Relativistically Broad Iron K-Lines of AGN

　　　　　　“ Ｐｒｏｂｉｎｇ　ＢＨ　ｓｐｉｎ ”　

Y. Tanaka

June 22, 2011 @ICRR

Black Holes are Very Simple• Mass: M

• Spin: J = a*GM2/c (0 < a* < 1)

• (Electric Charge: Q)

But to measure these quantities is not simple

Two feasible methods for estimating spin:

1. Determine R ISCO of an accretion disk applicable to stellar-mass BH in the soft (X-ray) state. Mass, Distance, Inclination optically determined.

2. Relativistically broad Fe-K line Fe-K line near BH is broadened redward due to Doppler effect and gravitational redshift (depends on a ). *

X-ray spectra of BH binaries in the “soft state” Multicolor blackbody disk (MCD) model (Ginga)

Determine RISCO based on the MCD model

Based on the MCD model, corresponds to RISCO

Spins of several BH in binaries estimated (McClintock et al 2011)

R ISCO/rg vs Spin parameter a *R

Black Holes are Very Simple• Mass: M

• Spin: J = a*GM2/c (0 < a* < 1)

• (Electric Charge: Q)

But to measure these quantities is not simple

Two feasible methods:

1. Determine R ISCO of an accretion disk applicable to stellar-mass BH in the soft (X-ray) state. Mass, Distance, Inclination optically determined.

2. Relativistically broad Fe-K line Fe-K line near BH is broadened redward due to Doppler effect and gravitational redshift (depends on a ). *

“Broad Iron Line” story initiated in 1985 Cyg X-1

Tenma Kitamoto et al.EXOSAT Barr et al.

broad narrow

Gas scintillation prop. counter: best energy resolution at that time

obs/em

Rest frame @6.4 keV

Newtonian

Special Relativity: Beaming and Transverse Doppler

General Relativity: Gravitational Redshift

Disk Emissivity

by Armitage & Reynolds

Fabian et al. 1989

Iron K-Line profile near a black hole

SPIN

Maximal

Kerr

MCG-6-30-15 (z=0.008)

Broad Fe-K line first observed with ASCA

Tanaka, Fabian et al 1994

Energy (keV)

Flu

x

(ph

oto

ns

Broad Fe-K Line from the AGN MCG-6-30-15 (z=0.008) first observed with ASCA

Tanaka, Fabian et al. (1995)

S ＵＺＡＫＵMCG-6-30-15

Red wing due to large gravitational redshiftimplying BH rapidly

spinning

a > 0.98*

Broad Fe K-Lines observed with ASCA

K. Nandra

Broad Fe K-Lines in Galactic BHBs

GX 339-4 (CXO)

GRS 1915+105 (CXO)

XTE J1650-500 (XMM)

Cyg X-1 (XMM) XTE J1550-564 (ASCA)

GRO J1655-40 (ASCA)

(JMM 02, 06)

(JMM 04)

(JMM 02)

(JMM 04)

(JMM 04)

Broad Fe line in ～ 20 systems: [J.Miller]

Fe K emission line

• Most prominent feature in X-ray spectrum of reprocessed (reflected) emission from surrounding matter (accretion disk, torus ?)

• Relativistic broad line is the result of strong gravitational field near the central BH

• Probing the spin of BH, in particular SMBH

• But the reality of the Relativistic Broad Line is still subject of debate !

because the line profile is sensitive to the underlying continuum. Fixing the correct continuum is not straightforward.

海老沢　天文月報　 p445, vol.103, 2010

Partial Covering

HXD

Compton-thick partial coverer may mimic a broad line 「すざ

く」

Patchy Absorber

taken from Dewangan 2011

海老沢　天文月報　 p445, vol.103, 2010

Partial Covering

HXD

Compton-thick partial coverer may mimic a broad line 「すざ

く」

　　　　　　　 Ｎ arrow Ｌ ine Ｓ eyfert １

Optical properties: _____narrow H lines: FWHM Hß<2000 km/s _____relatively weak [O III]5007 _____strong FeII emission

X-ray properties: _____steep power law: photon index > 2.0 _____significant soft excess _____rapid & large-amplitude variation

considered to be relatively low mass & high Eddington ratio

A convincing case exists. 1H0707-495

1H0707-495 time variability

Gallo et al. 2004

Γ = 2.4

Edge: 7.1 keV

Γ = 2.5

Edge: 8.2 keV

（ Boller et al. 2002 ）

（ Boller et al. 2003 ）

Deep edge, Strong soft comp.

Examples of NLS1

“Partial Covering” fit to two NLS1 spectra

Note the absence of narrow Fe-K line

Crummy+05 22 PG QSO +12 Seyf1

Sof t Excesses

Over mass range of three orders of magnitude

kT ： 100 ～ 150 eV

Excludes accretion disk origin !

Reflection from photoionized disk(Ross & Fabian 93, 04)

Also see Young+, Nayakshin+, Ballantyne+, Rozanska+, Dumont+

Fe-K line must be present !

XMM RGS Spectrum of the Soft Excess ____________________of 1H0707

Fe-L

Blustin & Fabian 09

Ratio to the PL + BB model

a > 0.98*

Remaining Issues

• Why not all AGN show broad lines?• How to determine the correct continuum ?• Black hole spin: tend to be high ( too few sample yet)

• NLS1: show distinct differences from BLS1 ______strong soft excess ______steep power-law ______lack of narrow Fe K-line ______high Fe abundance

Strong light bending close to BH

Martocchia & Matt, Miniutti & Fabian