1. Observing Black Holes With 1m-Class Telescopes Charles Bailyn Yale University With thanks to: J. McClintock (CfA), R. Remillard (MIT), J. Orosz (SDSU), Yale students and data aides C. Baldner, A. Cantrell, B. Cobb, S. Curry, Z. Dugan, M. Dwyer, F. Edelman, L. Ferrara, J. Greene, B. Heflin, R. Jain, L. Jeanty, R. Kennedy- Shaffer, D. Maitra, E. Neil, K. Whitman, CTIO/SMARTS staff M. Buxton, D. Gonzalez, J. Espinoza, A. Miranda, J. Nelan, S. Tourtellotte, R. Winnick

2. Observing Black Holes With 1m-Class Telescopes Introduction to Black Hole X-ray Transients Introduction to Black Hole X-ray Transients 2 ½ Strong-Field Relativistic Effects 2 ½ Strong-Field Relativistic Effects Recent results on BHXTs with SMARTS Recent results on BHXTs with SMARTS

3. Transient X-ray Binaries Accreting compact object Accreting compact object Eddington-limited outbursts (rise of days; duration of weeks; recurrence of decades) Eddington-limited outbursts (rise of days; duration of weeks; recurrence of decades) Superluminal jets Superluminal jets Quiescent light dominated by companion Quiescent light dominated by companion Scientist’s conception of GRO J1655-40 in outburst from Rob Hynes

4. The Mass Function Bailyn et al. 1995 GRO J1655-40 measurable only in quiescence! P K

5. Mass Limit of Neutron Stars R > Schwarzschild only if M Schwarzschild only if M < 3 Msun (modest change for spinning n.s.)  Equation of State agrees with experiment  Extrapolation is causal 1.5 < M/Msun < 2.2 1.5 < M/Msun < 2.2  Limit for Plausible Equations of State Higher limits require either Non-standard gravity Non-standard gravity Non-baryonic star Non-baryonic star

6. “Proof” of a Black Hole L=10^4 Lsun, T=10^3 Tsun => R =10^-4 Rsun L=10^4 Lsun, T=10^3 Tsun => R =10^-4 Rsun Millisecond time variability => R R<10^-3 Rsun P, K => M > 3Msun P, K => M > 3Msun => compact object too massive to be a neutron star => compact object too massive to be a neutron star Requires black hole, non-baryonic star, or non-GR gravity Requires black hole, non-baryonic star, or non-GR gravity

7. Finding a Black Hole Wait for new X-ray transient Wait for new X-ray transient Identify optical counterpart Identify optical counterpart Wait for quiescence Wait for quiescence Measure mass function Measure mass function If f(M)>3, you win! If f(M)>3, you win! (RXTE era discovery rate ~1/yr)

8. Determining Black Hole Mass Mass ratio measurable from line broadening (usually a small effect) Mass ratio measurable from line broadening (usually a small effect) Inclination from ellipsoidal variability Inclination from ellipsoidal variability  2ndary non-spherical (Roche lobe filling)  Two maxima and two minima per orbit  Amplitude depends on inclination

9. Ellipsoidal Variations

10. Problems with Ellipsoidal Variability Residual Disk Light (degenerate with inclination to first order) Residual Disk Light (degenerate with inclination to first order) Other light sources (hot spots etc) Other light sources (hot spots etc) Star spots (especially on late-type 2ndaries) Star spots (especially on late-type 2ndaries) Eclipses (star of disk, disk of star) Eclipses (star of disk, disk of star) NOTE: different temperature dependences

11. GRO J1655-40 (Greene. Bailyn & Orosz 2001) P = 2.62192(20) days f(M) = 2.73 +/- 0.09 Inclination 70 +/- 2 M_1 = 6.3 +/- 0.5 M_2 = 2.6 +/- 0.3

12. Dynamically Confirmed Black Hole Candidates

13. Extragalactic BHXBs: M33 X-7 (Orosz et al. 2007)

14. Tests of General Relativity Solar system: very high precision, weak field limit Solar system: very high precision, weak field limit Pulsars: very high precision, 1 st and 2 nd order fields Pulsars: very high precision, 1 st and 2 nd order fields Gravitational waves: strong field, multi- parameter not yet observed Gravitational waves: strong field, multi- parameter not yet observed Accreting black holes: strong field, multi- parameter, many constraints Accreting black holes: strong field, multi- parameter, many constraints

