Astronomi

Hvordan eksisterer en galakse i Abell 2261 uden et sort hul i midten?

Hvordan eksisterer en galakse i Abell 2261 uden et sort hul i midten?


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Her siger en kilde, at astronomer ledte efter et sort hul i den lyseste galakse i klyngen Abell 2261, A2261-BCG, men fandt intet:

Imidlertid har røntgenobservationer fra NASAs Chandra X-ray Observatory og Hubble Space Telescope fandt intet.

Hvordan er det muligt for denne galakse ikke at have et sort hul i midten?


Fysik kræver ikke et sort hul i midten af ​​en galakse, det indikerer bare, at det er sandsynligt.

Alt hvad du behøver er masse. Hvis massen ikke er tæt nok til at danne et sort hul, kan den stadig være høj nok til, at en galakse vokser.

(At finde intet er heller ikke det samme som intet at være der. Så ingen udelukker eksistensen af ​​et sort hul der)


Den lyseste klyngegalakse (BCG) i Abell 2261 ("Abell 2261-BCG") er en massiv elliptisk; disse synes næsten altid at have supermassive sorte huller i deres centre. Derudover har centrum af galaksen et stort område med relativt lav stjernetæthed (en "kerne"), noget der normalt menes at være produceret ved sammensmeltning af to SMBH'er til en, en begivenhed, der følger sammenlægningen af ​​to massive galakser til danner en massiv elliptisk. (Som en del af fusionen danner de to SMBH'er en binær; stjerner nær centrum af den fusionerede galakse kan gravitationsmæssigt interagere med denne binære, hvor det sædvanlige resultat er en krympning af binæren og udkastningen af ​​stjernen til en større radius; således bliver stjerner fortrinsvis sparket ud af centrum ind i den mellemliggende eller ydre del af galaksen, og densiteten af ​​stjerner i midten bliver lavere. Til sidst bliver SMBH-binæren så lille, at tyngdekraftsstråling krymper den endnu længere, til det punkt at de to SMBH'er smelter sammen og bliver en i midten af ​​galaksen.)

Det egentlige papir (Gültekin et al.) Bag denne artikel handler om at lede efter røntgenemission fra en tiltrædelsesdisk omkring den mulige SMBH i centrum af BCG (og også et par andre steder nær centrum). Da de ikke registrerer nogen røntgenstråler, konkluderer de "der er enten nej $ 10 ^ {10} M _ { odot} $ sort hul i kernen i A2261-BCG, eller det tiltrækker sig på et lavt niveau. "Så der er virkelig to muligheder:

  1. Der er en SMBH i galakse-centret, men den er stille (ikke akkreterer nok gas til at producere en masse røntgenstråler).

  2. Der ikke er en SMBH i galaksen, hvilket er mere spændende, fordi det er uventet.

Nu, der faktisk er en teoretisk mekanisme, som lejlighedsvis kan udstøde en SMBH fra centrum af en galakse. Når to SMBH'er smelter sammen for at danne en SMBH (se ovenfor), kan der være et "kick", der får den sammensmeltede SMBH til at blive skubbet ud fra galaksen centrum (størrelsen af ​​dette kick afhænger af ting som masseforholdet mellem de to SMBH'er, hvor hurtigt de enkelte SMBH'er drejede inden fusionen, og hvad retningw af disse spins var relative til kredsløbets bane inden fusionen). I de fleste tilfælde vil den udkastede SMBH falde tilbage i centrum af galaksen - muligvis oscillerende ind og ud et par gange, før dynamisk friktion nedsætter bevægelsen, og den lægger sig tilbage i midten af ​​galaksen. I ekstreme tilfælde kan det kastes hurtigt nok ud, så det helt undslipper galaksen. Hele denne proces vil også skubbe et antal stjerner ud af centrum af galaksen, hvilket måske kan hjælpe med at forklare, hvorfor dens kerne med lav densitet er så stor (dvs. en kombination af SMBH-binærfusionsprocessen og en resulterende SMBH-udstødning).

