Astronomija

Da li je Međunarodni istraživač Sun-Earth otkrio svemirske zrake osim gama zraka?

Da li je Međunarodni istraživač Sun-Earth otkrio svemirske zrake osim gama zraka?


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Gledajući dostupne skupove podataka koje je NASA opisala za Međunarodni istraživač Sun-Earth, vidim samo podatke o eksploziji gama zraka.

Da li je platforma bila sposobna za snimanje kosmičkih zraka osim gama zraka? Ako da, gdje su podaci?


NASA-ina definicija misije programa International Sun Earth Explorer glasi:

Međunarodni istraživač Sun-Earth, ili ISEE, bio je međunarodni program suradnje između NASA-e i ESA-e osmišljen za proučavanje interakcije sunčevog vjetra sa Zemljinim magnetskim sistemom, magnetosferom. Tri ISEE letjelice mjerile su energetske čestice, električna i magnetska polja i parametre plazme.

Odgovarajuća stranica misije ESA nudi više detalja o instrumentima i ima mnogo vrijednih poveznica o znanstvenim rezultatima, npr. prema ISEE 3 Pregled publikacija:

Drugim riječima, čini se da su zapažanja gama zraka najistaknutiji nalazi. Koliko mogu ocijeniti laikom, čini se da je skup podataka citiran u pitanju prilično potpun. Da bih bio 100% siguran, bojim se da bi trebalo ići u svaku publikaciju.


Da, nekoliko eksperimenata na ISEE satelitima bilo je posvećeno otkrivanju ili karakterizaciji solarnih i galaktičkih kosmičkih zraka, uključujući, između ostalih, eksperiment sa kosmičkim zrakama sa niskom energijom (zajedno sa eksperimentom sa kozmičkim zrakama sa srednjom energijom i eksperimentom sa kozmičkim zrakama visoke energije) i teški izotopski spektrometar teleskop (solid state detektor).

Podaci (ili rezultati, ako ne i neobrađeni podaci) iz nekih od ovih eksperimenata sigurno su dostupni na mreži u arhivi podataka na koju ste povezali (samo traženje "kosmičkog zraka" skraćuje proces), kao i niz drugih ISEE eksperimenata i instrumenata . Na primjer, ovdje se mogu naći tablice visokoenergijskih sastava kosmičkih zraka sa ISEE-3. Naravno, nije sve navedeno dostupno na mreži; ovaj niz niskoenergetskih ISEE-3 mjerenja pohranjen je na mikrofilmu.


Šta su rafali gama zraka i kako smo ih otkrili?

Eksplozije gama zraka (GRB) su bljeskovi gama zraka (elektromagnetno zračenje visoke frekvencije) koji dolaze od energetskih eksplozija u udaljenim galaksijama. Poznato je da su oni najzračeniji elektromagnetski događaji u svemiru. Rafali mogu trajati od deset milisekundi do nekoliko minuta (tipični rafal traje 20-40 sekundi). GRB su otkriveni krajem 1960-ih, međutim, to nije bilo namjerno otkriće. Otkrili su ih američki sateliti Vela koji su zapravo izgrađeni za otkrivanje impulsa gama zračenja koje emituje nuklearno oružje testirano u svemiru. Zašto? Pa, SAD su sumnjale da bi SSSR mogao pokušati provesti tajna nuklearna ispitivanja nakon potpisivanja Ugovora o zabrani nuklearnih pokusa 1963. godine.

Reklama

Reklama

Prvi detektor gama-zraka poslan u svemir bio je satelit Explorer XI. Pokrenut je 1961. godine i trajao je 7 mjeseci. Za sve to vrijeme bilo je korisno samo 6 dana (141 sat) posmatranja. Explorer XI otkrio je gama-zrake s energijom od 100 MeV i više. U ovom trenutku znanstvena zajednica nije očekivala da će vidjeti bilo kakve GRB-ove. Originalni rad iz 1965. godine spominje nekoliko različitih očekivanih mehanizama za gama-zrake koje je detektovao satelit Explorer XI, mehanizama koji se kreću od raspada piona do kosmičkih zraka koji komuniciraju sa elektronima - nema pomena (čak ni nagovještaja) gama-zraka rafali.

Prvo otkrivanje GRB-a došlo je sa satelita Vela, koji su bili u vlasništvu nekoliko ogranaka vlade Sjedinjenih Država. Njihova je svrha bila otkriti izvore gama-zraka prvenstveno na površini Zemlje i u atmosferi, kako bi bili sigurni da druge zemlje ne krše međunarodne ugovore upotrebom nuklearnog oružja. Ukupno se smatralo da je samo 16 događaja kosmičkog porijekla [ne sa Zemlje ili Sunca]. Ovi opaženi događaji imali su vremenski raspon od manje od 0,1 sekunde pa sve do 30 sekundi. Energije koje su otkrili sateliti Vela bile su između 0,2-1,5 MeV (što je niže od praga otkrivanja GRB-a kod nekoliko narednih satelita).


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POSEBNI IZVJEŠTAJ: Tok kozmičkih zraka koji nam se kreću

—- Bilješka : Važno izdanje vijesti za čitanje i razumijevanje & # 8212-
Zemlju i druge planete neprestano bombardiraju kosmički zraci (nabijene čestice iz kosmosa). Tok kozmičkih zraka vrlo visoke energije varira ovisno o tome gdje gledamo na nebo. Istraživač i vodeći autor Nathan Schwadron sa Univerziteta u New Hampshireu objavio je otkrića istraživačkih timova u naučnom časopisu Nature.

Nova otkrića otkrivena pomoću NASA-inog satelita IBEX (Interstellar Boundary Explorer), zajedno sa zemaljskim detektorima, ukazuju na to da kosmički zraci iz naše galaksije (Mliječni put), u interakciji s našom heliosferom, igraju snažnu ulogu u usmjeravanju ovih nabijenih čestica u naš Sunčev sistem. Schwadron podsjeća da smo prije pedeset godina vršili prva mjerenja solarnog vjetra i razumijevali prirodu onoga što je bilo izvan svemirskog prostora. Sada se otvara potpuno novo područje znanosti dok pokušavamo razumjeti fiziku skroz izvan heliosfere. & # 8221

UPDATE: Nismo daleko od svog cilja zahvaljujući još 3 sponzora koji su nas približili 300. Mislim da je važno možemo li to završiti u naredna 2 ili 3 dana. Primio sam više od sto e-poruka s naznakom da bi se željeli pridružiti u sljedećih nekoliko tjedana, ali ne mogu garantirati da će naša cijena s popustom proći prvu sedmicu ožujka. Kao što je spomenuto, vijesti će izlaziti bijesnim tempom tijekom sljedećih mjesec dana ili malo više, a uz vaše sponzorstvo mogu umanjiti svoje troškove iz džepa i još bolje, omogućit će dobrom broju ljudi koji imaju pristup inače ne bi mogao.

Razumijevanje utjecaja kosmičkih zraka na heliosferu je presudno kako bismo mogli bolje razumjeti kako nas heliosfera štiti. U osnovi, heliosfera odražava odnos između Sunca i Zemljinog magnetnog polja. Bez ove zaštite nema ni Sunca, ni Sunčevog sistema, ni Zemlje. Ako bilo koji od njih ukazuje na slabljenje, koje se u povijesti uvijek događa kao dio prirodnog ciklusa, doći će do promjena. Ne promjena na kraju svijeta & # 8211, ali sigurno promjena u našem svijetu kakav danas poznajemo.

Ažurirana jednadžba:
Povećanje naelektrisanih čestica smanjeno magnetno polje → Povećanje konvekcije vanjskog jezgra → Povećanje plamenskih oluja → Povećanje zemljotresa i vulkana → Hlađenje plašta i vanjskog jezgra → Povratak konvekcije vanjskog jezgra (Mitch Battros & # 8211 jul 2012)

Eric Christian, naučnik IBEX-ovog projekta iz NASA-inog svemirskog letačkog centra Goddard, kaže nam: & # 8220Helosfera je presudan sloj zaštite od opasnih kosmičkih zraka koji su štetni za živa bića. & # 8221 Srećom, naša Zemlja & # 8217s magnetna Polje je obično u stanju da zaštiti život na Zemlji od kosmičkih zraka koje nisu zaštićene našom heliosferom. Moramo razmotriti kako će nas heliosfera štititi u budućnosti ili kako nas je štitila u prošlosti. Razumijevanje heliosfere i načina na koji nas štiti dio je razumijevanja našeg doma u galaksiji.

U direktnoj korelaciji s ekspanzijom i kontrakcijom kosmičkih zraka koji utječu na našu heliosferu, snaga nabijenih čestica sunčevih vjetrova (solarne rakete, izbacivanje koronalne mase, koronalne rupe, nit) varirat će kako odgovara Suncu i dugoročnom i kratkoročnom ciklusa.

