Astronomija

Kako galaksija u Abell 2261 postoji bez crne rupe u centru?

Kako galaksija u Abell 2261 postoji bez crne rupe u centru?


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Ovdje izvor kaže da su astronomi tražili crnu rupu u najsjajnijoj galaksiji u jatu Abell 2261, A2261-BCG, ali nisu pronašli ništa:

Međutim, rentgenska zapažanja NASA-inog rentgenskog opservatorija Chandra i svemirskog teleskopa Hubble pokazuju nisam našao ništa.

Kako je moguće da ova galaksija nema crnu rupu u centru?


Fizika ne zahtijeva crnu rupu u središtu galaksije, ona samo ukazuje da je vjerovatno.

Sve što vam treba je masa. Ako masa nije dovoljno gusta da formira crnu rupu, još uvijek može biti dovoljno visoka da bi galaksija mogla rasti.

(Takođe, pronalazak ničega nije isto što i ništa što je tamo. Dakle, niko ne isključuje postojanje crne rupe tamo)


Najsjajnija nakupina galaksije (BCG) u Abell 2261 ("Abell 2261-BCG") masivna je eliptična; čini se da ove gotovo uvijek imaju supermasivne crne rupe u svojim središtima. Uz to, središte galaksije ima veliko područje relativno niske zvjezdane gustine ("jezgro"), za što se obično smatra da nastaje spajanjem dvije SMBH u jednu, događaj koji slijedi spajanjem dvije masivne galaksije u čine jednu masivnu eliptičnu. (Kao dio spajanja, dvije SMBH tvore binarnu jedinicu; zvijezde u blizini središta spojene galaksije mogu gravitacijski komunicirati s ovom binarnom jedinicom, pri čemu je uobičajeni rezultat smanjivanje binarnog sustava i izbacivanje zvijezde na veći radijus; Dakle, zvijezde se preferirano izbacuju iz središta u srednje ili vanjske dijelove galaksije, a gustoća zvijezda u središtu postaje manja.Na kraju, SMBH binarni sustav postaje toliko mali da ga gravitaciono zračenje još više smanjuje, do točke da se dva SMBH stope i postanu jedno u središtu galaksije.)

Stvarni članak (Gültekin i dr.) Iza tog članka govori o traženju emisije X-zraka sa akrecijskog diska oko moguće SMBH u centru BCG-a (kao i na nekoliko drugih lokacija u blizini centra). Budući da ne otkrivaju nijedan rendgen, zaključuju da "ne postoji $ 10 ^ {10} M _ { odot} $ crna rupa u jezgri A2261-BCG ili se ona prirasta na niskom nivou. "Dakle, postoje stvarno dvije mogućnosti:

  1. Tamo je SMBH u centru galaksije, ali miruje (ne akumulira dovoljno plina da proizvede puno X-zraka).

  2. Tamo nije SMBH u centru galaksije, što je uzbudljivije jer je neočekivano.

Eto, zapravo je teorijski mehanizam koji bi se povremeno mogao pojaviti izbaciti SMBH iz središta galaksije. Kada se dva SMBH spoje u jedan SMBH (vidi gore), može doći do "udarca" koji uzrokuje izbacivanje spojene SMBH iz centra galaksije (veličina ovog udarca ovisi o stvarima poput odnosa mase između dva SMBH, koliko su se brzo okretale pojedine SMBH prije spajanja i koje directionw od tih okretaja bili su u odnosu na orbitu binarnog sistema prije spajanja). U većini slučajeva, izbačeni SMBH će pasti natrag u središte galaksije - možda oscilirajući nekoliko puta i prije nego što dinamičko trenje uspori svoje kretanje i vrati se u središte galaksije. U ekstremnim slučajevima može se izbaciti dovoljno brzo da u potpunosti pobjegne iz galaksije. Čitav ovaj proces izbacit će brojne zvijezde i iz središta galaksije, što bi moglo objasniti zašto je njegovo jezgro male gustoće toliko veliko (tj. Kombinacija procesa SMBH-binarnog spajanja i rezultirajuće izbacivanje SMBH).

Dakle, moguće je da se tako nešto dogodilo u Abell 2261-BCG, a SMBH je trenutno negdje izvan centra galaksije. (Ili sjedi u središtu i jednostavno se ne prikazuje na rendgenskim zrakama.) Naravno, nisu pronašli dokaze za SMBH koji emitira rendgenske zrake. napolju galaksije nukleus, tako da stvarno ne znamo - i ne bih se iznenadio da je u centru ipak (mirni) SMBH.

(Rory Alsop je tačan da nemaju sve galaksije SMBH - na primjer, lokalna mala spiralna galaksija Messier 33 je proučavana sa Svemirski teleskop Hubble (Gebhardt i sur. 2001., a modeliranje zvjezdanih brzina u njegovom središtu sugerira gornju granicu od oko 1500 $ M _ { odot} $ za bilo koju moguću crnu rupu tamo. Ali čini se da ga ima svaka masivna eliptična vrsta koja je dovoljno pažljivo proučena, pa bismo očekivali da je ima i Abell 2261-BCG.)


Crne rupe



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Više informacija
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U aprilu 2019. naučnici su objavili prvu sliku crne rupe u galaksiji M87 pomoću teleskopa Event Horizon (EHT). Ova supermasivna crna rupa teži 6,5 milijardi puta veću masu od sunca i nalazi se u središtu M87, oko 55 miliona svjetlosnih godina od Zemlje.

Supermasivna crna rupa napaja mlazove čestica koje putuju gotovo brzinom svjetlosti, kako je opisano u našem najnovijem saopćenju za javnost. Ovi mlazovi proizvode svjetlost koja obuhvaća čitav elektromagnetski spektar, od radio talasa do vidljive svjetlosti do gama zraka.

Da bi stekli ključni uvid u svojstva crne rupe i pomogli u tumačenju EHT slike, naučnici su koordinirali promatranja sa 19 najmoćnijih svjetskih teleskopa na zemlji i u svemiru, prikupljajući svjetlost iz čitavog spektra. Ovo je najveća istodobna kampanja promatranja ikad izvedena na supermasivnoj crnoj rupi mlaznicama.

NASA-ini teleskopi uključeni u ovu posmatračku kampanju uključuju rentgensku opservatoriju Chandra, svemirski teleskop Hubble, brzu opservatoriju Neil Gehrels, nuklearni spektroskopski teleskop (NuSTAR) i svemirski teleskop Fermi gama-zraka.


Crna rupa nedostaje deset milijardi solarnih masa iz jedne od najvećih galaksija u svemiru

Tokom proteklih godina, brojni su naučnici pokušali nadgledati nestanak crne rupe u galaktičkoj grupi "Abell 2261", i iznijeli su brojne pretpostavke.

Ideja koja je prevladavala u posljednjih nekoliko decenija među astronomima je da je svaka galaksija u njenom središtu gigantska crna rupa koja proguta milione ili možda milijarde sunaca, a što je veća galaksija, to je veća masa crne rupe.

Galaksija bez crne rupe

Iznenađenje je uslijedilo prije deset godina kada je Marc Postman sa Naučnog instituta svemirskog teleskopa otkrio divovsku galaksiju u čijem središtu nije bila crna rupa.

Obično u jezgri svake galaksije postoji dodatna masa svjetlosti u centru koju emitiraju treperave zvijezde koje se skupljaju zbog gravitacije rupe, ali ta galaksija koju je Postman otkrio nije imala uobičajenu masu svjetlosti, a jezgra , koji je oblak zvijezda promjera oko 20 hiljada svjetlosnih godina, nije bio usred galaksije.

2012. godine, Todd Lauer iz Nacionalnog laboratorija za istraživanje optičko-infracrvene astronomije u Tucsonu u državi Arizona rekao je: "To uopće nije neobično." U kasnijim godinama Postman, Lauer i grupa drugih naučnika radili su na praćenju X-zraka i radio-talasa emitiranih iz galaksije kako bi pronašli nestalu crnu rupu.

Ova galaksija je najsjajnija u grupi galaksija poznatih kao "Abell 2261", a nalazi se na oko 2,7 milijardi svjetlosnih godina od Zemlje, unutar sazviježđa Herkules na sjevernoj nebeskoj hemisferi.

Znanstvenici pretpostavljaju da je masa nestale crne rupe ekvivalentna 10 milijardi solarnih masa ili više, što je veličina diva ako je usporedimo s crnom rupom u središtu Mliječnog puta, koja ima masu od oko 4 milion solarnih masa.

Gdje bi mogla nestati ova divovska rupa?