Så det er muligt, at noget som dette skete i Abell 2261-BCG, og SMBH er i øjeblikket et sted uden for galaksen. (Eller det sidder i midten og dukker bare ikke op i røntgenstråler.) Selvfølgelig fandt de ingen beviser for en røntgenemitterende SMBH uden for Galaxy-kernen, heller ikke, så vi ved det virkelig ikke - og jeg ville ikke blive overrasket, hvis der trods alt er en (hvilende) SMBH i centrum.

(Rory Alsop er korrekt, at ikke alle galakser har SMBH'er - for eksempel er den lokale lille spiralgalakse Messier 33 blevet undersøgt med Hubble-rumteleskop (Gebhardt et al. 2001, og modellering af stjernehastigheder i dets centrum antyder en øvre grænse på ca. 1500 $ M _ { odot} $ for ethvert muligt sort hul der. Men hver massiv elliptisk, der er blevet undersøgt nøje nok, ser ud til at have en, så vi ville forvente, at Abell 2261-BCG også havde en.)


Sorte huller



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I april 2019 frigav forskere det første billede af et sort hul i galaksen M87 ved hjælp af Event Horizon Telescope (EHT). Dette supermassive sorte hul vejer 6,5 milliarder gange solens masse og ligger i centrum af M87, ca. 55 millioner lysår fra Jorden.

Det supermassive sorte hul driver stråler af partikler, der bevæger sig næsten med lysets hastighed, som beskrevet i vores seneste pressemeddelelse. Disse stråler producerer lys, der spænder over hele det elektromagnetiske spektrum, fra radiobølger til synligt lys til gammastråler.

For at få afgørende indsigt i det sorte huls egenskaber og hjælpe med at fortolke EHT-billedet koordinerede forskere observationer med 19 af verdens mest kraftfulde teleskoper på jorden og i rummet og indsamlede lys fra hele spektret. Dette er den største samtidige observationskampagne, der nogensinde er gennemført på et supermassivt sort hul med jetfly.

NASA-teleskoperne, der var involveret i denne observationskampagne, omfattede Chandra X-ray Observatory, Hubble Space Telescope, Neil Gehrels Swift Observatory, Nuclear Spectroscopic Telescope Array (NuSTAR) og Fermi Gamma-ray Space Telescope.


En 10 milliarder solmasser sort hul mangler fra en af ​​de største galakser i universet

I løbet af de sidste år har en række forskere forsøgt at overvåge det sorte huls forsvinden i galaksegruppen "Abell 2261" og gjort en række antagelser.

Ideen, der har været fremherskende i de sidste par årtier blandt astronomer, er, at hver galakse i centrum er et kæmpe sort hul, der sluger millioner eller måske milliarder af soler, og jo større galaksen er, jo større er massen af ​​et sort hul.

En galakse uden et sort hul

Overraskelsen kom for et årti siden, da Marc Postman fra Space Telescope Science Institute opdagede en kæmpe galakse uden sort hul i centrum.

Normalt er der i kernen i hver galakse en yderligere lysmasse i midten udsendt af blinkende stjerner, der er samlet på grund af hulens tyngdekraft, men den galakse, som Postmand opdagede, havde ikke den sædvanlige lysmasse, og kernen , som er en sky af stjerner med en diameter på omkring 20 tusind lysår væk, var ikke midt i galaksen.

I 2012 sagde Todd Lauer fra National Optical-Infrared Astronomy Research Laboratory i Tucson, Arizona, "Dette er slet ikke usædvanligt." I de senere år arbejdede Postman, Lauer og en gruppe andre forskere med at overvåge røntgenstråler og radiobølger udsendt fra galaksen for at finde det manglende sorte hul.

Denne galakse er den lyseste i gruppen af ​​galakser kendt som "Abell 2261" og ligger ca. 2,7 milliarder lysår fra Jorden inde i stjernebilledet Herkules på den nordlige himmelhalvdel.

Forskere antager, at massen af ​​det manglende sorte hul svarer til 10 milliarder solmasser eller mere, hvilket er på størrelse med en kæmpe, hvis vi sammenligner det med det sorte hul i midten af ​​Mælkevejen, som har en masse på ca. 4 millioner solmasser.

Hvor kunne dette kæmpe hul forsvinde?

