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J/A+A/447/245       Cyg X-1 Spectral Evolution 1999-2004     (Wilms+, 2006)

Long Term Variability of Cyg X-1: IV. Spectral Evolution 1999-2004. Wilms J., Nowak M.A., Pottschmidt K., Pooley G.G., Fritz S. <Astron. Astrophys. 447, 245 (2006)> =2006A&A...447..245W
ADC_Keywords: Binaries, X-ray ; Stars, variable Keywords: stars: individual: Cyg X-1 - stars: binaries: close - X-rays: binaries - black hole physics Abstract: Continuing the observational campaign initiated by our group, we present the long term spectral evolution of the Galactic black hole candidate Cygnus X-1 in the X-rays and at 15GHz. We present about 200 pointed observations taken between early 1999 and late 2004 with the Rossi X-ray Timing Explorer and the Ryle radio telescope. The X-ray spectra are remarkably well described by a simple broken power law spectrum with an exponential cutoff. Physically motivated Comptonization models, e.g., by Titarchuk (1994ApJ...434..570T, compTT) and by Coppi (1999, eqpair), can reproduce this simplicity; however, the success of the phenomenological broken power law models cautions against ``over-parameterizing'' the more physical models. Broken power law models reveal a significant linear correlation between the photon index of the lower energy power law and the hardening of the power law at about 10keV. This phenomenological soft/hard power law correlation is partly attributable to correlations of broad band continuum components, rather than being dominated by the weak hardness/reflection fraction correlation present in the Comptonization model. Specifically, the Comptonization models show that the bolometric flux of a soft excess (e.g., disk component) is strongly correlated with the compactness ratio of the Comptonizing medium, with Ldisk∝(lh/ls_)-0.19. Over the course of our campaign, Cyg X-1 transited several times into the soft state, and exhibited a large number of ``failed state transitions''. The fraction of the time spent in such low radio emission/soft X-ray spectral states has increased from about 10% in 1996-2000 to about 34% since early 2000. We find that radio flares typically occur during state transitions and failed state transitions (at lh/ls∼3), and that there is a strong correlation between the 10-50keV X-ray flux and the radio luminosity of the source. We demonstrate that rather than there being distinctly separated states, in contrast to the timing properties the spectrum of Cyg X-1 shows variations between extremes of properties, with clear cut examples of spectra at every intermediate point in the observed spectral correlations. Objects: ---------------------------------------------------------- RA (2000) DE Designation(s) ---------------------------------------------------------- 19 58 21.7 +35 12 06 Cyg X-1 = V* V1357 Cyg ---------------------------------------------------------- File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 388 202 Best-fit results for the broken power-law model table1.fit 2880 31 FIT version of table1 table2.dat 394 202 Best-fit results for the compTT models table2.fit 2880 31 FIT version of table2 table3.dat 494 202 Best-fit results for the eqpair models table3.fit 2880 34 FIT version of table3