Jedna od mogućnosti je da ova rupa postoji, ali je statična, nakon što je privremeno ostala bez onoga što se može progutati, ali Lauer i njegovi kolege iznijeli su još jednu pretpostavku, a to je da se crna rupa udaljila od galaksije.

Bolje razumijevanje crnih rupa

Dokazivanje valjanosti potonje mogućnosti pružilo bi dublji uvid u neke od najnasilnijih i najdinamičnijih procesa u evoluciji galaksija i svemira, otkrivajući više tajni o gigantskim silama i rupama koje mogu baciti zvijezde i planete u svemir.

Doktor Lauer pripada naučnom timu koji sebe naziva '' Nuker Group '', a tokom protekle četiri decenije ova je grupa nastojala nadgledati jezgre udaljenih galaksija, koristeći teleskop Hubble i drugu naprednu opremu.

"Ono što se dogodilo u (Abbl 2261) otprilike je ono što se događa s najmasivnijim eliptičnim galaksijama u svemiru, na krajnjoj tački njihove evolucije", kaže Lauer.

Šezdesetih godina otkriće kvazara u središtima galaksija navelo je astronome da vjeruju da su supermasivne crne rupe odgovorne za gutanje zvijezda i stvaranje svjetlosne mase u galaktičkom jezgru.

Krajem stoljeća astronomi su došli do zaključka da svaka galaksija sadrži supermasivnu crnu rupu, milione ili milijarde puta veću od mase sunca, ali nije bilo jasnog objašnjenja kako su crne rupe nastale, jesu li evoluirale iz crnih rupa ili je nastao u drugom procesu rano u životu svemira.

A 1980. godine, 3 astronoma, Mitchell Begelman, Martin Rees i Roger Blandford, napisali su o tome kako su ove crne rupe utjecale na evoluciju galaksija. Sa njihove tačke gledišta, kada se dvije galaksije sudare i spoje zajedno, što je čest događaj u ranim fazama života svemira, centralne crne rupe konvergiraju se u binarni sistem, koji se sastoji od dvije crne rupe koje se okreću jedna oko druge.

Begelman i njegove kolege otkrili su da ove dvije ogromne crne rupe djeluju u interakciji sa sazviježđem koje ih okružuje, a s vremena na vrijeme jedna od ovih zvijezda približi se dvojcu, ali sile gravitacije ga potisnu iz centra, a s vremenom ih više zvijezda potisne daleko od centra. Postepeno se zvjezdasta svjetlost širi formirajući širu jezgru, sa malo uvijanja u sredini.

Pretpostavke o mjestu crne rupe

Kada su promatrali galaksiju "Abell 2261", Lauer i Postman su mislili da će pronaći gustoću u centru kao što je to bilo uočeno u drugim galaksijama. Umjesto toga, došlo je do smanjenja mase svjetlosti, kao da su supermasivna crna rupa i prateće zvijezde potpuno nestale.

Ovo je otkriće pokrenulo mnoga pitanja o scenariju koji su pretpostavili Begelman i njegove kolege, jer su se dvije crne rupe stopile ni iz čega, a spajanje je popraćeno ogromnim naletom gravitacijskih valova i valovima u svemiru poput onih koje je Einstein predvidio 1916. godine. pratili su ga LIGO uređaji za osmatranje vek kasnije, tačnije 2016. godine.

Da je ova eksplozija bila nasilna, kao što pretpostavljaju prethodne teorije, to bi uzrokovalo slanje crne rupe na drugo mjesto u galaksiji, ili čak izvan nje, nešto što naučnici koji su promatrali Apple 2261 nisu primijetili, pa su pronalazak nestalih rupa je bila vrlo važna Za dobivanje prihvatljivog naučnog objašnjenja.

Daljnjim istraživanjem eliptične galaksije (A2261-BCG) otkrivena su 4 mala čvora svjetlosti u difuznoj jezgri, povećavajući mogućnost da je crna rupa skrivena u jednom od njih.

Da bi to istražio, tim koji je vodila Sarah Burke Spolaor sa Univerziteta Zapadna Virginia promatrao je četiri čvora koristeći Opservatoriju Hubble i "Veliki niz opservatorija". Tim je zaključio da su 2 čvora najvjerojatnije male galaksije i da ne mogu sadržavati crnu rupu, dok će treći i četvrti čvor vjerojatno sadržavati rupu koja nedostaje.

Čeka Jamesa Webba

Sljedeća stanica u pokušaju otkrivanja tajne nestale rupe bio je NASA-in rendgenski svemirski opservatorij Chandra. Kayhan Gultekin sa Univerziteta u Michiganu, veteran naučnik iz tima Nookers, usmjerio je teleskop prema jezgru i četiri čvora i uvjeravao da bi se hipotetička crna rupa trebala hraniti brzinom od jednog od milion svoje normalne energije, ako je ikad postojalo. "Ili je crna rupa u središtu vrlo slaba ili ne postoji", napisao je Gultekin u e-mailu.

Astronomi s nestrpljenjem čekaju lansiranje svemirskog teleskopa James Webb, nove zvjezdarnice koja će zamijeniti Hubble, a koja bi trebala biti pokrenuta krajem idućeg oktobra, kako bi istovremeno ispitala četiri čvora i utvrdila da li će od njih sadrži nedostajuću crnu rupu.


Naučnici su možda izgubili trag supermasivne crne rupe

Tamo negdje u kosmosu mogla bi postojati crna rupa koja više nije u središtu svoje galaksije. U časopisu koji je objavilo Američko astronomsko društvo, naučnici su primijetili da supermasivna crna rupa za koju se misli da je središte Abella 2261 možda više nije tamo. Umjesto toga, znanstvenici kažu da je to moglo biti uklonjeno iz vlastite galaksije zbog procesa poznatog kao povlačenje gravitacijskog vala.

Tokom trzaja, dvije crne rupe jedna blizu druge u osnovi se stapaju, šaljući mreškanje po svemiru. U teoriji bi ove valove mogle odbaciti crnu rupu od trenutnog mjesta, navodi se u izvještaju Forbes. & ldquoTo je dovoljno da crnu rupu u potpunosti izbaci iz galaksije i da odavno nestane. Bilo bi krstarenje međugalaktičkim svemirom ", rekao je magazinu Kayhan Gultekin, vodeći astronom lista.

U ovom tekstu izdavači početnog časopisa moraju naglasiti da bi tehnički i dalje mogao biti na svom trenutnom mjestu, samo što ga sada ne mogu pronaći nakon što su ga mogli pronaći u prethodnim prilikama.

"Ipak, Gultekin kaže da prerano zaključuje da u A2261-BCG nema i supermasivne crne rupe," Forbes dodaje. "Ali da je & rsquos tamo nema, to bi bila jedina tako velika galaksija koja je još otkrivena bez tako masivne crne rupe u svom središtu. Čak i naša vlastita Mlječna staza & rsquos supermasivna crna rupa je relativno mirna, ali i tamo je."

U intervjuu za Vice prošlog ljeta Gultekin je priznao da se još može puno naučiti o crnim rupama, a rješavanje ove misterije moglo bi uvelike odgovoriti na neka od najvećih otvorenih pitanja.

& ldquoNajviše me oduševljava učenje o supermasivnim crnim rupama kroz gravitacijske valove, & rdquo Gultekin. & ldquoMoramo sa sigurnošću znati da se spajaju i ovo bi bio jedan od načina da se pokaže da se to događa. & rdquo

& ldquoSve vrste stvari možete naučiti gravitacijskim valovima o supermasivnim crnim rupama, kao populaciju ili pojedinačne izvore, a koje je ili zaista teško ili nemoguće naučiti tradicionalnom elektromagnetskom astronomijom, & rdquo, dodao je.


Nestala: Jedna crna rupa sa 10 milijardi solarnih masa

Astronomi pretražuju kozmičku izgubljenu i pronađenu jednu od najvećih, najgorih crnih rupa za koje se mislilo da postoje. Do sada ga nisu pronašli.

U posljednjih nekoliko decenija postalo je dijelom astronomskih nauka da se u središtu svake galaksije krije džinovska crna rupa u kojoj su nestali ekvivalenti miliona ili čak milijardi sunaca. Što je veća galaksija, to je crna rupa u središtu masivnija.

Stoga je bilo iznenađenje prije deset godina kada je Marc Postman, iz Naučnog instituta svemirskog teleskopa, koristeći svemirski teleskop Hubble za snimanje jata galaksija, pronašao supergigantsku galaksiju bez tragova crne rupe u svom središtu. Obično bi jezgro galaksije u svom središtu imalo dodatak svjetlosti, neku vrstu blistavog ogrtača, koji su proizvodile zvijezde koje su se tamo okupile gravitacijom džinovske crne rupe.

