The Orbital Modulation for the Spectrum and Mass Accretion Rate in Circinus X-1
Affiliation(s)
Xinjiang Astronomical Observatory, Chinese Academy of Sciences, Urumqi, China. University of Chinese Academy of Sciences, Beijing, China. Key Laboratory of Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, China.
Xinjiang Astronomical Observatory, Chinese Academy of Sciences, Urumqi, China. University of Chinese Academy of Sciences, Beijing, China. Key Laboratory of Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, China.
ABSTRACT
Using the data from the Proportional Counter Array on board theRossi X-Ray Timing Explorersatellite, we study the orbital modulation for the spectrum and mass accretion rate of Cir X-1 during its two orbital periods. We use a model consisting of a blackbody, a multicolor disk blackbody, and a line component to fit the spectrum and find that the spectrum is obviously modulated by the orbital phase. It is shown that the disk accretion rate in Cir X-1 undergoes three states during the orbital period. At the periastron with orbital phase 0-0.1, the disk accretion rate is sup-Eddington, then from phase 0.1 to the apastron (phase 0.5) it decreases dramatically and becomes near-Eddington, and from the apastron to the next periastron (phase 1) the disk accretion rate approximates Eddington and tends to be steady. We argue that the evolution of the disk accretion rate is attributed to the high orbital eccentricity of this source. The mass accretion rate onto the neutron star is much less than that onto the inner disk, indicating significant outflows in this source.
Using the data from the Proportional Counter Array on board theRossi X-Ray Timing Explorersatellite, we study the orbital modulation for the spectrum and mass accretion rate of Cir X-1 during its two orbital periods. We use a model consisting of a blackbody, a multicolor disk blackbody, and a line component to fit the spectrum and find that the spectrum is obviously modulated by the orbital phase. It is shown that the disk accretion rate in Cir X-1 undergoes three states during the orbital period. At the periastron with orbital phase 0-0.1, the disk accretion rate is sup-Eddington, then from phase 0.1 to the apastron (phase 0.5) it decreases dramatically and becomes near-Eddington, and from the apastron to the next periastron (phase 1) the disk accretion rate approximates Eddington and tends to be steady. We argue that the evolution of the disk accretion rate is attributed to the high orbital eccentricity of this source. The mass accretion rate onto the neutron star is much less than that onto the inner disk, indicating significant outflows in this source.
Cite this paper
G. Ding, C. Huang and J. Qu, "The Orbital Modulation for the Spectrum and Mass Accretion Rate in Circinus X-1," International Journal of Astronomy and Astrophysics, Vol. 2 No. 4, 2012, pp. 256-265. doi: 10.4236/ijaa.2012.24033.
G. Ding, C. Huang and J. Qu, "The Orbital Modulation for the Spectrum and Mass Accretion Rate in Circinus X-1," International Journal of Astronomy and Astrophysics, Vol. 2 No. 4, 2012, pp. 256-265. doi: 10.4236/ijaa.2012.24033.