Na isti način na koji se Zemljino magnetno polje formira na putu u čahuri ili fudbalu dok nas štiti, tako se to čini i heliosfera kao napuhano polje koje seže u međuzvjezdani medij koji pokreće solarni vjetar. Dok naše Sunce kruži oko središta naše galaksije (Mliječni put) otprilike svakih 225 miliona godina kao dio većeg ciklusa, ono prolazi kroz različite kraće cikluse koji se tkaju u i izvan orbitalnih tokova. Dok to čini, prolazi kroz područja međuzvjezdane sredine koja su sve manje gušta, što uzrokuje promjenu oblika i veličine heliosfere. Gusta područja mogu stisnuti heliosferu, dok manje gusta područja omogućavaju širenje ovog balona.

Šta koristimo za otkrivanje kosmičkih zraka?

Pored svemirskih satelita poput IBEX-a, na Zemlji postoji niz detektora koji se koriste za otkrivanje kosmičkih zraka ili drugih čestica povezanih sa događajima visoke energije koji proizvode kosmičke zrake. Naučni tim IBEX-a koristio je podatke iz nekoliko detektora, uključujući Super-kamiokande, Milagro i Ice Cube. Super-kamiokande ili Super-K je detektor smješten duboko u rudniku u Japanu. Djelujući do 2008. godine, Milagro je bio detektor smješten u planinama Novog Meksika. IceCube je detektor koji radi na Južnom polu.

Šta su kosmički zraci?

Na kozmičke zrake, kao nabijene čestice, utječu magnetska polja, uključujući međuzvjezdana magnetska polja, magnetsko polje našeg Sunca i Zemljino magnetsko polje. Nick Pogorelov, svemirski naučnik sa Univerziteta u Alabami i koji radi s IBEX podacima kaže. & # 8220Koliko se kosmički zraci približavaju našoj heliosferi, oni se mogu skrenuti, a većina njih ne može proći u unutrašnji Sunčev sistem. Kozmički zraci veće energije vjerovatnije će proći kroz našu heliosferu, a neki čak mogu proći kroz Zemljino magnetno polje da bi se otkrili na različite načine zbog njihove interakcije sa Zemljinom atmosferom. & # 8221


Kineski kozmički satelit 'Kralj majmuna' traži tamnu materiju

Analizom kosmičkih zraka u svemiru, kineski satelit "Kralj majmuna" sada pomaže utvrditi identitet tamne materije, otkriva novo istraživanje.

Satelit Dark Matter Particle Explorer (DAMPE), lansiran 2015. godine, prva je kineska svemirska opservatorija. Cilj DAMPE-a je pomoći u pronalaženju porijekla tamne materije - misteriozne, nevidljive supstance za koju istraživači sumnjaju da čini oko pet šestine sve materije u svemiru.

DAMPE je dobio nadimak "Wukong" po Sunu Wukongu, kralju majmuna, nestašnom junaku epske kineske priče "Putovanje na zapad", koji mijenja oblik. "Wu" znači "razumijevanje", a "kong" znači "praznina", tako da Wukong može značiti i "razumijevanje praznine" - stoga naziv podvlači misiju DAMPE-a da pomogne naučnicima da razumiju tamnu materiju. [Potraga za tamnom materijom u slikama]

DAMPE je posebno dizajniran za otkrivanje snopova energije najviše energije, poznatih kao gama zrake, kao i kosmičkih zraka. Potonje su čestice koje prolaze kroz vanjski svemir s izuzetno visokim količinama energije. Mnogi kozmički zraci sastoje se od jezgara atoma, ali neki su elektroni, dok su drugi pozitivno nabijeni antimaterijski pandan elektrona poznat kao pozitroni.

Neki modeli tamne materije sugeriraju da se ona može razbiti u kosmičke zrake - tačnije, parove elektrona i pozitrona. Kada ovi pozitroni pogodiju elektrone, oni se međusobno uništavaju, oslobađajući gama zrake. Međutim, postoje mnogi drugi potencijalni izvori kosmičkih zraka i gama zraka, poput pulsara - koji se brzo vrte u kolapsiranim zvijezdama - ili ostataka supernove, koji su ostaci zvijezda koje su umrle u katastrofalnim eksplozijama. DAMPE mjeri količinu energije u gama zracima i kosmičkim zracima kako bi pomogao u rasvjetljavanju onoga što su njihovi izvori.

Prethodni eksperimenti na balonu ili u svemiru koji su analizirali kosmičke zrake izravno su mjerili energije do 2 bilijuna elektrona volta, dok su zemaljski nizovi teleskopa mogli indirektno mjeriti energije do oko 5 bilijuna elektrona volta. (Jedan bilion elektrona volta otprilike je količina kinetičke energije koju spakuje leteći komarac.)

U usporedbi s tim, DAMPE može otkriti elektrone kosmičkih zraka i pozitrone s energijom od oko 10 bilijuna elektrona volta. "Proširuje direktno mjerenje elektrona kosmičkih zraka i pozitrona na najviše energije do sada", rekao je Jordan Goodman, astrofizičar čestica sa Univerziteta Maryland, koji nije učestvovao u istraživanju DAMPE, za Space.com. [100 godina kosmičkih zraka: Objašnjeno otkriće]

Do sada je DAMPE otkrio više od 3,5 milijardi kosmičkih zraka, od kojih najenergičniji prelaze 100 bilijuna elektronskih volti. Očekuje se da će DAMPE otkriti više od 10 milijardi kosmičkih zraka tokom svog predviđenog vijeka trajanja dužeg od pet godina.

DAMPE je pronašao "spektralni prekid" - pad broja elektrona kosmičkih zraka i pozitrona - na oko 900 milijardi elektronskih volti. "Niko nije siguran zašto je došlo do pauze", rekao je Goodman.

Prije toga, teleskop s pet teleskopa H.E.S.S. niza u Namibiji i CALorimetrijskog elektronskog teleskopa na Međunarodnoj svemirskoj stanici vidjeli su znakove ovog spektralnog prekida, ali Fermi gama-zračni teleskop nije.

"Naša su mjerenja razjasnila ponašanje elektronskog i pozitronskog spektra pri energijama od bilijuna elektron-volta", rekao je za Space.com koautor studije Yi-Zhong Fan, astrofizičar čestica pri Kineskoj akademiji nauka u Nanjingu. "Prvi rezultati DAMPE pokazuju njegovu sposobnost istraživanja nove astrofizike."

Čestice tamne materije mogle bi objasniti ovaj spektralni prekid ako mase tih čestica leže tačno ispod 900 milijardi elektronskih volti, rekao je Goodman. (Energija je ekvivalentna masi, što je dokazala Einsteinova poznata jednadžba E = mc ^ 2.) Kao takva, ovi nalazi osporavaju modele koji sugeriraju da čestice tamne materije mogu imati različite mase.

S druge strane, ovaj spektralni prekid mogao bi biti posljedica svemirskih zraka pulsara ili ostataka supernove koji se nekako hlade na putu kroz svemir, rekao je Fan. "U svakom slučaju, sada dobivamo solidne podatke na osnovu kojih bilo koji model mora biti testiran", rekao je Goodman.

Naučnici su svoja otkrića detaljno objavili u izdanju časopisa Nature od 30. novembra.


Istorija astronomije gama-zraka uključujući srodna otkrića

& ndash Becquerel otkriva jednu komponentu radioaktivnosti. Te emanacije Rutherford naziva beta zracima. Pojam radioaktivnost smislili su Kuri.

& ndash J.J. Thomson otkriva elektron kao negativno nabijenu česticu.

& ndash Rutherford otkriva drugu komponentu radioaktivnosti, koju naziva alfa zrakama.

& ndash Villard otkriva treću komponentu radioaktivnosti, koja postaje poznata kao gama zrake, slijedeći Rutherfordovu notaciju.

& ndash Einstein objavljuje Specijalnu teoriju relativnosti, suštinsku teorijsku osnovu za razumijevanje fizike čestica. Iz svoje teorije izvodi ekvivalenciju mase i energije prema formuli E = mc 2.

& ndash Einstein objašnjava fotoelektrični efekt kao interakciju između čestice elektromagnetskog zračenja i elektrona.

& ndash Einstein razvija koncept svjetlosnih kvanta (čestica elektromagnetskog zračenja).

& ndash Bragg demonstrira da gama zrake jonizuju gas baš kao i rentgenske zrake.

& ndash Rutherford otkriva atomsku jezgru.

& ndash von Laue, Knipping i amp Friedrich pokazuju valnu prirodu x-zraka.

& ndash Hess putem balonskih eksperimenata otkriva da je Zemlja bombardirana prodorom zračenja odozgo. Ovo otkriće potvrđuje Kolh & # 246rster. Ta zračenja Millikan kasnije naziva "Quotcosmic zrake".

& ndash Rutherford i amp Andrade pokazuju valnu prirodu gama zraka.

& ndash Rutherford otkriva osnovnu nabijenu česticu atomske jezgre, koju kasnije naziva protonom.

& ndash Compton otkriva da rendgenski zraci mogu izgubiti energiju kada se rasipaju elektrone. To se naziva Comptonovim efektom.

& ndash de Broglie pretpostavlja da bi čestice trebale imati talasasta svojstva.

& ndash Pauli uvodi svoj princip izuzeća koji zabranjuje da dvije identične čestice s pola cijelog spina (kasnije nazvane Fermions) istovremeno zauzimaju isto kvantno stanje. Ovaj princip najspektakularnije se pokazuje postojanjem bijelih patuljaka i neutronskih zvijezda, u kojima degenerirani elektron, odnosno neutronski pritisak, podupiru unutrašnjost ovih zvijezda protiv gravitacije.

