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.
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
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
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
A. Toor, “Millisecond X-Ray Bursts from Circinus X-1,” Astrophysical Journal, Vol. 215, No. 2, 1977, pp. L57-L60. doi:10.1086/182477
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.
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
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.
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.
A. F. Tennant, “High-Frequency Oscillations from CIR X-1,” Monthly Notices of the Royal Astronomical Society, Vol. 226, 1987, pp. 971-978.
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.
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
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
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.
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.
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.
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
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
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
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
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
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
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
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
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
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
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
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
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
G. T?r?k, P. Bakala, E. ?rámková, Z. Stuchlík and M. Urbanec, “On Mass Constraints Implied by the Relativistic Precession Model of Twin-Peak Quasi-Periodic Oscillations in Circinus X-1,” The Astrophysical Journal, Vol. 714, No. 1, 2010, pp. 748-757. doi:10.1088/0004-637X/714/1/748
A. D’Aì, E. Bozzo, A. Papitto, R. Iaria, T. Di Salvo1 L. Burderi, A. Riggio, E. Egron and N. R. Robba, “A Complete X-Ray Spectral Coverage of the 2010 May-June Outbursts of Circinus X-1,” Astronomy & Astrophysics, Vol. 543, 2012, p. 20. doi:10.1051/0004-6361/201118577
P. Murdin, D. L. Jauncey, I. Lerche, G. D. Nicolson, L. J. Kaluzienski, S. S. Holt and R. F. Haynes, “Binary Model of Circinus X-1. I—Eccentricity from Combined X-Ray and Radio Observations,” Astronomy and Astrophysics, Vol. 87, No. 3, 1980, pp. 292-298.
T. M. Tauris, R. P. Fender, E. P. J. van den Heuvel, H. M. Johnston and K. Wu, “Circinus X-1: Survivor of a Highly Asymmetric Supernova,” Monthly Notices of the Royal Astronomical Society, Vol. 310, No. 4, 1999, pp. 1165- 1169. doi:10.1046/j.1365-8711.1999.03068.x
H. M. Johnston, R. Fender and K. Wu, “High-Resolution Optical and Infrared Spectroscopic Observations of CIR X-1,” Monthly Notices, Vol. 308, No. 2, 1999, pp. 415- 423. doi:10.1046/j.1365-8711.1999.02702.x
R. Iaria, T. Di Salvo, L. Burderi and N. R. Robba, “Spectral Evolution of Circinus X-1 along Its Orbit,” The Astrophysical Journal, Vol. 561, No. 1, 2001, pp. 321-328. doi:10.1086/323226
G. Q. Ding, S. N. Zhang, T. P. Li and J. L. Qu, “Evolution of Hard X-Ray Spectra along the Orbital Phase in Circinus X-1,” The Astrophysical Journal, Vol. 645, No. 1, 2006, pp. 576-588. doi:10.1086/504308
R. E. Shirey, H. V. Bradt, A. M. Levine and E. H. Morgan, “X-Ray Timing and Spectral Evolution of Circinus X-1 versus Orbital Phase with the Rossi X-Ray Timing Explorer,” The Astrophysical Journal, Vol. 469, No. 1, 1996, pp. L21-L24. doi:10.1086/310264
R. T. Stewart, G. J. Nelson, W. Penninx, S. Kitamoto, S. Miyamoto and G. D. Nicolson, “On the Puzzling Nature of the X-Ray Binary Circinus X-1,” Monthly Notices of the Royal Astronomical Society, Vol. 253, 1991, pp. 212- 216.
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
R. Iaria, T. Di salvo, N. R. Robba and L. Burderi, “Study of the Circinus X-1 Broadband Spectrum at Orbital Phases Close to the Apoastron,” The Astrophysical Journal, Vol. 567, No. 1, 2002, pp. 503-509. doi:10.1086/338507
F. K. Lamb, C. J. Pethick and D. Pines, “A Model for Compact X-Ray Sources: Accretion by Rotating Magnetic Stars,” The Astrophysical Journal, Vol. 184, 1973, pp. 271-290. doi:10.1086/152325
H. L. Burger and I. J. Katz, “The Eddington Limit and Supercritical Accretion. II—Time-Dependent Calculations,” The Astrophysical Journal, Vol. 265, 1983, pp. 393-401. doi:10.1086/160684
G. Q. Ding, J. L. Qu and T. P. Li, “Partial Covering during Long-Term Dips in Circinus X-1,” The Astronomical Journal, Vol. 131, No. 3, 2006, pp. 1693-1701. doi:10.1086/499921
K. Asai, T. Dotani, K. Mitsuda, F. Nagase, Y. Kamado, E. Kuulkers and L. M. Lorraine, “Spectral Variations along the Branches in GX 5-1,” Publications of the Astronomical Society of Japan, Vol. 46, No. 5, 1994, pp. 479-491.
K. Mitsuda, H. Inoue, K. Koyama, K. Makishima, M. Matsuoka, Y. Ogawara, K. Suzuki, Y. Tanaka, N. Shibazaki and T. Hirano, “Energy Spectra of Low-Mass Binary X-Ray Sources Observed from TENMA,” Publications of the Astronomical Society of Japan, Vol. 36, No. 4, 1984, pp. 741-759.
D. Lin, R. A. Remillard and J. Homan, “Spectral States of XTE J1701-462: Link Between Z and Atoll Sources,” The Astrophysical Journal, Vol. 696, No. 2, 2009, pp. 1257- 1277. doi:10.1088/0004-637X/696/2/1257
G. Q. Ding, S. N. Zhang, N. Wang, J. L. Qu and S. P. Yan, “On the Nature of the First Transient Z Source XTE J1701-462: Its Accretion Disk Structure, Neutron Star Magnetic Field Strength, and Hard Tail,” The Astronomical Journal, Vol. 142, No. 2, 2011, pp. 34-51. doi:10.1088/0004-6256/142/2/34
S. N. Zhang, W. Cui and W. Chen, “Black Hole Spin in X-Ray Binaries: Observational Consequences,” The Astronomical Journal, Vol. 482, No. 2, pp. L155-L158. doi:10.1086/310705