J/A+A/452/975 Temporal variability of Cygnus X-1 (Axelsson+, 2006)
Probing the temporal variability of Cygnus X-1 into the soft state.
Axelsson M., Borgonovo L., Larsson S.
<Astron. Astrophys. 452, 975 (2006)>
=2006A&A...452..975A 2006A&A...452..975A
ADC_Keywords: Accretion ; Binaries, X-ray ; X-ray sources
Keywords: Accretion, accretion disks ; Stars: individual: Cyg X-1 ;
X-rays: binaries
Abstract:
We present results of fitting power density spectra from archived
Rossi X-ray Timing Explorer (RXTE) data of the source Cygnus X-1.
The data cover the observations of the source during 1996-2003,
and all spectral states are included.
Description:
This file contains the results of the fits of two Lorentzians and a
cut-off power-law to the X-ray power density spectra of Cygnus X-1.
The power spectra in all spectral states of the source are fitted with
this model. The majority of the data were first presented in Axelsson
et al. (2005A&A...438..999A 2005A&A...438..999A), but is included as Table 1 in Axelsson
et al. (2006A&A...452..975A 2006A&A...452..975A).
Note that some data has been refitted after further analysis as
described in Axelsson et al. (2006A&A...452..975A 2006A&A...452..975A), and some time
ranges therefore overlap. In addition, in the refitted cases one
parameter was frozen to the value given in the table. The error-bars
of this parameter (W1) are here equal to exactly zero.
Parameters of components which were not present in the fit are
identified by setting them to exactly zero.
Objects:
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RA (2000) DE Designation(s)
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19 58 21.7 +35 12 05 Cyg X-1 = HD 226868
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 277 1819 *Results of fitting two Lorentzians and cut-off
power-law to power spectra of RXTE/PCA
observations of Cyg X-1 from 1996-2003.
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Note on table1.dat:
The frequency range is from 0.01Hz to 25Hz, with reanalyzed data
(model Nb 3) extending to 50Hz. The energy range is 2-9keV.
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See also:
http://heasarc.gsfc.nasa.gov/FTP/xte/data/archive : XTE Archive
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 15 A15 --- ObsID Proposal number and sub-ID
17- 25 F9.3 d Tstart Start time in MJD
27- 35 F9.3 d Tstop Stop time in MJD
37 I1 --- Model [1/5] Model components presence (1)
39- 49 E11.5 ct/s F2-9keV Average 2-9keV flux
51- 61 E11.5 --- HR Average (9-20)keV/(2-4)keV flux ratio
63- 73 E11.5 --- A Normalization of power-law (2)
75- 85 E11.5 --- e_A Error of A
87- 97 E11.5 --- alpha Index of power-law (2)
99-109 E11.5 --- e_alpha Error of alpha
111-121 E11.5 Hz fc Cut-off frequency for power-law (2)
123-133 E11.5 Hz e_fc Error of fc
135-145 E11.5 --- W1 Width par of Lorentzian 1 (2)
147-157 E11.5 --- e_W1 Error of W1
159-169 E11.5 Hz H1 Height par of Lorentzian 1 (2)
171-181 E11.5 Hz e_H1 Error of H1
183-193 E11.5 Hz freq1 Peak frequency of Lorentzian 1 (2)
195-205 E11.5 Hz e_freq1 Error of freq1
207-217 E11.5 --- W2 Width par of Lorentzian 2 (2)
219-229 E11.5 --- e_W2 Error of W2
231-241 E11.5 Hz H2 Height par of Lorentzian 2 (2)
243-253 E11.5 Hz e_H2 Error of H2
255-265 E11.5 Hz freq2 Peak frequency of Lorentzian 2 (2)
267-277 E11.5 Hz e_freq2 Error of freq2
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Note (1): Model components presence as follows:
1 = only two Lorentzians are present,
2 = two Lorentzians and cut-off power-law,
3 = refitted results (two Lorentzians and cut-off power-law present),
4 = first Lorentzian and cut-off power-law only,
5 = purely cut-off power-law.
Note (2): We describe the power spectrum using a model of two Lorentzian
components and a cut-off power-law.
The Lorentzians have the form:
L(f)=H*W*ν/((f-ν)2+f*W*ν), where
H is the value of frequency times power at the peak frequency ν,
and W a dimensionless measure of the relative width of the profile
in the frequency times power (Pf) representation.
The cut-off power-law is of the form:
Pl(f)=A*f-α*e-(f/fc_)^ , where
A is the normalization constant, α is the exponent, and
fc is the turnover frequency.
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Acknowledgements:
Magnus Axelsson, magnusa(at)astro.su.se
Luis Borgonovo, luis(at)astro.su.se
Stefan Larsson, stefan(at)astro.su.se
(End) M. Axelsson, L. Borgonovo, S. Larsson [Stockholm Univ.] 31-Mar-2006