& ndash Fermi & amp Dirac uvode Fermi-Dirac statistiku kako bi opisali svojstva čestica sa polucjelovitim spinom (kasnije nazvanim Fermions), poput elektrona, neutrona i protona.

& ndash Davisson & amp Germer i (neovisno) G.P. Thomson otkriva difrakciju elektrona, demonstrirajući time da se elektroni ponašaju poput valova.

& ndash Compton definira kvant svjetlosti kao foton, pojam koji je prethodno smislio Lewis. Odsada su rentgenski i gama zraci fotoni.

& ndash Clay otkriva da se kosmički zraci odbijaju od Zemljinog magnetskog polja upoređivanjem opažanja na različitim geografskim širinama (& quotlatitude efekt & quot). Na kraju zaključuje da kozmičke zrake moraju biti uglavnom nabijene čestice.

& ndash Skobeltzyn promatra tragove nabijenih čestica visoke energije u nasumično proširenoj komori oblaka. Zaključuje dvije godine kasnije da ove nabijene čestice moraju biti kosmički zraci.

& ndash Geiger & amp Mueller izumili su Geiger-Mueller brojač za otkrivanje nabijenih čestica.

& ndash Bothe & amp Kolh & # 246rster primjenjuju metodu slučajnosti na dva Geiger-Muellerova brojača i otkrivaju da kosmički zraci na nivou tla sadrže čestice vrlo visoke energije koje mogu prodrijeti u 5 cm zlata.

& ndash Rossi izmišlja elektronički koincidencijski krug za mjerenje istovremenih impulsa u više Geiger-Muellerovih brojača. Ova tehnika se ubrzo koristi u fizičkim eksperimentima širom svijeta, uključujući i u proučavanju kosmičkih zraka.

& ndash Rossi predviđa da bi trebala postojati razlika između intenziteta kozmičkih zraka koji dolaze sa istoka i zapada, ovisno o predznaku njihovog električnog naboja uslijed skretanja Zemljinog magnetskog polja (& quotEfekat Istok-Zapad & quot).

& ndash Pauli predlaže postojanje & quotneutrino & quot, imena koje je kasnije smislio Fermi.

& ndash Chadwick otkriva neutron. Postojanje neutrona mnogo je godina ranije predvidio Rutherford.

& ndash Anderson otkriva i imenuje pozitron. Postojanje pozitrona je predvidio Dirac.

& ndash Chadwick, Blackett & amp Occhialini primjećuju da gama zrake koje prolaze kroz materiju mogu generirati elektronsko-pozitronske parove.

& ndash Tri nezavisna eksperimenta (Johnsona, Alvareza i amp Comptona i Rossija) mjere učinak Istok-Zapad i otkrivaju da je intenzitet kosmičkih zraka veći sa zapada, što implicira da su većina primarnih kozmičkih zraka pozitivno nabijene čestice.

& ndash Tijekom svog eksperimenta Istok-Zapad, Rossi otkriva zračne pljuskove kosmičkih zraka, ali ih ne proučava detaljno.

& ndash Yukawa predviđa postojanje mezona koji posreduju snažnu silu u atomskoj jezgri.

& ndash Anderson & amp Neddermeyer i Street & amp Stevenson neovisno najavljuju otkriće nabijenih čestica koje postaju poznate kao mioni.

& ndash Auger ponovo otkriva zračne tuševe sa kosmičkim zrakama, nesvjestan Rossijevog rada. Auger detaljno proučava tuševe.

& ndash Hulburt i Vegard nezavisno predlažu da je jonizacija gornjih slojeva Zemljine atmosfere, promatrana refleksijom radio talasa, uzrokovana ultraljubičastim zračenjem i rendgenskim zrakama sunca.

& ndash Lattes, Occhialini i amp Powell otkrivaju nabijene pione. To su mekuni Yukawa koji vežu atomsku jezgru.

& ndash Feenberg & amp Primakoff predviđaju da se gama zrake proizvode u međuzvjezdanom prostoru zbog Comptonovog rasipanja fotona niske energije sa visokoenergijskih elektrona.

& ndash Hulsizer & amp Rossi postavljaju gornju granicu od 0,01 na intenzitet nebeskih elektrona i gama zraka u odnosu na kosmičke zrake pri energijama iznad 4,5 GeV eksperimentom na balonu.

& ndash Freier i dr. i Bradt & amp Peters neovisno otkrivaju primarne jezgre kosmičkih zraka teže od helija eksperimentima na balonu.

& ndash Fermi opisuje postupak za ubrzanje nerelativističkih nabijenih čestica do energije kosmičkih zraka putem sudara s magnetskim poljima u međuzvjezdanom mediju. Ovaj proces postaje poznat pod nazivom & quotFermi mehanizam & quot.

& ndash Bolton, Stanley i amp Slee otkrivaju da je maglica Crab radio izvor.

& ndash Friedman, Lichtman & amp Byram eksperimentom na raketi V-2 potvrđuju da sunce emituje rendgenske zrake.

& ndash Bjorklund i dr. i Carlson i dr. samostalno otkriti neutralni pion. Ovaj mezon se vrlo brzo raspada u par gama zraka.

& ndash Borst sugerira da je radioaktivni raspad ono što pokreće svetlosne krivine supernove i da se emisija gama zraka može otkriti iz supernova.

& ndash Perlow & amp Kissinger postavljaju gornju granicu od 0,01 (cm 2 ster ster) -1 na tok nebeskih gama zraka pri energijama od 3,4 do 90 MeV eksperimentom na raketi V-2.

& ndash Biermann, Haxel & amp Schluter predviđaju da će solarne baklje proizvesti energetske neutrone koji bi trebali biti otkriveni na Zemlji.

& ndash Critchfield, Ney & amp Osaka postavljaju gornju granicu od 0,6% na intenzitet nebeskih gama zraka u odnosu na kosmičke zrake pri energijama iznad 1 GeV eksperimentom na balonu.

& ndash Hayakawa predviđa postojanje difuzne galaktičke emisije gama zraka zbog raspada neutralnih piona koji se oslobađaju kada se jezgre kosmičkih zraka sudare sa međuzvezdanim gasom.

& ndash Hutchinson predviđa postojanje difuzne emisije međuzvezdanih gama zraka zbog kočionog zračenja stvorenog sudarima elektrona kosmičkih zraka sa međuzvezdanom materijom.

& ndash Galbraith i pojačalo Jelley otkrivaju Cerenkov svjetlosne impulse iz zračnih tuševa kosmičkih zraka noću. Da će kosmički zraci donijeti malu količinu svjetlosti na noćno nebo, predvidio je Blackett nekoliko godina ranije.

& ndash Baade i amp Minkowski sugeriraju da su radio izvor Cygnus A dvije galaksije u sudaru.

& ndash Segre, Chamberlain i dr. otkriti antiproton.

& ndash Gigantski nalet neutrona primećen je tokom solarne baklje 23. februara putem zemaljskih detektora. To su sekundarni neutroni nastali sudarima protona Sunčevih baklji sa materijom u Zemljinoj atmosferi.

& ndash Cork i dr. otkrijte antineutron.

& ndash Reines i amp Cowan najavljuju prvo definitivno otkrivanje neutrina (u ovom slučaju elektronski antineutrino).

& ndash Hoyle & amp Burbidge sugeriraju da sudari između galaksija mogu rezultirati uništenjem materije i antimaterije, što bi proizvelo gama zrake, i moglo bi napajati ekstragalaktičke radio izvore poput Labuda A.

& ndash Explorers 1 i 3 pokrenuti su 31. januara, odnosno 26. marta. Van Allen i dr. otkrijte pojaseve nabijenih čestica u svemiru iznad Zemlje eksperimentima na tim satelitima. Pojasevi postaju poznati kao Van Allenovi radijacijski pojasevi.

& ndash Peterson i amp Winckler otkrivaju rafal gama zraka iz solarne baklje eksperimentom na balonu. Ovi autori su prvi koji su upotrijebili izraz "prasak quotgamma-ray", koji će biti povezan sa potpuno drugačijim fenomenom 15 godina kasnije.

& ndash Morrison sažima nekoliko ohrabrujućih predviđanja u vezi s emisijom gama zraka iz različitih nebeskih izvora. Pokazalo se da su ti proračuni divlje optimistični, ali su ključni za pokretanje polja astronomije promatranja gama zraka u narednih nekoliko godina.

& ndash Cocconi predlaže potragu za kosmičkim izvorima vrlo visokoenergetskih gama zraka pomoću tehnike vazdušnog tuširanja na zemlji.

& ndash Braccesi, Ceccarelli & amp Salandin postavili su gornju granicu pouzdanosti od 95% od 0,015 (cm 2 s) -1 za tok gama zraka iznad 100 MeV iz Labusa A eksperimentom na balonu.

& ndash Chudakov i dr. Instituta Lebedev slijede Cocconijev prijedlog i započinju potragu za zračnim tuševima od vrlo visokoenergetskih gama zraka na lokaciji na Krimu. Eksperiment traje nekoliko godina, ali nisu otkrivena jasna otkrića.