En af mulighederne er, at dette hul eksisterer, men er statisk, efter at det midlertidigt er løbet tør for, hvad der kan sluges, men Lauer og hans kolleger antog en anden antagelse, nemlig at det sorte hul bevægede sig væk fra galaksen.

En bedre forståelse af sorte huller

At bevise gyldigheden af ​​sidstnævnte mulighed ville give en dybere indsigt i nogle af de mest voldelige og dynamiske processer i galaksernes og universets udvikling og afsløre flere hemmeligheder om de gigantiske kræfter og huller, der kan kaste stjerner og planeter ud i rummet.

Dr. Lauer tilhører et videnskabeligt team, der kalder sig '' Nuker Group '', og i løbet af de sidste fire årtier har denne gruppe forsøgt at overvåge kernerne i fjerne galakser ved hjælp af Hubble-teleskopet og andet avanceret udstyr.

”Hvad der skete i (Abbl 2261) er omtrent hvad der sker med de mest massive elliptiske galakser i universet, ved slutpunktet for deres udvikling,” siger Lauer.

I 1960'erne førte opdagelsen af ​​kvasarer i galaksernes centre til, at astronomer troede, at supermassive sorte huller er ansvarlige for at sluge stjerner og producere lysmasse i den galaktiske kerne.

Ved slutningen af ​​århundredet var astronomerne kommet til den konklusion, at hver galakse indeholder et supermassivt sort hul, millioner eller milliarder gange større end solens masse, men der var ingen klar forklaring på, hvordan sorte huller dannedes, uanset om de udviklede sig fra sorte huller, eller det blev dannet i en anden proces tidligt i universets liv.

Og i 1980 skrev 3 astronomer, Mitchell Begelman, Martin Rees og Roger Blandford, om hvordan disse sorte huller påvirkede udviklingen af ​​galakser. Fra deres synspunkt, når to galakser kolliderer og smelter sammen, hvilket er en almindelig begivenhed i de tidlige stadier af universets liv, konvergerer de sorte sorte huller til et binært system bestående af to sorte huller, der drejer sig om hinanden.

Begelman og hans kolleger fandt ud af, at disse to enorme sorte huller interagerer med konstellationen, der omgiver dem, og fra tid til anden nærmer en af ​​disse stjerner sig til duoen, men tyngdekræfterne skubber den ud af centrum, og med tiden skubber flere stjerner væk fra centrum. Gradvist spredes stjernelyset til en bredere kerne med lidt vridning i midten.

Antagelser om placeringen af ​​det sorte hul

Da de observerede "Abell 2261" -galaksen, havde Lauer og Postman troet, at de ville finde en tæthed i midten, som de er blevet observeret i andre galakser. I stedet for var der et fald i lysmassen, som om det supermassive sorte hul og dets ledsagende stjerner var helt forsvundet.

Denne opdagelse rejste mange spørgsmål om scenariet, som Begelman og hans kolleger antog, da de to sorte huller fusionerede fra ingenting, og fusionen blev ledsaget af en enorm bølge af tyngdekraftsbølger og krusninger i rumtiden som dem, som Einstein forudsagde i 1916, skulle være overvåget af LIGO-observatoriet et århundrede senere, specifikt i 2016.

Hvis denne eksplosion var voldsom, som de tidligere teorier antager, ville den have forårsaget, at det sorte hul blev sendt til et andet sted i galaksen eller endda uden for det, noget som forskerne, der observerede Apple 2261, ikke bemærkede, så de fandt de manglende hul var meget vigtigt For at opnå en acceptabel videnskabelig forklaring.

Yderligere undersøgelse af den elliptiske galakse (A2261-BCG) afslørede 4 små lysnoder i en diffus kerne, hvilket øgede muligheden for, at et sort hul var skjult inde i en af ​​dem.

For at undersøge, observerede et hold ledet af Sarah Burke Spolaor fra West Virginia University de fire knudepunkter ved hjælp af Hubble Observatory og "Great Array of Observatories." Holdet konkluderede, at 2 af knudepunkterne sandsynligvis var små galakser og ikke kunne indeholde et sort hul, mens den tredje og fjerde knude sandsynligvis indeholdt det manglende hul.

