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Observing Black Holes With 1m-Class Telescopes

Observing Black Holes With 1m-Class Telescopes. Charles Bailyn Yale University.

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Observing Black Holes With 1m-Class Telescopes

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  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 • 2 ½ Strong-Field Relativistic Effects • Recent results on BHXTs with SMARTS

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

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

  5. Mass Limit of Neutron Stars • R > 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 • Limit for Plausible Equations of State Higher limits require either Non-standard gravity Non-baryonic star

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

  7. Finding a Black Hole • Wait for new X-ray transient • Identify optical counterpart • Wait for quiescence • Measure mass function • 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) • 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) • Other light sources (hot spots etc) • Star spots (especially on late-type 2ndaries) • 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 • Pulsars: very high precision, 1st and 2nd order fields • Gravitational waves: strong field, multi-parameter not yet observed • 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;

  16. Reversing the Question • 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. 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? Boundary layer X-rays Infalling Gas Neutron Star Black Hole

  18. Disks vs. ADAFs • Keplerian Accretion Disk: half energy dissipated in disk, half at boundary layer • 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

  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 • Changing nature of time-dependant accretion flow (disk, corona, ADAF etc) • 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 • In “high-soft” state, X-ray spectrum fits superposition of black bodies from disk • ISCO represents hottest contributing black body • Spectral modelling can measure ISCO • 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 • Now observed in several BHXNs (radio and X-ray observations) • Associated with “low-hard” (non-thermal) emission states • Collimation and energy mechanisms unclear – frame-dragging may be important • Correlation of jet strength with J would be important • Amount of mass ejected crucial to understand ADAFs

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

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

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

  30. Yale/SMARTS BHXN Program • Observe ~12 sources per night in O/IR • Quiescence: build up long-term ellipsoidal lightcurves • New outbursts – trigger X-ray observations • 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) • Optical precedes X-rays and lasts longer • Same sequence of states in rise and fall • O/IR is a superposition of thermal spectra

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

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

  34. O/IR vs X-rays in Aquila X-1 F.R.E.D.s

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

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

  37. Aquila X-1: 2000 Outburst

  38. Aquila X-1: 2000 Outburst Maitra & Bailyn, 2004

  39. 8 Years of Aquila X-1 • 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 • Mini-outbursts – no X-ray response in ASM • Optical precedes X-ray, as expected • Hysteresis of X-ray states, unexpected, also seen in black hole candidates

  40. 4U1543-47 • Soft X-ray transient with ~ 10 year recurrence timescale • Low mass function and low inclination > black hole system (Orosz et al. 2001) • A-star companion in ~ 1 day orbit • 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) • Optical precedes X-rays and lasts longer • Same sequence of states in rise and fall • 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 • Disk contribution both important and variable • Long term data sets modelled with consistent orbital parameters are crucial • Caution needed in comparing quiescent ADAF-associated X-ray emission!

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