& ndash Earl i (nezavisno) Meyer i amp Vogt otkrivaju primarne elektrone kosmičkih zraka putem eksperimenata na balonu.

& ndash Prva solarna opservatorija u orbiti (OSO-1) pokrenuta je 7. marta. U sebi ima nekoliko instrumenata, uključujući jedan osetljiv na visokoenergijske gama zrake sunca, ali takva zračenja nisu otkrivena.

& ndash Explorer 11 lansiran je 27. aprila noseći instrument osetljiv na gama zrake energije iznad 50 MeV.

& ndash Klin postavlja balon-eksperimentom gornju granicu pouzdanosti od 95% od 0,007 (cm 2 ster) -1 na tok nebeskih gama zraka pri energiji iznad 70 MeV, koristeći prvi visokoenergijski gama-teleskop dizajniran za to svrha.

& ndash Arnold i dr. detektirati difuznu pozadinu gama zraka pri energijama od 0,1 do 3 MeV eksperimentom na brodu Ranger 3, koji je letio pored Mjeseca.

& ndash Giaconni i dr. otkriti izvor rendgenskih zraka koji postoji izvan Sunčevog sistema eksperimentom na raketi Aerobee lansiranoj 19. juna. Ovaj vrlo jak izvor rendgenskih zraka nazvan je Scorpius X-1, što se na kraju shvatilo kao rentgenski zrak male mase Binarni (LMXB). Otkrivena je i difuzna rendgenska pozadina.

& ndash Schmidt vrši prvo mjerenje crvenog pomaka kvazara (3C 273). Termin kvazar je kasnije skovao Chiu.

& ndash Bowyer i dr. otkrijte maglu rakova u rendgenskim zrakama eksperimentom na raketi Aerobee lansiranoj 29. aprila.

& ndash Gell-Mann i Zweig neovisno iznose kvarkovsku teoriju materije. Termin kvark skovao je Gell-Mann.

& ndash Metzger i dr. predstavljaju dokaze za udarac u difuznoj gama-zraci u pozadini pri energiji od otprilike 1 MeV (udarac od MeV) na osnovu zapažanja izvršenih eksperimentima na brodovima Ranger 3 i 5, koji su obojici preletjeli mjesec 1962. godine.

& ndash Kraushaar i dr. objaviti gornju granicu, zasnovanu na istraživanjima Explorera 11, od 0,0003 (cm 2 ster ster) -1 na toku nebeskih gama zraka sa energijama iznad 50 MeV. Ova granica je izvedena iz vjerovatnog otkrivanja samo 31 nebeskog gama zraka. Nigdje na nebu nije primijećena koncentracija gama zraka.

& ndash Penzias i amp Wilson otkrivaju Kozmičku mikrotalasnu pozadinu (CMB).

& ndash Haymes gradi scintilacijski teleskop gama-zraka na Sveučilištu Rice ref.

& ndash Duthie, Cobb & amp Stewart tvrde da je detekcija visokoenergijskog izvora gama zraka u Labudu putem eksperimenta na balonu. Otkrivanje se nikada ne potvrđuje.

& ndash Fichtel i dr. započinju demonstracije prve svemirske visoko-energetske gama-zračene digitalizovane varnice kroz seriju letova balonom.

& ndash Treća orbitalna solarna opservatorija (OSO-3) pokrenuta je 8. marta i nosi nekoliko instrumenata, uključujući jedan osetljiv na gama zrake visoke energije iznad 50 MeV.

& ndash Vela 4a, b i 18. Satelit za istraživanje životne sredine (ERS-18) lansirani su 28. aprila. Ovi sateliti izvode nekoliko eksperimenata, uključujući instrumente osetljive na gama zrake.

& ndash Giaconni i dr. objaviti otkriće, na osnovu sondiranja raketa, Cen X-3. Mnogo godina kasnije, ovaj će se izvor shvatiti kao rentgenski binarni materijal velike mase (HMXB) koji sadrži pulsar na bazi akrecije.

& ndash Friedman & amp Byram otkrivaju kvazar 3C 273 i radio galaksiju M87 u rendgenskim zrakama eksperimentom na brodu i raketom Aerobee lansiranom 17. maja.

& ndash Prvi svemirski rafal Gamma-Ray (GRB) koji je ikada zabeležen otkriven je 2. jula preko satelita Vela 4a, b. Ovo otkriće neće biti objavljeno nekoliko godina zbog vojne klasifikacije.

& ndash Bell & amp Hewish otkrivaju prvi pulsar putem radio-promatranja.

& ndash Large, Vaughan & amp Mills otkrivaju Vela Pulsar putem radio-promatranja.

& ndash Clark, Garmire & amp Kraushaar najavljuju otkrivanje Galaktičke ravni i centra, izvedeno eksperimentom na brodu OSO-3, u visokoenergetskim (iznad 50 MeV) gama zracima. To su gama zrake koje je predvidio Hayakawa. Otkrivena je i izotropna komponenta visokoenergijskih gama zraka za koju se vjeruje da je vangalaktičkog porijekla.

& ndash Lovelace otkriva Crab Pulsara putem radio teleskopa Arecibo.

& ndash Prvi atmosferski gama-zračni teleskop Čerenkov izgrađen je u Arizoni u opservatoriji Mount Hopkins (kasnije preimenovanoj u opservatoriju Whipple). Ovaj teleskop od 10 metara još uvijek radi.

& ndash Fishman & amp Clayton započinju proučavanje linijskih gama zraka iz 56Co ref.

& ndash Fritz i sur. i Bradt i dr. samostalno otkriti rendgenske impulse iz Crab Pulsara eksperimentima na sondirnim raketama.

& ndash Fishman i sur. izvesti analizu 1967. balonskih posmatranja Rakova pulsara u niskoenergetskim gama zracima koja daje tačno merenje perioda spina pre otkrića.

& ndash Vela 5a, b lansirani su 23. maja sa rentgenskim i gama-detektorima.

& ndash Haymes, Johnson i dr. otkriti emisiju gama zraka energijom blizu 500 keV iz Galaktičkog centra kroz nekoliko eksperimenata na balonu.

& ndash Vette i dr. objaviti potvrdu, na osnovu zapažanja iz eksperimenta na brodu ERS-18, postojanja difuzne pozadine gama zraka pri energijama MeV.

& ndash Friedmann, Kendall & amp Taylor otkrivaju da su kvarkovi prave čestice (a ne samo teoretske pogodnosti) eksperimentom u Stanfordskom centru za linearni akcelerator (SLAC).

& ndash Vela 6a, b lansirani su 8. aprila noseći rendgenske i gama-detektore.

& ndash Kniffen & amp Fichtel potvrđuju detekciju Galaktičkog aviona u visokoenergetskim gama zrakama putem digitalizovane komore sa balonom na bazi balona.

& ndash Stecker pruža prvu sveobuhvatnu obradu astrofizičkih procesa proizvodnje gama zraka u knjizi pod naslovom & quotCosmic Gamma Rays & quot.

& ndash Šesta platforma za međuplanetarno nadgledanje (IMP-6) pokrenuta je 14. marta i nosi nekoliko instrumenata, uključujući gama-monitor.

& ndash Whitney i dr. otkrijte superluminalno kretanje u kvazaru 3C 273 putem radio-promatranja vrlo duge bazne interferometrije (VLBI).

& ndash Mjesečeva ekspedicija Apollo 15 pokrenuta je 26. jula. Jedan od instrumenata koje nosi osjetljiv je na gama zrake.

& ndash Browning, Ramsden i amp Wright otkrivaju impulsnu emisiju visokoenergijskih gama zraka iz Crab Pulsara iznad 50 MeV putem eksperimenta na balonu.

& ndash Sedma solarna opservatorija u orbiti (OSO-7) pokrenuta je 29. septembra. U njenu instrumentaciju ulaze rendgenski teleskop i monitor gama zraka.

& ndash Webster i amp Murdin i (neovisno) Bolton koriste optičku spektroskopiju da sigurno utvrde da je Cyg X-1 binarni sistem koji sadrži crnu rupu.

& ndash Mayer-Hasselwander i dr. najaviti otkrivanje difuzne gama-zrake u opsegu od 30 do 50 MeV putem balonske digitalizovane komore sa iskrama.

& ndash Chupp i sur. otkriti linije emisije gama-zraka iz solarnih baklji u avgustu eksperimentom na brodu OSO-7. To uključuje liniju za uništavanje pozitrona od 511 keV, liniju za hvatanje neutrona od 2.223 MeV i slabu detekciju linija C-pojačala de-pobude na 4.438 i ampl 6.129 MeV. Fotoni kontinuuma su takođe otkriveni do 10 MeV.

& ndash Kraushaar i dr. predstavljaju konačne rezultate OSO-3 promatranja visokoenergetskih galaktičkih gama zraka i potvrđuju identifikaciju izotropne komponente ekstragalaktičkog porijekla.

& ndash Drugi mali astronomski satelit (SAS-2) lansiran je 15. novembra. U njemu se nalazi digitalizovana iskra komora osetljiva na gama zrake visoke energije.

& ndash Kinzer i dr. announce the definitive detection, made via a balloon-borne experiment, of pulsed medium-energy gamma-ray emission from the Crab Pulsar.