Venter på James Webb

Det næste stop i et forsøg på at opdage hemmeligheden bag det manglende hul var NASAs Chandra X-ray Space Observatory. Kayhan Gultekin fra University of Michigan, en veteranforsker fra Nookers-teamet, rettet teleskopet mod kernen og de fire knudepunkter og forsikrede, at et hypotetisk sort hul skulle føde med en hastighed på en ud af en million af sin normale energi, hvis det nogensinde har eksisteret. "Enten er det sorte hul i midten meget svagt, eller det findes ikke," skrev Gultekin i en e-mail.

Astronomer venter utålmodigt på lanceringen af ​​James Webb Space Telescope, det nye observatorium, der skal erstatte Hubble, som er planlagt til at blive lanceret i slutningen af ​​næste oktober for at undersøge de fire knudepunkter på samme tid og afgøre, om nogen af dem indeholder det manglende sorte hul.


Forskere kan have mistet oversigten over et supermassivt sort hul

Derude, et eller andet sted i kosmos, kunne der være et gennemgående sort hul, der ikke længere var i centrum af sin galakse. I en tidsskrift udgivet af American Astronomical Society har forskere bemærket, at det supermassive sorte hul, der menes at være centrum for Abell 2261, måske ikke længere er der. I stedet siger forskere, at det kunne have været fjernet fra sin egen galakse på grund af en proces kendt som tyngdekraftsbølgen.

Under en rekyl fusioneres i det væsentlige to sorte huller i nærheden af ​​hinanden og sender krusninger over rummet. I teorien kunne disse krusninger skubbe det sorte hul væk fra dets nuværende placering, ifølge en rapport fra Forbes. & ldquoDet & rsquos nok til at sparke det sorte hul helt ud af galaksen og være langt væk. Det ville sejle i det intergalaktiske rum, ”fortalte Kayhan Gultekin, avisens førende astronom, til bladet.

I stykket sørger udgivere af den indledende tidsskrift for at påpege, at de teknisk set stadig kan være på sin nuværende placering, det er bare, at de ikke er i stand til at finde det nu efter at have været i stand til at finde det ved tidligere lejligheder.

"Alligevel siger Gultekin, at det & rsquos for tidligt til at konkludere, at der ikke er et supermassivt sort hul i A2261-BCG," Forbes tilføjer. "Men hvis det ikke er der, ville det være den eneste så store galakse, der endnu er opdaget uden et så massivt sort hul i centrum. Selv vores egen Mælkevej & supermassive sorte hul er relativt hvilende, men den er der."

I et interview med Vice sidste sommer indrømmede Gultekin, at der stadig er meget at lære om sorte huller, og at løse dette mysterium kan komme langt i at besvare nogle af de største udestående spørgsmål.

& ldquo Hvad der mest ophidser mig er at lære om supermassive sorte huller gennem tyngdebølger, sagde rdquo Gultekin. & ldquo Vi skal med sikkerhed vide, at de smelter sammen, og dette ville være en måde at vise, at det sker. & rdquo

& ldquoDer er alle mulige ting, du kan lære med tyngdebølger om supermassive sorte huller, som en befolkning eller individuelle kilder, som du enten er virkelig hård eller umulig at lære med traditionel elektromagnetisk astronomi, & rdquo tilføjede han.


Mangler: Et sort hul med 10 milliarder solmasser

Astronomer søger efter det kosmiske tabte og fundne efter et af de største, dårligst sorte huller, man antager at eksistere. Indtil videre har de ikke fundet det.

I de sidste par årtier er det blevet en del af astronomisk historie, at i midten af ​​enhver galakse lurer et kæmpe sort hul, hvori svarende til millioner eller endda milliarder af soler er forsvundet. Jo større galaksen er, desto mere massiv er det sorte hul i midten.

Så det var en overraskelse for et årti siden, da Marc Postman fra Space Telescope Science Institute, der brugte Hubble Space Telescope til at undersøge klynger af galakser, fandt en superkæmpe galakse uden tegn på et sort hul i midten. Normalt ville galaksenes kerne have et knæk af ekstra lys i midten, en slags mousserende kappe, produceret af stjerner, der var samlet der ved tyngdekraften i et kæmpe sort hul.

