supermassive black holes

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Supermassive black holes. Christopher | Vlad | David | Nino. What is a black hole?. M assive object from which nothing can escape. Even light is attracted by gravity. Schwarzschild radius is the distance for a given mass where the escape velocity is the speed of light - PowerPoint PPT Presentation

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Supermassive black holes

Christopher | Vlad | David | NinoSupermassive black holesWhat is a black hole?Massive object from which nothing can escape.Even light is attracted by gravity.

Schwarzschild radius is the distance for a given mass where the escape velocity is the speed of lightA black hole has its entire mass enclosed in its own Schwarzschild radius.

How can we see black holes?No light escapes

Hawking RadiationNot observedAccretion disksObserved radiation

An artist's rendering of the Cygnus X-1 system. (from http://spaceart1.ning.com/photo/cygnus-x1) How do black holes form?Type II Supernova of a massive starCollapse of a neutron starNothing can stop itDont know what happens after

How do we weigh black holes?Mass can be inferred from orbital velocities of stars around it

The position of a star around the Supermassive Black Hole Sgr A* (from http://www.sciencemag.org) Properties of SUPERMASSIVE BLACK HOLESMasses range from millions to billions of solar massesLocated at center of most galaxiesEspecially flat, normal galaxies with bulge component Active SMBHs emit energetic jetsX-Rays and Gamma raysPerpendicular to accretion disks (possibly) along rotation axisLimit star growth by clearing gas along their axis

PROPERTIES OF SUPERMASSIVE BLACK HOLESStrong X-Ray emittersAccount for half of radiation after Big BangSMBH rotation drags spacetime in direction of rotation (Roy Kerr) frame draggingLocal phenomenonCan delay matter falling in due to sideways motionWeaker tidal forces than BH of regular size/massSince larger surface area of event horizon

Eating or fasting? Different faces of SMBHsSMBHs may regulate galactic growth along with appetite for matterSaggitarius A* - dormant SMBH in Milky Way nearly emptyVery little matter in immediate surroundingsLarge amounts of matter in surroundingsQuasar galaxies, Seyfert galaxies, Blazar galaxiesQuasar galaxyMost variably-luminous objects in universe (> 1012 Lsolar )Powerful jets powered by accretion disk around SMBHCentral SMBH 10,000x times regular black hole3C 273 first quasar discovered early 1960sQuasar activity peaked in early universe

Eating or fasting? Different faces of SMBHSeyfert galaxyProduce spectral emissions from highly ionized gasLarge amounts of IR, UV, X-Ray rad.Jet velocity 500-4,000 km/sCentral SMBH mass 108 MsolarBlazar galaxyEmission jets pointed towards EarthRadiation spectrum radio to Gamma raysVariable / Unstable output At 9 billion ly can be detected with Earthly instrumentsSMBHs key for early universeFacilitate formation of galaxies

Why do we think they are black holes?Sphere of influencerh ~ GMBH/ 2 ~ 11.2(MBH/108MS)/( /200kms-1)2 pc

Keplerian velocity distribution near galactic centerMust be highly concentrated mass at center

Proper motion of stars in Milky way indicate singularity at galactic centerCalled Sagittarius A*

Higher concentration than normal of 22Ghz water masers imply an AGN in NGC 4258

10Other MethodsHubble Space Telescope high resolution imagesShows clearly gas or stellar dynamics at galactic nucleusOnly works if gravity is most influential force on gas

Reverberation or Echo mappingOnly for type 1 active galactic nuclei Can probe regions up to 1000 times the Schwarzschild Radius

How does the SMBH relate to the surrounding galaxy?MBH vs. blue luminosity of the bulge (whole galaxy if elliptical) Correlates to blue luminosity from the bulge Generally scattered correlation; less so for ellipticalsLatest relation given bylog(MBH) = (8.370.11) (0.4190.085)(B0T + 20.0)MBH vs. velocity dispersion, () relates to LB, which relates to MBHTighter correlation than mass vs. bulge light; maybe more fundamentalLatest relation(MBH/108MSun) = (1.660.24)(/200km s-1)4.680.43

Other Correlations with host galaxyMBH vs. bulge light concentration (C)Tight correlation; little scatteringPractical relation; needs only one measurementDepends on parametric characterization of light profile

MBH vs. Dark Matter Halo correlates tightly with large scale circular velocity distributionLess massive halos are less efficient at forming SMBH(MBH/108MSun) ~ 0.10(MDM/1012MSun)1.65How do Supermassive Black holes form?What came first?Supermassive Black Holes or galaxies ?

Proponents of galalxies first:Observed galaxies without SMBH (ex. NGC 2613)Bulge component in flattened normal galaxiesnecessary

Proponents of SMBH first:Uniform density shown by microwave background radiationNot sufficiently clumped to form SMBH from regular matter aloneSuggest SMBH from dark matterQuasar activity peaked 10 billion years agoPrimordial seed theoryCentral black hole can double its massevery 40 million years

Growth of Supermassive Black HolesStellar and intermediate mass black holes gravitate towards galactic centerCoalesce there to SMBH (ex. NGC 253)

Major growth from galactic collisions and mergersExample collision of Milky Way with Andromeda in 5 billion yearsNew Black Hole: 100 million MsolarBoth from SMBH mergers and influx of material

will supermassive black holes die?

Will stop growingEstimated terminal mass 1-10 billion Msolar

Hawking radiation30 Msolar black hole 1061 times current age of universe100 billion Msolar black hole1098 years

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