In the radiation-hydrodynamics model,the time lag and fractional root-mean-squared(rms)amplitude as a function of emitted photon energy should show a minimum on the normal branch oscillations.This has been seen in the...In the radiation-hydrodynamics model,the time lag and fractional root-mean-squared(rms)amplitude as a function of emitted photon energy should show a minimum on the normal branch oscillations.This has been seen in the Z-sources Cyg X-2 and GX 5-1.Here,using the observations from the Rossi X-ray Timing Explorer(RXTE),we study the energy dependence of normal branch QPOs in the peculiar Z-source Cir X-1.We discuss the results in the context of radiation-hydrodynamics and the Comptonization model.展开更多
Based the Alfven wave oscillation model(AWOM)and relativistic precession model(RPM)for twin kHz QPOs,we estimate the emission positions of most detected kHz QPOs to be at r=18+/-3 km(R/15 km),except Cir X-1 at r-30+/-...Based the Alfven wave oscillation model(AWOM)and relativistic precession model(RPM)for twin kHz QPOs,we estimate the emission positions of most detected kHz QPOs to be at r=18+/-3 km(R/15 km),except Cir X-1 at r-30+/-5 km(R/15 km).For the proposed Keplerian frequency as an upper limit to kHz QPO,the spin effects in Kerr Spacetime are discussed,which have about a 5%(2%)modification for that of the Schwarzchild case for the spin frequency of 1000(400)Hz.The application to the four typical QPO sources,Cir X-1,Sco X-1,SAX J1808.4-3658 and XTE 1807-294,is mentioned.展开更多
We have investigated the relation between the root mean square(rms)variability and the X-ray flux(rms-flux relation)of the Z source Cyg X-2,and as well the energy dependence based on the Rossi X-ray Timing Explorer(RX...We have investigated the relation between the root mean square(rms)variability and the X-ray flux(rms-flux relation)of the Z source Cyg X-2,and as well the energy dependence based on the Rossi X-ray Timing Explorer(RXTE)observations.We currently focus on the horizontal branch(HB),due to the negative correlation in flux of the soft and the hard X-rays.The rms-flux correlation has energy dependence as follows:positive at hard X-rays(above 10 keV)but negative at soft X-rays(below 10 keV).This provides a feature different from the previous one,and may be suggestive of different origins of X-rays below and above 10 keV.Nevertheless,the overall spectrum can be well fitted with a model consisting of a blackbody and Comptonization components,but the fitting results do not reveal any features around 10 keV that could account for such a change in the rms-flux relation.展开更多
基金supported by the National Basic Research Program of China(Grant No.2009CB824800)the National Natural Science Foundation of China(Grant No.10773017)+1 种基金the Natural Science Foundation of Xinjiang Uygur Autonomous Region of China(Grant No.200821164)the Program of the Light in Chinese Western Region(LCWR)(Grant No.LHXZ 200802)
文摘In the radiation-hydrodynamics model,the time lag and fractional root-mean-squared(rms)amplitude as a function of emitted photon energy should show a minimum on the normal branch oscillations.This has been seen in the Z-sources Cyg X-2 and GX 5-1.Here,using the observations from the Rossi X-ray Timing Explorer(RXTE),we study the energy dependence of normal branch QPOs in the peculiar Z-source Cir X-1.We discuss the results in the context of radiation-hydrodynamics and the Comptonization model.
基金supported by the National Basic Research Program of China(Grant No.2009CB824800)the National Natural Science Foundation of China(Grant No.10773017)
文摘Based the Alfven wave oscillation model(AWOM)and relativistic precession model(RPM)for twin kHz QPOs,we estimate the emission positions of most detected kHz QPOs to be at r=18+/-3 km(R/15 km),except Cir X-1 at r-30+/-5 km(R/15 km).For the proposed Keplerian frequency as an upper limit to kHz QPO,the spin effects in Kerr Spacetime are discussed,which have about a 5%(2%)modification for that of the Schwarzchild case for the spin frequency of 1000(400)Hz.The application to the four typical QPO sources,Cir X-1,Sco X-1,SAX J1808.4-3658 and XTE 1807-294,is mentioned.
基金supported by the National Basic Re-search Program of China(Grant No.2009CB 824800)the CAS Key Project(Grant No.KJCX2-YW-T03)+1 种基金the National Natural Science Foundation of China(Grant No.10773017)the Natural Science Foundation of Xin-jiang Uygur Autonomous Region of China(Grant No.200821164)
文摘We have investigated the relation between the root mean square(rms)variability and the X-ray flux(rms-flux relation)of the Z source Cyg X-2,and as well the energy dependence based on the Rossi X-ray Timing Explorer(RXTE)observations.We currently focus on the horizontal branch(HB),due to the negative correlation in flux of the soft and the hard X-rays.The rms-flux correlation has energy dependence as follows:positive at hard X-rays(above 10 keV)but negative at soft X-rays(below 10 keV).This provides a feature different from the previous one,and may be suggestive of different origins of X-rays below and above 10 keV.Nevertheless,the overall spectrum can be well fitted with a model consisting of a blackbody and Comptonization components,but the fitting results do not reveal any features around 10 keV that could account for such a change in the rms-flux relation.