Tværtimod, i det nøjagtige centrum af galakseens brede kerne, hvor en let bump i stjernelys burde have været, var der en svag dip. Desuden var hele kernen, en sky af stjerner omkring 20.000 lysår på tværs, ikke engang midt i galaksen.

”Åh, min Gud, dette er virkelig usædvanligt,” mindede Tod Lauer, en ekspert om galaktiske kerner ved National Optical Astronomy Observatory i Tucson, Arizona, og en forfatter på papiret, at have sagt, da Postmand viste ham fundet.

Det var i 2012. I årene siden har de to forskere og deres kolleger været på udkig efter røntgenbilleder eller radiobølger fra det manglende sorte hul.

Galaksen er den lyseste i en klynge kendt som Abell 2261. Det er omkring 2,7 milliarder lysår herfra i konstellationen Hercules på den nordlige himmel, ikke langt fra den fremtrædende stjerne Vega. Ved hjælp af standard tommelfingerregel skal det sorte hul, der mangler i midten af ​​2261-galaksen, være 10 milliarder solmasser eller mere. Til sammenligning er det sorte hul i midten af ​​Mælkevejsgalaksen kun omkring 4 millioner solmasser.

Så hvor har naturen stash svarende til 10 milliarder soler?

En mulighed er, at det sorte hul er der, men at det er blevet stille, midlertidigt er løbet tør for noget at spise. Men en anden provokerende mulighed, siger Lauer og hans kolleger, er, at det sorte hul helt blev kastet ud af galaksen.

At bevise sidstnævnte kunne give indsigt i nogle af de mest voldsomme og dynamiske processer i udviklingen af ​​galakser og kosmos, som astronomer har teoretiseret, men aldrig set - en dans af titankræfter og hvirvlende verdener, der kan kaste stjerner og planeter hen over tomrummet. .

”Det er et spændende mysterium, og vi er i sagen,” sagde Postman i en e-mail. Han tilføjede, at det kommende James Webb-rumteleskop ville have evnen til at kaste lys, så at sige, på sagen.

"Hvad sker der, når du skubber et supermassivt sort hul ud af en galakse?" Spurgte Lauer.

Lauer er en del af en uformel gruppe, der kalder sig Nukers. Gruppen kom først sammen under Sandra Faber fra University of California, Santa Cruz, i de tidlige dage af Hubble Space Telescope. I løbet af de sidste fire årtier har de forsøgt at belyse galaktiske kerners natur ved hjælp af Hubbles skarpe øje og andre nye faciliteter til at kigge ind i fjerne galaksers intime hjerter.

"Historien om A2261-BCG," sagde han med henvisning til galaksenes formelle navn i litteraturen, "er hvad der sker med de mest massive galakser i universet, de gigantiske elliptiske galakser, ved slutpunktet for galakseudviklingen."

Sorte huller er objekter så tætte, at ikke engang lys kan undslippe deres tyngdekoblinger. De er usynlige pr. Definition, men ruckus - røntgenstråler og radioskrig - forårsaget af materiale, der falder i dens greb, kan ses over hele universet. Opdagelsen i 1960'erne af kvasarer i centre for galakser fik først astronomer til at overveje, at supermassive sorte huller var ansvarlige for sådant fyrværkeri.

Ved århundredskiftet var astronomer kommet til den konklusion, at enhver galakse havde et supermassivt sort hul, millioner til milliarder gange mere massivt end solen, i sin bryst. Hvor de kom fra - uanset om de voksede fra mindre sorte huller, der var dannet ved sammenbruddet af stjerner eller dannet gennem en anden proces tidligt i universet - er ingen sikre. ”Der er en grop i hver fersken,” sagde Lauer.

Men hvordan påvirker disse enheder deres omgivelser?

I 1980 skrev tre astronomer, Mitchell Begelman, Martin Rees og Roger Blandford, om hvordan disse sorte huller ville ændre udviklingen i de galakser, de bor i. Da to galakser kolliderede og smeltede sammen - en særlig almindelig begivenhed i det tidligere univers - ville deres centrale sorte huller mødes og danne et binært system, hvor to sorte huller cirkulerer over hinanden.

