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The cosmic spin of SMBHs from radio observations

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The cosmic spin of SMBHs from radio observations

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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).

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?

Radio-loudness of quasars

Spin

Accretion

Data from Cirasuolo et al. (2003)

Martinez-Sansigre & Rawlings (2011)

Leiden, Feb 2011

Can we explain the radio luminosity function?

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)

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Modelling the LEGs with ADAFs

BH mass function

Graham et al. (2007)

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Modelling the LEGs with ADAFs

Distribution of Eddington ratios (flat prior due to ignorance)

BH mass function

Graham et al. (2007)

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Fit to the RLF

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Best-fitting distributions

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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

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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

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Parametric forms for spin distribution

Single-gaussian distribution

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Parametric forms for spin distribution

Double gaussian

distribution

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Parametric forms for spin distribution

Bayesian evidence chooses the double gaussian

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Jet efficiency

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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