# Presentation: 673187

## Early Formation of Massive Black Holes: Causes and Consequences

- Santa Fe
- 11 July 2006; JPO

*Co-conspirators:*
- K. Mack
- M. Ricotti
- L. Ciotti
- M.-G. Park
- S.Y.Sazonov
- R.A.Sunyaev

## Reasons to think about early formation of massive black holes

- Existence of z > 6 luminous quasars (cf X. Fan) coupled to short Eddington time.
- Simulations indicating that the “first stars” were massive, rapidly rotating, metal poor -> collapse to MBH.
- ULXs seen in nearby galaxies -> 102 - 103 solar mass BHs; difficult to make in situ.
- Unresolved hard X-Ray background-10%- may indicated abundant low-flux sources.

## Plan

- A): Evolution of primordial black holes.
- B): Formation of Pop III intermediate mass black holes.
- C): Dramatic effects of radiative preheating (*ie* “feedback”) on BH evolution.
- D): Conjectured evolution of IMBHs.
- E): Summary and conclusions.

## A): Primordial Black Holes

- Proposed by many authors as artifacts of phase changes at, for example, quark-hadron transition. No consensus.
- Fractional mass is small fraction of DM.
- At origin, some fraction of horizon mass.
- “Compensated” at birth but soon un-compensated.
- Distribution Poisson like.

## Observational Limits on PBH 

- Observational Limits on PBH

## Afshordi, McDonanld and Spergel, 2003: for BH =  m

- Afshordi, McDonanld and Spergel, 2003: for BH =  m

## Accretion on primordial BH

- Simple theory say MBH ~ MBH (Rees, Carr)
- But, viscosity and compton drag can reduce that considerably (Ricotti, Ostriker: 2006)
- Each will accrete a DM halo, that can increase substantially MBH accretion (Mack, Ostriker &Ricotti: 2006).
- Clustering could lead to substantial BH merging (Dokuchaev et al: 2005)
- Neutrino processes could -> instable accretion at neutrino decoupling era.

## Early accretion of naked black holes in Eddington units

## Early accretion of dressed black holes in Eddington units

## Growth of DM halos around primodial BHs

## Slide 11

## Summary of PBH possible properties

- Final mass range of 102 - 103 solar masses not prohibited.
- Final (naked) abundance of 1%-10% of halo mass is permitted.
- Final mass, clothed with DM halos of 104, and up to 100% of original halo mass permitted.
- DM halos of PBHs would be largely stripped off in formation of halos, with PBHs becoming centrally concentrated. Merging?

## Consequences of PBHs

- Early accretion -> X-Rays -> increased production of H2 -> enhanced star/galaxy formation (Ricotti and Ostriker).
- Early heating a small effect.
- Early ionization a small effect on 
- Possible seeding of galactic MBHs.
- Halo population of PBHs -> ULXs ?
***Test via gravitational lensing predicitions?***

## B) Pop III IMBHs

- Expectations that first stars were
- Massive
- Rapidly rotating
- Very low metallicity
- Observational limits unchanged.
- Consequences Unchanged

- -> IMBHs formed

## Other effects of Pop III IMBHs

- Made in halos so difficult to avoid effects in X-Ray counts.
- Unless mass and angular momentum range severely restricted will produce Pop III element signatures.
- Mergers and seeding of galactic MBHs still more likely due to central locations.

***Again, a significant population is not excluded by current observational limits.***

## C): Radiative effects in accretion onto BHs Physics included and excluded in BH accretion calc’s

- Included:
- Dynamics: gravity and hydrodynamics.
- Atomic physics: cooling, electron-ion coupling *etc*.
- Radiative emission processes.
- Sometimes included:
- Accretion to the region of the central engine.
- Visous effects, MHD.
- Not included (usually):
- Shocks and shock heating.
***Radiative heating due to luminosity of interior material***.
**This omission is strange, given the enormous observed luminosities of accreting black holes !**

## The Physics (cartoon version)

- For high flow rates (Mdot **->**     Mdot,Edd), gas cools at large radius: Tgas **->**  104.3 K  accreting to central disc.
- Then, luminous output -> Ledd, high X-ray luminosity. Accreting gas and discs transparent to > 10keV X-rays.
- Inflowing gas heated to 107.3 K reversing the flow and causing relaxation oscillations.

- Allowance for radiative preheating can qualitatively change the solution.

## Observational determination of the mean AGN emitted spectrum from individual objects and the X-Ray-background. 

- Observational determination of the mean AGN emitted spectrum from individual objects and the X-Ray-background.

## Slide 19

## Compton Temp and Radiative Heating

- Independent of Optical/UV absorption and of direction (for isotropic initial emission).

