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The W i d e s p r e a d Influence of Supermassive Black Holes Christopher Onken Herzberg Institute of Astrophysics Christopher Onken Herzberg Institute.

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Presentation on theme: "The W i d e s p r e a d Influence of Supermassive Black Holes Christopher Onken Herzberg Institute of Astrophysics Christopher Onken Herzberg Institute."— Presentation transcript:

1 The W i d e s p r e a d Influence of Supermassive Black Holes Christopher Onken Herzberg Institute of Astrophysics Christopher Onken Herzberg Institute of Astrophysics

2 The Milky Way  Sgr A*  Seen in X-rays, radio, IR  3.5 Million M   Sgr A*  Seen in X-rays, radio, IR  3.5 Million M  Near-IR (HKL) image (VLT) Radio (6 cm) image (VLA) X-ray image (Chandra) Optical image

3 “S” Stars  Orbits followed for ~10 years Keck VLT

4 Hypervelocity Stars  7 Galactic stars with radial velocities of 400+ km/s  Ejected from Galactic Center  No proper motions yet, so velocities are lower limits  7 Galactic stars with radial velocities of 400+ km/s  Ejected from Galactic Center  No proper motions yet, so velocities are lower limits

5 3-Body Interactions  Orbital energy is exchanged, ejecting one star at high speed  Remaining stars left in tighter orbit sverre.com

6 Larger Connections  Tight correlation between SBH mass and galaxy velocity dispersion (M-  )  Far beyond direct influence of SBH’s gravity  Tight correlation between SBH mass and galaxy velocity dispersion (M-  )  Far beyond direct influence of SBH’s gravity Stellar velocity  Black hole mass 

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

8 Feeding the Monster  Active Galactic Nuclei (AGNs)  SBHs that are actively accreting matter  Among the most luminous objects in the universe  Highly variable  Active Galactic Nuclei (AGNs)  SBHs that are actively accreting matter  Among the most luminous objects in the universe  Highly variable

9 Reverberation Mapping (an analogy) V838 Mon (HST imaging, )

10 Reverberation Mapping  Take advantage of variability  Changes in ionizing radiation drive changes in emission lines  Measure V

11 Reverberation Mapping  There is a time delay between variations in continuum and response of emission lines  Represents the travel time of the radiation from the SBH to the line-emitting gas  Time delay of 1 day = distance of 1 light-day  There is a time delay between variations in continuum and response of emission lines  Represents the travel time of the radiation from the SBH to the line-emitting gas  Time delay of 1 day = distance of 1 light-day

12 AGN Masses  From measurements of velocity (line width) and distance (time lag), the SBH mass can be estimated  Different emission lines have different widths and lags, but give consistent SBH masses  From measurements of velocity (line width) and distance (time lag), the SBH mass can be estimated  Different emission lines have different widths and lags, but give consistent SBH masses

13 AGN M-  Relation  AGNs consistent with inactive galaxy relation, but larger errorbars and larger scatter AGNs Inactive Galaxies Stellar velocity  Black hole mass 

14 Shortcut to AGN Masses  Approximate line width measurement from a single spectrum  Estimate radius of line-emitting gas from one measurement of the continuum luminosity  AGN mass from a single spectrum!  Approximate line width measurement from a single spectrum  Estimate radius of line-emitting gas from one measurement of the continuum luminosity  AGN mass from a single spectrum! Single spectrum Reverberation campaign AGN luminosity  Time delay 

15 Extending the M-  Relation  A handful of low-mass AGNs have measured velocity dispersions  Appear to follow the inactive galaxy relation, but may show flattening of slope at low  Stellar velocity  Black hole mass 

16 AGN Surveys Deep surveys of small area can find faint AGNs but miss the rare objects. AGN and Galaxy Evolution Survey (AGES) MMT AGN Luminosity  Black hole mass 

17 AGN Surveys Large area surveys produce tens of thousands of AGN masses, probing most of the history of the universe. AAT 2dF Quasar Redshift (2QZ) Survey AGN Luminosity  Black hole mass 

