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DYNAMICAL MASSES IN BLACK HOLE X-RAY BINARIES Jorge Casares (IAC)

DYNAMICAL MASSES IN BLACK HOLE X-RAY BINARIES Jorge Casares (IAC). Outline. 1.- Dynamical Masses: techniques, limitations and systematics 2.- Bowen emission: dynamical masses during outburst 3.- Search for dormant BH XTs: IPHAS/UVEX surveys 4.- Conclusions. 1.- BHs in XRBs.

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DYNAMICAL MASSES IN BLACK HOLE X-RAY BINARIES Jorge Casares (IAC)

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  1. DYNAMICAL MASSES IN BLACK HOLE X-RAY BINARIES Jorge Casares (IAC)

  2. Outline 1.- Dynamical Masses: techniques, limitations and systematics 2.- Bowen emission: dynamical massesduringoutburst 3.- Search for dormant BH XTs: IPHAS/UVEX surveys 4.- Conclusions

  3. 1.- BHs in XRBs • Mass distribution of BHs has strong impact in SNe models, evolution of massive stars, chemical enrichment • Stellar evolution models predict~ 108 BHremnants (Brown & Bethe 94). • But only BHs in interacting binaries can be easily detected and weighed accurately. • Best evidence for BH is dynamical i.e. a compact object with Mx > 3 M

  4. The Classic Method: Weighing BHs BHs do not burst nor pulse dynamical information must be extracted from donor star. Three experiments: V404 Cyg 1) Radial velocity curve q=MC/MX f (M) < MX R=λ/Δλ≥1500 required

  5. Weighing BHs e.g. in V404 Cyg we measure Vsini=40 km/s and then q=0.06 2) Measure Vrot sini R=λ/Δλ≥5000 required

  6. Weighing BHs GRO J1655-40 (Orosz & Bailyn. 97) 3) Fit ellipsoidal modulation Amplitude is strong function of inclination f(M) + q + i complete solution

  7. BHs in HMXBs: Cyg X-1 =0.25 M • Mass transfer is powered by stellar winds determination of q & i through Vsini and ellipsoidal fits can be biased low • Optical counterpart: O9.7 Iab (=HD 226868) • Velocity K= 64 km/s and Porb= 5.6 d. (Webster & Murdin; Bolton 1972) Typically O9.7 Iab has ≈ 33 M(and then MX≈ 7 M, i=90º) • But donor likely undermassive by factor ≤3 (van den Heuvel & Ostriker 73)

  8. M33 X-7: First eclipsing BH Eclipsing X-ray source with a 3.45d period (Peres et al. 1989) First ellipsoidal fitsandradial velocity curve of the O7-8III donor (Orosz et al. 2007) Eclipse+distanceconstrain parameter space: RC=19.6±1R, f=0.78±0.02 i=74.6±1.0o Mc=70±7 MMx=15.7±1.5 M

  9. BHs in X-ray Transients OUTBURST: Companion  103 fainter than X-ray irradiated disc Low mass donors have no winds and fill Roche lobes A0620-00 QUIESCENCE: companion dominates optical flux radial velocity studies

  10. P=30.8d Neil et al. 2007 Filippenko & Chornock 2001 IAUC7644 Galactic Black Holes with dynamical evidence Orosz 2003; Charles & Coe 2006 System Porb f(M) Spect. Type Classification Mx GRS 1915+105 33.5 d: 9.5 ± 3.0 M K/MIII Transient 14.0 ±4.4 M V404 Cyg 6.470 d 6.08 ± 0.06 M K0IV ,, 12 ±2 M Cyg X-1 5.600 d 0.244 ± 0.005 M 09.7Iab Persistent 10± 3M LMC X-1 4.229 d 0.14 ± 0.05 M 07III ,, 10.9 ± 1.4M M33 X-7 3.453 d 0.46 ± 0.08 M 07-8III ,, 15.7±1.5M XTE J1819-254 2.817 d 2.74 ± 0.04 M B9III Transient 7.1± 0.3M GRO J1655-40 2.620 d 2.73 ± 0.09 M F3/5IV ,, 6.3± 0.3M BW Cir 2.545d 5.75 ± 0.30 M G5IV ,, >7.8 M GX 339-4 1.754 d 5.8 ± 0.5 M -- ,, >6.0 M LMC X-3 1.704 d 2.3 ± 0.3 M B3 V Persistent 7.6± 1.3M XTE J1550-564 1.542 d 7.65 ± 0.38 M G8/K8IV Transient 9.1 ±0.6 M 4U 1543-475 1.125 d 0.25 ± 0.01 M A2V ,, 9.4 ±1.1 M H1705-250 0.520 d 4.65 ± 0.21 M K3/7V ,, 6 ±2 M GS 1124-684 0.433 d 3.01 ± 0.15 M K3/5V ,, 7.0± 0.6M XTE J1859+226 0.382 d : 7.4 ± 1.1 M : -- ,, GS2000+250 0.345 d 5.01 ± 0.12 M K3/7V ,, 7.5 ±0.3 M A0620-003 0.325 d 2.72 ± 0.06 M K4V ,, 6.6 ±0.3 M XTE J1650-500 0.3205 d 2.73 ± 0.56 M K4V ,, >2.5M GRS 1009-45 0.283 d 3.17 ± 0.12 M K7/M0V ,, 5.2± 0.6M GRO J0422+32 0.212 d 1.19 ± 0.02 M M2 V ,, 4± 1M XTE J1118+480 0.171 d 6.3 ± 0.2 M K5/M0V ,, 6.8± 0.4M Orosz et al. 2009 (LMC X-1), Cantrell et al. 2010 (A0620-00); Orsoz et al. 2010 (J1550-564)

