Seven-hour radio emission recorded from galaxy’s center – cause unknown
Astronomers have discovered an unusual, very energetic burst in the range of radio waves, whose origin is probably near the center of the milky way.
In the scientific journal nature, scott d. Hyman of sweet briar college in virginia and colleagues at other institutes in the u.S. Of the discovery of the object, designated gcrt j1745-3009. The signature of this energetic radio source is extraordinary and scientists are convinced that it is either a previously unknown form, i.E. A new class of cosmic object, or a previously unknown type of activity of an object of a known class. In any case about something completely new.
Image of the new source, located below a ring of supernova remnants
Until now, it was difficult to detect short-lived radio bursts, because the sky was scanned only in small sections for emissions in the radio wave range. Scott hyman’s team monitored the center of our galaxy for several years, which enabled them to track gcrt j1745-3009. Hyman celebrates his scientific triumph:
We have drawn the rough lot. An image of the galactic center, made by detecting radio waves of one meter wavelength, revealed multiple eruptions of one source during a 7-hour period from 30. September to 1. October 2002 – five eruptions that repeated at remarkably constant intervals.
Radio sources are the great unknowns in space
To monitor the sky, astronomers used the radio telescope at the national science foundation’s very large array in new mexico. The very large array’s wide-angle view allowed them to observe a rough area around the center of the milky way. Other radio telescopes always have only a small section in view. No wonder, then, that only a relatively small number of radio sources are known so far. Team member joseph lazio of the naval research laboratory (nrl) commented:
Although it is known that there are very many short-lived objects in the sky that emit in the waveband of rontgen or gamma rays, surprisingly very little has been done to search for bursts in the radio waveband, which are easier to produce for many astronomical objects.
The five outbursts of gcrt j1745-3009 were of equal brightness and shone for 10 minutes each, 77 minutes apart. Between the periodic high-energy flare-ups, there were no emissions at all.
How far gcrt j1745-3009 really is from us remains unknown. The radio source could actually be located at a distance of 24.000 light years from the center of the milky way, or much closer if a cosmic projection were involved. Only further research can give precise information about this.
Illustration of the central region of the milky way in the radio wave range. The arrow indicates the position of the supernova remnants, which appear to be brought closer in the upper image.
The mysterious radio source that caused these short-lived emissions had not been noticed before 2002. The researchers were also unable to detect any trace of her in older photographs they sifted through. No accompanying rontgen radiation was found coming from the same sources. Co-author paul ray of the naval research laboratory says:
The fact that no rontgen ray emissions were detected is baffling. Many sources that emit temporary rontgen ray flares, such as binary star systems with a black hole, also emit simultaneously in the radio wave range.
The characteristics of gcrt j1745-3009 are very different from the known short-lived radio sources. In an accompanying news views article in nature write shri r. Kulkarni and e. Steri phinney of the california institute of technology in pasadena
In our opinion, the claim that it is a new class [of astronomical objects] is plausible, but not beyond all doubt.
An important role is played by determining how far gcrt j1745-3009 really is from us. According to kulkarni and phinney, it could also be, for example, an unusual pulsar (pulsating only sporadically), a special brown dwarf, a strange binary system, or a magnetized white dwarf. In any case the "radio astronomy is ready to deliver new and exciting outbursts."