Disc Jet Connection in Cygnus X-3Disc Jet Connection in Cygnus X-3

Manojendu ChoudhuryUM-DAE Centre for Excellence in Basic Sciences

Cygnus X-3

Chandra image of Cygnus X-3 highlighting the X-ray halo surrounding the binary system.

Salient properties:-High Mass X-ray Binary (HMXB); Companion is Wolf-Rayet star. Binary period is 4.8 hours. Mass function of the system is unknown.

Persistent in X-ray, infra-red and radio bands. Binary modulation present in X-ray and infra-red bands. One of the brightest source in the radio frequency with the flux going upto > 10 Jy during the major flares.

Infra-red emission is said to originate in the winds from the Wolf- Rayet companion.

Radio emission originate from double sided jets, observed during the flaring states.

It is located at a distance of ~9 kpc, in one of the spiral arm of the Galaxy.The system is shrouded by an X-ray halo, causing reprocessing, absorption, scattering of the softer X-ray emission.

Chandra image of Cygnus X-3 highlighting the elongated X-ray excess, which may be due to dust from the companion, or material from a previous jet emitted from the compact object. Heindl et al. (2003)

Cygnus X-3: GBI monitoring at 2.2 GHz and 8.3 GHz

Cygnus X-3: GBI monitoring at 2.2 GHz and 8.3 GHz

Cygnus X-3: GBI monitoring at 2.2 GHz and 8.3 GHz

Cygnus X­3

This sources (along with GRS 1915+105 and Cyg X-1) are persistently radio loud.

Cygnus X-3: Long term multi­wavelength monitoring

Soft X-ray (2-12 keV, RXTE – ASM), hard X-ray (20-100 keV, CGRO – BATSE) & radio (2.2 Ghz, GBI) long term monitoring of the source. The region 1, 3 & 4 correspond to the low state of X-ray emission, with quiescent or minor radio flare in the radio. The region 2 correspond to the high state of X-ray emission, correspondingly the radio flaring state. Choudhury et al.

(2002)

Spearman's (partial) Rank Correlation coefficient.

The coefficient is computed from the sampling distribution which may be derived by a parametric analogy.

For correlation among three variables, say, A, X & Y, the null hypothesis  correlation  b/w  A & X arises entirely from those of Y with A & X separately.

­1 < SRC coeff. <1

Region: 4 No. of Data points:53

Spearman Corr. Coeff. Null Prob. D-Param.

ASM:GBI 0.837 ### 5.23

GBI:BATSE -0.751 ### -2.67

ASM:BATSE -0.737 ### -2.17

Region: 3 No. of Data points:22

Spearman Corr. Coeff. Null Prob. D-Param.

ASM:GBI 0.660 ### 2.69

GBI:BATSE -0.427 ### 0.36

ASM:BATSE -0.714 ### -3.19

Region: 2 No. of Data points:25

Spearman Corr. Coeff. Null Prob. D-Param.

ASM:GBI 0.561 ### 4.06

GBI:BATSE 0.100 ### 2.72

ASM:BATSE -0.502 ### -3.77

Region:3,4 No. of Data points:75

Cygnus X-3: Pivoting of X­ray spectra Obs. Id. CompST:- Power law:- Exposure (s)

KT(keV) d.of f. PCA

t norm. HEXTE

norm

30082-04-06-00 1.56 4.87 2.01 1.42 4641

25.94 0.49 108 1586

3.89E-002

20099-02-01-00 1.56 5.09 2.55 0.74 4579

10.51 1.91 86 1563

0.6

NH(1022 cm) 2

Gx

Observation Id: 30082-04-06-00Energy/Frequency FLUX5-12.5 keV12.5-60.0 keV5-.0-60.0 keV2.2GHz 48 mJy8.3 Ghz 80 mJy

Observation Id: 20099-02-01-00Energy/Frequency FLUX5-12.5 keV12.5-60.0 keV5-.0-60.0 keV2.2GHz 119 mJy8.3 Ghz 205 mJy

1.94e-9 erg/cm2s3.64e-9 erg/cm2s5.58e-9 erg/cm2s

2.85e-9 erg/cm2s2.61e-9 erg/cm2s5.46 e-9 erg/cm2s

The X-ray spectra of Cygnus X-3 during the low state. The pivoting occurs between 10-20 keV, with the softer flux correlated to the radio emission.

Cygnus X-3

GRS 1915+105

Cygnus X-1

GX-339-4

Quenching of radio emission

X-ray state transition causes quenching of the jet present in the low(-hard) state.

Choudhury et al. (2003)

Corbel et al. (2000)

Alternative explanation: Comptonizing region consisting of hybrid plasma population

Low-hard state.

High-soft state.

Zdziarski et al. (2002)

Geometry of the corona is the sameas TCAF model.