  11. Late Results on XTE J1859+226 Orbital period is not 9.2 hr (Filippenko & Chornock 2001 IAUC 7644) but either 6.6 or 7.7 hr GTC 10.4m spectroscopy 2x3 hr blocks in July & Aug 2010 K≈520 km/s f(M)=4-4.5 M 9.2 hr Corral-Santana et al. 2010 submitted

  12. Mass spectrum of BHs New strategies required Limited by errors and poor statistics 17 reliable masses of BHs: 4-16 M • Do BH masses cluster at a particular value? • What are the edges of the BH distribution? Typical errors 20%

  13. Systematics in Ellipsoidal Fits 1) Superhumps:modulation a few % longer than orbital caused by precessing disc Typically seen in outburst, when disc exceeds 3:1 resonance radius (O’Donoghue & Charles 1996) XTE J1118+480: near quiescence (Zurita et al. 2002)

  14. Systematics in Ellipsoidal Fits 2) Rapid aperiodic variability: Zurita, Casares & Shahbaz (2003) ~ 6hr flares in V404 CygPavlenko et al. (1996) All SXTs show flaring activity when observed at high time resolution. flaring originate in the disc whose contribution fades with λFits in the IR assumed to be safe

  15. Systematics in Ellipsoidal Fits 2) Rapid aperiodic variability: varies with time for a particular system A0620-00 Cantrell et al. (2008) i=51 ± 1 deg Mx=6.6 ± 0.3 M Cantrell et al. (2010) i=37 ± 6 deg Mx=10 ± 2 M Shahbaz et al. (1994) i=41 ± 3 deg Mx=11 ± 2 M Gelino et al. (2001) Critical because inclination dominates the mass error budget

  16. The Future: astrometry of donor stars Will provide accurate inclinations and masses ≤5% calibrate ellipsoidal fits VLTI+GRAVITY(2013): will provide 10 μas for mK=15and will resolve V404 Cyg and GRS 1915+105 Space Interferometry Mission (SIM 2016) High sensitivity : 20th mag Angular resolution: 3.5μas

  17. Evidence for superhump variability with P=3.24hr (Zurita et al. 2008) Shortest period BH binary 32 BH Candidates: prime targetsfor rv studies SWIFT J1753-0127:remained in low-hard state since discovery 2005 2007 2009 2010

  18. Since P=3.24hr then ΔV ≈ 10 and Vquiescent ~ 26 Too faint for dynamical studies BH Candidates: SWIFT J1753.5-0127 Outburst Amplitude vs Porb correlation (Shahbaz & Kuulkers 1998)

  19. Black Hole Candidates Only a few are brighter than R~23 (limit of 10m Telescopes) Beyond R~23 we need ELT New strategies to expand sample of dynamical BHs: 1.- Dynamical studies during outburst 2.- Search for new quiescent BHs

  20. Bowen Emission from the Donor HeII NIII/CIII AAT+NTT VLT Shahbaz et al. 2001 1.- Dynamical studies during outburst: Steeghs & Casares 2002 Detection of sharp high excitation emission lines Most prominent are CIII/NIII at λλ4630-40 NIII powered by fluorescence Doppler shift traces orbit of heated companion • Classic Black Hole candidate • Quiescence in 2000-01 • 2002 outburst NIII/CIIIemissionlines GX 339-4

  21. GX 339-4 Determine f (M) in new SXTs during outburst before they fade (and are lost in quiescence) Kem=317 ±10 km/s  K2 f(M)5.8 ± 0.5 M Black Hole!! (Hynes et al. 2003 ApJ 583 L95) Multigausian fit to NIII lines Porb=1.76 d from HeII velocities

