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The cosmic spin of SMBHs from radio observations. Alejo Martínez Sansigre (ICG-Portsmouth) & Steve Rawlings (Oxford). Assumptions:. Bolometric Luminosity. Jet power. e.g. Mckinney (2005), Hawley & Krolik (2006), Nemmen et al. (2007), Benson & Babul (2009), Tchekhovskoy et al. (2010).

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The cosmic spin of smbhs from radio observations

The cosmic spin of SMBHs from radio observations

Alejo Martínez Sansigre (ICG-Portsmouth)

&

Steve Rawlings (Oxford)


Assumptions:

Bolometric Luminosity

Jet power

e.g. Mckinney (2005), Hawley & Krolik (2006), Nemmen et al. (2007), Benson & Babul (2009), Tchekhovskoy et al. (2010).

Leiden, Feb 2011


Assumptions:

Bolometric Luminosity

Accretion rate

Jet power

e.g. Mckinney (2005), Hawley & Krolik (2006), Nemmen et al. (2007), Benson & Babul (2009), Tchekhovskoy et al. (2010).

Leiden, Feb 2011


Assumptions:

Radiative efficiency

Bolometric Luminosity

Accretion rate

Jet power

Jet efficiency

e.g. Mckinney (2005), Hawley & Krolik (2006), Nemmen et al. (2007), Benson & Babul (2009), Tchekhovskoy et al. (2010).

Leiden, Feb 2011



Radio-loudness of quasars

Spin

Accretion

Data from Cirasuolo et al. (2003)

Martinez-Sansigre & Rawlings (2011)

Leiden, Feb 2011



The radio LF

P. Best private communication

Leiden, Feb 2011


Modelling the HEGs with QSOs

Can convert Lx to accretion rate

Silverman et al. (2008)

Leiden, Feb 2011


Modelling the LEGs with ADAFs

BH mass function

Graham et al. (2007)

Leiden, Feb 2011


Modelling the LEGs with ADAFs

Distribution of Eddington ratios (flat prior due to ignorance)

BH mass function

Graham et al. (2007)

Leiden, Feb 2011


Fit to the RLF

Leiden, Feb 2011


Best-fitting distributions

Leiden, Feb 2011


Prediction z=1 RLF

Radio LFs from Willott et al. (2001) and Smolcic et al. (2009)

Martinez-Sansigre & Rawlings (2011)

Leiden, Feb 2011


Compare to cosmological simulations

Fanidakis et al. (2010)

Martinez-Sansigre & Rawlings (2011)

Leiden, Feb 2011


Spin history

Low-z

Low accn rate

High spin peak

High-z

High accn rate

All spin low

Leiden, Feb 2011


Chaotic accretion + mergers

Chaotic accretion leads to low spins

Martinez-Sansigre & Rawlings (2011)

Leiden, Feb 2011


Chaotic accretion + mergers

Chaotic accretion leads to low spins

Recent major mergers lead to high spins

Martinez-Sansigre & Rawlings (2011)

Leiden, Feb 2011


Interpretation

  • Physically, at z=0 the radio LF is dominated by low-accretion rate objects with high spins

  • A small fraction, however, originates in high-accretion rate objects with low spin

  • At higher redshifts, the density of high-accretion low-spin objects increases, an they eventually dominate the radio LF.

  • This means that the mean spin is higher at low redshift, and lower at high redshift.

  • This is consistent with the picture of chaotic accretion spinning SMBHs down, and major mergers spinning them up.

Leiden, Feb 2011


Thank you!

For more info: Martínez-Sansigre & Rawlings, MNRAS (2011), ArXiv: 1102.2228

Leiden, Feb 2011


Parametric forms for spin distribution

Power-law distribution

Leiden, Feb 2011


Parametric forms for spin distribution

Single-gaussian distribution

Leiden, Feb 2011


Parametric forms for spin distribution

Double gaussian

distribution

Leiden, Feb 2011


Parametric forms for spin distribution

Bayesian evidence chooses the double gaussian

Leiden, Feb 2011


Jet efficiency

e.g. Mckinney (2005), Hawley & Krolik (2006), Nemmen et al. (2007), Benson & Babul (2009), Tchekhovskoy et al. (2010).

Leiden, Feb 2011


Comparison to entire RLF

Leiden, Feb 2011

Martinez-Sansigre & Rawlings (2011)


Spin-down: chaotic accretion

Infalling gas from the galaxy is NOT expected to all be in the same angular momentum plane

Co- or counter-alignment will occur depending on relative J and orientation

Overall effect is for chaotic accretion to spin down a rapidly rotating SMBH, typically to a~0.1

King et al. (2006,2008)

Leiden, Feb 2011


Spin history

Martinez-Sansigre & Rawlings (2011)

Leiden, Feb 2011


Spin-up mechanism: BH mergers

Major mergers of low spin BHs leads to high spin coalesced BHs.

BH merger formula from Rezzolla et al. (2008)

Leiden, Feb 2011


Spin-up mechanism: BH mergers

Assume a Poisson distribution with a mean of 0.7 major mergers (following Robaina et al. 2010)

BH merger formula from Rezzolla et al. (2008)

Leiden, Feb 2011


ADAF component

Leiden, Feb 2011


QSO component

Leiden, Feb 2011


Radiative efficiency

Novikov & Thorne (1973), Mckinney & Gammie (2004), Beckwith et al. (2008,) Noble et al. (2009), Penna et al. (2010)

Leiden, Feb 2011


Producing jets

Figure from:

J. Krolik’s webpage

Leiden, Feb 2011


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