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Mysterious bursts of radio waves identified far outside galaxy

Mysterious bursts of radio waves identified far outside galaxy

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 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.



Source : http://www.world-science.net

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