Suprotno tome, u tačnom središtu širokog jezgra galaksije, gdje je trebao biti lagani udarac u svjetlosti zvijezda, došlo je do laganog padanja. Štaviše, celo jezgro, oblak zvezda širine oko 20.000 svetlosnih godina, nije bilo ni u sredini galaksije.

"O, Bože, ovo je zaista neobično", prisjetio se Tod Lauer, stručnjak za galaktička jezgra Nacionalnog opservatorija za optičku astronomiju u Tucsonu u državi Arizona i autor na papiru, kada je Postman pokazao nalaz.

To je bilo 2012. Tokom godina, dvoje istraživača i njihove kolege tragali su za rendgenskim zrakama ili radio-talasima iz nestale crne rupe.

Galaksija je najsjajnija u jatu poznatom kao Abell 2261. Nalazi se na oko 2,7 milijardi svjetlosnih godina odavde, u sazviježđu Herkules na sjevernom nebu, nedaleko od istaknute zvijezde Vege. Koristeći standardno pravilo, crna rupa koja nedostaje u središtu galaksije 2261 trebala bi biti 10 milijardi solarnih masa ili više. Uporedno, crna rupa u središtu galaksije Mliječni put ima samo oko 4 miliona sunčevih masa.

Pa gdje je priroda sakrila ekvivalent od 10 milijardi sunaca?

Jedna od mogućnosti je da je crna rupa tu, ali je utihnula, privremeno ostajući bez ičega. No, druga provokativna mogućnost, kažu Lauer i njegove kolege, je ta da je crna rupa uopće izbačena iz galaksije.

Dokazivanje potonjeg moglo bi pružiti uvid u neke od najnasilnijih i najdinamičnijih procesa u evoluciji galaksija i kosmosa, o kojima su astronomi teoretizirali, ali ih nikada nisu vidjeli - ples titanskih sila i vrtložnih svjetova koji mogu bacati zvijezde i planete u prazninu .

"To je intrigantna misterija, a mi smo na slučaju", rekao je poštar u e-poruci. Dodao je da će predstojeći svemirski teleskop James Webb imati sposobnost da rasvetli slučaj, da tako kažem, na slučaj.

"Šta se događa kada iz galaksije izbacite supermasivnu crnu rupu?" Pitao je Lauer.

Lauer je dio neformalne grupe koja sebe naziva Nukeri. Grupa se prvi put okupila pod Sandrom Faber sa Kalifornijskog univerziteta u Santa Cruzu, u ranim danima svemirskog teleskopa Hubble. Tokom protekle četiri decenije, pokušali su rasvetliti prirodu galaktičkih jezgara, koristeći oštro oko Hubble-a i druge nove objekte kako bi zavirili u intimna srca dalekih galaksija.

"Priča o A2261-BCG", rekao je, pozivajući se na formalno ime galaksije u literaturi, "je ono što se događa s najmasivnijim galaksijama u svemiru, divovskim eliptičnim galaksijama, na krajnjoj tački evolucije galaksije."

Crne rupe su objekti toliko gusti da čak ni svjetlost ne može pobjeći iz njihovih gravitacijskih kvačila. Oni su nevidljivi po definiciji, ali ruckus - rendgenski zraci i radio vriskovi - uzrokovan materijalom koji mu pada u ruke može se vidjeti širom svemira. Otkriće kvazara u centrima galaksija šezdesetih godina prošlog stoljeća prvo je navelo astronoma da smatraju da su supermasivne crne rupe odgovorne za takav vatromet.

Krajem stoljeća astronomi su došli do zaključka da je svaka galaksija u svojim grudima imala supermasivnu crnu rupu, milione do milijarde puta masivniju od sunca. Otkud su došli - jesu li izrasli iz manjih crnih rupa nastalih kolapsom zvijezda ili nastalih nekim drugim procesom rano u svemiru - niko nije siguran. "U svakoj breskvi ima koštica", rekao je Lauer.

Ali kako ti entiteti utiču na svoju okolinu?

1980. godine, tri astronoma, Mitchell Begelman, Martin Rees i Roger Blandford, napisali su o tome kako će ove crne rupe promijeniti evoluciju galaksija u kojima žive. Kada bi se dvije galaksije sudarile i spojile - što je posebno čest događaj u ranijem svemiru - njihove centralne crne rupe bi se susrele i formirale binarni sistem, dvije crne rupe koje su kružile jedna oko druge.

Begelman i njegove kolege tvrdili su da će ove dvije masivne crne rupe, koje se njišu oko sebe, stupiti u interakciju s morem zvijezda u koje su uronjene. Svako malo bi jedna od ovih zvijezda imala bliski susret s binarnom, a gravitacijske sile bi gurnite zvijezdu iz središta, ostavljajući crne rupe još čvršće povezanima.

Vremenom bi se više zvijezda bacalo dalje od centra. Postepeno, zvjezdana svjetlost koja je nekoć bila koncentrirana u centru širila bi se u šire, difuzno jezgro, s malim pregibom u središtu u kojem je binarni sistem crnih rupa plesao svoj par. Proces se naziva „ribanje“.

"Bili su daleko ispred igre", rekao je Lauer o trojici astronoma.

Pročišćena jezgra bila je situacija za koju su Lauer i Poštar mislili da su se susreli s Abellom 2261. Ali umjesto vrha u središtu jezgre, uslijedio je pad, kao da su supermasivna crna rupa i njezine prateće zvijezde jednostavno bile oduzeta.

To je pokrenulo dramatičniju mogućnost da se odigrao scenarij koji su zamislili Begelman i njegove kolege: Dvije crne rupe stopile su se u jednu gigantsku gutljaju ničega. Spajanje bi bilo praćeno kataklizmičnim rafalnim gravitacijskim valovima, valovima u prostoru i vremenu za koje je Einstein predvideo postojanje 1916. godine, a napokon LIGO instrumenti vidjeli stoljeće 2016. godine.

Da je taj rafal bio jednostran, poslao bi rezultirajuću supermasivnu crnu rupu koja leti kroz galaksiju, ili čak iz nje, nešto što astronomi nikada nisu primijetili. Dakle, pronalaženje pogrešne crne rupe bilo je od najveće važnosti.

Dalje ispitivanje A2261-BCG otkrilo je četiri mala čvora svjetlosti unutar difuzne jezgre. Može li jedan od njih biti u crnoj rupi?

Tim koji je predvodila Sarah Burke-Spolaor sa Univerziteta Zapadna Virginia uzdigao se do neba pomoću Hubble-a i radio-teleskopa Very Large Array u Socorro-u u Novom Meksiku. Spektroskopska Hubbleova mjerenja mogla su reći koliko su se brzo zvijezde u čvorovima kretale, a time i da li je potreban neki masivan objekt da ih održi na okupu.

Zaključili su da su dva čvora vjerovatno male galaksije s malim unutarnjim pokretima koje je kanibalizirala velika galaksija. Mjerenja trećeg čvora imala su tako velike trake grešaka da se još uvijek nije moglo isključiti ili isključiti kao mjesto crne rupe.

Četvrti, vrlo kompaktni čvor blizu donjeg ruba jezgre bio je previše slab za Hubble, izvijestio je Burke-Spolaor. "Za promatranje ovog čvora bilo bi potrebno previše vremena (stotine sati) za promatranje svemirskim teleskopom Hubble", rekla je u e-pošti, pa tako i dalje ostaje kandidat za skrovište.

Jezgro galaksije također emitira radio valove, ali oni nisu pomogli u potrazi, rekao je Burke-Spolaor.

"Prvobitno smo se nadali da će radio emisija biti neka vrsta doslovnog pištolja za pušenje, koji pokazuje aktivni mlaz koji usmjerava direktno na mjesto crnih rupa", rekla je. Ali radijska relikvija bila je stara najmanje 50 miliona godina, prema svojim spektralnim karakteristikama, što je značilo, rekla je, da bi velika crna rupa imala dovoljno vremena da se preseli negdje drugdje otkako je mlaz isključen.

Sljedeća stanica bila je NASA-ina orbitirajuća rentgenska opservatorija Chandra. Kayhan Gultekin sa Univerziteta u Michiganu, još jedan veteran Nuker koji nije bio u prvobitnom timu za otkrivanje, usmjerio je teleskop na jezgro jata i one sumnjive čvorove. Nema kockica. Pretpostavljena crna rupa morala bi se hraniti jednom milionitom od potencijalne stope da je uopće bila tamo, rekao je Gultekin.