15. Reversing the Question IF General Relativity applies and stars are baryonic, THEN these are Black Holes; IF General Relativity applies and stars are baryonic, THEN these are Black Holes;

16. Reversing the Question IF General Relativity applies and stars are baryonic, THEN these are Black Holes; IF General Relativity applies and stars are baryonic, THEN these are Black Holes; IF these are not Black Holes, THEN either General Relativity does not apply or there are non- baryonic stars. IF these are not Black Holes, THEN either General Relativity does not apply or there are non- baryonic stars. So, search for consequences of strong-field relativity, such as the event horizon, the inner- most stable circular orbit, possibly jet formation So, search for consequences of strong-field relativity, such as the event horizon, the inner- most stable circular orbit, possibly jet formation

17. Do Event Horizons Exist? Black Hole Infalling Gas Boundary layer X-rays Neutron Star

18. Disks vs. ADAFs Keplerian Accretion Disk: half energy dissipated in disk, half at boundary layer Keplerian Accretion Disk: half energy dissipated in disk, half at boundary layer Advection Dominated Accretion Flows Advection Dominated Accretion Flows  Two T plasma: ions hot, electrons cool  Thermal, kinetic energy advected inwards  >99% of energy dissipated at boundary layer  Requires low mass accretion rate Quiescent transients fit outer disk + ADAF Quiescent transients fit outer disk + ADAF

19. Evolution of Spectral States Esin et al. 1997 (see also McClintock & Remillard 2006)

20. A0620-00 in Quiescence Narayan, McClintock & Yi 1996

21. Black Holes vs. Neutron Stars Garcia et al. 2001

22. Problems and Uncertainties Dependence on orbital period – binary evolution Dependence on orbital period – binary evolution Changing nature of time-dependant accretion flow (disk, corona, ADAF etc) Changing nature of time-dependant accretion flow (disk, corona, ADAF etc) What about outflows (ADIOS, jets)? What about outflows (ADIOS, jets)?

23. Innermost Stable Circular Orbit Relativity predicts an ISCO at a radius determined by M and J of Black Hole Relativity predicts an ISCO at a radius determined by M and J of Black Hole In “high-soft” state, X-ray spectrum fits superposition of black bodies from disk In “high-soft” state, X-ray spectrum fits superposition of black bodies from disk ISCO represents hottest contributing black body ISCO represents hottest contributing black body Spectral modelling can measure ISCO Spectral modelling can measure ISCO With known mass and geometry, one can determine J With known mass and geometry, one can determine J

24. Recent ISCO Determinations McClintock et al. 2006

25. Recent ISCO Determinations McClintock et al. 2006

26. Superluminal Jets? Well-known special relativistic effect in quasars Well-known special relativistic effect in quasars Now observed in several BHXNs (radio and X-ray observations) Now observed in several BHXNs (radio and X-ray observations) Associated with “low-hard” (non-thermal) emission states Associated with “low-hard” (non-thermal) emission states Collimation and energy mechanisms unclear – frame-dragging may be important Collimation and energy mechanisms unclear – frame-dragging may be important Correlation of jet strength with J would be important Correlation of jet strength with J would be important Amount of mass ejected crucial to understand ADAFs Amount of mass ejected crucial to understand ADAFs

27. Small and Moderate Aperture Research Telescope System (SMARTS) Operates 4 1m-class telescopes at CTIO Operates 4 1m-class telescopes at CTIO Variety of instruments and operating modes Variety of instruments and operating modes Over a dozen participating institutions (now including NExScI) Over a dozen participating institutions (now including NExScI) ~25% of time available through NOAO ~25% of time available through NOAO

28. Current SMARTS Capabilities 1.5m + low and high resolution spectrographs (queue observing) 1.5m + low and high resolution spectrographs (queue observing) 1.3m + ANDICAM - dual channel O/IR (monitoring queue observing ONLY) 1.3m + ANDICAM - dual channel O/IR (monitoring queue observing ONLY) 1.0m + 4K CCD (user runs) 1.0m + 4K CCD (user runs) 0.9m + 2K CCD (user/service alternate) 0.9m + 2K CCD (user/service alternate)