&ndash Trombka et al. claim to confirm the detection of an excess of gamma rays of cosmic origin with an energy of roughly 1 MeV (the MeV bump) via an experiment aboard the Apollo 15 Service Module.

&ndash Kelbesadel, Strong & Olson announce the discovery of Gamma-Ray Bursts (GRBs) of cosmic origin. Their discovery paper is based on observations made from 1969 to 1972 via detectors aboard the Vela 5a,b and 6a,b satellites.

&ndash Cline et al. publish some spectra of GRBs based on data from an experiment aboard IMP-6. The observed energy spectra peak in hard x-rays and low-energy gamma rays.

&ndash Wheaton et al. announce the detection, made via x-ray telescopes on OSO-7, of x-ray emission down to energies below 10 keV from a GRB.

&ndash Fichtel et al. announce the strong detection, made via SAS-2 observations, of the Galactic Plane in high-energy gamma rays, and the extragalactic isotropic component.

&ndash Celestial Observation Satellite B (COS-B) is launched on August 9. It carries a digitized spark chamber sensitive to high-energy gamma rays, which operates successfully for more than six years.

&ndash Kniffen et al. announce the detection, made via SAS-2 observations, of an excess of high-energy gamma-ray radiation from the Galactic Anticenter region that cannot be tied to any known source. Bignami et al. subsequently apply the name "Geminga" to this mysterious object.

&ndash Thompson et al. announce the detection, made via SAS-2 observations, of the Vela Pulsar in high-energy gamma rays.

&ndash Helios 2 is launched on January 15. Included in its instrumentation is a tiny experiment by Cline et al. that is the first purpose-built GRB detector. The spacecraft goes into orbit around the sun. The Helios 2 experiment along with instruments in orbit near Earth initiate the first Inter-Planetary Network (IPN) of GRB detectors. This modest network can localize a GRB to a narrow swath on the sky.

&ndash The 1st High Energy Astrophysical Observatory (HEAO 1) is launched on August 12. It carries several x-ray and gamma-ray experiments.

&ndash Leventhal et al. conclusively demonstrate via a balloon-borne experiment that the emission from the Galactic Center is due to 511-keV positron annihilation.

&ndash Swanenburg et al. discover that quasar 3C 273 is a source of high-energy gamma rays based on COS-B observations.

&ndash The Pioneer Venus Orbiter (PVO) is launched on May 20. It carries several instruments, including a GRB detector. It goes into orbit around Venus on December 4. The GRB detector functions until 1992.

&ndash The 3rd International Sun Earth Explorer (ISEE-3) is launched on August 12. It carries several instruments, including detectors designed to observe solar flares and GRBs. The spacecraft is renamed the International Cometary Explorer (ICE) in 1982.

&ndash Venera 11 and 12 are launched on September 9 and 14, respectively. These spacecraft carry many experiments, including Konus and SIGNE 2 GRB detectors. The flight platforms fly by Venus on December 25 and 21, respectively. These, with Helios-2 and PVO, complete the first IPN, which localizes many GRBs to arc-minute-sized regions of "blank" sky.

&ndash Kniffen et al. announce the definitive measurement, made via a balloon-borne digitized spark chamber, of gamma-ray emission from the Galactic Center region in the 15 to 100 MeV range.

&ndash Prognoz 7 is launched on October 30. It carries several instruments, including SIGNE 2 GRB detectors.

&ndash An enormously intense burst of low-energy gamma rays is observed on March 5 (the March 5 event) via detectors aboard many satellites. Mazets et al. detect an 8-s periodicity in the lightcurve of the event via the Konus detectors aboard Venera 11 and 12, and they also notice additional events from the same source. Evans et al. use the IPN to tie the source to the SuperNova Remnant (SNR) N49 in the Large Magellanic Cloud (LMC). Eventually, the March 5 event source is understood as being the first member of a new family of sources that become known as Soft Gamma Repeaters (SGRs). These are distinct from the classical GRB sources. This particular object receives the designation SGR 0526-66.

&ndash Mazets et al. announce the discovery, based on Venera 11 and 12 observations, of a second SGR, which becomes known as SGR 1900+14.

&ndash The 3rd High Energy Astrophysical Observatory (HEAO 3) is launched on September 20. It carries several experiments, including a high resolution gamma-ray spectrometer.

&ndash The Solar Maximum Mission (SMM) is launched on February 14. One of the instruments it carries is called the Gamma-Ray Spectrometer (GRS). Another is the Hard X-Ray Burst Spectrometer (HXRBS) that is sensitive to photons up to energies of 500 keV.

&ndash Hudson et al. announce the detection, made via an experiment aboard HEAO 1, of the 2.223 and 4.43 MeV lines during a large solar flare in July 1978. This was the first confirmation of the solar 2.223 MeV neutron-capture line that was initially observed in 1972.

&ndash Chupp et al. detect neutrons from the sun during a solar flare in June via the GRS aboard SMM. This is the first such detection, confirming a prediction made three decades earlier by Biermann et al.

&ndash Caraveo et al. announce the detection, made via COS-B observations, of extended gamma-ray emission from the Orion Cloud.

&ndash Swanenburg et al. release the Second COS-B Catalog of high-energy gamma-ray sources. The majority of these sources are unidentified.

&ndash Venera 13 and 14 are launched on October 30 and November 4, respectively. Each spacecraft carries several instruments, including Konus GRB detectors. The flight platforms fly by Venus on March 1 and 4 of 1982, respectively.

&ndash Mayer-Hasselwander et al. publish a detailed map of the Galactic Plane in high-energy gamma rays based on COS-B observations.

&ndash Prince et al. announce, based on HEAO 3 gamma-ray spectrometer observations from November 1979, the first high-spectral-resolution measurement of the 2.223 MeV neutron-capture line during a solar flare.

&ndash Samorski & Stamm publish evidence for PeV gamma rays from the Galactic x-ray binary source Cygnus X-3, as detected by the Kiel air-shower array. This detection is apparently subsequently confirmed by observations made by other air-shower arrays and atmospheric Cherenkov telescopes. However, the statistical significance of all the results is weak. In the end, Cygnus X-3 and similar object Hercules X-1 are not confirmed as emitters of TeV or PeV gamma rays, but the huge excitement from the putative detections greatly increases the interest in very-high-energy gamma-ray astronomy.

&ndash Bignami, Caraveo et al. identify faint x-ray and optical counterparts for the mysterious "Geminga" gamma-ray source.

&ndash Mahoney et al. announce the discovery, based on HEAO 3 gamma-ray spectrometer observations, of a gamma-ray emission line at 1.81 MeV from the Galactic Plane. This radiation is due to the decay of 26Al, a radioactive isotope of aluminum that is produced in supernovae.

&ndash Share et al. announce the detection, made via the GRS aboard SMM, of the gamma-ray emission line from the Galactic Center at 1.81 MeV due to the decay of 26Al.

&ndash Forrest et al. announce the detection, made via the GRS aboard SMM, of meson-decay gamma rays in a solar flare in June 1982.

&ndash Laros et al. announce the discovery, based on IPN observations, of a third SGR, which becomes known as SGR 1806-20.

&ndash Shelton and others discover Supernova 1987A on February 24 via optical observations.

&ndash Matz et al. announce the detection, made via the GRS aboard SMM, of gamma rays from SN1987A due to the radioactive decay of 56Co.

&ndash Teegarden, Tueller, et al. observe Doppler broadening of 56Co gamma-ray emission lines via GRIS (Gamma-Ray Imaging Spectrometer), a balloon-borne experiment. This is interpreted as evidence for mixing in SN1987A.

&ndash Weekes et al. publish the first firm detection of TeV gamma rays from an astrophysical source. This detection of the Crab Nebula was made via the Whipple Observatory 10-m reflector using the atmospheric Cherenkov imaging technique.

&ndash Granat is launched on December 1. It carries several instruments that can detect x-rays and gamma rays, including GRB detectors, and the SIGMA coded-aperture telescope that can image the sky in low-energy gamma rays.

&ndash Leising & Share publish a gamma-ray lightcurve for SN1987A based on SMM GRS observations. The lightcurve is powered by the radioactive decay of 56Co.

&ndash The "Gamma" spacecraft is launched on July 11. It carries the Gamma-1 telescope that is sensitive to high-energy gamma rays. Unfortunately, the high-voltage power supply for the spark chamber in this instrument fails shortly after launch, greatly reducing its angular resolution.

&ndash Ulysses is launched on October 6. It carries several instruments, including a GRB experiment. The spacecraft's 5-AU solar-polar orbit carries it well out of the plane of the ecliptic, which provides excellent additional baseline for the IPN for the next 18 years.

&ndash ROSAT (Röntgensatellit) is launched on June 1. This observatory is sensitive to extreme ultraviolet photons and x-rays. It would go on to observe well over a hundred thousand x-ray sources, which would prove to be a useful asset for identifying gamma-ray sources.

&ndash The Compton Gamma Ray Observatory is carried into orbit aboard Space Shuttle Atlantis on April 5 and is deployed on April 7. Its four instruments (BATSE &ndash Burst And Transient Source Experiment, OSSE &ndash Oriented Scintillation Spectrometer Experiment, COMPTEL &ndash COMPton TELescope, and EGRET &ndash Energetic Gamma Ray Experiment Telescope) combined are sensitive to gamma rays from 20 keV to 30 GeV, a remarkable six orders of magnitude in photon energy.

