"Long before it's in the papers"
April 15, 2015


Hunt for alien-filled galaxies yields nothing “obvious,” but some “interesting”

April 15, 2015
Courtesy of Penn State University
and World Science staff

As­tro­no­mers are con­tin­u­ing a search for ga­lax­ies that might be thor­oughly pop­u­lated by al­iens—turn­ing up noth­ing “ob­vi­ous,” but some pos­si­ble, out of 100,000, the sci­ent­ists report.

One interesting zone turned up right in our own galaxy, they add.

The search in­volved de­tect­ing “mid-in­fra­red” light that such civ­il­iz­a­tions would probably give off as they used up en­er­gy, said as­tron­o­mer Ja­son T. Wright of Penn­syl­va­nia State Uni­vers­ity, who started the proj­ect. Such en­er­gy use re­sults in heat emis­sions in the form of in­fra­red light, a low­er-en­er­gy form of light than vis­i­ble light. We feel in­fra­red light as heat.

“This same bas­ic phys­ics causes your com­put­er to ra­di­ate heat while it is turned on,” Wright said. Al­iens might use such pro­cesses “to pow­er com­put­ers, space flight, com­mu­nica­t­ion, or some­thing we can’t yet imag­ine.” While the en­er­gy ra­di­ates away as in­fra­red, it ul­ti­mately comes from stars—just as the en­er­gy we use is trace­a­ble back to the Sun, he added.

The proj­ect is known as the Glimps­ing Heat from Al­ien Tech­nolo­gies Sur­vey, or G-HAT. The first pa­per result­ing from the pro­ject ap­pears in the As­t­ro­phys­i­cal Jour­nal Sup­ple­ment Se­ries on April 15.

The­o­ret­i­cal phys­i­cist Free­man Dyson pro­posed in the 1960s that we could de­tect ad­vanced al­ien civ­il­iz­a­tions through mid-in­fra­red light. The nec­es­sary tech­nol­o­gy be­came avail­a­ble when NASA de­ployed a sat­el­lite tel­e­scope called WISE, for Wide-Field In­fra­red Sur­vey Ex­plor­er, in 2009.

Rog­er Grif­fith, a re­search­er at Penn State and the lead au­thor of the pa­per, scoured al­most the whole cat­a­log of the WISE sat­el­lite’s de­tections—nearly 100 mil­lion en­tries—for ga­lax­ies that seemed to be shin­ing too much mid-in­fra­red light. He then ex­am­ined and cat­e­go­rized around 100,000 of the most prom­is­ing im­ages. 

“We found about 50 ga­lax­ies that have un­usu­ally high lev­els of mid-in­fra­red radia­t­ion. Our fol­low-up stud­ies of those ga­lax­ies may re­veal if the or­i­gin of their radia­t­ion re­sults from nat­u­ral as­tro­nom­i­cal pro­cesses, or if it could in­di­cate the pres­ence of a highly ad­vanced civ­il­iz­a­tion,” Wright said.

Mat­thew Povich, an as­tron­o­mer at Ca­l Poly Po­mo­na, and a co-invest iga­tor on the proj­ect, said, “Once we had iden­ti­fied the best can­di­dates for al­ien-filled ga­lax­ies, we had to de­ter­mine wheth­er they were new dis­cov­er­ies that needed fol­low-up stu­dy, or well-known ob­jects that had a lot of mid-in­fra­red emis­sion for some nat­u­ral rea­son.” 

Jes­si­ca Mal­don­ado, a Ca­l Poly Po­mo­na un­der­grad­u­ate, searched the as­tro­nom­i­cal lit­er­a­ture for the best of the ob­jects de­tected as part of the study to see which were well known and which were new to sci­ence. “Ms. Mal­don­ado dis­cov­ered that about a half doz­en of the ob­jects are both un­stud­ied and really in­ter­est­ing look­ing,” Povich said.

“Rog­er and Jes­si­ca did find some puz­zling new ob­jects. They are al­most cer­tainly nat­u­ral as­tro­nom­i­cal phe­nom­e­na, but we need to study them more care­fully be­fore we can say for sure ex­actly what’s go­ing on,” said proj­ect mem­ber Steinn Sig­urds­son, an as­tron­o­mer at Penn State.