29. Current SMARTS Capabilities 1.5m + spectrograph/IR imager (service and queue observing) 1.5m + spectrograph/IR imager (service and queue observing) 1.3m + ANDICAM - dual channel O/IR (monitoring queue observing ONLY) 1.3m + ANDICAM - dual channel O/IR (monitoring queue observing ONLY) 1.0m + 4K CCD (user runs) 1.0m + 4K CCD (user runs) 0.9m + 2K CCD (user/service alternate) 0.9m + 2K CCD (user/service alternate)

30. Yale/SMARTS BHXN Program Observe ~12 sources per night in O/IR Observe ~12 sources per night in O/IR Quiescence: build up long-term ellipsoidal lightcurves Quiescence: build up long-term ellipsoidal lightcurves New outbursts – trigger X-ray observations New outbursts – trigger X-ray observations Outburst monitoring – state changes, multi- wavelength correlations Outburst monitoring – state changes, multi- wavelength correlations

31. Expectations for Optical/IR During Outburst Cycle Disk Instabilities lead to Fast Rise and Exponential Decay (FRED) Disk Instabilities lead to Fast Rise and Exponential Decay (FRED) Optical precedes X-rays and lasts longer Optical precedes X-rays and lasts longer Same sequence of states in rise and fall Same sequence of states in rise and fall O/IR is a superposition of thermal spectra O/IR is a superposition of thermal spectra

32. Aquila X-1 Neutron star transient (displays bursts) Neutron star transient (displays bursts) Shortest recurrence time (~ 1 year) Shortest recurrence time (~ 1 year) Orbital period ~ 18 hours Orbital period ~ 18 hours Nearby neighbor ~ 2 mags brighter in quiescence Nearby neighbor ~ 2 mags brighter in quiescence Declination ~ 0: everyone can play! Declination ~ 0: everyone can play! SMARTS lightcurve in Maitra & Bailyn 2008 SMARTS lightcurve in Maitra & Bailyn 2008

33. O/IR vs X-rays in Aquila X-1

34. F.R.E.D.s

35. O/IR vs X-rays in Aquila X-1 F.R.E.D.s L.I.S.s

36. O/IR vs X-rays in Aquila X-1 F.R.E.D.s L.I.S.s Mini- outbursts

37. Aquila X-1: 2000 Outburst

38. Maitra & Bailyn, 2004

39. 8 Years of Aquila X-1 F.R.E.D.s – similar to expectations F.R.E.D.s – similar to expectations L.I.S.s – variable flux, low/hard X-rays, also seen in other neutron star transients L.I.S.s – variable flux, low/hard X-rays, also seen in other neutron star transients Mini-outbursts – no X-ray response in ASM Mini-outbursts – no X-ray response in ASM Optical precedes X-ray, as expected Optical precedes X-ray, as expected Hysteresis of X-ray states, unexpected, also seen in black hole candidates Hysteresis of X-ray states, unexpected, also seen in black hole candidates

40. 4U1543-47 Soft X-ray transient with ~ 10 year recurrence timescale Soft X-ray transient with ~ 10 year recurrence timescale Low mass function and low inclination > black hole system (Orosz et al. 2001) Low mass function and low inclination > black hole system (Orosz et al. 2001) A-star companion in ~ 1 day orbit A-star companion in ~ 1 day orbit OUTBURST IN SUMMER 2002! OUTBURST IN SUMMER 2002!

41. 4U1543-47 in 2002 Buxton & Bailyn 2004

42. 4U1543-47 in 2002 Buxton & Bailyn, 2004

43. 4U1543-47 in 2002 Buxton & Bailyn, 2004

44. 4U1543-47 in 2002

45. Recent SMARTS data of GX 339-4

46. Expectations for Optical/IR During Outburst Cycle Disk Instabilities lead to Fast Rise and Exponential Decay (FRED) Disk Instabilities lead to Fast Rise and Exponential Decay (FRED) Optical precedes X-rays and lasts longer Optical precedes X-rays and lasts longer Same sequence of states in rise and fall Same sequence of states in rise and fall O/IR is a superposition of thermal spectra O/IR is a superposition of thermal spectra

47. “Typical” Quiescent Data (Greene. Bailyn & Orosz 2001) P = 2.62192(20) days f(M) = 2.73 +/- 0.09 Inclination 70 +/- 2 M_1 = 6.3 +/- 0.5 M_2 = 2.6 +/- 0.3

48. A0620-00 in Quiescence Cantrell et al. 2008

49. V4641 Sgr in Quiescence Cantrell et al. in prep.

50. Quiescent Behavior Optical lightcurves vary with time Optical lightcurves vary with time Disk contribution both important and variable Disk contribution both important and variable Long term data sets modelled with consistent orbital parameters are crucial Long term data sets modelled with consistent orbital parameters are crucial Caution needed in comparing quiescent ADAF-associated X-ray emission! Caution needed in comparing quiescent ADAF-associated X-ray emission!