## Nature of Radiative Heating (Dalgarno and McCray.....)

- Results depend on three quantities:
- Specific spectrum of radiating source, very roughly summarized by TX
- Metallicity of the gas Z/Zsolar.
- Parameter  = n/F.
- -------------------------------------------
- Well known results (for ~ solar metallicity)
- High values of  => Teq = 104 K (approximately)
- Low values of  => Teq = TX
- Intermediate values of  =>  unstable to either of above.

- Implies: in high luminosity state  is small and T -> Tcompt

## Published Work: Ciotti and O on accretion of MBH within elliptical galaxy

- Detailed spherically,  symmetric, time-dependent hydro of accreting MBH in E galaxy with
- Assumed accretion efficiency (0.001 -> 0.100).
*Assumed* Spectrum with TX = 107.5->109.0.
- No star formation.
- -------------------------------------------------------------------------------------
- Relaxation oscillations: cooling, infall, photo-heating, expanding hot bubble, cooling....
- Most time in non-accreting state (fduty ~ 0.006), galaxy looks like normal elliptical.
- In burst mode looks like a quasar.
- Final MBH masses reasonable.
- Elliptical gas luminosity reasonable.

## Luminosity Distribution as Observed

- “Cooling flow” model

## Slide 24

## Hydro Results

- Parallel to earlier work: Compton heating less important but compensated for by line heating.

**MBH**

- Mgas

## QSO luminosity in grouped bursts.

## 10 40 ≤  LX,gas ≤ 1042

- 10 40 ≤  LX,gas ≤ 1042

## Quasar bursts of ~ 1046erg/sec initially heat gas and increase luminosity, and then cause expansion and lower luminosity.

- Quasar bursts of ~ 1046erg/sec initially heat gas and increase luminosity, and then cause expansion and lower luminosity.

- Then, low accretion phase until onset of cooling. Then repeat.

- Zoom to higher time resolution.

## Repeat with allowance for starburst; feedback from both AGN and stars.

- Accurate stellar dynamical model (separate Hernquist profiles for DM and stars). Orbits evolved as mass profile changes.M87 type gal.
- Accurate stellar evolution (Renzini) for mass loss in PN, red-giant winds, SN etc. Gives mass, energy and metals input vs time.
- Star-formation via conventional formalism from cold collapsing regions. Gives additional (M,E,Z).
- AGN radiative feedback with detailed atomic phys.

## Red: MBH

- Green: Old stars
- Black: Gas emission

- Energy Input Rates from MBH, old stars and gas

- Note: “quiet” level now computed by high resolution code. Not “sub-Bondi”.

## t = 2 x 10^7 yrs; see Forman (2006)

- t = 2 x 10^7 yrs; see Forman (2006)

- There is detailed fine-structure on a 107 yr timescale

## Mass flow rates from recycled gas, to MBH and wind

## Stellar density distributions: starburst component in cusp

- New stars:
- Rate
- Cumulative

- Old stars:

## Primary Predictions

- High temperature, high density phases are probably too brief ( ≤ dynamical time) to be easily observed.
- Longer timescale (~ cooling time) low density high temperature central bubbles should be observable.
- Cooling shell phases are unstable to R-T and will appear as central,filamentary, cool gas.
- Stellar population of central regions of elliptical galaxies should be red (metal rich) and relatively young. If they are blue and old they came in via mergers.

## Summary of co-evolution of nulear regions and central MBHs

- Feedback *must* be important. Radiative feedback will cause oscillations, out-gassing and transition to high T  state for gas in ellipticals.
- Re-cycled gas from stellar mass loss (40%) *must* produce nuclear starbursts.
- Star-formation, SNII and AGN feedback use up and drive gas out of the nucleus. Comparably important. Duty cycle <~ 1%.
- Both feedback processes limit the growth of the central MBH (Magorrian relation) and reduce the gas fraction to ~ 1%.
- Detailed spectral properties provide a test for specific radiative heating proposal.
- ----------------------------------------
- Mechanical feedback from AGN (not included yet) is probably equally important.

## D) Possible Demography of IMBHs

- They may exist with abundance 1% -10% of DM abundance by z = 10, either formed primordially or via Pop III. Mass 102 - 103 solar masses.
- Merging at the centers of halos they seed galaxy formation and MBH growth.
- Remnant IMBHs in the halos passing through disc molecular clouds -> ULXs.

## Summary

- Early formation of IMBHs a possibility to be taken seriously.
- Should be apparent in very faint X-ray counts.
- Could be detectable in gravitational lensing experiments.
- Dynamical effects in low mass galaxies may be significant.