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)
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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). - PowerPoint PPT Presentation
Transcript of The cosmic spin of SMBHs from radio observations
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?
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The radio LF
P. Best private communication
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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
BH mass function
Distribution of Eddington ratios (flat prior due to ignorance)
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)
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Fanidakis et al. (2010)
Compare to cosmological simulations
Martinez-Sansigre & Rawlings (2011)
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Spin history
Low-zLow accn rateHigh spin peak
High-zHigh accn rateAll spin low
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Chaotic accretion + mergers
Chaotic accretion leads to low spins
Martinez-Sansigre & Rawlings (2011)
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Chaotic accretion + mergers
Chaotic accretion leads to low spins
Recent major mergers lead to high spins
Martinez-Sansigre & Rawlings (2011)
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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
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Parametric forms for spin distribution
Power-law distribution
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Single-gaussian distribution
Parametric forms for spin distribution
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Double gaussiandistribution
Parametric forms for spin distribution
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Bayesian evidence chooses the double gaussian
Parametric forms for spin distribution
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Jet efficiency
e.g. Mckinney (2005), Hawley & Krolik (2006), Nemmen et al. (2007), Benson & Babul (2009), Tchekhovskoy et al. (2010).
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Comparison to entire RLF
Martinez-Sansigre & Rawlings (2011)
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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)
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Spin history
Martinez-Sansigre & Rawlings (2011)
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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)
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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)
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ADAF component
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QSO component
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Radiative efficiency
Novikov & Thorne (1973), Mckinney & Gammie (2004), Beckwith et al. (2008,) Noble et al. (2009), Penna et al. (2010)
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Producing jets
Figure from:J. Krolik’s webpage
