# Presentation: 181166

## Mitch Begelman
JILA, University of Colorado

**Mitch Begelman**
**JILA, University of Colorado**

**FORMATION AND GROWTH OF SUPERMASSIVE BLACK HOLE SEEDS**

## COLLABORATORS

**COLLABORATORS**

**Marta Volonteri (Cambridge/Michigan)**
**Martin Rees (Cambridge)**

## NEED TO EXPLAIN:

**QSOs with M>10****9****M******** ****at z>6 **
**Age of Universe < 20 t****Salpeter **
****
** ****Eddington-limited accretion would have to:**
**Start early**
**Be nearly continuous**
**Start with M****BH ****>10 – 100 M******** **

## ORIGIN OF SEEDS: 2 APPROACHES 

**Pop III remnants **
**~100 (?) M******** BHs form at z~20**
**Sink to center of merged haloes**
**Accrete gas/merge with other seeds**
** ****Direct collapse**
**Initial BH mass = ?**
**How is fragmentation avoided?**
**Growth mainly by accretion of gas**
**Problems faced by both:**
**angular momentum transport**
**Can            be exceeded?**

## WHAT ANGULAR MOMENTUM PROBLEM?

WHOSE                       LIMIT?

                EDDINGTON
SEEDS FROM DIRECT COLLAPSE?

**WHAT ANGULAR MOMENTUM PROBLEM?**
**WHOSE ****                     **** LIMIT?**
**                **
**                ****EDDINGTON**
**SEEDS FROM DIRECT COLLAPSE?**

## DM

- Halo with slight rotation

**“****BARS**
**WITHIN**
**BARS”**

*(Shlosman, Frank & Begelman 89)*

- Dynamical loss of angular momentum through nested global gravitational instabilities

## Slide 7

## Global ang. mom. transport (“Bars within Bars”) : 

**                                                          ****M********  ****yr****-1**
**                                                       **
**Mass distribution isothermal,  **
**Accumulated mass dominates for**
** ****BWB fails at                ? **

## Local ang. mom. transport (           ) : 

**                                                          ****M********  ****yr****-1**
**                                                       **
**            ****viscosity parameter  **
**If *****T***** const. or incr. inwards,                                  likely to reach center                 **

**FRAGMENTATION UNLIKELY TO STOP INFALL**** **

## TEMPERATURE DEPENDENCE 

**Metal-free, H****2****-dissociated gas falls in**
**(Metal rich and/or H****2 ****fragments?)**
**Inflow rate, mass accumulation ****HIGH**
** **
**Infall requires H****2 ****or pollution by Pop III**
**Inflow rate, mass accumulation ****LOW**

## WHOSE                 LIMIT?           

**WHOSE                 LIMIT?           **

**SUPPOSE A SEED BH SETTLES IN THE MIDDLE OF THE ACCUMULATED GAS**

**Max. BH accretion rate is            **_**for the mass of the ENVELOPE**_

**ACCUMULATED GAS**

**BH**

## RAPID GROWTH OF A PREGALACTIC BH

**“****QUASISTAR”**

**Pregalactic halo **

**Seed BH can grow from ~10 to >10****5 ****M****Sol**** at**
**                                                      ***(Begelman, Volonteri & Rees 06)*** **

**ACCUMULATED GAS**

**+ FORMATION OF THE SEED?**

## WHAT IS A “QUASISTAR”? 

**Self-gravitating structure laid down by infall**
**Entropy small near center, increases with r **
**Very different from the supermassive stars postulated by Hoyle and Fowler**** **

**YOU’VE GOT TO BE KIDDING**

## QUASISTAR PROPERTIES 

**Mass m***** ****(M********) increases with time **
**Core with  **
**Envelope**
**Entropy increases outward – convectively stable**
**Outer radius                           constant**
**Core radius                  shrinks**
**Core mass ~ 10 M******** ****constant**
**When                        core temp.                                               **
**               ****rapid cooling by thermal neutrinos**

## +

**CORE COLLAPSE AND FORMATION OF ~10-20 M******** SEED BH**

**SUBSEQUENT ACCRETION AT EDDINGTON LIMIT FOR QUASISTAR MASS **

**+**

## CONCLUSIONS

**Angular momentum transport is fast if global gravitational instabilities set in (“Bars within Bars”)**** **
**BH can grow at Eddington limit for the surrounding envelope, which can be                             ****cvcvcvc****for the BH**
**Seed can form in situ from the infalling envelope itself (aided by ****ν**** ****cooling) or can be captured Pop III remnant **