Begelman og hans kolleger hævdede, at disse to massive sorte huller, der svingede rundt, ville interagere med havet af stjerner, de var nedsænket i. Hver af og til ville en af ​​disse stjerner have et tæt møde med de binære, og tyngdekræfterne ville skub stjernen ud af midten, og lad de sorte huller være endnu tættere bundet.

Over tid ville flere stjerner blive kastet væk fra centrum. Gradvist spredte stjernelys, der engang var koncentreret i centrum, sig ud i en bredere, diffus kerne med et lille knæk i midten, hvor sort-hul-binæret lavede sin parringsdans. Processen kaldes "skure".

”De var langt foran spillet,” sagde Lauer om de tre astronomer.

En skuret kerne var den slags situation, som Lauer og Postman troede, de var stødt på med Abell 2261. Men i stedet for en top i centrum af kernen var der en dukkert, som om det supermassive sorte hul og dets ledsagende stjerner simpelthen havde været taget væk.

Dette rejste den mere dramatiske mulighed for, at scenariet, som Begelman og hans kolleger havde forestillet sig, havde spillet: De to sorte huller var fusioneret til en gigantisk mundfuld af ingenting. Fusionen ville have været ledsaget af en katastrofal udbrud af tyngdekraftsbølger, krusninger i rumtiden, som Einstein forudsagde at eksistere i 1916 og endelig set af LIGO-instrumenterne et århundrede senere, i 2016.

Hvis denne burst var skæv, ville det have sendt det resulterende, supermassive sorte hul, der flyver gennem galaksen eller endda ud af det, noget astronomer aldrig havde observeret. Så det var yderst vigtigt at finde det vildfarende sorte hul.

Yderligere kontrol af A2261-BCG afslørede fire små knuder af lys inden i den diffuse kerne. Kunne en af ​​dem have det sorte hul?

Et hold ledet af Sarah Burke-Spolaor fra West Virginia University tog til himlen med Hubble og radioteleskopet Very Large Array i Socorro, New Mexico. Spektroskopiske målinger fra Hubble kunne fortælle, hvor hurtigt stjernerne i knuderne bevægede sig, og dermed om det var nødvendigt med en massiv genstand for at holde dem sammen.

To af knuderne, konkluderede de, var sandsynligvis små galakser med små indre bevægelser, der blev kannibaliseret af den store galakse. Målinger af den tredje knude havde så store fejlstænger, at den endnu ikke kunne styres ind eller ud som det sorte huls placering.

Den fjerde, meget kompakte knude nær kernens nederste kant var for svag for Hubble, rapporterede Burke-Spolaor. ”At observere denne knude ville have krævet en overdreven tid (hundreder af timer) til at observere med Hubble Space Telescope,” sagde hun i en e-mail, og derfor forbliver det også en kandidat til skjulestedet.

Galaxy kernen udsender også radiobølger, men de hjalp ikke søgningen, sagde Burke-Spolaor.

”Vi håbede oprindeligt, at radioemissionen ville være en slags bogstavelig rygepistol, der viser en aktiv stråle, der peger direkte tilbage til placering i sort hul,” sagde hun. Men radiorelikvien var mindst 50 millioner år gammel i henhold til dens spektrale egenskaber, hvilket betød, sagde hun, at det store sorte hul ville have haft rigelig tid til at bevæge sig et andet sted, siden strålen slukkede.

Næste stop var NASAs kredsløb Chandra X-ray Observatory. Kayhan Gultekin fra University of Michigan, en anden veteran Nuker, der ikke var på det oprindelige opdagelsesteam, sigtede teleskopet mod klyngekernen og de mistænkelige knuder. Ingen terninger. Det formodede sorte hul skulle fodres med en milliontedel af dets potentielle hastighed, hvis det overhovedet var der, sagde Gultekin.

”Enten et sort hul i midten er meget svagt, eller så er det ikke der,” skrev han i en e-mail. Det samme gælder tilfældet med et binært sorthulssystem, han sagde, at det ville være nødvendigt at spise meget lidt gas for at forblive skjult.

I mellemtiden har Imran Nasim fra University of Surrey, som ikke var en del af Postmans team, offentliggjort en detaljeret analyse af, hvordan fusionen af ​​to supermassive sorte huller kunne reformere galaksen til det, astronomerne har fundet.

