timing features of xte j1807-294 in 2003 march outburst
DESCRIPTION
Timing Features of XTE J1807-294 in 2003 March outburst. --Possible Evidence for Accreting Blobs. Fan Zhang et al. (astro-ph/0602529). Content. 1. Introduction LMXBs : correlations of spectral state and timing variability MXPs : basic observational results - PowerPoint PPT PresentationTRANSCRIPT
Timing Features of XTE J1807-294 in 2003 March outburst
Fan Zhang et al. (astro-ph/0602529)
--Possible Evidence for Accreting Blobs
Content
1. Introduction LMXBs : correlations of spectral state and timing variability MXPs : basic observational results
2. Timing features of J1807-294 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/0410551
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 J1808.4-3658 ----- burst oscillation-spin
Introduction of MXPs
Introduction of MXPsAccretion powerd millisecond X-ray pulsar Ultra-compact group (Porb<40 min) XTE J1807-294 (2003) XTE J1751-305 (2002) XTE J0929-314 (2002) Relatively wide group (Porb=2.~4.28 hour) SAX J1808.4-3658 (1998) XTE J1814-338 (2003) IGR J00291+5934 (2005) ---------type I thermal nuclear outburst ---------kHz QPOs
Frequency correlation in MXPs
Lightcurve of MXPs
-----Wijnands (astro-ph/0501264)
Why choose XTE J1807-294? 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 J1807-294: 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 betweenLu,Ll,LhHz,Lh,Lb
2, Additional componentsof L_h2, L_LFN
3,shift factor of 1.5 forLu, 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 J1807-294, so they are not specific components for atoll or Z sources.
2. L_b and L_LFN appear simultaneously in the spectrum of XTE J1807-294, 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 J1807-294.
4. 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, 1301Bildsten, L. 1993, Apj, 418, L21
Strohmyer, T. E. Astro-ph/0301544
Possible Origin: 1.Accreting inhomogeneous disk flow 2.Nuclear burning, e.g. ‘fires’ on the NS surface
(Bildsten 1993)
Thanks !