"Ili je bilo koja crna rupa u centru vrlo slaba ili je nema", napisao je u e-mailu. Isto vrijedi i za slučaj binarnog sustava crnih rupa, rekao je da bi trebalo jesti vrlo malo benzina da bi ostao skriven.

U međuvremenu je Imran Nasim sa Sveučilišta Surrey, koji nije bio dio Postmanovog tima, objavio detaljnu analizu kako bi spajanje dvije supermasivne crne rupe moglo reformirati galaksiju u ono što su astronomi pronašli.

"Jednostavno, odziv gravitacijskog vala" izbacuje "supermasivnu crnu rupu iz galaksije", objasnio je Nasim u e-poruci. Izgubivši svoje supermasivno sidro, oblak zvijezda oko binarnog dijela crne rupe širi se, postajući sve difuzniji. Gustina zvijezda u toj regiji - najgušći dio cijele džinovske galaksije - samo je jedna desetina gustine zvijezda u našem susjedstvu Mliječnog puta, što rezultira noćnim nebom koje bi izgledalo anemično u usporedbi s našim.

Sve je to još jedan razlog zbog kojeg astronomi s nestrpljenjem očekuju lansiranje svemirskog teleskopa James Webb, dugo očekivanog nasljednika Hubble-a, koji je sada zakazan za kraj oktobra. Taj će teleskop moći istodobno ispitati sva četiri čvora i utvrditi je li bilo koji od njih supermasivna crna rupa.

"Ovdje vidite našu veliku sofisticiranost", rekao je Lauer. „Hej, možda je u čvorovima! Hej, možda nije! Bolje pretražite sve! "


Nestala: Jedna crna rupa sa 10 milijardi solarnih masa

Astronomi pretražuju kozmičku izgubljenu i pronađenu jednu od najvećih, najgorih crnih rupa za koje se mislilo da postoje. Do sada ga nisu pronašli.

U posljednjih nekoliko decenija postalo je dijelom astronomskih nauka da se u središtu svake galaksije krije džinovska crna rupa u kojoj su nestali ekvivalenti miliona ili čak milijardi sunaca. Što je veća galaksija, to je crna rupa u središtu masivnija.

Stoga je bilo iznenađenje prije deset godina kada je Marc Postman, iz Naučnog instituta svemirskog teleskopa, koristeći svemirski teleskop Hubble za snimanje jata galaksija, pronašao supergigantsku galaksiju bez tragova crne rupe u svom središtu. Obično bi jezgro galaksije u svom središtu imalo dodatak svjetlosti, neku vrstu blistavog ogrtača, koji su proizvodile zvijezde koje su se tamo okupile gravitacijom džinovske crne rupe.

Suprotno tome, u tačnom središtu širokog jezgra galaksije, gdje je trebao biti lagani udarac u svjetlosti zvijezda, došlo je do laganog padanja. Štaviše, celo jezgro, oblak zvezda širine oko 20.000 svetlosnih godina, nije bilo ni u sredini galaksije.

"O, Bože, ovo je zaista neobično", prisjetio se Tod Lauer, stručnjak za galaktička jezgra Nacionalnog opservatorija za optičku astronomiju u Tucsonu u državi Arizona i autor na papiru, kada je Postman pokazao nalaz.

To je bilo 2012. Tokom godina, dvoje istraživača i njihove kolege tragali su za rendgenskim zrakama ili radio-talasima iz nestale crne rupe.

Galaksija je najsjajnija u skupu poznatom kao Abell 2261. Nalazi se na oko 2,7 milijardi svjetlosnih godina odavde, u sazviježđu Herkules na sjevernom nebu, nedaleko od istaknute zvijezde Vege. Koristeći standardno pravilo, crna rupa koja nedostaje u središtu galaksije 2261 trebala bi biti 10 milijardi solarnih masa ili više. Uporedno, crna rupa u središtu galaksije Mliječni put ima samo oko 4 miliona sunčevih masa.

Pa gdje je priroda sakrila ekvivalent od 10 milijardi sunaca?

Jedna od mogućnosti je da je crna rupa tu, ali je utihnula, privremeno ostajući bez ičega. No, druga provokativna mogućnost, kažu Lauer i njegove kolege, je ta da je crna rupa uopće izbačena iz galaksije.

Dokazivanje potonjeg moglo bi pružiti uvid u neke od najnasilnijih i najdinamičnijih procesa u evoluciji galaksija i kosmosa, o kojima su astronomi teoretizirali, ali ih nikada nisu vidjeli - ples titanskih sila i vrtložnih svjetova koji mogu bacati zvijezde i planete u prazninu .

"To je intrigantna misterija, a mi smo na slučaju", rekao je poštar u e-poruci. Dodao je da će predstojeći svemirski teleskop James Webb imati sposobnost da rasvetli slučaj, da tako kažem, na slučaj.

"Šta se događa kada iz galaksije izbacite supermasivnu crnu rupu?" Pitao je Lauer.

Lauer je dio neformalne grupe koja sebe naziva Nukeri. Grupa se prvi put okupila pod Sandrom Faber sa Kalifornijskog univerziteta u Santa Cruzu, u ranim danima svemirskog teleskopa Hubble. Tokom protekle četiri decenije, pokušali su rasvetliti prirodu galaktičkih jezgara, koristeći oštro oko Hubble-a i druge nove objekte kako bi zavirili u intimna srca dalekih galaksija.

"Priča o A2261-BCG", rekao je, pozivajući se na formalno ime galaksije u literaturi, "je ono što se događa s najmasivnijim galaksijama u svemiru, divovskim eliptičnim galaksijama, na krajnjoj tački evolucije galaksije."

Crne rupe su objekti toliko gusti da čak ni svjetlost ne može pobjeći iz njihovih gravitacijskih kvačila. Oni su nevidljivi po definiciji, ali ruckus - rendgenski zraci i radio vriskovi - uzrokovan materijalom koji mu pada u ruke može se vidjeti širom svemira. Otkriće kvazara u centrima galaksija šezdesetih godina prošlog stoljeća prvo je navelo astronoma da smatraju da su supermasivne crne rupe odgovorne za takav vatromet.

Krajem stoljeća astronomi su došli do zaključka da je svaka galaksija u svojim njedrima imala supermasivnu crnu rupu, milione do milijarde puta masivniju od sunca. Odakle su došli - jesu li izrasli iz manjih crnih rupa nastalih kolapsom zvijezda ili nastalih nekim drugim procesom rano u svemiru - niko nije siguran. "U svakoj breskvi ima koštica", rekao je Lauer.

Ali kako ti entiteti utiču na svoju okolinu?

1980. godine, tri astronoma, Mitchell Begelman, Martin Rees i Roger Blandford, napisali su o tome kako će ove crne rupe promijeniti evoluciju galaksija u kojima žive. Kada bi se dvije galaksije sudarile i spojile - što je posebno čest događaj u ranijem svemiru - njihove centralne crne rupe bi se susrele i formirale binarni sistem, dvije crne rupe koje su kružile jedna oko druge.

Begelman i njegove kolege tvrdili su da će ove dvije masivne crne rupe, koje se njišu oko sebe, stupiti u interakciju s morem zvijezda u koje su uronjene. Svako malo bi jedna od ovih zvijezda imala bliski susret s binarnom, a gravitacijske sile bi gurnite zvijezdu iz središta, ostavljajući crne rupe još čvršće povezanima.

Vremenom bi se više zvijezda bacalo dalje od centra. Postepeno, zvjezdana svjetlost koja je nekoć bila koncentrirana u centru širila bi se u šire, difuzno jezgro, s malim pregibom u središtu u kojem je binarni sistem crnih rupa plesao svoj par. Proces se naziva „ribanje“.

"Bili su daleko ispred igre", rekao je Lauer o trojici astronoma.

Pročišćena jezgra bila je situacija za koju su Lauer i Poštar mislili da su se susreli s Abellom 2261. Ali umjesto vrha u središtu jezgre, uslijedio je pad, kao da su supermasivna crna rupa i njezine prateće zvijezde jednostavno bile oduzeta.

To je stvorilo dramatičniju mogućnost da se odigrao scenarij koji su zamislili Begelman i njegove kolege: Dvije crne rupe stopile su se u jednu gigantsku gutljaju ničega. Spajanje bi bilo praćeno kataklizmičnim rafalnim gravitacijskim valovima, valovima u prostoru i vremenu za koje je Einstein predvideo postojanje 1916. godine, a napokon LIGO instrumenti vidjeli stoljeće 2016. godine.