Cygnus X-3: High soft state.Evolution of the X-ray spectra with radio flaring

The soft X-ray (RXTE – ASM, 2 – 12 keV) and the radio (GBI, 2.2 Ghz), show far more complicated evolution in the high state, compared to the low state.The X-ray spectra dominated by multicoloured disc black body spectrum, plus a hard (Comptonizing) component, except in the post flare phase.

The state can be further classified into 3 phases:-

The radio quiescent phase. The X-ray spectra has a strong disc black body and an equally strong Comptonizing component.

Pre-radio flare. The Comptonizing component becomes vanishingly small, resulting in a flare that follows. The flare may result in a time scale of a day or less (minor ones).

Post-radio flare. The succession of radio flares, both minor as well as major, is stopped by the change in the X-ray spectrum, with the spectral shape hardening in the soft X-ray region. The disc black body component becomes insignificant. The spectral shape is explained by the similar components of the low state, viz. CompST & power law.

     I

I

I I I I

II II I I

Evolution of X-ray emission with radio flaring events

Evolution of X-ray emission with radio flaring events

Quiescent Radio Emission

Flux tau50500 7.9 1.8 1.9 24.05% 23.93 2.22 6 75.95%51587 6.6 1.44 3.4 51.51% 13.39 1.59 3.2 48.49%51588 5.1 1.42 3.7 72.55% 21.69 1.39 1.4 27.45%

Pre-Radio FlareComp ST

MJD Total Flux Flux % of Total Flux tau Flux % of Total Flux

50604 6.6 1.53 6 90.91% 18.27 4.07 0.6 9.09%50624 6.9 1.55 5.9 85.51% 18.34 3.31 1 14.49%51586 5.3 1.56 4.4 83.02% 42.31 3.41 0.9 16.98%51589 4.5 1.53 3.8 84.44% 53.53 2.4 0.7 15.56%51646 3.6 1.63 3.3 91.67% 54.33 2.53 0.3 8.33%51650 5.8 1.7 5 86.21% 80.79 9.91 0.8 13.79%

Post-Radio Flare

Total Flux Gamma Flux tau50495 8.5 2.43 4.2 49.41% 4.03 8.12 4.3 50.59%50632 9.9 2.62 4 40.40% 5.12 7.05 5.9 59.60%51676 7.9 2.62 2.7 34.18% 6.18 6.36 5.2 65.82%

Model Paramaters and Flux contribution

Disk Black Body Comp ST MJD Total Flux Ktin (keV) % of Total Flux KTE (keV) Flux % of Total Flux

Disk Black BodyKtin (keV) KTE (keV)

Powerlaw Comp ST MJD % of Total Flux KTE (keV) Flux % of Total Flux

X-ray spectral parameters with radio flaring events

Soft & hard X-ray anti-correlation: Time lag between hard and soft X-rays

Binary template of Cygnus X-3. The RXTE-ASM monitoring data of the source, covering nearly 3 years of observation, is folded at the quadratic ephemeris.

RXTE-PCA lightcurve of Cygnus X-3, before and after correction for binary modulation

Soft & hard X-ray anti-correlation: Time lag between hard and soft X-rays

Time lag between the hard and soft X-rays, with the hard X-ray lagging, during the low (and hard) state. Cross-correlation is obtained after correcting for the binary modulation.

Choudhury & Rao (2004)

MJD Observ. Id. Delay (s) Statistical Coefficient

50321 10126­01­01­01(error) F.F.T. (error) Pearson (Null Prob.) Spearman (Null prob.)

~ ­0.48 (~0.04)50322 10126­01­01­02 ~ ­0.44 (~0.04)50952 30082­04­04­00 ~ ­0.61 (~0.08)50953 30082­04­05­00 ~ ­0.58 (~0.08)50954 30082­04­06­00 0 – 1000 ~ ­0.40 (~0.08) — —

620 (±70) ­0.51 (~10­12) ­0.58 (~10­30)750 (±120) ­0.46 (~10­4) ­0.43 (~10­13)700 (±50) ­0.66 (~10­11) ­0.69 (~10­36)950 (±60) ­0.73 (~10­13) ­0.75 (~10­39)

The viscous time scale for radiation pressure dominated optically thick accretion disc

tvisc=30α−1M−1 /2R7 /2 M−2s

whereα→viscosityparameter (unitsof 0.01) ,M→massof compact object (unitsos solar mass) ,R→radiationlocationof accretiondisc (units of 107 cm) , M→massaccretion rate(unitsof 1018g /s )

Takingα=1,M=10, M=3 (15Eddingtonaccretionrate), for tvisc≈1000 s ,R∼7

i. e . for a10solar massblackhole R∼25Schwartzchild radius