Science Summary Omer Blaes (UCSB)

1. Science Summary Omer Blaes (UCSB)

2. Accretion Theory – Simulations (Hawley) MRI is now nearly 20 years old, and is the only game in town as far as ab initio treatment of turbulence. But has it yet realized its promise? • Important to distinguish DYNAMICS from THERMODYNAMICS: • Dynamics is reasonably well-treated by simulations and there are many results. • Not (yet!) so much with thermodynamics (energy dissipation and heat transport). Local (Shearing Box) Results: Magnetorotational turbulence transports angular momentum robustly with stress proportional to magnetic pressure. MRI does NOT go away with increasing numerical resolution! Turbulence level is influenced by viscosity, resistivity, presence or absence of net vertical field and perhaps other things still not understood. As yet, no locally generated corona with significant power, but surface layers are strongly magnetized. (Disk reflection modelers take note: density is NOT constant, nor is material in hydrostatic equilibrium with thermal pressure.) No radiation pressure driven thermal instability, because thermal pressure is only correlated with stress after a time lag (turbulence dissipates which then produces thermal pressure).

3. Prad>>Pgas Pgas>>Prad Radiation dominated branch is thermally STABLE. (“Viscous” instability is still an open question.) -Turner (2004); Hirose, Krolik & Blaes (2009); Hirose, Blaes, & Krolik (2009)

4. Global Simulation Results for Black Hole Accretion (Hawley) • Collimated, Poynting-flux dominated jets are produced by • Blandford-Znajek mechanism. Spinning black hole threaded • by a dipole field entrained by MRI accretion flow is necessary. • No diskoseismic modes, but there are spiral acoustic waves. • Stress is nonzero at ISCO, implying an enhanced accretion • efficiency. Results depend on field geometry. • Fe Ka line may not be affected “too much” by plunging region. Observers: be aware that available XSPEC models with simple ISCO physics must have systematic errors at SOME level. Debate rages on among theorists as to how big a level that is.

5. RIAF’s, Sgr A* and M87 (Moscibrodzka) Moscibrodzka • Sub-mm polarization based on GRMHD can also give spin (a/M~0.9) as well as axis • direction. (Shcherbakov poster) • Rotating hot spots for NIR and X-ray flares: NIR polarization also gives spin • magnitude (a/M~0.4-1) and direction. (Eckart) But WHY should accretion flow angular momentum be aligned with black hole spin axis? (Bardeen-Petterson alignment probably doesn’t work in this regime [H/R>a].)

6. More on Black Hole Jet Theory (Tchekhovskoy) { Confined Deconfined

7. Outflows/Winds Mechanisms (Proga): Thermal, Radiation, Magnetic -Fast outflow in GRO J1655-40 does indeed appear to be magnetically driven by process of elimination. Still, a low density slow thermal wind caused by irradiation heating should produce a mass loss rate 7 times higher than the accretion rate! New simulations of large (~10 pc) scale radiation-driven outflows in AGN (Kurosawa): 3D simulations – clumpy bipolar outflow generated by cos i dependence of disk emission. Possibly related to NLR on larger scales? Also new 2D models with self consistent accretion luminosity based on what mass is left flowing through inner boundary.

8. X-ray BAL’s can be observed in lensed objects (Chartas): -Variability implies wind launched from NEAR the hole. Radiative driving probably responsible (v/c correlated with X-ray photon index). Requires steep spectra and/or shielding (what’s the geometry?). Implied energy outflow efficiencies ~1! Multi-D Radiative Transport (Sim): 3 classes of spectra depending on viewing angle: Weaker continuum plus reflection plus narrow absorption lines (intermediate). Direct continuum plus reflection (polar). NO transmitted continuum,no narrow absorption lines, just complex scattered and reprocessed photons (high inclination).

9. Fe Ka Lines in AGN (Brenneman) Superb data which, however, can be challenging to model! Exciting implications: black hole demographics, radio loud/quiet dichotomy, … Theorists need to work harder to provide observers with more physically motivated models of hard X-ray emission.

