NEW CONSTRAINTS ON
THE BLACK HOLE SPIN IN
RADIO LOUD QUASARS

Andreas Schulze (NAOJ, EACOA Fellow))
Chris Done, Youjun Lu, Fupeng Zhang, Yoshiyuki Inoue
East Asian Young Astronomers Meeting, EAYAM 2017
Ishigaki, Japan, 13.-17.11.2017

Active Galactic Nuclei (AGN) Zoo▪
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QSO/quasar
Seyfert galaxyBlazar, FSRQ, BL Lac
Radio galaxies
FR I / FR IIHERG / LERG
LINERS

Alexander & Hickox (2012)

AGN Unification: Radio properties?
What causes AGN to be radioloud (RL) or radio quiet (RQ) /have relativistic jets?
◆ Black hole mass MBH◆ Eddington ratio λ=Lbol / Ledd
◆ BH spin

Urry & Padovani (1995)

RL/RQ dichotomy
R=f6cm /f2500 > 10~ 10% of AGN are radio loud➢ RL/RQ dichotomy

White et al. (2007)

Balokovic et al. (2012)

Parameter dependence of RL fraction➢ Radio loud fraction changes with BH mass and Eddington ratio(e.g. Laor 2000, Kratzer et al. 2015)➢ RL fraction highest at high BH mass and low Eddington ratio

Radio loudness governed by MBH and λ?
➢ BH mass and Eddington may play a role but are not sufficient toproduce RL quasar➢ Even at high MBH, low λ majority of population is RQ➢ What else?
⇒ BH spin

The spin paradigm➢ Energy can be extracted from a spinning black hole e.g. via theBlandford-Znajek process (Blandford & Znajek 1977)➢ Magnetic field extracts spin energy⇒ Collimation of radio jets=> radio loud AGN

NASA/JPL-Caltech

Radiative efficiency as tracer of BH spin
➢ BH spin sets inner edge of accretion
disk (ISCO)➢ sets radiative efficiency ε⇒ For thin-disk accretion ε~0.05-0.42(for non-spinning – max.-spin BH)⇒ Focus on luminous, radiatively
efficient type-1 QSOs
(thin accretion disks)

Madau et al. (2014)➢ Lbol=ε ṀAD c2

SED for RL and RQ QSOs

⇒ Use [OIII] as average tracer of Lbol
via probing the peak of SED in UVregime

a = 0.0
a = 0.9-10.0log nFn [erg s 1cm 2]➢ At fixed optical luminosity, difference
in SED in EUV regime expected asfunction of BH spin
➢ EUV cannot be directly probed-10.5-11.0-11.5-12.0[OIII] (5007A)-12.5
14L5100

L[OIII]

15161718

log rest frequency[Hz]19Sample of RL and RQ quasars➢ Focus on luminous type-1 QSOs from SDSS
Sample:➢ SDSS DR7 QSO catalog, uniform target within FIRST footprint➢ i<18.9 (to match optical depth and FIRST depth for RL/RQ classification)➢ 0.3<z<0.84➢ measured BH mass from Hbeta and measured [OIII] luminosity➢ Accretion rates from Wu et al. (2013)➢ RL: 757
RQ: 7187⇒ Control RL and RQ sample for BH mass, Luminosity, ṀAD(1) match on grid (2) match individual objects⇒ Do RL and RQ have same average radiative efficiency?
Lbol=ε ṀAD c2

Enhanced LOIII in RL quasars
Difference in LOIII between RL and RQ QSOs in grid on MBH,L5100 orMBH, ṀAD⇒ Radio loud QSOs have enhanced LOIII

Schulze et al. (in prep.)Enhanced LOIII in RL quasars➢ Compare RL QSOs and matched RQ sample, in z, MBH and L5100➢ Mean offset in log LOIII distributions of 0.18 dex => factor 1.5⇒ KS-test: D=0.188 p=5.204e-20⇒ Result independent of definition of RL

Narrow emission lines in spectral stack
Stack of RL and RQ matched QSO samples
OIII profile:⇒ enhancement due to core emission⇒ trend is not driven by outflows/shocks⇒ same enhancement present in all high excitation narrow lines

Broad emission lines in spectral stack⇒ Low ionization broad lines of Balmer lines and MgII show no strong
difference between RL and RQ stack⇒ High ionization broad line of HeII does show enhancement in RL stack,similar to narrow lines

RL quasars have higher BH spin
⇒ RL quasars have higher Lbol at a given ṀADLbol=ε ṀAD c2⇒ have average radiative efficiency factor 1.5 higher than RQ quasars⇒ RL quasars have higher average
BH spin⇒ different BH spin distributions

assume:RQ: ε=0.1 => a=0.67
RL: ε=0.15 => a=0.89
Schulze et al. 2017, ApJ, 849, 4

Thank you!