| Cai J-M, Zhou Z-W, Yuan Y-F and Guo G-C (2007), "Quantum decoherence modulated by special relativity", Phys. Rev. A., October, 2007. Vol. 76(4), pp. 042101-+. |
| Abstract: By investigating the evolution of a moving spin- (1)/(2) Dirac electron coupled with a background magnetic noise, we demonstrate that the effects of special relativity will significantly modify the decoherence properties of the spin state. The dephasing could be much suppressed, and for a sufficiently long time the decoherence even seems to halt. This interesting phenomenon stems from the dressed environment induced by special relativity. |
BibTeX:
@article{pra76_42101,
author = {Cai, J.-M. and Zhou, Z.-W. and Yuan, Y.-F. and Guo, G.-C.},
title = {Quantum decoherence modulated by special relativity},
journal = {Phys. Rev. A},
year = {2007},
volume = {76},
number = {4},
pages = {042101-+},
url = {http://ads.bao.ac.cn/abs/2007PhRvA..76d2101C},
doi = {10.1103/PhysRevA.76.042101}
}
|
| Chen Y and Yuan Y (2009), "Quasielastic electron scattering in nuclear matter", J.Phys. G., May, 2009. Vol. 36(5), pp. 055102-+. |
| Abstract: We have investigated the longitudinal response function and the Coulomb sum rule of electron quasielastic scattering in nuclear matter in the relativistic random phase approximation (RPA). It has been shown that the attractive potential between nucleons due to the $ meson in the DDRH model cancels the repulsive contribution of the $ meson to a certain extent. Comparison among the results calculated in the DDRH model and in other models has been made. The nonlinear items in the nonlinear Walecka model are crucial to obtain a self-contained meson Green's functions in calculations. The effects of $ and $ mesons on zero sound are also examined. |
BibTeX:
@article{jpg36_55102,
author = {Chen, Y. and Yuan, Y.},
title = {Quasielastic electron scattering in nuclear matter},
journal = {J.Phys. G},
year = {2009},
volume = {36},
number = {5},
pages = {055102-+},
url = {http://ads.bao.ac.cn/abs/2009JPhG...36e5102C},
doi = {10.1088/0954-3899/36/5/055102}
}
|
| Chen Y, Yuan Y and Liu Y (2009), "Neutrino mean free path in neutron star matter with $ isobars", Phys.Rev. C., May, 2009. Vol. 79(5), pp. 055802-+. |
| Abstract: The $-isobar degrees of freedom are taken into account in neutron star matter and their contributions to neutrino mean free paths are evaluated. It is found that the charged-current contributions are comparable to those from the neutral-current reactions. The contributions of $-isobars may be a leading sector of neutrino opacities in neutron star matter, but the effects of the process in which the baryon transforms between nucleon and $ are unimportant. |
BibTeX:
@article{prc79_55802,
author = {Chen, Y. and Yuan, Y. and Liu, Y.},
title = {Neutrino mean free path in neutron star matter with $ isobars},
journal = {Phys.Rev. C},
year = {2009},
volume = {79},
number = {5},
pages = {055802-+},
url = {http://ads.bao.ac.cn/abs/2009PhRvC..79e5802C},
doi = {10.1103/PhysRevC.79.055802}
}
|
| Cheng KS, Yuan YF and Zhang JL (2002), "Phase Transitions in Rotating Neutron Stars: Effects of Stellar Crusts", Astrophysical Journal., January, 2002. Vol. 564, pp. 909-913. |
| Abstract: As a rapidly rotating neutron star spins down due to the loss of its angular momentum, its central density increases and the nuclear matter in its core converts to quark matter, which leads to a drastic decrease of the stellar moment of inertia, and even results in an era of spin-up of the pulsar (Glendenning, Pei, amp Weber 1997). We find that given a certain equation of state in the liquid core, even if the backbending of the moment of inertia as a function of the rotating frequency occurs, an increase of the total moment of inertia by only 1% could carry adequate angular momentum and stop the star spin-up. This small discrepancy in the total moment of inertia might be due to the different properties of subnuclear matter in the crust, especially to different transition density and pressure at the inner boundary of the solid crust between various models. The strong dependence of the phenomenon of backbending on the physical state of the crust provides, in principle, a new observational approach to check and constrain theories on subnuclear matter. |
BibTeX:
@article{apj564_909,
author = {Cheng, K.~S. and Yuan, Y.~F. and Zhang, J.~L.},
title = {Phase Transitions in Rotating Neutron Stars: Effects of Stellar Crusts},
journal = {Astrophysical Journal},
year = {2002},
volume = {564},
pages = {909-913},
url = {http://ads.bao.ac.cn/abs/2002ApJ...564..909C},
doi = {10.1086/324330}
}
|