10. More Reflection/Reprocessing/Absorption • Reflection in AGN also produces a forest of soft X-ray emission which, when • when relativistically smeared, can fit the RGS spectra of NLS1’s. In future, • such fitting may be able to probe gravitational field further from hole. (Boller) • New XSPEC models becoming available: • MYTorus: X-ray absorption and reprocessing in a torus geometry (Murphy) • High energy resolution reflection models with newer atomic data (Garcia • poster)

11. Empirical Attempts to Probe of Nature of AGN Accretion Flow • SDSS/XMM-Newton Quasar Survey (Young): • 473 Sources! • aOX-Lopt real. • Within patchy disk corona model, suggests that covering factor of corona • increases with luminosity. • Use of BHXRB states to simulate aOX (Sobolewska): • Spread in AGN BH masses gives aOX-L2500 correlation. • Type 1 AGN and NLS1 data overlap with soft state simulations. • LINERS are most probably hard state. • X-ray binaries and AGN (CHAMP) (Constantin): • X-ray photon spectral index G is negatively correlated with L/Ledd in low • luminosity AGN (i.e. softer when dimmer), opposite to what is seen in QSO’s • - same behavior seen in hard/soft states of BHXRB’s. Agrees with ADAF models. • X-ray Eclipses (Risaliti): • NH variations on hour-day time scales in 10 Seyferts! • Inferred velocities and distances of absorbing clouds match • BLR, and X-ray source size must be a few gravitational radii. • Clouds have cometary shape. • Is this interpretation of the data unique?

12. NGC 4151 Red: HRC 0.1-10 keV Green: optical [OIII] Blue: radio (1.4 GHz) Wang J. et al. 2009, ApJ, 704, 1195 Chandra Imaging of Seyfert Nuclear Regions (Wang)

13. YSO’s X-ray Irradiation of Protoplanetary Disks (Ercolano): >1 keV photons penetrate deeply and affect ionization and therefore MRI and magnetic physics in general (active, dead, and undead zones). Complex chemistry affected by recombination on dust grains. 0.1-1 keV photons heat outer layers and drive photo-evaporation. Finally explains rapid inside-out dispersal of disk after million year time scale. Warm winds agree with observed emission lines. (Magnetic driving might also be important, but simpler and more predictive photo-evaporation wind appears to work just fine.)

14. YSO’s – Interaction Between Magnetospheric Accretion Stream and Star • TW Hya and V4046 Sgr (Brickhouse, Kastner) • BEAUTIFUL X-ray line diagnostics distinguish hot coronal emission from accretion • shock structure. Reasonable densities and temperatures inferred, but simple 1D • post-shock settling models do NOT reproduce observations. • Theory Informed by Solar Corona (Cranmer) • Blobs in accretion stream splash into star, generating waveswhich shake • magnetic field lines. Alfven wave turbulence on closed field lines cascade and • dissipate – and provide coronal heating at about the right level. Wave pressure on • open field lines can also launch winds, but not quite enough to explain observation? • MHD Simulations of Accretion Column (Sacco poster) • Both 1D and 2D, complete with spectral line synthesis.

15. Disk Accretion Onto Magnetized Stars (Romanova, Kulkarni, Long Poster) Two Accretion Modes: Stable (Funnel Streams) Unstable (Tongues)

16. Disk Accretion Onto Magnetized Stars – Some Highlights • Tilted magnetosphere drives large scale, trailing spiral waves in disk. • MRI is now being included – produces more variability and funnel streams • are more episodic. Variability depends on relative directions between disk • and stellar field. • Reconnection between disk and stellar magnetic fields, if collisionless, can • accelerate particles to high energies. • Funnel streams need not rotate with star, causing QPO’s at frequencies • reflecting inner disk rather than stellar spin frequency. • Conical winds form when matter comes in faster than B-field can diffuse • outward for zero or slow stellar rotation. Rapid rotation can add a Poynting • flux dominated jet. • Possible scenario for NS LMXB kHz QPO’s (small magnetospheres): • upper QPO due to tongues, lower QPO due to funnel streams.

17. CV’s • Magnetic (Mauche): • Chandra HETG spectrum of EX Hya – He-like forbidden lines missing due to • photo-excitation. Fe L-shell lines provide better density diagnostics (MASSIVE • amount of theoretical investment) and give n~1014 cm-3. Radial velocity variations • of X-ray emission lines can measure white dwarf mass! • HETG spectrum of AE Aqr: X-ray plasma is high density and/or close to white • dwarf (“It’s accretion, stupid.”) Radial velocities vary with white dwarf spin phase! • Non-magnetic (Wheatley): • Kepler data on V344 Lyr – WOW! • In quiescence, X-rays (eclipses imply from WD boundary layer) are 100 times • brighter than disk instability model predicts. • In outburst, hard X-rays are extended – what’s causing them? • Non-magnetic CV’s contribute to Galactic ridge emission. • Compton cooling may help explain various temperature discrepancies (Mukai) • -plea for boundary layer models including this.

