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Mysterious bursts of radio waves identified far outside galaxy

July 10, 2014
Courtesy of the Max Planck Institute for Radio Astronomy
and World Science staff

Mys­te­ri­ous split-sec­ond pulses of ra­di­o waves are com­ing from deep in out­er space, and no­body knows what causes them, ac­cord­ing to as­tro­no­mers.

Re­search­ers led by Lau­ra Spitler from the Max Planck In­sti­tute for Ra­di­o As­tron­o­my in Bonn, Ger­ma­ny say they have found the first so-called “fast ra­di­o burst” in the sky’s north­ern hem­i­sphere, us­ing the Are­ci­bo ra­di­o tel­e­scope in Puerto Rico.

Optical sky image of the area in Au­riga where the fast ra­dio burst FRB 121102 was de­tect­ed. The posi­tion of the burst, between the old super­nova rem­nant S147 (left) and the star form­ation re­gion IC 410 (right) is marked with a green cir­cle.
(© Ro­gelio Ber­nal An­dreo (Deep­Sky­Colors.com))


The mys­tery is rem­i­nis­cent of that of gamma-ray bursts, dis­cov­ered in the 1960s and now thought to come from gi­ant stars col­laps­ing to form black holes. The new phe­nom­e­non, in the form of ra­di­o rath­er than gamma-rays—a dif­fer­ent form of light—re­mains an enig­ma.

The flashes last only a few thou­sandths of a sec­ond. Sci­en­tists us­ing the Parkes Ob­serv­a­to­ry in Aus­tral­ia had recorded such events be­fore, but the lack of si­m­i­lar find­ings by oth­er tel­e­scopes led to specula­t­ion that the Aus­tral­ian in­stru­ment might have been pick­ing up sig­nals from sources near­by Earth. 

The find­ing at Are­ci­bo is the first de­tec­tion us­ing a dif­fer­ent tel­e­scope: the burst came from the di­rec­tion of the con­stella­t­ion Au­ri­ga in the North­ern sky, ac­cord­ing to the sci­en­tists, who de­tail their find­ings July 10 in the on­line is­sue of The As­t­ro­phys­i­cal Jour­nal.

“There are only sev­en bursts eve­ry min­ute some­where in the sky on av­er­age, so you have to be pret­ty lucky to have your tel­e­scope point­ed in the right place at the right time,” said Spitler, the pa­per’s lead au­thor. “The char­ac­ter­is­tics of the burst seen by the Are­ci­bo tel­e­scope, as well as how of­ten we ex­pect to catch one, are con­sist­ent with the char­ac­ter­is­tics of the pre­vi­ously ob­served bursts from Parkes.”

“The ra­di­o waves show eve­ry sign of hav­ing come from far out­side our gal­axy – a really ex­cit­ing prospect,” added Vic­to­ria Kaspi of the McGill Uni­vers­ity in Montreal and prin­ci­pal in­ves­ti­ga­tor for the pulsar-survey proj­ect that de­tected the burst

Pos­si­ble causes, sci­en­tists said, in­clude a range of ex­ot­ic as­t­ro­phys­i­cal ob­jects, such as evap­o­rat­ing black holes, merg­ers of neu­tron stars, or flares from mag­ne­tars—a type of neu­tron star with ex­tremely pow­er­ful mag­net­ic fields.

The pulse was de­tected on Nov. 2, 2012, at Are­ci­bo, with the world’s larg­est and most sen­si­tive single-dish ra­di­o tel­e­scope.

The re­sult con­firms pre­vi­ous es­ti­mates that the bursts oc­cur roughly 10,000 times a day over the whole sky, said the astron­omers, who in­ferred the huge num­ber by cal­cu­lat­ing how much sky was ob­served, and for how long, to make the few de­tec­tions so far re­ported.

The bursts ap­pear to be com­ing from be­yond the Milky Way gal­axy based on mea­sure­ments of an ef­fect known as plas­ma dis­per­sion. Pulses that trav­el through the cos­mos are dis­tin­guished from man-made in­ter­fer­ence by the ef­fect of elec­trons in space, which cause longer ra­di­o waves to trav­el more slowly.


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Mysterious split-second pulses of radio waves are coming from deep in outer space, and nobody knows what causes them, according to astronomers. Researchers led by Laura Spitler from the Max Planck Institute for Radio Astronomy in Bonn, Germany say they have found the first so-called “fast radio burst” in the sky’s northern hemisphere, using the Arecibo radio telescope in Puerto Rico. The mystery is reminiscent of that of gamma-ray bursts, discovered in the 1960s and now thought to come from giant stars collapsing to form black holes. The new phenomenon, in the form of radio rather than gamma-rays—a different form of light—remains an enigma. The flashes last only a few thousandths of a second. Scientists using the Parkes Observatory in Australia had recorded such events before, but the lack of similar findings by other telescopes led to speculation that the Australian instrument might have been picking up signals originating from sources nearby Earth. The finding at Arecibo is the first detection using a different telescope: the burst came from the direction of the constellation Auriga in the Northern sky, according to the scientists, who detail their findings July 10 in the online issue of The Astrophysical Journal. “There are only seven bursts every minute somewhere in the sky on average, so you have to be pretty lucky to have your telescope pointed in the right place at the right time,” said Spitler, the paper’s lead author. “The characteristics of the burst seen by the Arecibo telescope, as well as how often we expect to catch one, are consistent with the characteristics of the previously observed bursts from Parkes.” “The radio waves show every sign of having come from far outside our galaxy – a really exciting prospect,” added Victoria Kaspi of the McGill University in Montreal and principal investigator for the pulsar-survey project that detected the burst Possible causes, scientists said, include a range of exotic astrophysical objects, such as evaporating black holes, mergers of neutron stars, or flares from magnetars — a type of neutron star with extremely powerful magnetic fields. The pulse was detected on Nov. 2, 2012, at Arecibo, with the world’s largest and most sensitive single-dish radio telescope. The result confirms previous estimates that these strange cosmic bursts occur roughly 10,000 times a day over the whole sky. This astonishingly large number is inferred by calculating how much sky was observed, and for how long, in order to make the few detections that have so far been reported. The bursts appear to be coming from beyond the Milky Way galaxy based on measurements of an effect known as plasma dispersion. Pulses that travel through the cosmos are distinguished from man-made interference by the effect of interstellar electrons, which cause radio waves to travel more slowly at lower radio frequencies. The burst detected by the Arecibo telescope has three times the maximum dispersion measurement that would be expected from a source within the galaxy, the scientists report.