NSF Grant Supports Research on Neutron Stars
Science fiction has humankind traveling among the stars, but back on 21st-century Earth that’s not happening yet, presenting a challenge to researchers hoping to better understand celestial objects trillions of miles away.
Dr. Peter Gonthier of the Hope College physics faculty has received a grant from the National Science Foundation (NSF) to develop tools to assist in the process. Through the $222,730, three-year award, he and the Hope students working with him will collaborate with researchers at Rice University in creating a computer simulation to aid scientists who are studying magnetars, a subset of neutron stars.
A professor of physics, Gonthier explained that neutron stars are the remains of supernovae, massive stars that exploded. They might be only a dozen miles in diameter yet have the mass of two of Earth’s sun, and can have a surface temperature of about a million degrees. The neutron stars classified as magnetars are detectable because of the X-rays and gamma rays that come from them.
“We can’t reproduce the conditions in the lab,” Gonthier said. “We don’t experience these environments. We can only anticipate the type of physics that occurs.”
“This proposal aims to develop state-of-the-art models for the atmospheric emission of magnetars, focusing on what observers can detect with current telescopes and planned facilities,” he said. “The prime objective is to deliver a suite of observable signal predictions to enhance interpretation of data from X-ray telescopes.”
Gonthier noted that magnetars, which can’t be seen by the eye or conventional telescopes, are understood to be a variety of neutron star known as pulsars. He said that while more than 2,000 pulsars have been discovered at radio wavelengths so far, only about 30 of those are magnetars — although millions are believed to exist.
Pulsars rotate rapidly, completing a revolution between once every 10 seconds and a thousand times a second. Highly magnetized, they shoot out a beam of radiation that, given the spinning, makes the star seem to pulse as the beam passes into view like a lighthouse effect. They were discovered in the 1960s when scientists observed radio waves coming from them. The range of electromagnetic radiation, however, is much broader, covering also microwaves, infrared, visible light, ultraviolet light, X-rays and, at the highest end, gamma rays.
The first magnetar was discovered in March 1979, through a giant flare of gamma radiation detected by multiple satellites and probes. Magnetars have especially strong magnetic fields, and behave differently than other pulsars. Starquakes on their surface, for example, disturb the magnetic fields, leading to flares similar to those seen on the surface of the sun. More study, Gonthier noted, should help reveal not only how they behave and why, but whether or not they’re so unique that they may even need to be classified differently.
“Are these objects very different than pulsars?” he said. “Do they belong in the same population as normal pulsars?”
Gonthier has been studying pulsars since 1991. He has received multiple external grants in support of his research, including from NASA and previously from the NSF. The team at Rice with which Gonthier and his students are collaborating is led by Dr. Matthew Baring, with whom Gonthier has worked on a variety of projects since the early nineties.