Timing Features of XTE J in 2003 March outburst Fan Zhang et al. (astro-ph/ ) --Possible Evidence for Accreting Blobs

Content 1. Introduction  LMXBs : correlations of spectral state and timing variability  MXPs : basic observational results 2. Timing features of J  Four flares distinguished in 2003 March RXTE observation  Correlations among count rate, basic fractional pulse amplitude and QPO frequencies 3. Discussion of our results  Constraints on QPO models  Possible origin of the relatively soft broad ‘ puny ’ flares

Introduction of LMXBs Van der Klis 2004, astro-ph/

Source state

Power density spectrum

Common frequency correlation ? L_Hz ~150Hz ? L_h2 (harmonic) ? L_LFN

Open questions Is hecto-hertz QPO specific for atoll ? Is L_h harmonic specific for Z ? Does LFN really vary in different Z ? Are twin kHz QPOs correlated with NS spin ? MXP,e.g. SAX J burst oscillation-spin

Introduction of MXPs

Accretion powerd millisecond X-ray pulsar Ultra-compact group (Porb<40 min) XTE J (2003) XTE J (2002) XTE J (2002) Relatively wide group (Porb=2.~4.28 hour) SAX J (1998) XTE J (2003) IGR J (2005) type I thermal nuclear outburst kHz QPOs

Frequency correlation in MXPs

Lightcurve of MXPs -----Wijnands (astro-ph/ )

Why choose XTE J ?  Twin kHz QPOs – inner disk evolution  Binary parameters – pulse profiles – NS surface emission  Compton dominated spectrum  No type I thermonuclear bursts  so we can focus on studying the effect of disk evolutions on the NS surface emission

XTE J : 4 flares 1. Hours-to-days low-amplitude intensity fluctuation; 2. Stronger soft emission enhancement 3. Apparent basic pulse amplitude variability

Power Spectra

Frequency correlation 1,Common frequency correlations between Lu,Ll,LhHz,Lh,Lb 2, Additional components of L_h2, L_LFN 3,shift factor of 1.5 for Lu, Ll, L_LFN

Correlations between net count rate,kHz QPOs and the fractional basic pulse profile Are parallel tracks related to the flares? Inner disk movement is correlated with NS surface emissions

Discussion: constraints on QPO models 1.Both L_Hz and L_h harmonic are observed in one source XTE J , so they are not specific components for atoll or Z sources. 2.L_b and L_LFN appear simultaneously in the spectrum of XTE J , so they are two components with different origins.  L_LFN of GX17+2 is a different component from L_LFN observed in other Z sources, so its distribution can not be explained by the same QPO model for L_b of atoll or L_LFN of other Z sources. 3.Shift factor of about 1.5 exists also in XTE J The kHz QPO frequency separation varies around 191Hz. Abramowicz et al. 2003, A&A, 404, L21

Discussion: origin of the flares Inner disk radius variability (Accretion rate? Accretion pattern?)  groups 1-3, groups 4-6 QPO frequency variability NS emission variability  Variable relationship between a0/c0 and c0 Poutanen, J. & Gierlinski, M. 2003, MNRAS, 343, 1301 Bildsten, L. 1993, Apj, 418, L21 Strohmyer, T. E. Astro-ph/ Possible Origin: 1.Accreting inhomogeneous disk flow 2.Nuclear burning, e.g. ‘fires’ on the NS surface (Bildsten 1993)

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