Among the dis­cov­er­ies with­in our own Milky Way gal­axy are a bright “neb­u­la” or cloudy zone around the near­by star 48 Li­brae, and a clus­ter of ob­jects easily de­tected by WISE in a patch of sky that looks black when viewed using only vis­i­ble light. “This clus­ter is probably a group of very young stars form­ing in­side a pre­vi­ously un­dis­cov­ered mo­lec­u­lar cloud, and the 48 Li­brae neb­u­la ap­par­ently is due to a huge cloud of dust around the star, but both de­serve much more care­ful stu­dy,” Povich said.

“As we look more care­fully at the light from these ga­lax­ies,” said Wright, “we should be able to push our sen­si­ti­vity to al­ien tech­nol­o­gy down to much low­er lev­els, and to bet­ter dis­tin­guish heat re­sult­ing from nat­u­ral as­tro­nom­i­cal sources from heat pro­duced by ad­vanced tech­nolo­gies. This pi­lot study is just the be­gin­ning.”

* * *

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Astronomers are continuing a search for galaxies that might be thoroughly populated by aliens— turning up nothing “obvious,” but some possible, out of 100,000 galaxies, a report said. The search involved detecting “mid-infrared” light that such civilizations would probably give off as they used up energy, said astronomer Jason T. Wright of Penn State University, who started the project. Such energy use results in heat emissions in the form of so-called infrared light, a lower-energy form of light than visible light. We feel infrared light as heat. “This same basic physics causes your computer to radiate heat while it is turned on,” Wright said. Aliens might use such processes “to power computers, space flight, communication, or something we can’t yet imagine.” While the energy radiates away as infrared, it ultimately comes from stars—just as the energy we use is traceable back to the Sun, he added. The project is known as the Glimpsing Heat from Alien Technologies Survey, or G-HAT. A first paper appeared in the Astrophysical Journal Supplement Series on April 15, 2015. Theoretical physicist Freeman Dyson proposed in the 1960s that we could detect advanced alien civilizations through mid-infrared light. The necessary technology became available when NASA deployed a satellite telescope called WISE, for Wide-Field Infrared Survey Explorer, in 2009. Roger Griffith, a researcher at Penn State and the lead author of the paper, scoured almost the whole catalog of the WISE satellite’s detections—nearly 100 million entries—for galaxies that seemed to be shining too much mid-infrared light. He then examined and categorized around 100,000 of the most promising images. “We found about 50 galaxies that have unusually high levels of mid-infrared radiation. Our follow-up studies of those galaxies may reveal if the origin of their radiation results from natural astronomical processes, or if it could indicate the presence of a highly advanced civilization,” Wright said. Matthew Povich, an astronomer at Cal Poly Pomona, and a co-investigator on the project, said, “Once we had identified the best candidates for alien-filled galaxies, we had to determine whether they were new discoveries that needed follow-up study, or well-known objects that had a lot of mid-infrared emission for some natural reason.” Jessica Maldonado, a Cal Poly Pomona undergraduate, searched the astronomical literature for the best of the objects detected as part of the study to see which were well known and which were new to science. “Ms. Maldonado discovered that about a half dozen of the objects are both unstudied and really interesting looking,” Povich said. “Roger and Jessica did find some puzzling new objects. They are almost certainly natural astronomical phenomena, but we need to study them more carefully before we can say for sure exactly what’s going on,” said project member Steinn Sigurdsson, an astronomer at Penn State. Among the discoveries within our own Milky Way galaxy are a bright nebula around the nearby star 48 Librae, and a cluster of objects easily detected by WISE in a patch of sky that appears totally black when viewed with telescopes that detect only visible light. “This cluster is probably a group of very young stars forming inside a previously undiscovered molecular cloud, and the 48 Librae nebula apparently is due to a huge cloud of dust around the star, but both deserve much more careful study,” Povich said. “As we look more carefully at the light from these galaxies,” said Wright, “we should be able to push our sensitivity to alien technology down to much lower levels, and to better distinguish heat resulting from natural astronomical sources from heat produced by advanced technologies. This pilot study is just the beginning.”