Our understanding of the universe’s expansion, starting from the Big Bang nearly 13.8 billion years ago, has been filled with puzzling discrepancies. The starring role in our quest for answers is now being played by an intriguing celestial event: the reappearing supernova Refsdal.
A new study led by Patrick Kelly, an assistant professor of physics and astronomy at the University of Minnesota, uses a unique celestial phenomenon—the reappearing supernova Refsdal—to offer fresh insights into the rate of the universe’s expansion, known as the Hubble constant. By triangulating measurements of the supernova’s location, Kelly’s team derived a value for the Hubble constant much closer to the rate calculated using cosmic microwave background than the standard candle method.
The Universe’s Enigma: Hubble Constant Dilemma
For nearly a century, scientists have been grappling with the universe’s expansion rate. Two popular methods to calculate this rate—the standard candle method and the cosmic microwave background method—yield conflicting results. The recent study leverages the curious case of supernova Refsdal to propose a potential solution.
Supernova Refsdal: A New Perspective
Supernova Refsdal, named after its discoverer, Patrick Kelly, has shown up a record five times in images taken by the Hubble Space Telescope. This reappearing act, caused by the gravity of a nearby galaxy cluster bending the supernova’s light, offers an exciting opportunity to measure the Hubble constant.
Research Findings: Unraveling the Mystery
In the study published in the journal Science, Kelly’s team used measurements of supernova Refsdal’s location to derive a new value for the Hubble constant. Their findings suggest that the universe is expanding at about 41.4 miles per second per megaparsec, aligning more closely with the cosmic microwave background estimate.
The research opens up exciting opportunities for further study. This includes identifying potential unknown particles that may impact the universe’s expansion, exploring the role of dark energy, and refining measurement methods using phenomena like reappearing supernovas.