Black Hole Physics with Constellation-X Chris Reynolds Department of Astronomy University of Maryland College Park

Outline Black hole accretion – Using accreting black holes for gravitational physics – The simplicity of thin accretion disks Probing strong gravity with X-ray spectroscopy – X-ray reflection spectroscopy and broad iron lines – We are studying strong-field gravitation physics today Constellation-X – Opening-up the physics/astrophysics of black hole spin – New probes of Kerr metric

I : Black Hole Accretion John Hawley Get geometrically-thick disk with complex flows if accretion rate is… < ~0.01 of Eddington rate or > Eddington rate

Reynolds & Miller (2008)

Comparison of disk velocity derived from a 3-d MHD simulation (dotted) with simple test-particle velocity (solid)… confirms analytic result that deviations are O[(h/r) 2 ]

II : X-ray spectroscopy and probes of strong gravity X-rays from corona/jet irradiate accretion disks… creates a backscattered spectrum rich in spectral features Calculations of spectrum emitted by accretion disk in response to X-ray irradiation (Ross & Fabian 2005) Very similar fluorescence features seen from surface of Sun during X-ray bright solar flare

Line profiles encode host of effects including strong light bending. No light bending With light bending

MCG : AGN with very well studied “broad iron line” MCG (supermassive BH) w/Suzaku (Miniutti et al. 2006) Extremely broad iron line  originate from matter very close to rapidly spinning BH (R emit  2Rg, R horizon  1Rg)

GX339-4 (stellar-mass BH) w/Suzaku (J.Miller, C.Reynolds et al. 2008)

III : Constellation-X and black hole spin Non-spinningRapidly-spinning Theoretical assumption : X-ray reflection / iron line emission truncates at the innermost stable circular orbit (ISCO conjecture; confirmed by simulations) Black hole spin then determined from extent of “red wing” of broad iron line (independent of BH mass) KERRDISK model Brenneman & Reynolds (2006)

Constellation-X simulation; 1 million photons in 2-10keV band Constrains a=0.90  0.05 for a model =0.90 Need 15ks to get this spectrum for a bright AGN 10Ms program will yield AGN spins Easily obtain spin of every accessible stellar- mass BH that goes into outburst

Volonteri et al. (2005) MergersAccretion

M87 / VLA (NRAO)

Arcs trace orbits of disk material around black hole… can be compared with predicted GR orbits Iron line intensity as function of energy and time. Theoretical Con-X simulation (assuming 3x10 7 Msun black hole) IV : Constellation-X and the Kerr Metric Armitage & Reynolds (2003)

Relativistic iron line reverberation

Reynolds et al. (1999) Young & Reynolds (2000) Transfer function encodes flare-position as well as geometry of space-time Time Energy

Summary Geometrical and kinematic simplicity of thin accretion disks allows study of gravitational physics via X-ray spectroscopy Constellation-X will open the window on the astrophysics of black hole spin – Determine spin for supermassive BHs – Distinguish merger vs. accretion scenarios for SMBH growth – Determine spin for every accessible Galactic BH that goes into outburst… determine natal (birth) spin Constellation-X will allow new probes of the Kerr metric – Rapid iron line variability used to probe “Keplerian” orbits – Relativistic iron line reverberation reveals photon dynamics close to the BH

Backup slides

I : Black Hole Accretion Define dimensionless mass accretion rate Three regimes of accretion… 1. <10 -2 : Hot, quasi-spherical, inefficient flow (e.g., Galactic Center, low-state stellar-mass BHs) < <1 : Thin, radiatively-efficient disk (e.g., many AGN, high-state stellar-mass BHs) 3. >1 : Radiation-pressure dominated, thick disk (powerful quasars, ULXs?, SS433?)

Reynolds & Miller (2008) Density slice B phi

A procedure for testing the Kerr Metric Fit each track for (r,a) assuming Kerr metric – Kerr metric  a(r)=constant, M(r)=constant r=3r g ; a=0.95; M=3  10 7 M sun Currently developing track simulations and fitting tools to judge sensitivity

R=1000rg R=100rg R=30rg R=10rg R=6rg Disk Inclination Inner edge of disk (spin)

Gallery of selected broad iron lines MCG MCG IRAS18325NGC2992 Fairall 93C382 PG1211NGC3516 NGC4151Mrk766 GX339-4 GRS XTEJ1550 Cygnus X-1 Similar line profiles from stellar-mass and super- massive black hole systems… demonstrates insensitivity of line profile to mass

Improving constraints on relativistic Fe K line variability by adding high energy response MCG for 2ksMCG for 10ks Simulations with 4xSXT (Ir coating) + single HXT T orb =5ks for 10 7 M  BH at 6R g. Broad line+reflection constraints improved by including a HXE. Even in 2ks, “R” can be constrained to 40% (vs no constraint without HXE) and the iron line parameters to ~30% accuracy (x2 improvement). A modest HXE improves the feasibilty of tracking variations in Fe K and reflection on <orbital timescales.

Observing strategy and sample size… Strategy : target known AGN on the basis of flux and the presence of a broad iron line… “run down the log N - log S curve” Using HEAO-A1 LogN-LogS… – f is fraction of sources with broad lines – n ph is number of 2-10keV photons needed for individual measurement Need precusor survey to identify sources with broad iron lines – Start with suitable parent sample (e.g. Swift/BAT survey) – Snapshot survey of 500 AGN (10Ms total provides sufficient s/n to determine presence of relativistic iron lines) – Some fraction of this precusor work will be conducted by XMM and Suzaku beforehand

Black hole spin from thermal accretion disk continuum Frontera et al. (2001) Features : applicable in states when iron line is hard to discern. But need to know mass, distance, inclination independently Theoretical uncertainty : Precise form of disk spectrum after processing by disk atmosphere. Also relies on ISCO conjecture.

Iron line emission truncates close to ISCO due to steeply rising ionization parameter of the matter… no combined iron combined iron  iron line emission Spin constraints from iron line technique (90% confidence)… MCG , a>0.94 GX339-4, a=0.93  0.05 Dabrowski et al Brenneman & Reynolds 2006 Reis et al Reynolds & Fabian 2008 Miller et al. 2008

Keplerian orbit of a single “hot spot” a=0.98 i=30 o R=30R=3R=2.5R=6R=15

The radio-quiet/radio-loud dichotomy in AGN Accretion rate (Eddington Units) Radio loudness (L rad /L B ) Rapid spinners? Slow spinners? Sikora et al. (2007)

MCG XMM-Newton/350ks Simple power-law fit (excluding 3-8keV)

Brenneman & Reynolds (2006) Formal limit on spin a>0.987 Reasonable deviations from ISCO conjecture  a>0.94