The cosmic spin of SMBHs from radio observations

The cosmic spin of SMBHs from radio observations

Alejo Martínez Sansigre (ICG-Portsmouth) &

Steve Rawlings (Oxford)

Leiden, Feb 2011

Assumptions:

Jet power

Bolometric Luminosity

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

Leiden, Feb 2011

Assumptions:

Accretion rate

Jet power

Bolometric Luminosity

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

Leiden, Feb 2011

Assumptions:

Accretion rate

Radiative efficiency

Jet efficiency

Jet power

Bolometric Luminosity

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

Radio loudness of quasars?Radio loudness of quasars?

Leiden, Feb 2011

Radio-loudness of quasars

Data from Cirasuolo et al. (2003) Martinez-Sansigre & Rawlings (2011)

Accretion

Spin

Can we explain the radio luminosity function?

Can we explain the radio luminosity function?

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

BH mass function

Distribution of Eddington ratios (flat prior due to ignorance)

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

Fanidakis et al. (2010)

Compare to cosmological simulations

Martinez-Sansigre & Rawlings (2011)

Leiden, Feb 2011

Spin history

Low-zLow accn rateHigh spin peak

High-zHigh accn rateAll 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.

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

Single-gaussian distribution

Parametric forms for spin distribution

Leiden, Feb 2011

Double gaussiandistribution

Parametric forms for spin distribution

Leiden, Feb 2011

Bayesian evidence chooses the double gaussian

Parametric forms for spin distribution

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

Martinez-Sansigre & Rawlings (2011)

Leiden, Feb 2011

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

Spin-down: chaotic accretion

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