18 Putting the Pieces Together  Need to combine the information from different types of surveys to develop a complete picture of SBH growth  Still need to identify a mechanism for feeding the SBH  Need to combine the information from different types of surveys to develop a complete picture of SBH growth  Still need to identify a mechanism for feeding the SBH

19 Mergers?  Many AGNs appear to be in mid-collision  Number of AGNs has fallen over the last 10 billion years, roughly in line with declining merger rate of dark matter halos  Many AGNs appear to be in mid-collision  Number of AGNs has fallen over the last 10 billion years, roughly in line with declining merger rate of dark matter halos Dark blue: 2 massive galaxies Green: 2 massive SBHs Number of AGNs   Universe Age Merger rate  Universe Age 

20 Merger Simulations  Model gas, stars, & dark matter  Use empirical relations to insert formation of new stars  Model gas, stars, & dark matter  Use empirical relations to insert formation of new stars Produce too many big, blue galaxies--too many new stars formed because too much cold gas remains in the merged galaxy.

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

22 Simulation Predictions  5% feedback efficiency chosen to match observed M-  relation  Removal of gas by AGN cuts off star formation (no big blue galaxies) Stellar velocity  Black hole mass  Galaxy mass  Red Blue Galaxy color

23 Predicted AGN Activity  Provides a reasonable match to observed distribution of accretion rates Predictions from a single merger simulation AGES

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

25 Too Strong?  Simulated jets blast through the surrounding gas and don’t input energy for very long

26 But If It DOES Work…  AGN feedback could solve another problem: a lack of “warm” (10 6 K) gas in some galaxy clusters  Hot gas should be cooling, condensing onto the central galaxy, forming stars  AGN energy input could explain why that doesn’t occur  AGN feedback could solve another problem: a lack of “warm” (10 6 K) gas in some galaxy clusters  Hot gas should be cooling, condensing onto the central galaxy, forming stars  AGN energy input could explain why that doesn’t occur X-rays: color, radio: contours

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

28 Progress Report  The last 10 years have seen significant developments in our understanding  Plenty of interesting questions remain  How are the first SBHs formed?  Are SBHs and star clusters related?  Can mergers explain everything?  Do galaxies really “explode”?  The last 10 years have seen significant developments in our understanding  Plenty of interesting questions remain  How are the first SBHs formed?  Are SBHs and star clusters related?  Can mergers explain everything?  Do galaxies really “explode”?

29 Future Steps: Observations: Milky Way  Passage of time improves knowledge of “S” star orbits  Probing fainter stars with better angular resolution and deeper observations  More follow-up for hypervelocity stars

30 Future Steps: Observations: Mass Measurements  Continuing observations of low-mass AGNs, nuclear star clusters  TMT will allow a large number of new SBH mass measurements  Continuing observations of low-mass AGNs, nuclear star clusters  TMT will allow a large number of new SBH mass measurements Predicted SBH Mass  Distance from Sun 

31 Future Steps: Observations: Reverberation Mapping  Recent campaign at MDM Observatory  2-D reverberation mapping with Kronos MDM 1.3m Time delay  Gas velocity 

32 Future Steps: Observations: AGN Surveys  SDSS (~80,000 AGNs, ~8,000 deg 2, g<20.2)  2SLAQ (~10,000 AGNs, g<21.8, ~400 deg 2 ) with 2dF instrument on AAT  SDSS (~80,000 AGNs, ~8,000 deg 2, g<20.2)  2SLAQ (~10,000 AGNs, g<21.8, ~400 deg 2 ) with 2dF instrument on AAT SDSS Telescopes 2dF

33 Future Steps: Simulations  Improved computing power will allow higher spatial & temporal resolutions  Include more detailed physics  Improved computing power will allow higher spatial & temporal resolutions  Include more detailed physics “Columbia” at NASA-Ames: 43 teraflops -2GHz Pentium 4: few gigaflops -Xbox 360: ~100 gigaflops

34 Summary  SBHs reveal themselves by their extreme influence on their immediate surroundings  But recent evidence points to SBHs having important effects on larger size scales, impacting their host galaxies and even galaxy clusters  SBHs reveal themselves by their extreme influence on their immediate surroundings  But recent evidence points to SBHs having important effects on larger size scales, impacting their host galaxies and even galaxy clusters

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