Da je taj rafal bio jednostran, poslao bi rezultirajuću supermasivnu crnu rupu koja leti kroz galaksiju, ili čak iz nje, nešto što astronomi nikada nisu primijetili. Dakle, pronalaženje pogrešne crne rupe bilo je od najveće važnosti.

Dalje ispitivanje A2261-BCG otkrilo je četiri mala čvora svjetlosti unutar difuzne jezgre. Može li jedan od njih biti u crnoj rupi?

A team led by Sarah Burke-Spolaor of West Virginia University took to the sky with Hubble and the Very Large Array radio telescope in Socorro, New Mexico. Spectroscopic measurements by Hubble could tell how fast the stars in the knots were moving, and thus whether some massive object was needed to keep them together.

Two of the knots, they concluded, were probably small galaxies with small internal motions being cannibalized by the big galaxy. Measurements of the third knot had such large error bars that it could not yet be ruled in or out as the black hole’s location.

The fourth, very compact knot near the bottom edge of the core was too faint for Hubble, Burke-Spolaor reported. “Observing this knot would have required an overblown amount of time (hundreds of hours) observing with Hubble Space Telescope,” she said in an email, and so it also remains a candidate for the hiding spot.

The galaxy core also emits radio waves, but they didn’t help the search, Burke-Spolaor said.

“We were originally hoping the radio emission would be some kind of literal smoking gun, showing an active jet that points directly back to black-hole location,” she said. But the radio relic was at least 50 million years old, according to its spectral characteristics, which meant, she said, that the large black hole would have had ample time to move elsewhere since the jet turned off.

Next stop was NASA’s orbiting Chandra X-ray Observatory. Kayhan Gultekin of the University of Michigan, another veteran Nuker who was not on the original discovery team, aimed the telescope at the cluster core and those suspicious knots. No dice. The putative black hole would have to be feeding at one-millionth of its potential rate if it were there at all, Gultekin said.

“Either any black hole at the center is very faint, or it isn’t there,” he wrote in an email. The same goes for the case of a binary black-hole system, he said it would need to be eating very little gas to stay hidden.

In the meantime, Imran Nasim, of the University of Surrey, who was not part of Postman’s team, has published a detailed analysis of how the merger of two supermassive black holes could reform the galaxy into what the astronomers have found.

“Simply, gravitational wave recoil ‘kicks’ the supermassive black hole out of the galaxy,” Nasim explained in an email. Having lost its supermassive anchor, the cloud of stars around the black-hole binary spreads out, becoming more diffuse. The density of stars in that region — the densest part of the entire giant galaxy — is only one-tenth the density of stars in our own neighborhood of the Milky Way, resulting in a night sky that would appear anemic compared with our own.

All this is another reason that astronomers eagerly await the launch of the James Webb Space Telescope, the long-awaited successor to Hubble, which is now scheduled for the end of October. That telescope will be able to examine all four knots at the same time and determine whether any of them are a supermassive black hole.

“Here you see our great sophistication,” Lauer said. “Hey, maybe it’s in the knots! Hey, maybe it isn’t! Better search everything!”


Excavating a Dinosaur in a Galaxy Cluster


Ophiuchus Galaxy Cluster
Credit: X-ray: Chandra: NASA/CXC/NRL/S. Giacintucci, et al., XMM-Newton: ESA/XMM-Newton
Radio: NCRA/TIFR/GMRT Infrared: 2MASS/UMass/IPAC-Caltech/NASA/NSF

We are pleased to welcome two guest bloggers, Maxim Markevitch and Simona Giacintucci, who led the study described in our latest press release. Markevitch, an expert on galaxy clusters X-ray studies, got his PhD at the Space Research Institute of the Russian Academy of Sciences. He worked on ASCA X-ray data in Japan, then at the Chandra X-ray Center for the first 10 years of Chandra operations, and is now at the NASA Goddard Space Flight Center. He received the AAS Rossi Prize. Giacintucci, the lead author of the study, is an expert in radio phenomena in galaxy clusters. She got her PhD at Bologna University. She was a postdoc at the CfA and an Einstein fellow at the University of Maryland, and is now at the Naval Research Lab.

Galaxy clusters are colossal concentrations of dark matter, galaxies, and tenuous, 100-million-degree plasma. This plasma — gas where the electrons have been stripped from their atoms — slowly loses heat by emitting radiation in the form of X-rays. Around the central peaks of many clusters, where matter concentrates, the plasma gets dense enough* to cool quite fast, on a timescale shorter than the cluster's lifetime (a few billion years). The higher the plasma's density, the more X-rays it emits and the faster it cools. As it cools down, it contracts and becomes denser still, and so on, entering a runaway cooling process. Left unchecked, this process should deposit vast quantities of cold gas in the cluster centers.

We know for a fact that the plasma cools down because we do observe those X-rays — but we don't find nearly as much cold gas in the cluster centers as such runaway cooling must deposit. This has been a puzzle for a long while, and the solution the astronomers converged upon is that there must be some source of additional heat in the central regions of clusters — their “cores” — that doesn't let the plasma cool below 10 million degrees or so.

Early Chandra X-ray images of galaxy clusters pointed to the likely source: the supermassive black holes (SMBH) that sit in the centers of the cluster central galaxies, pull in the surrounding matter, and eject a tiny part of it (just before it sinks irretrievably into the black hole) at nearly the speed of light back into the surrounding gas. Where those jets hit the gas, they blow huge bubbles in it, stir it, generate shocks like sonic booms, etc. (all of these features have been seen in the Chandra images of the cluster cores). The current wisdom holds that these processes together supply the needed heat to prevent runaway cooling from occurring, but at the same time are not so powerful that they blow up the whole plasma cloud, implying some kind of a gentle, self-regulated feedback loop may be occurring.


An invisible sphere surrounded by a donut

From our far-off view of this great black hole, it might look like a bright, flat ring. But that's not exactly the case.

We're largely seeing the "face" of the event horizon, like the face of a coin, as opposed to the side or edge, explained Chris Fryer, an astrophysicist at Los Alamos National Laboratory who had no role in the collaboration.

Yet from another view, we would see that the event horizon is not a flat disk with a big hole in the middle (where an enormous black hole lies). "It’s a donut sort of thing -- but not a frisbee," said Lai.

Still, we are viewing this black hole -- and the event horizon around it -- from an ideal angle. It's a bit like hovering above Earth and looking down onto the North Pole, said Bentz. This allows us to glimpse the ring around the rotating black hole, which scientists suspect is a great big sphere, like Earth.

It's an invisible sphere surrounded by a donut of hot gas, if you will.


Missing: One black hole with 10 billion solar masses

Astronomers are searching the cosmic lost-and-found for one of the biggest, baddest black holes thought to exist. So far they haven’t found it.

In the past few decades, it has become part of astronomical lore that at the center of every galaxy lurks a giant black hole into which the equivalent of millions or even billions of suns have disappeared. The bigger the galaxy, the more massive the black hole at its center.

So it was a surprise a decade ago when Marc Postman, of the Space Telescope Science Institute, using the Hubble Space Telescope to survey clusters of galaxies, found a supergiant galaxy with no sign of a black hole in its center. Normally, the galaxy’s core would have a kink of extra light in its center, a kind of sparkling cloak, produced by stars that had been gathered there by the gravity of a giant black hole.

On the contrary, at the exact center of the galaxy’s wide core, where a slight bump in starlight should have been, there was a slight dip. Moreover, the entire core, a cloud of stars some 20,000 light-years across, was not even in the middle of the galaxy.

“Oh, my God, this is really unusual,” Tod Lauer, an expert on galactic nuclei at the National Optical Astronomy Observatory in Tucson, Arizona, and an author on the paper, recalled saying when Postman showed him the finding.

That was in 2012. In the years since, the two researchers and their colleagues have been looking for X-rays or radio waves from the missing black hole.

The galaxy is the brightest one in a cluster known as Abell 2261. It is about 2.7 billion light-years from here, in the constellation Hercules in the northern sky, not far from the prominent star Vega. Using the standard rule of thumb, the black hole missing from the center of the 2261 galaxy should be 10 billion solar masses or more. Comparatively, the black hole at the center of the Milky Way galaxy is only about 4 million solar masses.

So where has nature stashed the equivalent of 10 billion suns?

One possibility is that the black hole is there but has gone silent, having temporarily run out of anything to eat. But another provocative possibility, Lauer and his colleagues say, is that the black hole was thrown out of the galaxy altogether.

Proving the latter could provide insight into some of the most violent and dynamic processes in the evolution of galaxies and the cosmos, about which astronomers have theorized but never seen — a dance of titanic forces and swirling worlds that can fling stars and planets across the void.