51. Black Hole X-ray Transients in 2008 22 “Dynamically Confirmed Black Hole Candidates” 22 “Dynamically Confirmed Black Hole Candidates” Most have masses well above neutron stars Most have masses well above neutron stars Strong field relativistic effects apparently manifested Strong field relativistic effects apparently manifested Complexity of outburst cycle and accretion flow beginning to be explored Complexity of outburst cycle and accretion flow beginning to be explored

53. Future Work New sources from RXTE/ASM, Swift, including Local Group targets New sources from RXTE/ASM, Swift, including Local Group targets Daily SMARTS data for ~ dozen sources and for new sources Daily SMARTS data for ~ dozen sources and for new sources Exploration of state changes and careful binary parameter measurements necessary to interpret X- ray data Exploration of state changes and careful binary parameter measurements necessary to interpret X- ray data IR-dominated non-thermal component may probe inner accretion flow (is there mid-IR emission in quiescence?) IR-dominated non-thermal component may probe inner accretion flow (is there mid-IR emission in quiescence?) Goal: a full time-dependent description of the mass flow Goal: a full time-dependent description of the mass flow

54. Outburst of 1550-564 in 2000 Jain et al. 2001

55. IR Dominated Flares Significant O/IR emission from central source Significant O/IR emission from central source Peaks in mid-IR (Spitzer ToO not yet activated) Peaks in mid-IR (Spitzer ToO not yet activated) Cannot be thermal and in binary system Cannot be thermal and in binary system Associated with transition to low state, QPOs and radio emission Associated with transition to low state, QPOs and radio emission Similar to other “optical plateaus”? Similar to other “optical plateaus”? Energetic synchrotron source from jet?? Energetic synchrotron source from jet??

56. V4641 Sgr Quiescent Lightcurves

57. X-ray lightcurves 2003 Maitra & Bailyn 2006

58. Conclusions from Outbursts of V4641 Sgr Optical/X-ray delay suggests optical is dominated by reprocessing Optical/X-ray delay suggests optical is dominated by reprocessing If so, variability NOT from Doppler boosting, but intrinsic (why??) If so, variability NOT from Doppler boosting, but intrinsic (why??) Outburst cycle not like other sources – short duration, short recurrence time, no thermal state Outburst cycle not like other sources – short duration, short recurrence time, no thermal state

60. V4641 Sgr = SAX1819.3-2525 Strong black hole candidate: f(m)=6 Mo Strong black hole candidate: f(m)=6 Mo Most massive, hottest 2ndary star (R ~ 13.5 in quiescence!) Most massive, hottest 2ndary star (R ~ 13.5 in quiescence!) Short, violently variable outbursts: microblazar?? Short, violently variable outbursts: microblazar??

61. Simultaneous X-ray/Optical Observations of V4641 Sgr Bailyn et al. (2007)

62. Accretion Disk Instabilities T = 

63. Outburst Physics II: X-ray Irradiation

64. Importance of O/IR Data of (Transient) X-ray Binaries In quiescence, observe companion stars > binary parameters In quiescence, observe companion stars > binary parameters In outburst, observe outer parts of disk > boundary condition for inner parts of flow In outburst, observe outer parts of disk > boundary condition for inner parts of flow

65. Optical and Infrared Lightcurves of Soft X-ray Transients Theoretical Expectations Theoretical Expectations Observational Capabilities Observational Capabilities Recent data 1 – Aql X-1 Recent data 1 – Aql X-1 Recent data 2 – 4U1543-47 Recent data 2 – 4U1543-47 Conclusions: outburst physics, triggers, future projects Conclusions: outburst physics, triggers, future projects

66. Optical and Infrared Lightcurves of Soft X-ray Transients Theoretical Expectations Theoretical Expectations Observational Capabilities Observational Capabilities Recent data 1 – Aql X-1 Recent data 1 – Aql X-1 Recent data 2 – 4U1543-47 Recent data 2 – 4U1543-47 Conclusions: outburst physics, triggers, future projects Conclusions: outburst physics, triggers, future projects

67. Aquila X-1: 1999 Outburst

68. Aquila X-1: 2000 Outburst

69. Hysteresis in outburst morphology (also in 1999 outburst – Maccarone & Coppi) Hysteresis in outburst morphology (also in 1999 outburst – Maccarone & Coppi) Slightly softer high/soft state in decline – no equivalent in outburst Slightly softer high/soft state in decline – no equivalent in outburst Are we seeing the heated neutron star surface at the end of the outburst?? Are we seeing the heated neutron star surface at the end of the outburst??