”Simpelthen” sparker ”tyngdekraftsbølgen det supermassive sorte hul ud af galaksen,” forklarede Nasim i en e-mail. Efter at have mistet sit supermassive anker, spredes stjerneskyen omkring sort-hul-binæret og bliver mere diffust. Tætheden af ​​stjerner i denne region - den tætteste del af hele den gigantiske galakse - er kun en tiendedel af densiteten af ​​stjerner i vores eget kvarter ved Mælkevejen, hvilket resulterer i en nattehimmel, der ser ud til at være anæmisk sammenlignet med vores egen.

Alt dette er en anden grund til, at astronomer ivrigt afventer lanceringen af ​​James Webb Space Telescope, den længe ventede efterfølger til Hubble, som nu er planlagt til slutningen af ​​oktober. Teleskopet vil være i stand til at undersøge alle fire knuder på samme tid og afgøre, om nogen af ​​dem er et supermassivt sort hul.

”Her ser du vores store raffinement,” sagde Lauer. ”Hej, måske er det i knuderne! Hej, måske er det ikke! Bedre søgning i alt! ”


Mangler: Et sort hul med 10 milliarder solmasser

Astronomer søger efter det kosmiske tabte og fundne efter et af de største, dårligst sorte huller, man antager at eksistere. Indtil videre har de ikke fundet det.

I de sidste par årtier er det blevet en del af astronomisk historie, at i midten af ​​enhver galakse lurer et kæmpe sort hul, hvori svarende til millioner eller endda milliarder af soler er forsvundet. Jo større galaksen er, desto mere massiv er det sorte hul i midten.

Så det var en overraskelse for et årti siden, da Marc Postman fra Space Telescope Science Institute, der brugte Hubble Space Telescope til at undersøge klynger af galakser, fandt en superkæmpe galakse uden tegn på et sort hul i midten. Normalt ville galakseens kerne have et strejf af ekstra lys i centrum, en slags mousserende kappe, produceret af stjerner, der var samlet der ved tyngdekraften i et kæmpe sort hul.

Tværtimod, i det nøjagtige centrum af galakseens brede kerne, hvor en let bump i stjernelys burde have været, var der en svag dip. Desuden var hele kernen, en sky af stjerner omkring 20.000 lysår på tværs, ikke engang midt i galaksen.

”Åh, min Gud, dette er virkelig usædvanligt,” mindede Tod Lauer, en ekspert om galaktiske kerner ved National Optical Astronomy Observatory i Tucson, Arizona, og en forfatter på papiret, at have sagt, da Postmand viste ham fundet.

Det var i 2012. I årene siden har de to forskere og deres kolleger været på udkig efter røntgenbilleder eller radiobølger fra det manglende sorte hul.

Galaksen er den lyseste i en klynge kendt som Abell 2261. Det er omkring 2,7 milliarder lysår herfra i konstellationen Hercules på den nordlige himmel, ikke langt fra den fremtrædende stjerne Vega. Ved hjælp af standard tommelfingerregel skal det sorte hul, der mangler i midten af ​​2261-galaksen, være 10 milliarder solmasser eller mere. Til sammenligning er det sorte hul i midten af ​​Mælkevejsgalaksen kun omkring 4 millioner solmasser.

Så hvor har naturen stash svarende til 10 milliarder solsikker?

En mulighed er, at det sorte hul er der, men at det er blevet stille, midlertidigt er løbet tør for noget at spise. Men en anden provokerende mulighed, siger Lauer og hans kolleger, er, at det sorte hul helt blev kastet ud af galaksen.

At bevise sidstnævnte kan give indsigt i nogle af de mest voldelige og dynamiske processer i udviklingen af ​​galakser og kosmos, som astronomer har teoretiseret, men aldrig set - en dans af titankræfter og hvirvlende verdener, der kan kaste stjerner og planeter hen over tomrummet. .

”Det er et spændende mysterium, og vi er i sagen,” sagde Postman i en e-mail. Han tilføjede, at det kommende James Webb-rumteleskop ville have evnen til at kaste lys, så at sige, på sagen.