“It’s an intriguing mystery, and we’re on the case,” Postman said in an email. He added that the upcoming James Webb Space Telescope would have the capability to shed light, so to speak, on the case.

“What happens when you eject a supermassive black hole from a galaxy?” Lauer asked.

Lauer is part of an informal group who call themselves Nukers. The group first came together under Sandra Faber of the University of California, Santa Cruz, in the early days of the Hubble Space Telescope. Over the past four decades, they have sought to elucidate the nature of galactic nuclei, using the sharp eye of Hubble and other new facilities to peer into the intimate hearts of distant galaxies.

“The story of A2261-BCG,” he said, referring to the galaxy’s formal name in literature, “is what happens with the most massive galaxies in the universe, the giant elliptical galaxies, at the end point of galaxy evolution.”

Black holes are objects so dense that not even light can escape their gravitational clutches. They are invisible by definition, but the ruckus — X-rays and radio screams — caused by material falling into its grasp can be seen across the universe. The discovery in the 1960s of quasars in the centers of galaxies first led astronomers to consider that supermassive black holes were responsible for such fireworks.

By the turn of the century, astronomers had come to the conclusion that every galaxy harbored a supermassive black hole, millions to billions of times more massive than the sun, in its bosom. Where they came from — whether they grew from smaller black holes that had formed from the collapse of stars, or formed through some other process early in the universe — nobody is sure. “There is a pit in every peach,” Lauer said.

But how do these entities affect their surroundings?

In 1980, three astronomers, Mitchell Begelman, Martin Rees and Roger Blandford, wrote about how these black holes would alter the evolution of the galaxies they inhabit. When two galaxies collided and merged — an especially common event in the earlier universe — their central black holes would meet and form a binary system, two black holes circling each other.

Begelman and his colleagues argued that these two massive black holes, swinging around, would interact with the sea of stars they were immersed in. Every once in a while, one of these stars would have a close encounter with the binary, and gravitational forces would push the star out of the center, leaving the black holes even more tightly bound.

Over time, more stars would be tossed away from the center. Gradually, starlight that was once concentrated at the center would spread out into a broader, diffuse core, with a little kink at the center where the black-hole binary was doing its mating dance. The process is called “scouring.”

“They were way ahead of the game,” Lauer said of the three astronomers.

A scoured core was the kind of situation that Lauer and Postman thought they had encountered with Abell 2261. But instead of a peak at the center of the core, there was a dip, as if the supermassive black hole and its attendant stars had simply been taken away.

This raised the more dramatic possibility that the scenario envisioned by Begelman and his colleagues had played out: The two black holes had merged into one gigantic mouthful of nothing. The merger would have been accompanied by a cataclysmic burst of gravitational waves, space-time ripples predicted to exist by Einstein in 1916 and finally seen by the LIGO instruments a century later, in 2016.

If that burst was lopsided, it would have sent the resultant supermassive black hole flying through the galaxy, or even out of it, something astronomers had never observed. So finding the errant black hole was of the utmost importance.

Further scrutiny of A2261-BCG revealed four little knots of light within the diffuse core. Could one of them be harboring the black hole?

A team led by Sarah Burke-Spolaor of West Virginia University took to the sky with Hubble and the Very Large Array radio telescope in Socorro, New Mexico. Spectroscopic measurements by Hubble could tell how fast the stars in the knots were moving, and thus whether some massive object was needed to keep them together.

Two of the knots, they concluded, were probably small galaxies with small internal motions being cannibalized by the big galaxy. Measurements of the third knot had such large error bars that it could not yet be ruled in or out as the black hole’s location.

The fourth, very compact knot near the bottom edge of the core was too faint for Hubble, Burke-Spolaor reported. “Observing this knot would have required an overblown amount of time (hundreds of hours) observing with Hubble Space Telescope,” she said in an email, and so it also remains a candidate for the hiding spot.

The galaxy core also emits radio waves, but they didn’t help the search, Burke-Spolaor said.

“We were originally hoping the radio emission would be some kind of literal smoking gun, showing an active jet that points directly back to black-hole location,” she said. But the radio relic was at least 50 million years old, according to its spectral characteristics, which meant, she said, that the large black hole would have had ample time to move elsewhere since the jet turned off.

Next stop was NASA’s orbiting Chandra X-ray Observatory. Kayhan Gultekin of the University of Michigan, another veteran Nuker who was not on the original discovery team, aimed the telescope at the cluster core and those suspicious knots. No dice. The putative black hole would have to be feeding at one-millionth of its potential rate if it were there at all, Gultekin said.

“Either any black hole at the center is very faint, or it isn’t there,” he wrote in an email. The same goes for the case of a binary black-hole system, he said it would need to be eating very little gas to stay hidden.

In the meantime, Imran Nasim, of the University of Surrey, who was not part of Postman’s team, has published a detailed analysis of how the merger of two supermassive black holes could reform the galaxy into what the astronomers have found.

“Simply, gravitational wave recoil ‘kicks’ the supermassive black hole out of the galaxy,” Nasim explained in an email. Having lost its supermassive anchor, the cloud of stars around the black-hole binary spreads out, becoming more diffuse. The density of stars in that region — the densest part of the entire giant galaxy — is only one-tenth the density of stars in our own neighborhood of the Milky Way, resulting in a night sky that would appear anemic compared with our own.

All this is another reason that astronomers eagerly await the launch of the James Webb Space Telescope, the long-awaited successor to Hubble, which is now scheduled for the end of October. That telescope will be able to examine all four knots at the same time and determine whether any of them are a supermassive black hole.

“Here you see our great sophistication,” Lauer said. “Hey, maybe it’s in the knots! Hey, maybe it isn’t! Better search everything!”


Ask Ethan: Why Doesn’t Every Galaxy Have A Supermassive Black Hole?

There are some 400 billion objects flying through the Milky Way galaxy with enough mass that — if they were all made of hydrogen and helium atoms — they’d ignite nuclear fusion in their cores and become stars. Most of them actually are stars, but many of them are former stars, existing today as white dwarfs, neutron stars, or black holes. Of the black holes that we have, most of them fall into the category of “stellar mass” black holes, meaning that they arose from stars and have masses that individual stars also possess. But a few black holes grew to be much more massive, and at the center of the Milky Way lies our most massive black hole of all: the 4 million solar mass, supermassive behemoth known as Sagittarius A*. In fact, most galaxies have supermassive black holes, and that’s what Patreon supporter Steve Shaber wrote in to ask about:

“[You’ve said] that najviše galaxies have a supermassive black hole at the center. I heard the same statement on television this morning. But why would any galaxy ne have a supermassive black hole? Do astronomers know for certain that some galaxies lack a black hole at the center — that there’s a hole (so to speak) where the black hole ought to be?”

Oh yes, yes we do know. Here’s the science behind the galaxies without a supermassive black hole at their centers.

10⁶ year) timescales, rather than all at once. Due to its close proximity to Earth, it’s possible that the Event Horizon Telescope could image its central region to even better spatial resolutions than 3C 279. (X-RAY: NASA/CXC/UNIV OF HERTFORDSHIRE/M.HARDCASTLE ET AL., RADIO: CSIRO/ATNF/ATCA)

When we look out at the galaxies in the Universe, they come not only in a variety of shapes, sizes, ages, and stellar populations, but also with a wide assortment of activity levels. Some galaxies emit X-rays and radio waves from their centers: a sign of their central black holes actively feeding on matter.

This electromagnetic emission fools many into believing that black holes — objects where gravity is so intense, that nothing, not even light, can escape from its gravitational pull — are somehow a paradox.

That’s not the case at all, though, because this emission doesn’t come from inside the event horizon, but exclusively from outside. The radiation, in fact, comes from matter that’s external to the black hole, from stars, globular clusters, gas, and other objects. When they get close enough to the vicinity of the black hole, the intense tidal forces, which can be quintillions of times stronger than the tides from the Earth-Moon system, rip them apart. That mass then becomes part of an accretion disk (or accretion flow), where it heats up, emits radiation, and much of it eventually falls in, where it grows the black hole in mass.

When we look out at the galaxies we see across cosmic time, many of them appear active. In fact, the image above comes from NASA’s Chandra’s X-ray telescope, and is one of the deepest images of the sky ever taken. More than 7 million seconds — the equivalent of about three months of continuous observation — went into observing this small patch of sky, and practically every point of light appearing in this image corresponds to an active, feeding, supermassive black hole at the center of a galaxy.