See also: J/AZh/78/408 : Variability of Cyg X-1 in 1994-1998 (Karitskaya+, 2001) J/PAZh/26/27 : Variability of Cyg X-1 (V1357) in 1995-1996 (Karitskaya+, 2000) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 19 A19 "date" ObsStart Date of the start of the observation, YYYY-MM-DDThh:mm:ss 21- 39 A19 "date" ObsEnd Date of the end of the observation, YYYY-MM-DDThh:mm:ss 41- 48 F8.2 d MJDStart MJD of the start of observation 50- 57 F8.2 d MJDStop MJD of the end of observation 59- 63 I5 s ExpTime Exposure time 65- 70 F6.1 ct/s CR Count rate 72- 78 F7.5 ct/s e_CR rms uncertainty on CR 80- 85 F6.4 cm-2/s Fph(2-5) 2-5keV band photon flux (G1) 87- 96 E10.5 mW/m2 Fene(2-5) 2-5keV band energy flux 98-103 F6.4 cm-2/s Fph(5-10) 5-10keV band photon flux (G1) 105-114 E10.5 mW/m2 Fene(5-10) 5-10keV energy flux 116-123 F8.6 cm-2/s Fph(10-50) 10-50keV band photon flux (G1) 125-134 E10.5 mW/m2 Fene(10-50) 10-50keV band energy flux 136-144 F9.7 cm-2/s Fph(50-100) 50-100keV band photon flux (G1) 146-155 E10.5 mW/m2 Fene(50-100) 50-100keV band energy flux 158-163 F6.4 cm-2/s Fph(2-100) 2-100keV band photon flux (G1) 165-174 E10.5 mW/m2 Fene(2-100) 2-100keV band energy flux 176-182 F7.3 --- chi2 chi2 value 183-185 I3 --- DOF Degree of freedom 187-193 F7.5 --- chi2red Reduced chi2 value 196-205 E10.8 10+22cm-2 nH Hydrogen column density 207-215 F9.7 10+22cm-2 e_nH 90% uncertainty range on nH 217-226 F10.7 keV cutoffE Cutoff energy 228-238 F11.8 keV e_cutoffE 90% uncertainty range on cutoffE 240-246 F7.3 keV FoldE Folding energy 247-253 F7.3 keV e_FoldE 90% uncertainty range on FoldE 255-260 F6.4 keV lineE Fe Kalpha line energy 262-267 F6.4 keV e_lineE 90% uncertainty range on LineE 269-279 F11.9 keV lineEsigma Fe Kalpha width (sigma) 282-290 F9.7 keV e_lineEsigma 90% uncertainty range on lineEsigma 292-300 F9.7 --- lineEN Fe Kalpha norm (total photons in line) 302-310 F9.7 --- e_lineEN 90% uncertainty range on lineEN 312-317 F6.4 --- PI1 Photon index below break energy 319-324 F6.4 --- e_PI1 90% uncertainty range on PI1 326-332 F7.4 keV BreakE Break energy 334-340 F7.4 keV e_BreakE 90% uncertainty range on BreakE 342-347 F6.4 --- PI2 Photon index above break energy 349-354 F6.4 --- e_PI2 90% uncertainty range on PI2 357-363 F7.4 --- bknpowerN Photon flux of bkn powerlaw at 1keV 365-372 F8.5 --- e_bknpowerN 90% uncertainty range on bknpoweN 374-380 F7.5 --- Factor Flux normalization factor 382-388 F7.5 --- e_Factor 90% uncertainty range on Factor
Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 19 A19 "date" ObsStart Date of the start of the observation, YYYY-MM-DDThh:mm:ss 21- 39 A19 "date" ObsEnd Date of the end of the observation, YYYY-MM-DDThh:mm:ss 41- 48 F8.2 d MJDStart MJD of the start of observation 50- 57 F8.2 d MJDStop MJD of end of observation 59- 63 I5 s ExpTime Exposure time 65- 70 F6.1 ct/s CR Count rate 72- 78 F7.5 ct/s e_CR rms uncertainty on CR 80- 85 F6.3 cm-2/s FphDisk Accretion disk unabsorbed photon flux (G1) 87- 96 E10.5 mW/m2 FeneDisk Accretion disk unabsorbed energy flux 98-103 F6.3 cm-2/s FphTotal Bolometric unabsorbed photon flux (G1) 105-114 E10.5 mW/m2 FeneTotal Bolometric unabsorbed energy flux 116-121 F6.4 cm-2/s Fph(2-5) 2-5keV band photon flux (G1) 123-132 E10.5 mW/m2 Fene(2-5) 2-5keV band energy flux 134-139 F6.4 cm-2/s Fph(5-10) 5-10keV band photon flux (G1) 141-150 E10.5 mW/m2 Fene(5-10) 5-10keV energy flux 152-159 F8.6 cm-2/s Fph(10-50) 10-50keV band photon flux (G1) 161-170 E10.5 mW/m2 Fene(10-50) 10-50keV band energy flux 172-180 F9.7 cm-2/s Fph(50-100) 50-100keV band photon flux (G1) 182-191 E10.5 mW/m2 Fene(50-100) 50-100keV band energy flux 193-198 F6.2 --- chi2 chi2 value of the best fit 200-202 I3 --- DOF Degree of freedom 204-210 F7.5 --- chi2red Reduced chi2 value 212-221 E10.8 10+22cm-2 nH Hydrogen column density 223-231 F9.7 10+22cm-2 e_nH 90% uncertainty range on nH 233-239 F7.5 keV Tin Inner disk temperature 241-247 F7.5 keV e_Tin 90% uncertainty range on Tin 249-255 F7.2 --- diskbbN Norm of disk (see XSPEC manual) 257-264 F8.3 --- e_diskbbN 90% uncertainty range on diskbbN 266-272 F7.3 keV kT Temperature of