1. 1 Astrophysical black holes Chris Reynolds Department of Astronomy

2. 2 Topics Observational evidence for black holes X-ray studies of strong-gravity region First observational studies of BH spin Future directions

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5. 5 Observational evidence for black holes Early X-ray observations [1965] discovered a powerful X-ray source in Cygnus Cygnus X-1 – Binary star system… black hole in orbit around a massive O-star – Black hole mass 7-13 M – X-rays produced due to accretion of stellar wind from O-star – 2kpc away

6. 6 How do we know the black hole mass? Period 5.6 days K = V sin i = 75km/s Newtonian analysis… – M BH >f – Cyg X-1… f=0.24M BH Feed in knowledge of i and companion mass… M=7-13M sun 6 “golden” cases with f>3M sun Brocksopp et al. (1998)

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9. 9 A. Ghez (UCLA) Strong evidence for a 3-4 million solar mass BH at the Galactic Center (closest stellar approach only 40AU!)

10. 10 Chandra+VLA image of GC (Baganoff et al. 2001) X-ray studies of black holes

11. 11 MCG-6-30-15 (Seyfert gal) (L X ~10 36 W) 3C273 (Quasar) L X ~10 38 W

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13. 13 X-ray “reflection” imprints well-defined features in the spectrum

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15. 15 Relativistic effects imprint characteristic profile on the emission line… Iron line profile in MCG-6-30-15

16. 16 MCG-6-30-15 Suzaku (Miniutti et al. 2006)

17. 17 Also see Suzaku results on broad iron lines at this meeting: MCG-5-23-16 (Reeves et al.) NGC 3516 (Markowitz et al.) Systematic surveys of the XMM archive are showing that ~1/2 of type-1 AGN show broad iron lines (largely confirming ASCA results) MCG-5-23-16 (Dewangan 2003) NGC2992 IRAS 18325 (Iwasawa 2004)

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19. 19 Brenneman & Reynolds (2006) Assuming no emission from within r ms a>0.987 (formal 90% limit) XMM analysis of MCG-6-30-15

20. 20 Black Hole Quasi-periodic oscillations High-frequency QPOs – Comparable frequency to orbital frequency in inner accretion flow – Often found in pairs with 3:2 ratio Stable frequencies – probably determined by gravitational potential – Could be an excellent probe of the mass and spin!!

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23. 23 QPO theory Lack of standard QPO theoretical framework is problem Global modes of accretion disk – “Diskoseismology”; Wagoner, Nowak, Kato… – Produce g-, p-, and c-modes – Linear theory… no natural explanation for 3:2 ratio Resonance model – Parametric resonance between vertical/radial epicyclic frequencies (Abramowicz & Kluzniak) – Source of free energy? Fundamental g-mode (Nowak & Wagoner) Movie by Mike Nowak

24. 24 The Future of BH X-ray Studies Armitage & Reynolds (2004) Dynamical timescale variability… probes orbital motions in accretion disk

25. 25 Powerful probe of turbulent disk physics. Also, arcs approximately trace test-particle Keplerian orbits in  =  plane. Iwasawa et al. (2004)

26. 26 Light crossing timescale allows reverberation effects to be studied.

27. 27 Chandra Deep Field

28. 28 Constellation-X simulations… Simulated 100ks; F 2-10 =10 -12 erg/s/cm 2 Simulated 1Ms; z=1; F 2-10 =10 -14 erg/s/cm 2 ~4 such source per Con-X field

29. 29 Imaging a black hole mm-VLBI

30. 30 Imaging a black hole Micro-arcsecond X-ray Imaging Mission (MAXIM) HST (0.1 arcsec) MAXIM (0.05  -arcsec)

31. 31 ~20,000 km Current MAXIM concept Group and package Primary and Secondary Mirrors as “Periscope” Pairs “Easy” Formation Flying (microns) All s/c act like thin lenses- Higher Robustness Possibility to introduce phase control within one space craft- an x-ray delay line- More Flexibility Offers more optimal UV-Plane coverage- Less dependence on Detector Energy Resolution Each Module, self contained- Lower Risk. ~500-1000 m Baseline A scalable MAXIM concept.