18. Other Miscellaneous Sources • X-ray Pulsars (Suzaki): • Detailed fits to pulse profiles consistent with distinct (and occasionally • time-varying) accretion column geometries in different sources. • Symbiotics: • Mira – Can use accretion disk flickering to DETERMINE (!) nature of companion • from characteristic time scales in innermost disk. It’s a white dwarf, NOT a main • sequence star. (Sokoloski) • Mira AB can be resolved with imaging! Something is focusing the wind to make it • appear to be Roche lobe overflow. (Karovska poster) • Extremely successful Swift program has more than doubled (from 4 to 10) known • hard X-ray symbiotics in last 6 months! Contain massive (1.3 Msun) white dwarfs • – possible SN Ia progenitors. (Luna) • PSR J1023+0038 (Bogdanov): • Did have an optical disk in 2000-01. If only we had X-ray observations then. • Now a ms pulsar. Possible transition from LMXB to MSP? One of several systems • that we might catch in the act of changing its identity.

19. Neutron Star LMXB’s (Z, Atoll, Banana, “Flaring branch” that isn’t really flaring – ugh! I guess you have to be in this field to master the phenomenology.) • Bright LMXB’s (Balucinska-Church): • Flaring in Cyg X-2 – like Z-sources: unstable nuclear burning • Flaring in Sco X-1 – like Z-sources: unstable nuclear burning plus • Mdot variations • No flaring in Atoll sources because no unstable nuclear burning. • Chandra grating spectra (Schulz): • Phase-resolved with orbital period – wealth of detail when • adequately observed! Can determine geometry of ionization layers • (thin on top of disk in 4U 1822-37), disk outer edge (4U 0614+091), • and accretion coronae (extended in Cyg X-2).

20. Variability (Uttley) -PSD in AGN looks like Cyg X-1 soft state, and high frequency break scales inversely with black hole mass and directly with Eddington ratio. -2008 discovery of first (and still the only) believable QPO in AGN: RE J1034+396 -XMM-Newton observations of hard state of GX 339-4: disk component DOES vary on long time scales, and LEADS variations in hard photon energies. At high frequencies, disk LAGS variations in hard photon energies (reverberation – finally!).

21. X-Ray Binaries Sivakoff: X-ray Binaries in Cen A Most of the point sources (90%) turn out not to be transients. Persistent sources also dominate X-ray binary population in other galaxies. Homan: BHXRB State Transitions Mdot does not uniquely determine spectral state at high luminosities. Peak luminosity is determined by hard to soft transition luminosity. Brighter sources show flaring, resulting in additional structure in hardness-intensity diagram. Associated with steep power law state. This and intermediate “state” have HFQPO’s. In latter state, they appear when rms noise drops in hardsoft transition, near time (~few days) of radio flare. Type C LFQPO frequency related to hardness. Type B LFQPO frequency related to luminosity. Winds appear to be more associated with softer states. Sub-Eddington neutron star XRB hardness-intensity diagrams are similar to those of black holes. There now exists a single neutron star that spans BH-like HID’s to Sco X-1-like and Cyg X-2-like Z-source HID’s.

22. Malzac: Cyg X-1 Corona and Jet BELM – a new code that self-consistently handles evolution of lepton and photon distributions, including synchrotron emission and absorption (thermalization by synchrotron boiler). Proton temperature must be low compared to hot two-temperature accretion flow models of hard state. Strongly magnetized plasma (Pmag>Pgas) might produce a self-consistent hot plasma for hard state. But nonthermal high energy excess requires a weak B-field. I.e. must have two spatially separated regions. Nowak: Cyg X-1 hard state in all (6) X-ray satellites – simultaneously! Modeling requires accounting for absorption by blobs in accretion stream and dust scattering halo. VERY broad (0.5-500 keV) spectrum, with very gratifying agreement between all instruments! Broad (as well as narrow) Fe Ka line is present. Required inner radius varies between 6M and 40M, depending on continuum model. (Multiple continuum models adequately fit spectrum, including one involving a condensation in inner hot flow that acts as a seed photon source.)

23. Lots of interesting science that touches on all of astrophysics, from planet formation to galaxies to cosmology. Simulations are getting more powerful and including more and more of the relevant physics. New missions (Smith): Astro-H, GEMS, and (I hope!) IXO, AXTAR,…