detect the line or improve the limit substantially.\u201d\"Bank47\"<\/a><\/p>\n

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