"Long before it's in the papers"
June 04, 2013

RETURN TO THE WORLD SCIENCE HOME PAGE


Galaxy seen blasting its neighbor

Dec. 17, 2007
Courtesy NASA
and World Science staff

In a never-before seen event, a pow­er­ful jet from a gal­ax­y’s gi­ant, cen­tral black hole is pum­mel­ing a near­by gal­axy, ac­cord­ing to as­tro­no­mers. The beam may pro­foundly dis­turb plan­ets in its path and lat­er trig­ger a burst of star forma­t­ion, they said. 

A com­pos­ite im­age from sev­er­al ob­ser­va­to­ries shows what as­tro­no­mers say is a jet from a black hole at the cen­ter of a gal­axy, strik­ing an­oth­er gal­axy. The beam is dif­fi­cult to see in the ar­ea where it emerges, from the bright zone in the mid­dle of the large gal­axy at low­er left. It be­comes more ap­par­ent where as­tro­no­mers say it is strik­ing the sec­ond gal­axy, to the up­per right of the first one. There, it cre­ates what ap­pears as a blue spot in on the low­er right of the smaller gal­axy. Con­tin­u­ing on­ward to the up­per right of the pic­ture, the rem­nants of a beam ap­pear dis­rupted and de­flect­ed, re­sem­bling a vast wisp of smoke. This is si­m­i­lar to the way a stream of wa­ter from a hose will splay out af­ter hit­ting a wall at an an­gle, re­search­ers ex­plain. In the im­age, da­ta from sev­er­al wave­lengths of light have been com­bined: X-rays from Chan­dra (col­ored pur­ple); op­ti­cal and ul­tra­vio­let da­ta from the Hub­ble Space Te­le­scope (red and or­ange); and ra­dio emis­sion from the Very Large Ar­ray (VLA) and MER­LIN (blue) te­le­scopes. (Im­age cred­it: X-ray: NA­SA/CX­C/C­fA/D.E­ et al.; Op­ti­cal/UV: NA­SA/STScI; Ra­di­o: NS­F/VLA/C­fA/D.Evans et al., STFC/JBO/MER­LIN)


NASA’s Chan­dra X-ray Ob­serv­a­to­ry, the re­search­ers ex­plained, has re­vealed that both ga­lax­ies—or­bit­ing each oth­er in a sys­tem called 3C321—have cen­tral “su­per­mas­sive” black holes. The smaller gal­axy, as­tro­no­mers said, seems to have swung in­to the path of a beam com­ing from the black hole of the larg­er gal­axy.

“We’ve seen many je­ts pro­duced by black holes, but this is the first time we’ve seen one punch in­to anoth­er gal­axy,” said Dan Ev­ans, a sci­ent­ist at the Har­vard-Smith­son­ian Cen­ter for As­t­ro­phys­ics in Cam­bridge, Mass. and lead­er of the stu­dy. “This je­t could be caus­ing all sorts of prob­lems for the smaller gal­axy.”

Black holes are ob­jects so dense that their gravita­t­ion sucks in an­y­thing that comes too close, in­clud­ing light. But some near­by ma­te­ri­al does­n’t fall in­side the black hole, and in­stead gets ejected in beams, a phe­nom­e­non be­lieved to re­sult from mag­net­ic fields.

The larg­est black holes are thought to lurk at the cen­ters of ga­lax­ies. Jets from these are found to pro­duce co­pi­ous radia­t­ion, es­pe­cially pow­er­ful X-rays and gamma-rays, which can be deadly in large quan­ti­ties. The com­bined ef­fects of this radia­t­ion and par­t­i­cles trav­el­ing at near-light speed in the beam could se­verely dam­age plan­e­tary at­mo­spheres in the je­t’s path, as­tro­no­mers say; for in­stance, pro­tec­tive lay­ers of ozone in the up­per at­mo­spheres could be de­stroyed.

Su­per­mas­sive black hole je­ts car­ry tor­rents of en­er­gy far from their or­i­gin, and un­der­stand­ing them is a key goal for as­t­ro­phys­i­cists. “We see je­ts all over the un­iverse, but we’re still strug­gling to un­der­stand some of their bas­ic prop­er­ties,” said co-in­vest­iga­tor Mar­tin Hard­cas­tle of the Un­ivers­ity of Hert­ford­shire in the U.K. The new find­ing “gives us a chance to learn how they’re af­fect­ed when they slam in­to some­thing like a gal­axy and what they do af­ter that.”