These black holes are truly a wonder to observe. We’ve learned, from what we’ve seen, that the Milky Way’s most massive black hole, of

4 million solar masses, is actually on the small side of things. Most galaxies of comparable sizes that are active have much larger black holes. Andromeda, which is at most about twice the mass of the Milky Way, has a black hole that’s more like

80–100 million solar masses. Many other galaxies have black holes reaching into the billions or even tens of billions of solar masses.

And, at the limits of our observational capabilities, we find galaxies from when the Universe was only a tiny fraction of its present age, less than a billion years old, that have supermassive black holes that are hundreds, or even close to a thousand, times as massive as our own.

I couldn’t blame you for thinking, based on the evidence of what we do see, that every galaxy in the Universe should have a supermassive black hole at its center. After all, only a fraction of the black holes that exist are supermassive, and only a fraction of the supermassive black holes that exist are active in any way. For example, the galaxy NGC 1277 is close enough and has a massive enough black hole that the Event Horizon Telescope should be able to image it directly, but its inactivity renders it unobservable via this direct method.

Furthermore, the supermassive black hole at the center of our own galaxy is the only one close enough to measure its mass from the motion of individual stars within it. It’s an eminently reasonable thought that every galaxy in the Universe should have a supermassive black hole, especially considering that the processes that we think lead to their formation:

  • early, very massive stars form,
  • some go supernova and some directly collapse,
  • their remnants dynamically interact with the surrounding matter,
  • causing them to sink to the proto-galaxy’s center,
  • where they merge,
  • and then these “seeds” of supermassive black holes accrete matter and grow,
  • leading to what we observe today,

ought to occur everywhere a galaxy is present.

But there’s another part to the story, and that’s what changes everything. Yes, we think that every galaxy — from the process of star-formation and evolution — should spawn the seeds of supermassive black holes, and that given enough time, those seeds should grow into bona fide supermassive black holes. As long as galaxies remain in isolation, it’s very difficult to imagine that something would come along to get rid of these monsters, since, when you work out the equations that govern energy and momentum conservation, you learn that you’d pretty much need something to come along that was more massive than the supermassive black hole if you wanted to gravitationally “kick” it out of the galaxy.

Sure, supernova explosions can kick smaller, stellar mass black holes out of a galaxy we’ve seen evidence for that occurrence in our own Milky Way relatively recently, in fact. But even the largest, most powerful supernova couldn’t kick a supermassive black hole out of a parent galaxy. There simply isn’t enough energy to get a mass that large moving with enough speed for it to achieve escape velocity.

But there is a way to do it: take another galaxy, one that’s more massive than at least the supermassive black hole you’re asking about, one that very likely also has its own supermassive black hole, and bring it close enough so that you get a gravitational interaction between the two galaxies.

The first observational evidence that such a happenstance could lead to a black hole getting kicked out of a galaxy was uncovered back in 2012, when a supermassive black hole was observed moving out of its host galaxy at a speed of about 5 million kilometers per hour: about 0.5% the speed of light. Above, you can see a picture of two galaxies — with both optical and X-ray data shown — where one of the galaxies is very unusual: it has X-ray emission that’s offset from the center, dominant in one direction, and is moving with a large speed relative to the host galaxy. If you’re interested in learning more, the galaxy is known as CID-42, and is located about 4 billion light-years away.

So what could be causing this?

The best explanation is that there was a recent collision between two galaxies, and that their supermassive black holes collided as well. Because of how gravitational waves work, with an inspiral, merger, and ringdown phase, large amounts of energy can be radiated away. In fact, whenever two black holes merge, about

10% of the mass of the smaller black hole is converted into gravitational radiation via Einstein’s E = mc². That large energy conversion can sometimes “kick” the post-merger black hole, and in this case, it looks like it kicked it hard enough that it’s being ejected from the galaxy.

Now, you might worry — if you know quite a bit about energy and momentum — that the supermassive black holes ought to follow their host galaxies, and so if the galaxies merge, you’d expect that the supermassive black holes would remain with those galaxies post-merger as well.

Don’t doubt your intuition this is what usually happens, most likely. But there are certain parameters that can change the story. Remember the following facts:

  1. the correlation between galaxy mass and supermassive black hole mass is only a general one, and there are plenty of instances of high-mass galaxies with lower-mass black holes and lower-mass galaxies with higher-mass black holes,
  2. that when black holes merge, they’ll roughly follow the center-of-momentum frame for the two black holes,
  3. but that when galaxies merge, they’ll roughly follow the center-of-momentum for the gaseous (and dark matter) components of the host galaxies,
  4. and that if “fact 2” and “fact 3” give you different momentum vectors, it’s actually very easy for two galaxies to merge and produce a post-merger galaxy where the main pre-existing supermassive black holes have also merged, but are no longer part of that new galaxy.

Indeed, we might have reason to worry if we only ever saw this one example of a galaxy that’s losing a supermassive black hole, or if the data were more ambiguous about what’s happening, such as if another active black hole were part of the CID-42 system. (There isn’t one.)

But it’s definitively not the only example. We discovered a quasar, 3C 186, which we fully suspect is powered by a supermassive black hole, just like all quasars. Only, when we went looking for the host galaxy associated with this quasar, we found that it was moving at

2000 km/s, or about 0.7% the speed of light, relative to the quasar itself. It takes a huge amount of energy to displace a black hole like this, and quasars are often thought to “activate” in the aftermath of a galaxy merger.

Discovered in 2017, this system appears to exhibit similar properties to CID-42, only this time, the black hole is truly enormous at

1 billion solar masses. It’s eminently possible that gravitational waves are emitted more strongly in one direction than another, and the post-merger black hole will recoil in the opposite direction. The fact that gravitational waves can carry so much energy is very likely what’s propelling these black holes out of their host galaxies.

One of the place to look for these black holes in the process of being ejected, as astronomer Yashashree Jadhav noted back in 2019, is for galaxies whose “central” black holes are actually offset from their centers. Indeed, in many such galaxies, it’s noted that those black holes appear to be moving relative to the rest of the galaxy at high speeds: hundreds or even thousands of km/s, or between about 0.1% and 1% the speed of light.

Some of them could be binary supermassive black holes — which we have observed — but somehow where only one member is visible and the other isn’t. (That latter option is something that hasn’t been observed.) It’s possible that other dynamics caused these large black hole velocities, but it’s difficult to think of a mechanism that could impart so much energy to them that wouldn’t also affect the host galaxy similarly. Even the most powerful supernovae, for example, are hundreds of millions of time too weak to cause this effect.

The best story we have today, using only known physics and applying it to the full suite of what we’ve observed, indicates that there ought to be many galaxies out there, even large ones, that lost their supermassive black holes in a recent merger. Although we’ve seen quite a number of these galaxies that look suspiciously devoid of black holes, we have yet to find a supermassive black hole wandering through intergalactic space all by its lonesome.

When we put all of this together, it weaves a remarkable tapestry for the story of supermassive black holes. Yes, most galaxies have one, and with every merger, burst of central star formation, or absorption of satellite galaxies, the central black hole will only grow. But occasionally, major (or modest) mergers may lead to supermassive black hole mergers, and they can kick the resultant supermassive black hole out of the host galaxy entirely. We’ve seen some evidence for this, but there are plenty of additional signals and consequences that should arise if this is the case.

There should be many galaxies, particularly in the richest regions of galaxy clusters, that house only very small supermassive black holes, or possibly even none at all.

Galaxies like the Milky Way, with very low-mass supermassive black holes for their sizes, might not be on their first supermassive black holes we may have lost an earlier, more massive one some time ago.

And we should have supermassive black holes populating intergalactic space, where they might transit in front of background light sources, causing an effect like gravitational microlensing. Unless something is done to mitigate the effects of satellite pollution, however, this last effect might be practically impossible to detect.

Right now, the only mechanism we know of that could separate supermassive black holes from their host galaxies involve a dual merger — of black hole-black hole mergers alongside a galaxy-galaxy merger — where the final momenta of the resulting black holes and galaxies are sufficiently different from one another.

But to learn how common supermassive black hole ejections are, what fraction of galaxies have lost them, and whether there are other mechanisms for black hole ejection (or not), will require further scientific study. Furthermore, learning how (and whether) supermassive black holes regrow is also a tremendous unknown.

However, one thing is certain, whether we like it or not: not every galaxy always has a supermassive black hole, and no matter how much time it’s spent growing one, a merger with the right properties can always take it away. While it might be tempting to make blanket statements that all galaxies have supermassive black holes, the real Universe, as is so often the case, is full of surprising ways to get even the dirtiest of jobs done.