| Cui Y-D, Yuan Y-F, Li Y-R and Wang J-M (2012), "A General Relativistic External Compton-Scattering Model for TeV Emission from M87", The Astrophysical Journal., February, 2012. Vol. 746, pp. 177. |
| Abstract: M87 is the first detected non-blazar extragalactic tera-electron-volt (TeV) source with rapid variation and a very flat spectrum in the TeV band. To explain the two peaks in the spectral energy distribution of the nucleus of M87, which is similar to that of blazars, the most commonly adopted models are the synchrotron self-Compton-scattering models and the external inverse Compton (EIC) scattering models. Considering that there is no correlated variation in the soft band (from radio to X-ray) matching the TeV variation and that the TeV sources should not suffer from $$ absorption due to the flat TeV spectrum, the EIC models are advantageous in modeling the TeV emission from M87. In this paper, we propose a self-consistent EIC model to explain the flat TeV spectrum of M87 within the framework of fully general relativity, where the background soft photons are from the advection-dominated accretion flow around the central black hole, and the high-energy electrons are from the mini-jets that are powered by the magnetic reconnection in the main jet. In our model, both the TeV flares observed in the years 2005 and 2008 could be well explained: the $$ absorption for TeV photons is very low, even inside the region very close to the black hole 20R$_g$ 50R$_g$ ; at the same region, the average EIC cooling time (10$^2$ 10$^3$ s) is short, which is consistent with the observed timescale of the TeV variation. Furthermore, we also discuss the possibility that the accompanying X-ray flare in 2008 is due to the direct synchrotron radiation of the mini-jets. |
BibTeX:
@article{apj746_177,
author = {Cui, Y.-D. and Yuan, Y.-F. and Li, Y.-R. and Wang, J.-M.},
title = {A General Relativistic External Compton-Scattering Model for TeV Emission from M87},
journal = {The Astrophysical Journal},
year = {2012},
volume = {746},
pages = {177},
url = {http://adsabs.harvard.edu/abs/2012ApJ...746..177C},
doi = {10.1088/0004-637X/746/2/177}
}
|
| Gong X, Xu S, Bai S, Cao Z, Chen G, Chen Y, He X, Heinzel G, Lau Y-K, Liu C, Luo J, Luo Z, Pulido Patón A, Rüdiger A, Shao M, Spurzem R, Wang Y, Xu P, Yeh H-C, Yuan Y and Zhou Z (2011), "A scientific case study of an advanced LISA mission", Classical and Quantum Gravity., May, 2011. Vol. 28(9), pp. 094012-+. |
| Abstract: A brief status report of an ongoing scientific case study of the Advanced Laser Interferometer Antenna (ALIA) mission is presented. Key technology requirements and primary science objectives of the mission are covered in the study. Possible descope options for the mission and the corresponding compromise in science are also considered and compared. Our preliminary study indicates that ALIA holds promise in mapping out the mass and spin distribution of intermediate mass black holes possibly present in dense star clusters at low redshift as well as in shedding important light on the structure formation in the early Universe. |
BibTeX:
@article{cqg28_94012,
author = {Gong, X. and Xu, S. and Bai, S. and Cao, Z. and Chen, G. and Chen, Y. and He, X. and Heinzel, G. and Lau, Y.-K. and Liu, C. and Luo, J. and Luo, Z. and Pulido Patón, A. and Rüdiger, A. and Shao, M. and Spurzem, R. and Wang, Y. and Xu, P. and Yeh, H.-C. and Yuan, Y. and Zhou, Z.},
title = {A scientific case study of an advanced LISA mission},
journal = {Classical and Quantum Gravity},
year = {2011},
volume = {28},
number = {9},
pages = {094012-+},
url = {http://ads.bao.ac.cn/abs/2011CQGra..28i4012G},
doi = {10.1088/0264-9381/28/9/094012}
}
|
| Hao J-M and Yuan Y-F (2013), "Progenitor delay-time distribution of short gamma-ray bursts: Constraints from observations", aap. Vol. 558, pp. A22. |
| Abstract: Observations of long gamma-ray bursts (LGRBs) offer a unique opportunity to probe the history of cosmic star formation, although whether LGRBs are biased tracers remains highly debated. Based on an extensive sample of LGRBs compiled by Robertson amp Ellis, we analyze various models of star formation rate, combining the possible effect of the cosmic metallicity evolution under the assumption that LGRBs preferentially occur in low-metallicity galaxies. The models of star formation rate tested in this work include empirical fits from observational data as well as a self-consistent model calculated from the hierarchical structure formation scenario. Comparing with the observational data, we find a relatively higher metallicity cut of Z gt 0.6 Z $_⊙$ for the empirical fits and no metallicity cut for the self-consistent model. These results imply that there is no strong bias toward low metallicity in LGRB host galaxies, in contrast to previous studies suggesting a cut of Z 0.1-0.3 Z $_⊙$, and that the inferred low-metallicity dependencies of LGRBs are strongly related to the specific models of star formation rate. Furthermore, a significant fraction of LGRBs that occur in small halos down to 3 times 10$^8$ M $_⊙$ can provide an alternative explanation for the difference between the star formation rate and the LGRB rate. |
