Multiwavelength rapid timing of X-ray binaries

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1 Multiwavelength rapid timing of X-ray binaries Poshak Gandhi JAXA International Top Young Fellow Martin Durant Andy Fabian Piergiorgio Casella Vik Dhillon Jon Miller Elena Mason Kazuo Makishima Julien Malzac Tom Marsh Tariq Shahbaz X-ray Astronomy 2011 Berlin 2011 Jun 30

2 Ilustration: L. Calçada What is the source of the optical power of X-ray binaries? Gandhi et al. (2008) ESO press release 36/08

3 (van Paradijs & McClintock 1994) Comparison to blackbody optical reprocessing model Reprocessed emission f(incident flux, area of reprocessor)

4 Speedy aperiodic optical variations in X-ray binaries target sky mag 1s (V404 Cyg: Uemura+02) 0.5 s ( Motch+82 (GX 339-4: ( Kanbach+01 (XTE J :

5 1. GX Classic BH binary transient: ;( Hynes+03 ) - M>6 M sun ;( Zdziarski+04 ) - d~7-9 kpc - i>45 degs (Munoz-Darias+08); - microquasar (e.g. Gallo+05); (Summary: Shidatsu+11).

ULTRACAM @VLT ULTRACAM (on the VLT): ultra-fast,

u g Imaging region r / i / z Storage region

6 ULTRACAM (on the VLT): ultra-fast, triple-beam CCD camera Frame-transfer CCDs with negligible dead-time Speeds ~ 500 frames / sec Beam splitters => 3 filter simultaneous imaging u g Imaging region r / i / z Storage region

7 ULTRACAM 1. GX de ΔT=50 ms Animation: binsim

8 Simultaneous light curves (ΔT=2.5 s) (ΔT=50 ms) (ΔT=50 ms) Comparison star (ΔT= 50 ms) Cts s -1 ( kev RXTE PCA (<~ 60

9 (Gandhi+10) (CCF) Optical and X-ray simultaneous timing + VLT RXTE PCA u 2.5 s resolution, ~1 h of data GX : 2007 low/hard state

10 (Gandhi+10) (CCF) New fast red component in CCF? + r u VLT RXTE PCA g g r u 2.5 s resolution, ~1 h of data GX : 2007 low/hard state

11 ( CCF ) Sub-second X-O Cross Correlation Function (Gandhi+ 2008) VLT r r r + RXTE PCA 150 ms 1 Average 50 ms resolution, ~1 h of data (x3) GX : 2007 low/hard state Optical Lag (seconds)

12 ULTRACAM de 2. Swift J Galactic halo BH transient - Very short period ~ 3h (Zurita+08) - Lives in the low/hard state - Radio weak source Animation: binsim ΔT=39 ms

13 Swift J (Durant+08)

14 Asymmetric and complex optical/x-ray cross-correlation functions in X-ray binaries GX 339-4: Gandhi et al Swift J : Durant et al Origin? Reprocessing XTE J : 2001 al. Kanbach et All X-ray data: RXTE PCA

15 1. Small time delay, sharp positive response 150 ms 1 Average Optical Lag (seconds) (Gandhi+ 2008)

16 2. Anti-correlation GX 339-4: Gandhi et al Swift J : Durant et al XTE J : 2001 al. Kanbach et All X-ray data: RXTE PCA

17 3. Small optical coherence times Auto Correlation Function (Poisson corrected) GX XTE J X-rays (PCA) X-rays (PCA) Optical (white) ( u, g, r )Optical Lag (s) Optical ACFs narrower than X-ray ACF for two sources

18 4. How much reprocessing is expected? All sources in low/hard state with L X /L Edd <~0.01

19 Speedy optical variability: scales and power Fastest flares have timescales <~ ms. => R <~ 10 4 km <~ 10 3 R G Brightness temperature => T B >~ 10 7 K Equipartition => B > 10 4 G

20 Models for XTE J Optical (cyclo)synchrotron. Interaction between components. Merloni+00 Magnetic corona Esin+01 Advection flow (ADAF) Markoff+01 Pure jet Malzac+04 Magnetic reservoir jet + corona Yuan+05 ADAF+jet Veledina+11 Synchrotron-self-Compton+reprocessing

21 GX 339-4: Two separate components? Or one? Observed optical Observed X-rays soft hard g r rms optical flux rms X-ray flux RMS spectrum optical and X-ray slopes differ, suggesting two different components (Gandhi+10).

22 B field dissipation anti-correlation Jet / Outflow Schematic cartoon Disk Release of coronal B energy density optical cyclosynchrotron (Gandhi+10)

23 Jet 150 ms positive correlation Jet / Outflow Schematic cartoon Disk (Gandhi+10) Time delay of 150 ms => jet optical (cyc)syn, at R lightspeed, or R v Alvenic, for jet poloidal field perturbations on times ~ tens x t dynamical ~ 100 ms; (Livio+03; Malzac+04)

24 Outer disc slow positive correlation Jet / Outflow Schematic cartoon Disk (Gandhi+10) Slow delay on ~seconds time lag => Positive Opt/X CCF due to reprocessing on outer disc

25 Inferences from CCF characteristic times Positive correlation delay => perturbation delay from disc/corona to jet Slow positive correlation delay => constrain reprocessing in outer disc (Gandhi+10) Anti-correlation time => size of corona/hot flow and/or strength of X- ray flaring episodes.

26 Swift J : Weak positive CCF and faint jet Radio Upper-limits (Durant+ 2009) Strong jetted sources have sharp positive correlation (Gandhi+10)

27 Complex optical/x-ray correlations XTE J : Kanbach GX 339-4: 2001 al. et Gandhi et al Models outnumber sources! Swift J : Durant et al P. Gandhi JAXA 2009 Sep 24

28 X-ray : Optical Cross-Correlation Function (CCF) (Durant+11) Neutron star binaries Cyg X-2 Optical Delay (s)

29 IR : clean probe of jet? Corbel & Fender 2002

30 X-ray/IR CCF Infrared variability GX low/hard state IR lag 100 ms X-rays/XTE Infrared/VLT/ISAAC (Casella+10, Gandhi+11 submitted)

Multi-wavelength timing gives independent,

31 Rapid optical flaring in low/hard state observations of several binaries. Summary Optical not reprocessed simply. Complex CCF => jet/corona/disk interaction. Multi-wavelength timing gives independent, quantitative constraints on accretion on a wide range of timescales.

Rapid optical and X-ray timing observations of GX 339 4: flux correlations at the onset of a low/hard state

Mon. Not. R. Astron. Soc. 390, L29 L33 (2008) doi:10.1111/j.1745-3933.2008.00529.x Rapid optical and X-ray timing observations of GX 339 4: flux correlations at the onset of a low/hard state P. Gandhi,