70. Conclusions I: Outburst Mechanisms D.I.M. + irradiation + 2-part flow works for some outbursts D.I.M. + irradiation + 2-part flow works for some outbursts L.I.S. and mini-outbursts in Aql X-1 L.I.S. and mini-outbursts in Aql X-1 Hysteresis in X-ray states in Aql X-1 Hysteresis in X-ray states in Aql X-1 IR-strong reflares in 1543-47 and 1550-564 IR-strong reflares in 1543-47 and 1550-564 MORE PHYSICS REQUIRED!

71. Conclusions II: Triggers Optical triggers for new outbursts lead time: 1 week especially useful for repeating outbursts should help to get rise as well as fall Optical triggers for new outbursts lead time: 1 week especially useful for repeating outbursts should help to get rise as well as fall IR triggers for reflares requires real-time reduction of IR data detailed radio/X-ray response not yet known IR triggers for reflares requires real-time reduction of IR data detailed radio/X-ray response not yet known

72. Conclusions III: Future Work Daily SMARTS data for Aql X-1, GX339-4, GRS1915+105, Cen X-4, A0620-00, GS1124-68, GRO 1655-40, XTE 1550-564, 4U1543-47 NEW SOURCES! Daily SMARTS data for Aql X-1, GX339-4, GRS1915+105, Cen X-4, A0620-00, GS1124-68, GRO 1655-40, XTE 1550-564, 4U1543-47 NEW SOURCES! Monitoring spectroscopy would be nice! Monitoring spectroscopy would be nice! As would short timescale photometry As would short timescale photometry

73. A Technical Difficulty Light dominated by accretion flow

74. Transient Systems Outbursts Outbursts  Rise time: days  Decay time: months  Recurrence time: decades  Peak luminosity: brightest X-ray sources Quiescence barely detectable in X-rays Quiescence barely detectable in X-rays

75. Black Hole Mass Distribution (update to Bailyn et al. 1998) Eleven between 5-10 solar masses Eleven between 5-10 solar masses Two >10 solar masses Two >10 solar masses One <5 solar masses One <5 solar masses ALL neutron stars <2 solar masses ALL neutron stars <2 solar masses Selection effects unlikely Selection effects unlikely Mass gap from supernova events? Mass gap from supernova events?

76. Disks vs. ADAFs Keplerian Accretion Disk: half energy dissipated in disk, half at boundary layer Keplerian Accretion Disk: half energy dissipated in disk, half at boundary layer Advection Dominated Accretion Flows Advection Dominated Accretion Flows  Two T plasma: ions hot, electrons cool  Thermal, kinetic energy advected inwards  Requires low mass accretion rate Quiescent transients fit outer disk + ADAF Quiescent transients fit outer disk + ADAF

77. A0620-00 in Quiescence Narayan, McClintock & Yi 1996

78. X-ray Binaries GRO J1655-40 (picture courtesy Rob Hynes)

79. QPOs in Black Holes Remillard et al. 2002

80. The Innermost Stable Orbit Holds promise of measuring black hole spin! Thermal Disk Models: superposition of blackbodies – Rin a parameter of the fit Thermal Disk Models: superposition of blackbodies – Rin a parameter of the fit Quasi-Periodic Oscillations: direct measure of frequency of inner disk? Quasi-Periodic Oscillations: direct measure of frequency of inner disk? Both methods model dependent!

81. Aquila X-1: 2000 Outburst

82. Black Hole Mass Distribution

83. Lessons for Moderate Aperture Telescopes (2-5m) in the GMT Era Should have fewer instruments (but better) Should have fewer instruments (but better) Should have fewer projects (but bigger) Should have fewer projects (but bigger) To maintain department/consortium access to a full range of capabilities, we will have to trade time across mountains To maintain department/consortium access to a full range of capabilities, we will have to trade time across mountains