"Hvad sker der, når du skubber et supermassivt sort hul ud af en galakse?" Spurgte Lauer.

Lauer er en del af en uformel gruppe, der kalder sig Nukers. Gruppen kom først sammen under Sandra Faber fra University of California, Santa Cruz, i de tidlige dage af Hubble Space Telescope. I løbet af de sidste fire årtier har de forsøgt at belyse galaktiske kerners natur ved hjælp af Hubbles skarpe øje og andre nye faciliteter til at kigge ind i fjerne galaksers intime hjerter.

"Historien om A2261-BCG," sagde han, idet han henviste til galaksens formelle navn i litteraturen, "er hvad der sker med de mest massive galakser i universet, de gigantiske elliptiske galakser, ved slutpunktet for galakseudviklingen."

Sorte huller er objekter så tætte, at ikke engang lys kan undslippe deres tyngdekoblinger. De er usynlige pr. Definition, men ruckus - røntgenstråler og radioskrig - forårsaget af materiale, der falder i dens greb, kan ses over hele universet. Opdagelsen i 1960'erne af kvasarer i galaksernes centre fik først astronomer til at overveje, at supermassive sorte huller var ansvarlige for sådant fyrværkeri.

Ved århundredskiftet var astronomer kommet til den konklusion, at enhver galakse havde et supermassivt sort hul, millioner til milliarder gange mere massivt end solen, i sin bryst. Hvor de kom fra - hvad enten de voksede fra mindre sorte huller, der var dannet ved sammenbrud af stjerner eller dannet gennem en anden proces tidligt i universet - er ingen sikre på. ”Der er en grop i hver fersken,” sagde Lauer.

Men hvordan påvirker disse enheder deres omgivelser?

I 1980 skrev tre astronomer, Mitchell Begelman, Martin Rees og Roger Blandford, om hvordan disse sorte huller ville ændre udviklingen i de galakser, de bor i. Da to galakser kolliderede og smeltede sammen - en særlig almindelig begivenhed i det tidligere univers - ville deres sorte sorte huller mødes og danne et binært system, hvor to sorte huller cirkulerer hinanden.

Begelman og hans kolleger hævdede, at disse to massive sorte huller, der svingede rundt, ville interagere med havet af stjerner, de var nedsænket i. Hver af og til ville en af ​​disse stjerner have et tæt møde med de binære, og tyngdekraften ville skub stjernen ud af midten, og lad de sorte huller være endnu tættere bundet.

Over tid ville flere stjerner blive kastet væk fra centrum. Efterhånden ville stjernelys, der engang var koncentreret i centrum, sprede sig ud i en bredere, diffus kerne med et lille knæk i midten, hvor sort-hul-binæret lavede sin parringsdans. Processen kaldes "skure".

”De var langt foran spillet,” sagde Lauer om de tre astronomer.

En skuret kerne var den slags situation, som Lauer og Postman troede, de var stødt på med Abell 2261. Men i stedet for en top i centrum af kernen var der en dukkert, som om det supermassive sorte hul og dets ledsagende stjerner simpelthen havde været taget væk.

Dette rejste den mere dramatiske mulighed for, at scenariet, som Begelman og hans kolleger havde forestillet sig, havde spillet: De to sorte huller var fusioneret til en gigantisk mundfuld af ingenting. Fusionen ville have været ledsaget af en katastrofal udbrud af tyngdekraftsbølger, krusninger i rumtiden, som Einstein forudsagde at eksistere i 1916 og endelig set af LIGO-instrumenterne et århundrede senere, i 2016.

Hvis denne burst var skæv, ville det have sendt det resulterende supermassive sorte hul, der flyver gennem galaksen eller endda ud af det, noget astronomer aldrig havde observeret. Så det var yderst vigtigt at finde det vildfarende sorte hul.

Yderligere kontrol af A2261-BCG afslørede fire små knuder af lys inden i den diffuse kerne. Kunne en af ​​dem have det sorte hul?

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 most galaxies have a supermassive black hole at the center. I heard the same statement on television this morning. But why would any galaxy ikke 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 sort hul 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, sagde i en erklæring. "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 Natur.

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


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