Stellar Black Hole Is So Massive It Shouldn't Exist

Editor's Note: The findings of this study have been called into question because of a potential error in the analysis of starlight from the companion star. That error would mean the black hole is about the size of our sun, rather than 70 times the mass of our sun.

A gigantic stellar black hole 15,000 light-years from Earth is twice as massive as what researchers thought was possible in our own galaxy.

The black hole is 70 times more massive than the sun, the scientists wrote in a new study. Previously, scientists thought the mass of a stellar black hole, formed from the gravitational collapse of massive stars, couldn't exceed 30 times that of the sun.

"We thought that very massive stars with the chemical composition typical of our galaxy must shed most of their gas in powerful stellar winds as they approach the end of their life," lead study author Jifeng Liu, deputy director-general of the Chinese Academy of Sciences' National Astronomical Observatories, navodi se u izjavi. "Therefore, they should not leave behind such a massive remnant."

It is thought that our Milky Way galaxy contains some 100 million stellar black holes, yet scientists have discovered only about two dozen of them, according to the statement. That's because, until a couple of years ago, the only way scientists could discover these giant beasts was by detecting the X-rays they emitted while they chomped away at their stellar companions. But most black holes in our galaxy don't have much of an appetite and thus don't release X-rays, the researchers explained in the statement.

So Liu and his team turned to another method: They scanned the skies with China's Large Sky Area Multi-Object Fiber Spectroscopic Telescope. Using this telescope, they searched for stars that orbit seemingly invisible objects, held on tight by the object's gravity. That's how the researchers came across one star 15,000 light-years away that was dancing around nothing &mdash but was held in an orbit by something that could only be a black hole, they wrote.

After finding the star, which they named LB-1, the researchers used two huge optical telescopes &mdash the Gran Telescopio Canarias in La Palma, Spain, and the Keck I telescope in Hawaii &mdash to determine the mass of the star and its black hole companion. They found that the star was eight times more massive than the sun and orbited a black hole 70 times more massive than the sun. The star orbited the black hole every 79 days, the researchers reported.

The black hole "is twice as massive as what we thought possible," Liu said in the statement. "Now, theorists will have to take up the challenge of explaining its formation." Recently, astronomers have been challenged by discoveries that point to the existence of black holes that are more massive than experts thought was possible. For example, the Laser Interferometer Gravitational-Wave Observatory (LIGO) and Virgo gravitational-wave detectors have spotted ripples in space-time caused by the collision of black holes in distant galaxies, and these black holes are more massive than expected, according to the statement.

"This discovery forces us to re-examine our models of how stellar-mass black holes form," LIGO director and University of Florida professor David Reitze, who was not involved in the study, said in the statement. "This remarkable result, along with the LIGO-Virgo detections of binary black hole collisions during the past four years, really points towards a renaissance in our understanding of black hole astrophysics."

The findings were published Nov. 27 in the journal Priroda.

A gigantic black hole 15,000 light-years from our planet is twice as massive as what researchers thought was possible in our own galaxy.

Stellar Black Hole in Our Galaxy Is So Massive It Shouldn't Exist : Read more

A gigantic black hole 15,000 light-years from our planet is twice as massive as what researchers thought was possible in our own galaxy.

Stellar Black Hole in Our Galaxy Is So Massive It Shouldn't Exist : Read more happy wheels

A gigantic black hole 15,000 light-years from our planet is twice as massive as what researchers thought was possible in our own galaxy.

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Scientists generally believe that there are two types of black holes.

The more common stellar black holes - up to 20 times more massive than the Sun - form when the centre of a very big star collapses in on itself.

In my opinion, per the alternative perspective provided by the 'The Evolutioning of Creation: Volume 2', what is missing is an understanding of matter as a whole. To my way of thinking, 'whole matter' is conglomeration of ordinary matter and dark matter. So scientists have to stop thinking of dark matter as being distinguishable from ordinary matter. Wherein the creation of matter as a whole induces a complementary displacement, or warping in the dark energy medium of the space-time fabric, its promulgation is interdependent on its insistence and persistence. For within this warping, there is yet another perturbation in the whole matter created an almost indistinguishable dual relationship of newly created positive density matter in an envelopment of negative density matter. This complementary displacement insulates the newly created positive density matter in an envelopment of negative density matter. This envelope of negative density matter, known as dark matter, then infiltrates the spaces in matter, providing it with the ability to interact, bond, and evolve. Indeed it would require much more dark matter to fill the spaces among ordinary matter down to its smallest constituent parts.

Rather consider that dark matter is what engenders the force of gravity for ordinary matter to bond, then the accretion and accumulation of ordinary matter is just the resultant consequence of this force. In which case it can be interpreted, that dark matter is responsible for density of ordinary matter in a whole matter perspective. Such is it that gravitational lensing is representative of this relationship as well. Where one assumes the relative density of ordinary matter as an influence in the gravitational distortion of the spacetime fabric, it is really the dark matter envelopment of the ordinary matter that is in play here. The visibility and complexion of ordinary matter is just a result of this whole matter interaction.

Still if we are to agree with the expectation of dark matter to meet the expectation of its contribution in the scheme of the total mass-energy density in the universe, then one must consider that there is an excess of dark matter outside of the whole matter conglomeration. So for dark matter to meet the expectation of its contribution in the scheme of the total mass-energy density in the universe. So where the universe's total energy is broken down to as 68% dark energy, 27% mass-energy via dark matter, and 5% mass-energy via ordinary matter, the percentage of energy distribution suggests a differing evolutionary purpose for dark matter. As suggested of these hypothetical particles, dark matter is theorized to account for the missing gravitational energy required to keep galaxies from flying apart. If dark matter is to truly account for 85% of the missing matter required to account for the missing gravitational energy, then dark matter must pervade every space between ordinary matter. Like the hypothetical graviton, dark matter density mirrors that of ordinary matter density in effect, negative mass density and positive mass density. And even though ordinary matter (positive mass density) reveals its coherency in particle form upon detection, dark matter (negative mass density) does not.

In which case it would then follow that dark matter can be accumulated, separate of ordinary matter. It would therefore also follow that the gravitational force is more representative of negative density mass than positive density mass. Therefore it would not be a great leap of imagination to view the notion of black holes as made up only of dark matter. Example: Upon this hypothesis then, one can expect that there is a require transition to separate ordinary matter from its complementary dark matter. It starts first with the disintegration of matter, as a whole, as it interacts with the event horizon of the black hole. As the positive density mass is 'squeezed' upon its own gravitational acceleration toward the black hole, liken to the spaghettification effect, its matter changes to allow for its disintegration via transmutation and the massive release of photons due to alpha decay and beta decay. This is the effect wherein positive density mass is collected within the event horizon, into a plasma, increasing its photon density. This 'squeezing' effect is like extracting out the dark matter from the whole matter, allowing for the ordinary matter to be reduced to its smallest constituent components. The dark matter is then absorbed into the black hole, and the remnants of ordinary matter are discarded and radiated out at high velocity back into the cosmos to start, once again, to reintegrated into the universe via bonding and evolving.

Sensationalized headline misleads the average lay person that this new black hole discovery somehow purports a century of scientific foundation. It could not be further from the truth. The truth is that whatever we imagine as the limits of our knowledge, only limits our ability to accept the next fantastic discovery. While the detected gravitational signals have been analyzed as the effects of a gigantic merger of two black holes, there may be other explanations yet to be revealed.

The problem with the expectation that black holes must be a certain size has its foundation in the expectation of it being a positive density mass gravitational singularity, in accordance with the Schwartzchild radius calculations. However if we apply the understanding of a black hole as being a negative density mass gravitational well, the size is of no consequence because dark matter is expected to be more energy dense than ordinary matter.

Indeed while there continue to be discoveries, or evidence thereof, of extraordinarily large black holes or considered larger than normal galaxies as seen from billions of years ago, or even unto what we have concluded as our limit as proposed of the expected Big Bang, scientist do not still have a definitive perspective of what that means for cosmogony. The Big Bang is more representative of our theory for an inflationary universe, than it is for how our universe began its reverse engineering.

That is not to say the existing presentation of collective theories is not safely ensconced in the scientific method. We just shouldn't limit ourselves when opening up new paths of thought. While we let the math guide us, we should still be open to greater possibilities within the unobservable universe.

A gigantic black hole 15,000 light-years from our planet is twice as massive as what researchers thought was possible in our own galaxy.

Stellar Black Hole in Our Galaxy Is So Massive It Shouldn't Exist : Read more


Pogledajte video: A supermassive black hole goes missing puzzling scientists (Oktobar 2022).