The ef­fect of the je­t on the com­pan­ion gal­axy is probably sub­s­tan­tial, re­search­ers said, be­cause the ga­lax­ies are very close by as­tronomical stan­dards—a­bout 20,000 light years apart. A light-year is the dis­tance light trav­els in a year. They lie about the same dis­tance apart as Earth is from the cen­ter of our gal­axy.

The so-called “death star” gal­axy in 3C321 was disco­vered us­ing both space and ground-based tele­scopes, re­search­ers said. A bright spot in ra­di­o tel­e­scope im­ages, they re­marked, shows where the je­t has struck the side of the gal­axy.

A un­ique as­pect of the find­ing, they added, is how short-lived the event is in cos­mic terms: they es­ti­mate the je­t be­gan hit­ting the gal­axy a mil­lion years ago, a small frac­tion of the sys­tem’s life­time. This would sug­gest the align­ment is rare in the near­by uni­verse. But the event may not be all bad news for the vic­tim­ized gal­axy, they added: the huge in­flux of en­er­gy and radia­t­ion could prompt many stars and plan­ets to form in the de­struc­tion’s wake. The find­ings are to ap­pear in the re­search pub­lica­t­ion As­t­ro­phys­i­cal Jour­nal.


* * *

Send us a comment on this story, or send it to a friend

 

Sign up for
e-newsletter
   
 
subscribe
 
cancel

On Home Page         

LATEST

  • Meet­ing on­line may lead to hap­pier mar­riages

  • Pov­erty re­duction, environ­mental safe­guards go hand in hand: UN re­port

EXCLUSIVES

  • Was black­mail essen­tial for marr­iage to evolve?

  • Plu­to has even cold­er “twin” of sim­ilar size, studies find

  • Could simple an­ger have taught people to coop­erate?

  • Diff­erent cul­tures’ mu­sic matches their spe­ech styles, study finds

MORE NEWS

  • F­rog said to de­scribe its home through song

  • Even r­ats will lend a help­ing paw: study

  • D­rug may undo aging-assoc­iated brain changes in ani­mals

In a never-before seen event, a powerful jet from a galaxy’s giant, central black hole is pummeling a nearby galaxy, according to astronomers. The beam may profoundly disturb planets in its path and later trigger a burst of star formation, they said. NASA’s Chandra X-ray Observatory, the researchers explained, has revealed that the galaxies—orbiting each other in a system called 3C321—have central “supermassive” black holes. The smaller galaxy, astronomers said, seems to have swung into the path of a beam coming from the black hole of the larger galaxy. “We’ve seen many jets produced by black holes, but this is the first time we’ve seen one punch into another galaxy,” said Dan Evans, a scientist at the Harvard-Smithsonian Center for Astrophysics and leader of the study. “This jet could be causing all sorts of problems for the smaller galaxy.” Black holes are objects so dense that their gravitation sucks in anything that comes too close, including light. But some nearby material doesn’t fall inside the black hole, and instead gets ejected in beams, a phenomenon believed to result from magnetic fields. The largest black holes are thought to lurk at the centers of galaxies. Jets from these are found to produce copious radiation, especially powerful X-rays and gamma-rays, which can be deadly in large quantities. The combined effects of this radiation and particles traveling at near-light speed in the beam could severely damage planetary atmospheres in the jet’s path, astronomers say; for instance, protective layers of ozone in the upper atmospheres could be destroyed. Supermassive black hole jets carry torrents of energy far from their origin, and understanding them is a key goal for astrophysicists. “We see jets all over the universe, but we’re still struggling to understand some of their basic properties,” said co-investigator Martin Hardcastle of the University of Hertfordshire in the U.K. The new finding “gives us a chance to learn how they’re affected when they slam into something like a galaxy and what they do after that.” The effect of the jet on the companion galaxy is probably substantial, researchers said, because the galaxies are very close by astronomical standards—about 20,000 light years apart. A light-year is the distance light travels in a year. They lie about the same distance apart as Earth is from the center of our galaxy. The so-called “death star” galaxy in 3C321 was discovered using both space and ground-based telescopes, researchers said. A bright spot in radio telescope images, they remarked, shows where the jet has struck the side of the galaxy. A unique aspect of the finding, they added, is how short-lived the event is in cosmic terms: they estimate the jet began hitting the galaxy a million years ago, a small fraction of the system’s lifetime. This would suggest the alignment is rare in the nearby universe. But the event may not be all bad news for the victimized galaxy, they added: the huge influx of energy and radiation could prompt many stars and planets to form in the destruction’s wake. The findings are to appear in the research publication Astrophysical Journal.