&ndash Akimov et al. detect gamma rays extending to 1 GeV via the Gamma-1 telescope on the Gamma spacecraft during solar flares on March 26 and June 15.

&ndash Several strong solar flares in June are observed by all four instruments aboard CGRO. OSSE detects several gamma-ray emission lines from a solar flare on June 4. EGRET detects high-energy gamma-ray emission from a solar flare on June 11. COMPTEL detects neutrons from a solar flare on June 15, and these data are used to create the first "image" of a star (i.e., the sun) in particles other than photons.

&ndash The University of Utah's "Fly's Eye I" experiment detects a 3.2 x 10 20 eV cosmic ray on October 15, the most energetic particle ever detected.

&ndash Meegan et al. announce two discoveries based on BATSE observations: the GRBs are distributed isotropically on the sky, and there are fewer faint bursts than expected if the bursts sources are distributed uniformly throughout space. These results grow stronger as the observations accumulate, suggesting that the GRB sources are located at cosmological distances. The final BATSE Catalog would ultimately contain 2704 GRBs.

&ndash Hartman et al. announce the detection, made via EGRET observations, of the quasar 3C 279 in high-energy gamma rays. This represents the discovery of "blazars" as being a class of powerful and variable sources.

&ndash Punch et al. announce the detection, made via Whipple Observatory observations, of TeV photons from the blazar Markarian 421. This is the first extragalactic TeV source to be discovered.

&ndash Sreekumar et al. announce the detection, made via EGRET observations, of high-energy gamma rays from the LMC, which is the first detection in gamma rays of a normal galaxy beyond the Milky Way. It is quite certain that these gamma rays result from the collisions of cosmic rays with gas within that galaxy, and the conclusion is reached that the cosmic-ray density in the LMC is the same as in the Milky Way.

&ndash Halpern & Holt announce the discovery, based on ROSAT observations, of soft x-ray pulsations from Geminga. Bertsch et al. announce the discovery, based on EGRET observations, of Geminga's high-energy gamma-ray pulsations. Geminga is finally identified it is a rotation-powered pulsar.

&ndash Duncan & Thompson and (independently) Paczynski propose that the March 5 event source (SGR 0526-66) is a highly-magnetized (

5 x 10 15 G) neutron star. They suggest that a "starquake" in the crust of such an object can result in a disturbance in the magnetic field that can cause a strong gamma-ray outburst. Such a neutron star is called a "magnetar".

&ndash Mirabel & Rodriguez announce the discovery, based on Very Large Array (VLA) radio observations, that the Galactic x-ray and gamma-ray source 1E140.7-2942 has a pair of radio jets. It is dubbed a "microquasar", and is the first known example. This source is also called "X-Ray Nova Muscae" and the "Galactic Center Annihilator". It is an LMXB that contains a black hole. A year earlier, variable gamma-ray emission at 511 keV from this source was discovered by Bouchet et al. via the SIGMA instrument on GRANAT.

&ndash Kurfess et al. announce, based on OSSE observations, the first direct measurement of the mass of 57Co produced in SN1987A. The ratio of 57Ni/56Ni is estimated to be slightly larger than, but consistent with, the solar ratio of 57Fe/56Fe. This is a great improvement over earlier indirect estimates, which yielded much higher values for the ratio.

&ndash The Advanced Satellite for Cosmology and Astrophysics (ASCA) is launched on February 23. This observatory is sensitive to x-rays. It would become a very successful mission, which includes helping to identify several gamma-ray sources.

&ndash Kanbach et al. announce the detection, made via EGRET observations, of gamma rays, with energies up to 1 GeV, for eight hours after a solar flare on 1991 June 11. These gamma rays are due to meson decay and electron bremsstrahlung.

&ndash Kouveliotou et al. announce the discovery, based on BATSE observations, that the so-called "short" and "long" GRBs differ spectroscopically, in that the short bursts tend to be harder than the long bursts. The dividing line between the groups is found to be at a burst duration of 2 seconds.

&ndash Hurley et al. detect on February 17 high-energy gamma-ray emission during a GRB via EGRET observations. This high-energy emission continues long after the low-energy gamma-ray emission from the burst ceases, and includes an 18-GeV photon that arrives 90 minutes after the burst began. These high-energy photons would later be understood as being a component of the GRB afterglow.

&ndash Observations from the SIGMA instrument on GRANAT are used to discover the source GRS 1915+105 on August 15, which becomes known as "Old Faithful", due to its semi-regular hard-x-ray/soft-gamma-ray outbursts that occur every 45 to 90 minutes. Mirabel & Rodriguez announce in September that this source is the first microquasar in our Galaxy known to exhibit superluminal motion.

&ndash Iyudin et al. announce the detection, made via COMPTEL observations, of the radioactive decay of 44Ti at 1.16 MeV in the Cas A SNR.

&ndash The WIND spacecraft is launched on November 1. Included amongst its instruments are the Transient Gamma-Ray Spectrometer (TGRS) and a KONUS GRB detector.

&ndash Paczynksi and Lamb debate each other in Washington DC on April 22 regarding the distance scale to the GRBs. After the debate, the audience is split or undecided on whether the bursts lie at cosmological distances or within the halo of our Galaxy.

&ndash Diehl et al. release the first map at 1.809 MeV of the entire Galactic Plane, based on COMPTEL observations, and estimate the total amount of radioactive 26Al in the Galaxy to be less than or equal to one solar mass.

&ndash Naya, Tueller et al. announce, based on GRIS balloon-borne observations, the first firm measurement of the width of the 26Al line at 1.809 MeV line in the Galactic Center Region.

&ndash The Rossi X-ray Timing Explorer (RXTE) is launched on December 30. This observatory is sensitive to x-rays and soft gamma-rays. It would become a very successful mission, which includes helping to identify many gamma-ray sources.

&ndash The BeppoSAX (Satellite per Astronomia X) observatory is launched on April 30. This observatory is sensitive to x-rays and soft gamma-rays. It would become a very successful mission, which includes localizing many GRB afterglows on the sky with arc-minute accuracy.

&ndash Prompt x-ray emission from a GRB is imaged via a BeppoSAX Wide Field Camera (WFC) on July 20, and a coarse localization is obtained. A variety of follow-up observations are carried out, but these are done much too late to detect an afterglow, and, hence, no fine localization is made.

&ndash Several x-ray counterparts of GRBs are finely localized via BeppoSAX WFC and Narrow Field Instrument (NFI) observations, the first being on February 28. These are ultimately used to help identify optical and radio counterparts to GRBs. The May 8 event is especially important, because it is the first to result in a measured redshift (= 0.835), and the decay of the radio afterglow reveals behavior indicative of a relativistic jet. This and subsequent evidence leads to the conclusion that so-called "long" GRBs are enormous explosions that occur in star forming regions of galaxies at cosmological distances.

&ndash Johnson et al. announce the detection, made via OSSE observations, of gamma rays with energies up to 300 keV from the Seyfert galaxy NGC 4151.

&ndash Remarkable TeV gamma-ray flares are detected from the blazar Markarian 501, and are followed around the clock with several atmospheric Cherenkov telescopes: Whipple (in Arizona), HEGRA (High Energy Gamma Ray Astronomy array, on La Palma), CAT (Cherenkov Array at Themis, in France), and TAP (Telescope Array Prototype, in Utah).

&ndash BeppoSAX localizes a GRB on April 25 that is circumstantially tied to an underluminous and nearby (redshift = 0.0085) supernova known as SN1998bw.

&ndash Kouveliotou et al. announce the discovery, based on RXTE and ASCA observations, of x-ray pulsations from SGR 1806-20 that suggest the underlying object is a neutron star with a dipole magnetic field strength equal to that of a magnetar. A similar conclusion is reached for SGR 1900+14 several months later. Henceforth, SGRs are generally regarded as magnetars.

&ndash Kouveliotou et al. announce the discovery, based on BATSE observations, of a fourth SGR, which becomes known as SGR 1627-41.

&ndash A giant outburst from SGR 1900+14 is widely observed on August 27, which results in the shutdown of several spacecraft, and affects radio communications on Earth due to the increased ionization of the outer atmosphere.

&ndash Iyudin et al. announce the discovery, based on COMPTEL observations, of 44Ti emission at 1.16 MeV from an SNR in the Vela Region.

&ndash An extremely luminous GRB is observed on January 23. The 2nd Robotic Optical Transient Search Experiment (ROTSE-II) detects prompt optical emission bright enough to have been visible by an Earth-bound observer with binoculars, which is remarkable given the great distance (redshift = 1.60).

&ndash Hartman et al. release the Third EGRET Catalog, which includes 271 high-energy gamma-ray sources above 100 MeV. The majority of the sources, 170, are unidentified. The identified sources include 93 blazars, 5 pulsars, a radio galaxy (Cen A), a normal galaxy (LMC), and the sun.

