The W i d e s p r e a d Influence of Supermassive Black HolesChristopher OnkenHerzberg Institute of Astrophysics

The Milky WaySgr A*Seen in X-rays, radio, IR3.5 Million MNear-IR (HKL) image (VLT)Radio (6 cm) image (VLA)X-ray image (Chandra)Optical image

S StarsOrbits followed for ~10 yearsKeckVLT

Hypervelocity Stars7 Galactic stars with radial velocities of 400+ km/sEjected from Galactic CenterNo proper motions yet, so velocities are lower limits

3-Body InteractionsOrbital energy is exchanged, ejecting one star at high speedRemaining stars left in tighter orbitsverre.com

Larger ConnectionsTight correlation between SBH mass and galaxy velocity dispersion (M-)Far beyond direct influence of SBHs gravityStellar velocity Black hole mass

Star Clusters Instead of SBHs?Some galaxies seem to have nuclear star clusters but may not have SBHsStar clusters also seem to be correlated with galaxy properties (mass, in this case)Black hole mass or Cluster mass Stellar velocity Galaxy mass

Feeding the MonsterActive Galactic Nuclei (AGNs)SBHs that are actively accreting matterAmong the most luminous objects in the universeHighly variable

Reverberation Mapping(an analogy)V838 Mon (HST imaging, 2002-2005)

Reverberation MappingTake advantage of variabilityChanges in ionizing radiation drive changes in emission linesMeasure V

Reverberation MappingThere is a time delay between variations in continuum and response of emission linesRepresents the travel time of the radiation from the SBH to the line-emitting gasTime delay of 1 day = distance of 1 light-day

AGN MassesFrom measurements of velocity (line width) and distance (time lag), the SBH mass can be estimatedDifferent emission lines have different widths and lags, but give consistent SBH masses

AGN M- RelationAGNs consistent with inactive galaxy relation, but larger errorbars and larger scatterAGNsInactive GalaxiesStellar velocity Black hole mass

Shortcut to AGN MassesApproximate line width measurement from a single spectrumEstimate radius of line-emitting gas from one measurement of the continuum luminosityAGN mass from a single spectrum!Single spectrumReverberation campaignAGN luminosity Time delay

Extending the M- RelationA handful of low-mass AGNs have measured velocity dispersionsAppear to follow the inactive galaxy relation, but may show flattening of slope at low Stellar velocity Black hole mass

AGN SurveysDeep surveys of small area can find faint AGNs but miss the rare objects.AGN and Galaxy Evolution Survey (AGES)MMTAGN Luminosity Black hole mass

AGN SurveysLarge area surveys produce tens of thousands of AGN masses, probing most of the history of the universe.AAT2dF Quasar Redshift (2QZ) SurveyAGN Luminosity Black hole mass

Putting the Pieces TogetherNeed to combine the information from different types of surveys to develop a complete picture of SBH growthStill need to identify a mechanism for feeding the SBH

Mergers?Many AGNs appear to be in mid-collisionNumber of AGNs has fallen over the last 10 billion years, roughly in line with declining merger rate of dark matter halosDark blue: 2 massive galaxiesGreen: 2 massive SBHsNumber of AGNs Universe AgeMerger rate Universe Age

Merger SimulationsModel gas, stars, & dark matterUse empirical relations to insert formation of new starsProduce too many big, blue galaxies--too many new stars formed because too much cold gas remains in the merged galaxy.

SBHs as the Solution?Add SBH to the modelAssume gas close to the SBH falls in (becomes an AGN)Small amount of AGN energy (~5%) heats gas in the galaxy

Simulation Predictions5% feedback efficiency chosen to match observed M- relationRemoval of gas by AGN cuts off star formation (no big blue galaxies)Stellar velocity Black hole mass Galaxy mass RedRedBlueBlueGalaxy color

Predicted AGN ActivityProvides a reasonable match to observed distribution of accretion ratesPredictions from a single merger simulationAGES

Is This Feedback Reasonable?Jets and other outflows are seen in AGNs

Too Strong?Simulated jets blast through the surrounding gas and dont input energy for very long

But If It DOES WorkAGN feedback could solve another problem: a lack of warm (106 K) gas in some galaxy clustersHot gas should be cooling, condensing onto the central galaxy, forming starsAGN energy input could explain why that doesnt occurX-rays: color, radio: contours

Another Merger+SBH Signature?Mergers could also explain flatter inner profile of massive galaxiesMergers of roughly equal mass galaxies with SBHs flatten the central stellar density profileDensity of stars Galaxy radius

Progress ReportThe last 10 years have seen significant developments in our understandingPlenty of interesting questions remainHow are the first SBHs formed?Are SBHs and star clusters related?Can mergers explain everything?Do galaxies really explode?

Future Steps: Observations:Milky WayPassage of time improves knowledge of S star orbitsProbing fainter stars with better angular resolution and deeper observationsMore follow-up for hypervelocity stars

Future Steps: Observations:Mass MeasurementsContinuing observations of low-mass AGNs, nuclear star clustersTMT will allow a large number of new SBH mass measurementsPredicted SBH Mass Distance from Sun

Future Steps: Observations:Reverberation MappingRecent campaign at MDM Observatory2-D reverberation mapping with KronosMDM 1.3mTime delay Time delay Gas velocity Gas velocity

Future Steps: Observations:AGN SurveysSDSS (~80,000 AGNs, ~8,000 deg2, g

Future Steps: SimulationsImproved computing power will allow higher spatial & temporal resolutionsInclude more detailed physicsColumbia at NASA-Ames:43 teraflops

-2GHz Pentium 4: few gigaflops-Xbox 360: ~100 gigaflops

SummarySBHs reveal themselves by their extreme influence on their immediate surroundingsBut recent evidence points to SBHs having important effects on larger size scales, impacting their host galaxies and even galaxy clusters