A mental testing exists for a leading explanation for the nature of dark issue , but it bank on fascinate a supernova in the moment of explosion . Although we now do that quite oft , the supernova need to be closer than any we have see for decennium , and we have to have a Vasco da Gamma - beam telescope direct in the right direction when it bechance . A team of scientists is using this scenario to fence for launching more gamma - ray satellite , so we can have the sky insure when the outcome occurs .
Strong grounds for the existence of dark topic was come across a century ago , and it haskept coming since . Nevertheless , attempts to key more than a lilliputian fraction have go . The long abortive pursuit to find most of the universe ’s affair is starting to be used by the enemies of skill as evidence for its loser , and alternative explanations aregaining more reporting , even while few scientists find them plausible .
Perhaps , as in all the good mystery story , the detectives need a prosperous interruption .
Schematic showing an axion produced in a supernova core collapse being converted to a gamma ray by the strong magnetic field, and reaching an Earth better suited for gamma-ray satellites.Image credit: Benjamin Safdi, UC Berkeley
One explanation for what we have , and have not , escort , is that coloured matter is compile ofaxions , theoretic particles whose tiny mass is correct by their astonishing abundance . QCD Axions , favored by chain physicists , dissent from other proposed saturnine matter mote in that they interact with the other fundamental forces besides somberness , but have a maximum mass 32 times small than an electron .
unluckily , QCD axions would be at the bound of our capacity to detect them with be instruments , thanks to the exceeding failing of their interactions with the three non - gravitative personnel . Efforts have been made for 40 years using a variety of coming , but like so many other dark matter searches , have yet to succeed .
We have a bun in the oven that if axions are literal , core collapsesupernovae ( all types other thanIa ) produce immense amounts of them in their first few seconds . That ’s not very utilitarian if we ca n’t notice them , but models of axion deportment propose their interactions with the electromagnetic violence would convert those passing through inviolable magnetic fields into gamma rays .
The neutron stars create bymost core collapse supernovaeoften have charismatic subject field of the required strength , Dr Benjamin Safdi of the University of California , Berkeley and colleagues fence . Not only can we find these Vasco da Gamma light beam , they propose , but we can also distinguish them from those unloose by supernovae directly .
There are just two flies in this ointment . The first is that to detect enough old-hat - axion gamma irradiation to be able to be convincing , the supernova postulate to be nearby . Ideally , it would be inside the Milky Way , but the majority of plosion in one of the orbiter galaxies that fence ours would also be suitable , Safdi and co - authors figure .
That means we could be waiting a while . We have n’t regard a supernova inside the Milky Way for more than 400 years , although some may have occurred but been hide by dust . The abundance of enormous stars in theLarge Magellanic Cloud(LMC ) make a lot of supernova prospects , but the last one there was still 37 years ago , in the form ofSN 1987a . Best not to hold in your breath .
" If we were to see a supernova , like supernova 1987A , with a modern gamma - ray of light telescope , we would be able to detect or harness out this QCD axion , this most interesting axion , across much of its parametric quantity space — basically the entire parametric quantity infinite that can not be probed in the laboratory , and much of the argument space that can be probed in the science laboratory , too , " Safdi said in astatement .
We ca n’t do anything about the supernova drought , but we can speak the other potential obstructor . The anticipated upsurge of gamma rays is thought to last just 10 seconds or so . That ’s not sufficient for a gamma light beam - detection instrument to be alerted by a telescope operating elsewhere in the spectrum and grow its aid to the right spot .
accordingly , we call for to have a Vasco da Gamma - ray eye on the right-hand part of the sky for the project to come after . If Vasco da Gamma - ray telescope were like optical ace , with very pocket-sized fields of persuasion , the outlook might be dim . The Large Area Telescope , one of the Fermi Gamma - ray Space Telescope ’s two cat’s-paw , is the one currently operating tool Safdi and co - authors think is up to the line . It reckon about a one-fifth of the sky at a time .
“ It would be a substantial shame if a supernova hold up off tomorrow and we omit an opportunity to detect the axion , ” Safdi added . “ It might not hail back for another 50 year . ”
“ The best - slip scenario for axions is Fermi catches a supernova . It ’s just that the chance of that is small , ” Safdi say . “ But if Fermi saw it , we ’d be able to measure out its mass . We ’d be capable to measure its interaction strength . We ’d be able to determine everything we need to know about the axion , and we ’d be incredibly confident in the sign because there ’s no average matter which could create such an outcome . ”
The alternative is to boom our mental ability in this part of the spectrum . Safdi and colleagues are promoting an thought for a full - sky gamma ray watch . They even have a name for it ; GALactic AXion Instrument for Supernova ( GALAXIS ) .
Much as scientists want to find dingy affair , we do n’t envy someone trying to persuade funding bodies to pay for a web of gamma - ray telescopes to wait for an event that may not fall out for 100 . Fortunately , just as Fermi has been a deep origin ofother scientific data point , GALAXIS could do lot else while it look .
Nevertheless , the whole idea relies not only on axions being real , but that they also have the specific characteristics call for them by string theory . “ It seems almost impossible to have a consistent hypothesis of gravity combined with quantum automobile mechanic that does not have particle like the axion , ” Safdi aver .
However , with a significant pool of physicists deeply shady of drawstring theory , not everyone agree . GALAXIS , plus a worthy supernova , might settle that debate , but first arrangement must be establish to launch the instruments .
The study is published inPhysical Review Letters .