&ndash The wavefront-sampling Cherenkov telescopes CELESTE in France and STACEE (Solar Tower Atmospheric Cherenkov Effect Experiment) in New Mexico begin operation. These instruments use large arrays of solar heliostat mirrors to achieve a lower energy gamma-ray threshold than conventional imaging Cherenkov telescopes.

&ndash The Milagro experiment in New Mexico, based on the water Cerenkov technique, becomes fully operational in January, and runs around the clock. Eventually this instrument is used to carry out a full survey of the northern sky for gamma rays at TeV energies. Several new sources, including extended ones, are discovered in the Galactic Plane, along with diffuse Galactic gamma-ray emission.

&ndash Schoenfelder et al. release the First COMPTEL Source Catalog. It covers the energy range from 0.75 to 30 MeV. The catalog contains 32 steady sources, 31 GRBs and 21 solar flares. The steady sources include spin-down pulsars, stellar-mass black holes, SNRs, interstellar clouds, and Active Galactic Nuclei (AGNs). Line detections include the 26Al line at 1.809 MeV, the 44Ti line at 1.157 MeV, the 56Co lines at 0.847 MeV & 1.238 MeV, and the neutron-capture line at 2.223 MeV.

&ndash CGRO disintegrates in Earth's atmosphere on June 4 following a controlled re-entry. The decision to deliberately re-enter the spacecraft came after the failure of one of its gyroscopes on 1999 December 19.

&ndash HETE-2 (High Energy Transient Explorer) x-ray observatory is launched on October 9, which is primarily designed to study GRBs.

&ndash RHESSI (Ramaty High Energy Solar Spectroscopic Imager) solar observatory is launched on February 5. Soon after, gamma rays from solar flares are imaged for the first time.

&ndash INTEGRAL (INTErnational Gamma-Ray Astrophysics Laboratory) gamma-ray observatory is launched on October 17.

&ndash HEGRA is used to detect a source named "TeV 2032+4130", the first unidentified TeV gamma-ray source.

&ndash A powerful GRB is observed on March 29 by HETE-2, which is unambiguously tied to a very luminous supernova, SN2003dh.

&ndash MAGIC-I (Major Atmospheric Gamma-ray Imaging Cherenkov Telescope I) is inaugurated on La Palma in October. MAGIC-I consists of a single large 17-m diameter imaging atmospheric Cherenkov telescope.

&ndash The H.E.S.S. (High Energy Stereoscopic System) array of four atmospheric Cherenkov telescopes is inaugurated in Namibia in September.

&ndash Swift GRB Explorer is launched on November 20.

&ndash A giant outburst from SGR 1806-20 is observed on December 27 by Swift, RHESSI and INTEGRAL.

&ndash A very powerful gamma-ray-line solar flare is observed via RHESSI on January 20. This flare exhibits very strong evidence for meson-decay gamma rays.

&ndash Harris et al. announce the marginal detection, made via the cooled germanium spectrometer (SPI) aboard INTEGRAL, of gamma-ray emission from the decay of 60Fe in the Galactic Plane at 1.173 and 1.333 MeV. The 60Fe/26Al ratio is estimated. This result is firmed up two years later by Wang et al.

&ndash Swift and HETE-2 observations in May and July localize x-ray counterparts for the so-called "short" GRBs. It is found that these short bursts are associated with galaxies, but not with star formation regions within the galaxies. This circumstantial evidence suggests these events may be due to mergers of pairs of compact objects (e.g., two neutron stars, or a neutron star and a black hole).

&ndash H.E.S.S. is used to discover many new sources of TeV gamma rays, including SNRs, pulsar wind nebulae, the Galactic Center, a binary pulsar, an x-ray binary, and numerous new blazars.

&ndash MAGIC-I is used to discover TeV gamma rays from black hole candidate Cygnus X-1 and quasar 3C 279. The latter is the first quasar to be detected at TeV energies.

&ndash The Swift satellite localizes two "long" GRBs in the late Spring that are subsequently quite thoroughly studied but are clearly not associated with supernovae.

&ndash AGILE (Astro-rivelatore Gamma a Immagini LEggero) is launched on April 23. It carries an instrument that is sensitive to high-energy gamma rays.

&ndash VERITAS (Very Energetic Radiation Imaging Telescope Array System), located at the Whipple Observatory in Southern Arizona, celebrates first light in April. VERITAS consists of four 12-m diameter atmospheric Cherenkov telescopes.

&ndash VERITAS and MAGIC-I observations are used to discover TeV gamma rays from SNR IC 443.

&ndash A catalog of very-high-energy gamma-ray sources goes on line at http://tevcat.uchicago.edu/.

&ndash Weidenspointner et al. announce the discovery, based on INTEGRAL SPI observations, that the 511-keV annihilation-line radiation from the Galactic Center is lopsided. The distribution of 511-keV intensity correlates with the locations of LMXBs. The LMXBs are suggested to be the likely source of at least some of these gamma rays.

&ndash The apparently brightest GRB ever is detected on March 19 via the Swift satellite and several ground-based instruments. The optical emission was bright enough to have been briefly visible to the naked eye, in spite of the large distance (redshift = 0.937).

&ndash VERITAS is used to detect TeV photons from the intermediate BL Lac object W Comae.

&ndash MAGIC-I is used to detect the Crab Pulsar. This is the first detection of a pulsar by a ground-based gamma-ray telescope.

&ndash The Fermi Gamma-ray Space Telescope (formerly known as GLAST, the Gamma-ray Large Area Space Telescope) is launched on June 11. It carries an instrument that is exceptionally sensitive to high-energy gamma rays, as well as a GRB monitor.

&ndash A young, radio-quiet pulsar is discovered in SNR "CTA 1" via Fermi/GLAST observations. Several of the unidentified EGRET sources in star-forming regions and near SNRs turn out to be such pulsars.

&ndash The most energetic GRB ever detected is observed on September 16 via the Swift and Fermi satellites. It is the first GRB detected by the Fermi LAT (Large Area Telescope). The burst is twice as energetic as GRB990123, the previous record holder.

&ndash The most distant GRB ever observed is detected on April 23 via the Swift satellite. Follow-up ground-based observations measure the redshift to be 8.2, which translates into a distance of more than 13 billion light years. This GRB is also the most distant object ever detected by humankind, except for the CMB.

&ndash The Fermi LAT detects GeV gamma rays from a short GRB on May 10.

The HEASARC is hiring! - Applications are now being accepted for a scientist with significant experience and interest in the technical aspects of astrophysics research, to work in the HEASARC at NASA Goddard Space Flight Center (GSFC) in Greenbelt, MD. Refer to the AAS Job register for full details.


How do we "see" using gamma-ray light?

Gamma-ray astronomy did not develop until it was possible to get our detectors above all or most of the atmosphere, using balloons or spacecraft. The first gamma-ray telescope, carried into orbit on the Explorer XI satellite in 1961, picked up fewer than 100 cosmic gamma-ray photons!

Unlike optical light and X-rays, gamma rays cannot be captured and reflected in mirrors. The high-energy photons would pass right through such a device. Gamma-ray telescopes use a process called Compton scattering, where a gamma-ray strikes an electron and loses energy, similar to a cue ball striking an eight ball.

This image shows the CGRO satellite being deployed from the Space Shuttle orbiter. This picture was taken from an orbiter window. The two round protrusions are one of CGRO's instruments, called "EGRET".


Current science

We know today that galactic cosmic rays are atom fragments such as protons (positively charged particles), electrons (negatively charged particles) and atomic nuclei. While we know now they can be created in supernovas, there may be other sources available for cosmic ray creation. It also isn't clear exactly how supernovas are able to make these cosmic rays so fast.

Cosmic rays constantly rain down on Earth, and while the high-energy "primary" rays collide with atoms in the Earth's upper atmosphere and rarely make it through to the ground, "secondary" particles are ejected from this collision and do reach us on the ground.

But by the time these cosmic rays get to Earth, it's impossible to trace where they came from. That's because their path has been changed as they travelled through multiple magnetic fields (the galaxy's, the solar system's and Earth's itself.)

Scientists are trying to trace back cosmic ray origins by looking at what the cosmic rays are made of. Scientists can figure this out by looking at the spectroscopic signature each nucleus gives off in radiation, and also by weighing the different isotopes (types) of elements that hit cosmic ray detectors.

The result, NASA adds, shows very common elements in the universe. Roughly 90 percent of cosmic ray nuclei are hydrogen (protons) and 9 percent are helium (alpha particles). Hydrogen and helium are the most abundant elements in the universe and the origin point for stars, galaxies and other large structures. The remaining 1 percent are all elements, and it's from that 1 percent that scientists can best search for rare elements to make comparisons between different types of cosmic rays. The Pierre Auger Observatory collaboration found some variations in the arrival trajectories of cosmic rays in 2017, providing some hints about where the rays could have originated.

Scientists can also date the cosmic rays by looking at radioactive nuclei that decrease over time. Measuring the half-life of each nuclei gives an estimate of how long the cosmic ray has been out there in space.

In 2016, a NASA spacecraft found most cosmic rays likely come from (relatively) nearby clusters of massive stars. The agency's Advanced Composition Explorer (ACE) spacecraft detected cosmic rays with a radioactive form of iron known as iron-60. Since this form of cosmic ray degrades over time, scientists estimate it must have originated no more than 3,000 light-years from Earth &mdash the equivalent distance of the width of the local spiral arm in the Milky Way.