Comptonizing plasma 274-281 F8.3 keV e_kT 90% uncertainty range on kT 283-290 F8.6 --- taup Optical depth of Comptonizing plasma 292-300 F9.6 --- e_taup 90% uncertainty range on taup 302-310 F9.7 --- compTTN Norm of compTT model 312-321 F10.7 --- e_compTTN 90% uncertainty range on compTTN 323-332 F10.7 --- Refl omega/2pi for the reflecting medium 334-342 F9.6 --- e_Refl 90% uncertainty range on Refl 344-350 F7.5 keV Reflsigma omega/2pi for the reflecting medium (sigma) 352-358 F7.5 keV e_Reflsigma 90% uncertainty range on Reflsigma 360-368 F9.7 --- ReflN omega/2pi for the reflecting medium norm 370-378 F9.7 --- e_ReflN 90% uncertainty range on ReflN 380-386 F7.5 --- Factor Flux normalization factor 388-394 F7.5 --- e_Factor 90% uncertainty range on Factor
Byte-by-byte Description of file: table3.dat
Bytes Format Units Label Explanations
1- 19 A19 "date" ObsStart Earliest time entering observation, YYYY-MM-SSThh:mm:ss 22- 40 A19 "date" ObsEnd Latest time entering observation, YYYY-MM-SSThh:mm:ss 42- 49 F8.2 s MJDStart MJD of the start of observation 51- 58 F8.2 s MJDStop MJD of the end of observation 60- 64 I5 s TimeExp Exposure time of each file 66- 71 F6.1 ct/s CR Count rate of each file 73- 79 F7.5 ct/s e_CR rms uncertainty of each count rate 81- 86 F6.3 cm-2/s FphDisk Accretion disk unabsorbed photon flux (G1) 88- 97 E10.5 mW/m2 FeneDisk Accretion disk unabsorbed energy flux 99-104 F6.3 cm-2/s FphTotal Bolometric unabsorbed photon flux (G1) 106-115 E10.5 mW/m2 FeneTotal Bolometric unabsorbed energy flux 118-123 F6.4 cm-2/s Fph(2-5) 2-5keV band Photon flux (G1) 126-135 E10.5 mW/m2 Fene(2-5) 2-5keV band Energy flux 140-145 F6.4 cm-2/s Fph(5-10) 5-10keV band Photon flux (G1) 147-156 E10.5 mW/m2 Fene(5-10) 5-10keV band Energy flux 159-166 F8.6 cm-2/s Fph(10-50) 10-50keV band Photon flux (G1) 169-178 E10.5 mW/m2 Fene(10-50) 10-50keV band Energy flux 181-189 F9.7 cm-2/s Fph(50-100) 50-100keV Photon flux (G1) 192-201 E10.5 mW/m2 Fene(50-100) 50-100keV band Energy flux 204-209 F6.2 --- chi2 Chi-squared value of the best fit 212-214 I3 --- DOF Degrees of freedom 217-223 F7.5 --- chi2red Reduced Chi-squared 226-235 E10.8 10+22cm-2 nH Hydrogen column density 238-246 F9.7 10+22cm-2 e_nH 90% uncertainty range of nH parameter 249-255 F7.5 keV Tin Innner disk temperature 258-264 F7.5 keV e_Tin 90% uncertainty range of Tin parameter 267-277 F11.5 --- DiskbbN norm of the disk 280-290 F11.5 --- e_DiskbbN 90% uncertainty range of DiskbbN 293-298 F6.4 keV LineE Fe Kalpha line energy 301-306 F6.4 keV e_LineE 90% uncertainty range of LineE 309-315 F7.5 keV LineEsigma Fe Kalpha line width 318-325 F8.6 keV e_LineEsigma 90% uncertainty range of LineEsigma 328-336 F9.7 --- LineEN Fe Kalpha norm (total photons in line) 339-347 F9.7 --- e_LineEN 90% uncertainty range of LineEN 350-356 F7.5 --- lhls Ratio of hard to soft compactness 359-365 F7.5 --- e_lhls 90% uncertainty range of lhls 368-374 F7.5 --- taup optical depth of Comptonizing plasma 377-383 F7.5 --- e_taup 90% uncertainty range of taup 386-395 E10.7 --- Refl Omega/2pi for reflecting medium 398-405 F8.6 --- e_Refl 90% uncertainty range of Refl 408-420 E13.12 --- xi Ionization parameter of reflector 423-430 F8.3 --- e_xi 90% uncertainty range of xi 439-447 F9.7 --- eqpairN Norm of eqpair model 450-460 F11.8 --- e_eqpairN 90% uncertainty range of eqpairN 471-477 F7.5 --- Factor Flux normalization factor 488-494 F7.5 --- e_Factor 90% uncertainty range of Factor
Global notes: Note (G1): in ph/cm2/s
Acknowledgements: Joern Wilms, j.wilms(at)warwick.ac.uk
(End) Patricia Vannier [CDS] 17-Oct-2005
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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