  22. Echo Tomography O(t) = X(t) * T(t-) • Time delays between X-ray and optical variability to map reprocessing regions in a binary T(t-) depends on geometry and varies with orbital phase • disc geometry • binary separation a • inclination i • mass ratio q=M2/MX Credit: K.0’Brien Most works use broad band filters delays consistent with disc reprocessing

  23. Bowen line Echo Tomography : Sco X-1 Narrow filters to amplify reprocessed signal from companion: Bowen+HeII & continuum continuum subtracted lightcurves of lines Muñoz-Darias et al. 2007 Flaring Branch W3 =0.52 W4 =0.42 =0.60 W1 W5 W2 =0.73

  24. MAXI SWIFT INTEGRAL XTE SAX ASCA 32 BH candidates CGRO ROSAT GRANAT GINGA Cen X-2 17 dynamical BHs 2.- Search for new quiescent BHs BH demography: how many? Discovered at a rate ~1.7/yr since GINGA Extrapolation of SXTs since late 80’s + assuming outburst duty cycle ~ 50 yrs suggest ~ 103dormant BH SXTs (van den Heuvel 93, Romani 98) BH SXTs known are the tip of iceberg of Galactic population

  25. The IPHAS/UVEX Survey • INT Photometric Surveys of the northern Galactic plane (|b|<5º) in Hα , r’,i’(IPHAS) and u’,g’, HeI5876 (UVEX) down to r’=20 (Drew et al. 2005) • Covers ~1800 sq. deg with ~5x105 Hα emitters in 300 Mill. stellar objects (0.1%) CV BH XRT

  26. IPHAS/UVEX/2MASS Cross-match of IPHAS/UVEX /2MASS with these colour cuts yields ~5000 candidates. Most will still be contaminants so follow-up spectroscopy required for confirmation.

  27. Conclusions • Best way to measure BH masses is through dynamical studies of X-ray binaries • SXTsprovide many more & cleaner cases than HMXBs:17 confirmed BHs with masses in the range 4—14 M(caution with systematics in ellip. mod. and hence i) • Tip of iceberg of hidden population of~103 BH binaries • Betterstatistics&≤10% errorsneeded to derive constraints to close binary evolution and SNe models.

  28. Conclusions 2 possible avenues to increase the population: • Exploit Bowen Fluorescenceto get dynamical information during outburst. • Discover new hybernant BHsusing appropriate colour cuts in deep surveys such as IPHAS/UVEX.

  29. DECAY TO QUIESCENCE: Aug 2010 WHT i>18.9 Russell et al. ATel #2775 Corral-Santana et al. ATel #2818 OUTBURST: 26 Oct 2009 IMACS i=15-16 Torres et al. ATel#2263 XTE J1752-223 Faint quiescent counterparts in crowded fields hamper radial velocity studies of donor star

  30. A low mass BH in LS 5039 ? • Spacially resolved radio emission Microquasar or pulsar wind? • First γ-ray Binary detected by HESS at TeV with Lγ=1034 ergs/s • Radial velocity curveof the 06.5V((f)) indicate Porb=3.906 d(Casares et al. 2005). But the orbital parameters depend on the spectral lines used. • HI and HeI may be contaminated by wind emission because show larger scatter and the solution is blue-shiftted (as expected by contamination from P-Cygni) We adopted the HeII solution

  31. 2) Donor almost fills Roche lobe at periastron assume is pseudo-synchronized 1) We fitted UNIFIED MODELS (NLTE+Sphericity) to stellar spectrum to yield Teff, log g, M, R and V∞ i = 23.2 -- 26.8o Combining 1+2+orbital solution we get a full solution to the masses. The result suggests thatLS 5039 might be a black hole with 3-5 solar masses

  32. BH Candidates TOTAL = 49 BH transients in 44 years, 17 with dynamical evidence

  33. The K-correction Measures the displacement of emission line region wrt center of mass Kem/K2= 1- f (1+q) with f () 1 ( = disc opening angle) Muñoz-Darias et al. 2005 f = 0 0 f 1 f = 1 Real K2 can be determined with extra information on q and .

  34. XTE/VLT campaign on burster 4U 1636-536 June 2007 3 bursts detected at orbital phases 0.20, 0.55 and 0.83 Time lag varies with amount of continuum subraction, approaching prediction for model with Mns=1.4 Msun, q=0.3, i=36-60, α=12deg χ2 fits to the 3 burst delays as function of continuum subtraction yields i=45-50deg and optimum subtraction ~0.85 Muñoz-Darias, O’Brien et al., in preparation

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