An experiment called ISS-CREAM (Cosmic Ray Energetics and Mass) launched to the International Space Station in 2017. It is expected to operate for three years, answering questions such as whether supernovas generate most cosmic ray particles, when cosmic ray particles originated, and if all the energy spectra seen for cosmic rays can be explained by a single mechanism. The ISS also hosts the CALorimetric Electron Telescope (CALET), which searches for the highest-energy types of cosmic rays. CALET launched there in 2015.

Cosmic rays can also be detected by balloon, such as through the Super Trans-Iron Galactic Element Recorder (SuperTIGER) experiment that includes participation from NASA's Jet Propulsion Laboratory and several universities. It has flown several times, including a record 55-day flight over Antarctica between December 2012 and January 2013. "With the data from this flight we are studying the origin of cosmic rays. Specifically, testing the emerging model of cosmic-ray origins in OB associations, as well as models for determining which particles will be accelerated," the SuperTIGER website said.

Citizen scientists can also participate in the search for cosmic rays by registering at the website crayfis.io. There, they will join the CRAYFIS experiment run by the Laboratory of Methods for Big Data Analysis (LAMBDA) at the National Research University Higher School of Economics in Russia. Researchers there are examining ultra-high energy cosmic rays using mobile phones.


Cosmic Sources of Gamma Rays

Today, we know much more about this radiation and where it comes from in the universe. Astronomers detect these rays from extremely energetic activities and objects such as supernova explosions, neutron stars, and black hole interactions. These are difficult to study because of the high energies involved, they are sometimes very bright in "visible" light, and the fact that our atmosphere protects us from most gamma rays. To "see" these activities properly, astronomers send specialized instruments to space, so they can "see" the gamma rays from high above Earth's protective blanket of air. NASA's orbiting Brzo satellite and the Fermi gama-teleskop are among the instruments astronomers currently use to detect and study this radiation.


Clarity on cosmic rays from deep beneath Antarctic ice

The IceCube Neutrino Observatory, Fermi Gamma-ray Space Telescope, and other telescopes around the world have pinpointed a source of high-energy cosmic rays for the first time.

A single high-energy neutrino that flashed through Antarctic ice in September 2017 acted as a new cosmic courier in the fast-moving enterprise of multimessenger astronomy – and heralded a breakthrough in a 106-year-old mystery in the process.

When the IceCube Neutrino Observatory detected this unusually high-energy neutrino, they sent a notice out to telescopes around (and above) the world to let them know what direction it came from.

The Fermi Gamma-ray Space Telescope responded to the call and sent back exciting news: they knew exactly where the neutrino had come from, and the source was spectacular.

Four billion light years away, in the constellation Orion, an active galaxy known as a “blazar” lies tucked under the hunter’s arm. The supermassive black hole – millions to billions of times the mass of our sun – at the centre of the galaxy accelerates the gas around it, shooting out energetic jets of radiation and particles travelling at near light speed. (Blazars are the specific case when the jets happen to be directed toward Earth.)

Blazars are a type of active galaxy with one one of its jets pointing toward us. In this artistic rendering, a blazar emits both neutrinos and gamma rays that could be detected by the IceCube Neutrino Observatory as well as by other telescopes on Earth and in space.
(Credit: IceCube/NASA)

Fermi could see the gamma-rays created when particles in these jets collided.

The discovery marks the first time the source of an extra-galactic neutrino has been definitively identified and another major success for the burgeoning field of multimessenger astrophysics.

“This result is the first of its kind. We have never before used multimessenger astrophysics to pinpoint the origins of high-energy cosmic rays,” said France Córdova, Director of the National Science Foundation, during the press conference announcing the findings.

“We can better understand the universe’s immense cosmic accelerators. We still can’t produce anything with nearly the energy of these cosmic particles, so we have to turn to the heavens to deepen our understanding of the highest-energy processes.”

Neutrinos are elusive subatomic particles that zip through the universe at nearly the speed of light. They are neutral, meaning they lack an electrical charge, and don’t interact via the electromagnetic force, so they are notoriously difficult to detect and to track. We can see them only when one happens to crash into the nucleus of an atom. Given a detector the size of your body, Córdova said, you would measure such a collision only once every 100,000 years.

To maximize the chances of detecting a neutrino, you need many neutrino detectors. That’s where the IceCube Neutrino Observatory comes in.

Located at the Amunsden-Scott South Pole Station in Antarctica, the detector sits within a cubic kilometre of crystal-clear ice (containing more than a billion tonnes, or 10 38 atoms to collide with) that is permeated by more than 80 long strings of sensitive equipment. Dotted along those strings, like pearls on a necklace, are thousands of digital optical monitors, ready to detect the radiation produced when a neutrino crashes into an atom.

Neutrinos and cosmic rays go hand-in-hand: the same physical processes that produce cosmic rays produce neutrinos as well. That means neutrinos can act as a proxy for gleaning information about cosmic rays (which, despite the moniker, are not rays at all, but rather high-energy protons and atomic nuclei that constantly bombard the Earth from space).

Determining the source of cosmic rays is next to impossible as charged particles, their paths are bent and twisted by magnetic fields they encounter as they travel across the universe. Once they arrive at Earth, they collide with particles in the atmosphere, further obscuring their origins.

Neutrinos, by contrast, are straight shooters. As elusive as they are, neutrinos’ ghostliness confers a great advantage: since they don’t interact with light or magnetic fields, they travel unimpeded on straight paths through the universe – and those paths point straight back to where they came from.

“The goal is to track cosmic ray sources by looking for neutrinos. They will point back at the source because they are neutral particles,” said Francis Halzen, IceCube principal investigator from the University of Wisconsin-Madison. “On September 22, 2017, that’s exactly what one neutrino did.”

Within 43 seconds of the detection, the IceCube detectors reconstructed the energy and the direction of the neutrino and blasted the information out to the broader astronomical community. In the end, more than 20 telescopes looked in the direction of the event, each adding another piece of information to the puzzle.

In this artistic composition, based on a real image of the IceCube Lab at the South Pole, a distant source emits neutrinos that are detected below the ice by IceCube sensors, called DOMs.
(Credit: IceCube/NSF)

“The beauty of this is that if Fermi hadn’t found the blazar, it would have been just another neutrino detection for us,” said Halzen. “For Fermi, it would have been just another blazar event. It was elevated to a discovery of a cosmic ray source by having the two telescopes working in unison.

“That was only the beginning. Once we knew of an interesting direction in the sky, we looked back at years of data on tapes and disks in that direction. We found that in 2014, there was a flare in neutrinos – more than 12 that came in 150 days.”

The energies of the neutrinos matched exactly what theory would predict from a cosmic accelerator such as a blazar.

Being able to study the high-energy universe via neutrinos unlocks a wealth of new possibilities, according to Niayesh Afshordi, a Perimeter Associate Faculty member. “Photons have been historically the only way we’ve managed to learn about the universe – so using neutrinos is a really novel way of seeing these things,” he said.

“This simultaneous observation of gamma rays and neutrinos basically tells us what might be responsible for the origin of gamma rays – because it must be something that produces neutrinos at the same time. That narrows down the range of possibilities in a very dramatic way. That’s really the exciting thing. You can exponentially narrow the range of possibilities if you have multiple probes of a physical process.”

Perimeter Associate Faculty member Cliff Burgess watched the announcement as it was live-streamed in Perimeter’s Black Hole Bistro. The announcement serendipitously coincided with the 2018 Tri-Institute Summer School on Elementary Particles (TRISEP), an international summer school organized jointly by Perimeter Institute, SNOLAB, and TRIUMF, and held this year at Perimeter, where Halzen was also an invited speaker.

Perimeter residents gather to watch the NSF press conference by the IceCube Collaboration together with other observatories around the world and in space of the identification of the first likely source of high-energy neutrinos and cosmic rays.

“Francis did an amazing thing for us,” said Burgess. “We invited him before any of this was in the cards, as far as we knew. What normally happens in this case is that the researcher will say, ‘There’s some nice thing that’s going to happen, but I’m embargoed, and I can’t tell you about it.’”

Instead, Halzen devoted one of his lectures to sharing the findings with the students. “He said it was the first time he had told anybody. This was his first talk on it, to students at this school. For a school, that never happens. It was just spectacular,” Burgess said. “He was getting feedback – clearly the students were engaged. They were the first people in the world to see it. That’s phenomenal.”

Burgess said that, as a theorist, he’s most interested to find the holes and missing edges in the puzzle as it is pieced together: “There are going to be flaws in the picture. There’s going to be things that won’t quite work at first, and that’s where the excitement is.”

Afshordi added: “This is kind of the birth of multimessenger astronomy, with gravitational waves and neutrinos, and I think it’s going to get much more exciting. You can do actual astronomy with it, with many objects and various surveys that will happen hopefully over the next few decades.”

Watch: View the NSF press conference on the breakthrough.

Find out more: Read the papers in Science as was as companion follow up papers and view the IceCube FAQ about the results.

Free resources: Click to download Perimeter’s free lesson “Where Did All the Neutrinos from the Sun Go?”

Povezani: Neutron star collision sparks new era of discovery


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