Avi Blizovsky
Image credit: NRAO/AUI/NSF
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Radio astronomers have discovered a series of powerful radio bursts from near the center of the Milky Way. This is actually a type that was previously unknown to astronomers. The team examining the galactic center for the National Science Foundation's Large Array of Radio Telescopes observed 5 bursts occurring every 77 minutes, each lasting about XNUMX minutes. The team hopes to match X-ray photographs to these radio bursts to pinpoint the source of these unusual emissions.
The astronomers, from Sweet Briar College and the Naval Research Center, have been monitoring the center of the Milky Way for several years and they revealed their findings in the March 3 issue of the journal Nature.
Lead researcher Dr. Scott Hyman, professor of physics at Sweet Briar College, said the discovery came after analyzing additional observations made in 2002 and provided by researchers at Northwestern University. "We reached the goal" said Heyman. According to him, the observation of the center of the Milky Way is done by collecting radio waves with a wavelength of one meter. In this area, many outbursts from the source were detected during a seven-hour observation on September 30, 2002. In fact, five outbursts were detected that repeated themselves at remarkably regular intervals.
Hyman, four of his students from Suite Briar, and his NRL colleagues Namir Cassin and Joseph Lazio, encountered these emissions from two sources while exploring the galactic center in 1998. This led the team to launch an ongoing monitoring operation of the galactic center using the Large Radio Telescope Array in New Mexico. The National Radio Observatory, which operates the VLA, approved the program. The data was collected, and used as a basis for locating the new radio source.
The team monitored the center of the galaxy for transient and luminary sources of about 250 known sources, but the five bursts from a new source, dubbed GCRT J1745-3009, were the strongest so far. The five bursts were of the same brightness, each lasting ten minutes and the entire cycle occurring every 77 minutes. "This is a new source, it has not been discovered since 2002, nor did we discover its presence in early photographs.
Although the exact nature of the object remains mysterious, team members believe it is likely the first member of a new group of objects with an unknown state and an unknown type of activity.
"A key clue to understanding the source of the radio bursts is that the emissions look consistent," Hyman said. "There are very few types of consistent bursts in the universe. A natural astronomical maser - the equivalent of laser emissions in the microwaves - and one type of coherent sources - but only in a specific spectrum range. In contrast, the new outbreaks were detected in a particularly wide band.
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If the mystery isn't enough, NRL astronomer Dr. Paul Ray and his colleague Dr. Craig Marquardt of NASA's Goddard Space Flight Center located the source by looking at X-ray frequencies, but found no convincing evidence. "The non-reduction of emissions in the X-ray field is intriguing," he said. Many sources posit regular X flares, for example a binary system whose one component is a black hole, which also has an accompanying emission at radio frequencies. If in the following observations the X-rays are ruled out, or alternatively confirmed, this will help to understand the nature of the source.
NRL plans to build the largest and most sensitive Long Wavelength Array (LWA) telescope, which will revolutionize future studies of other radio variables. The program, called LWA, developed at the University of New Mexico and led by a team from Northwestern University, will be located in New Mexico, not far from the VLA.
Original Source: NRAO News Release
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