References
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[1] L. J. Kaluzienski, S. S. Holt, E. A. Boldt and P. J. Serlemitsos, “Evidence for a 16.6 Day Period from Circinus X-1,” Astrophysical Journal, Vol. 208, No. 2, 1976, pp. L71-L75. doi:10.1086/182235 [2] G. L. Case and D. Bhattacharya, “A New Sigma-D Relation and Its Application to the Galactic Supernova Remnant Distribution,” Astrophysical Journal, Vol. 504, No. 2, 1988, pp. 761-772. doi:10.1086/306089 [3] B. Margon, M. Lampton, S. Bowyer and R. Cruddace, “A Pulsing X-Ray Source in Circinus,” Astrophysical Journal, Vol. 169, 1971, pp. L23-L25. doi:10.1086/180806 [4] A. Toor, “Millisecond X-Ray Bursts from Circinus X-1,” Astrophysical Journal, Vol. 215, No. 2, 1977, pp. L57-L60. doi:10.1086/182477 [5] G. D. Nicolson, I. S. Glass and M. W. Feast, “Recent Changes in the Optical, Infrared and Radio Emission from Circinus X-1,” Monthly Notices of the Royal Astronomical Society, Vol. 191, 1980, pp. 293-299. [6] R. A. Preston, D. D. Morabito, A. E. Wehrle, D. L. Jauncey, M. J. Batty, R. F. Haynes, A. E. Wright and G. D. Nicolson, “VLBI Observations of a Radio Flare of Circinus X-1,” Astrophysical Journal, Vol. 268, No. 2, 1983, pp. L23-L26. doi:10.1086/184022 [7] A. F. Tennant, A. C. Fabian and R. A. Shafer, “The Discovery of X-Ray Bursts from CIR X-1,” Monthly Notices of the Royal Astronomical Society, Vol. 219, 1986, pp. 871-881. [8] A. F. Tennant, A. C. Fabian and R. A. Shafer, “Observation of Type I X-Ray Bursts from CIR X-1,” Monthly Notices of the Royal Astronomical Society, Vol. 221, 1986, pp. 27P-31P. [9] A. F. Tennant, “High-Frequency Oscillations from CIR X-1,” Monthly Notices of the Royal Astronomical Society, Vol. 226, 1987, pp. 971-978. [10] A. F. Tennant, “Observations of 1.4-Hz Quasi-Periodic Oscillations in CIR X-1,” Monthly Notices of the Royal Astronomical Society, Vol. 230, 1988, pp. 403-404. [11] J. L. Qu, W. Yu and T. P. Li, “The Cross Spectra of Circinus X-1: Evolution of Time Lags,” The Astrophysical Journal, Vol. 555, No. 1, 2001, pp. 7-11. doi:10.1086/321460 [12] J. L. Qu, Y. Lu, G. Q. Ding, F. Zhang, Y. J. Lei and Z. B. Li, “The Time Lag Spectrum of Cir X-1 on Its Normal Branch,” Science China Physics, Mechanics and Astronomy, Vol. 53, No. 1, 2010, pp. 60-63. doi:10.1007/s11433-010-0035-z [13] R. T. Stewart, J. L. Caswell, R. F. Haynes and G. J. Nelson, “Circinus X-1—A Runaway Binary with Curved Radio Jets,” Monthly Notices of the Royal Astronomical Society, Vol. 261, No. 3, 1993, pp. 593-598. [14] T. Oosterbroek, M. van der Klis, E. Kuulkers, J. van Paradijs and W. H. G. Lewin, “Circinus X-1 Revisited: Fast-Timing Properties in Relation to Spectral State,” Astronomy and Astrophysics, Vol. 297, No. 1, 1995, pp. 141-158. [15] W. N. Brandt, A. C. Fabian, T. Dotani, F. Nagase, H. Inoue, T. Kotani and Y. Segawa, “ASCA Observations of the Iron K Complex of Circinus X-1 near Zero Phase: Spectral Evidence for Partial Covering”, Monthly Notices of the Royal Astronomical Society, Vol. 283, No. 3, 1996, pp. 1071-1082. [16] R. E. Shirey, H. V. Bradt, A. M. Levine and E. H. Morgan, “Quasi-Periodic Oscillations Associated with Spectral Branches in Rossi X-Ray Timing Explorer Observations of Circinus X-1,” The Astrophysical Journal, Vol. 506, No. 1, 1998, pp. 374-383. doi:10.1086/306247 [17] R. E. Shirey, H. V. Bradt and A. M. Levine, “The Complete “Z” Track of Circinus X-1,” The Astrophysical Journal, Vol. 517, No. 1, 1999, pp. 472-487. doi:10.1086/307188 [18] W. N. Brandt and N. S. Schulz, “The Discovery of Broad P Cygni X-Ray Lines from Circinus X-1 with the Chandra High-Energy Transmission Grating Spectrometer,” The Astrophysical Journal, Vol. 544, No. 2, 2000, pp. L123-L127. doi:10.1086/317313 [19] G. Q. Ding, J. L. Qu and T. P. Li, “Evolution of Hard X-Ray Spectra along the Branches in Circinus X-1,” The Astrophysical Journal, Vol. 596, No.2, 2003, pp. L219-L222. doi:10.1086/379338 [20] S. Boutloukos, M. van der Klis, D. Altamirano, M. Klein-Wolt, R. Wijnands, P. G. Jonker and R. P. Fender, “Discovery of Twin kHz QPOs in the Peculiar X-Ray Binary Circinus X-1,” The Astrophysical Journal, Vol. 653, No. 2, 2006, pp. 1435-1444. doi:10.1086/508934 [21] R. Fender, K. Wu, H. Johnston, T. Tzioumis, P. Jonker, R. Spencer and M. van der Klis, “An Ultra-Relativistic Outflow from a Neutron Star Accreting Gas from a Companion,” Nature, Vol. 427, No. 6971, 2004, pp. 222-224. doi:10.1038/nature02137 [22] S. Heinz, N. S. Schulz, W. N. Brandt and D. K. Galloway, “Evidence of a Parsec-Scale X-Ray Jet from the Accreting Neutron Star Circinus X-1,” The Astrophysical Journal, Vol. 663, No. 2, 2007, pp. L93-L96. doi:10.1086/519950 [23] D. E. Calvelo, R. P. Fender, A. K. Tzioumis, N. Kawai, J. W. Broderick and M. E. Bell, “Radio Observations of Circinus X-1 over a Complete Orbit at an Historically Faint Epoch,” Monthly Notices of the Royal Astronomical Society, Vol. 419, No. 1, 2012, pp. 436-451. doi:10.1111/j.1365-2966.2011.19708.x [24] D. E. Calvelo, R. P. Fender, A. K. Tzioumis and J. W. Broderick, “Millimetre Observations of a Sub-Arcsecond Jet from Circinus X-1,” Monthly Notices of the Royal Astronomical Society: Letters, Vol. 419, No. 1, 2012, pp. L54-L58. doi:10.1111/j.1745-3933.2011.01175.x [25] J. C. A. Miller-Jones, A. Moin, S. J. Tingay, C. Reynolds, C. J. Phillips, A. K. Tzioumis, R. P. Fender, N. J. McCallum, G. D. Nicolson and V. Tudose, “The First Resolved Imaging of Milliarcsecond-Scale Jets in Circinus X-1,” Monthly Notices of the Royal Astronomical Society: Letters, Vol. 419, No. 1, 2012, pp. L49-L53. doi:10.1111/j.1745-3933.2011.01176.x [26] P. Soleri, S. Heinz, R. A. Fender, R. Wijnands, V. tudose, D. Altamirano. P. G. Jonker, M. van der Klis, L. Kuiper, C. Kaiser and P. Casella, “ A Parsec Scale X-Ray Extended Structure from the X-Ray Binary Circinus X-1,” Monthly Notices of the Royal Astronomical Society: Letters, Vol. 397, No. 1, 2009, pp. L1-L5. doi:10.1111/j.1745-3933.2008.00574.x [27] P. H. Sell, S. Heinz, D. E. Calvelo, V. Tudose, P. Soleri, R. P. Fender, P. G. Jonker, N. S. Schulz, W. N. Brandt, M. A. Nowak, “Parsec-Scale Bipolar X-Ray Shocks Produced by Powerful Jets from the Neutron Star Circinus X-1,” The Astrophysical Journal, Vol. 719, No. 2, 2010, pp. L194-L198. doi:10.1088/2041-8205/719/2/L194 [28] N. S. Schulz and W. N. Brandt, “Variability of the X-Ray P Cygni Line Profiles from Circinus X-1 near Zero Phase,” The Astrophysical Journal, Vol. 572, No. 2, 2002, pp. 971-983. doi:10.1086/340369 [29] G. T?r?k, P. Bakala, E. ?rámková, Z. Stuchlík and M. 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