BibTeX:
@article{aap558_22,
author = {Jing-Meng Hao and Ye-Fei Yuan},
title = {Progenitor delay-time distribution of short gamma-ray bursts: Constraints from observations},
journal = {aap},
year = {2013},
volume = {558},
pages = {A22},
url = {http://www.aanda.org/articles/aa/abs/2013/10/aa21471-13/aa21471-13.html},
doi = {10.1051/0004-6361/201321471}
}
|
| Hao J-M and Yuan Y-F (2013), "Is the Metallicity of the Progenitor of Long Gamma-Ray Bursts Really Low?", apj., July, 2013. Vol. 772, pp. 42. |
| Abstract: Observations of long gamma-ray bursts (LGRBs) offer a unique opportunity to probe the history of cosmic star formation, although whether LGRBs are biased tracers remains highly debated. Based on an extensive sample of LGRBs compiled by Robertson amp Ellis, we analyze various models of star formation rate, combining the possible effect of the cosmic metallicity evolution under the assumption that LGRBs preferentially occur in low-metallicity galaxies. The models of star formation rate tested in this work include empirical fits from observational data as well as a self-consistent model calculated from the hierarchical structure formation scenario. Comparing with the observational data, we find a relatively higher metallicity cut of Z gt 0.6 Z $_☉$ for the empirical fits and no metallicity cut for the self-consistent model. These results imply that there is no strong bias toward low metallicity in LGRB host galaxies, in contrast to previous studies suggesting a cut of Z 0.1-0.3 Z $_☉$, and that the inferred low-metallicity dependencies of LGRBs are strongly related to the specific models of star formation rate. Furthermore, a significant fraction of LGRBs that occur in small halos down to 3 times 10$^8$ M $_☉$ can provide an alternative explanation for the difference between the star formation rate and the LGRB rate. |
BibTeX:
@article{apj772_42,
author = {Hao, J.-M. and Yuan, Y.-F.},
title = {Is the Metallicity of the Progenitor of Long Gamma-Ray Bursts Really Low?},
journal = {apj},
year = {2013},
volume = {772},
pages = {42},
url = {http://ads.bao.ac.cn/abs/2013ApJ...772...42H},
doi = {10.1088/0004-637X/772/1/42}
}
|
| Huang L, Liu S, Shen Z-Q, Yuan Y-F, Cai MJ, Li H and Fryer CL (2009), "Polarized Emission of Sagittarius A*", The Astrophysical Journal., September, 2009. Vol. 703, pp. 557-568. |
| Abstract: We explore the parameter space of the two-temperature pseudo-Newtonian Keplerian accretion flow model for the millimeter and shorter wavelength emission from Sagittarius A*. A general relativistic (GR) ray-tracing code is used to treat the radiative transfer of polarized synchrotron emission from the flow. The synchrotron self-Comptonization and bremsstrahlung emission components are also included. It is shown that the model can readily account for the millimeter to submillimeter emission characteristics with an accretion rate of 6 times 10^17 g s^-1 and an inclination angle of 40deg. However, the corresponding model-predicted near-infrared (NIR) and X-ray fluxes are more than one order of magnitude lower than the observed ''quiescent'' state values. While the extended quiescent-state X-ray emission has been attributed to thermal emission from the large-scale accretion flow, the NIR emission and flares are likely dominated by emission regions either within the last stable orbit of a Schwarzschild black hole or associated with outflows. With the viscous parameter derived from numerical simulations, there is still a degeneracy between the electron heating rate and the magnetic parameter. A fully GR treatment with the black hole spin incorporated will resolve these issues. |
BibTeX:
@article{apj703_557,
author = {Huang, L. and Liu, S. and Shen, Z.-Q. and Yuan, Y.-F. and Cai, M.~J. and Li, H. and Fryer, C.~L.},
title = {Polarized Emission of Sagittarius A*},
journal = {The Astrophysical Journal},
year = {2009},
volume = {703},
pages = {557-568},
url = {http://ads.bao.ac.cn/abs/2009ApJ...703..557H},
doi = {10.1088/0004-637X/703/1/557}
}
|
| Janiuk A and Yuan Y-F (2010), "The role of black hole spin and magnetic field threading the unstable neutrino disk in gamma ray bursts", Astron. Astrophys.., January, 2010. Vol. 509, pp. A55+. |
| Abstract: Aims: We report on the third phase of our study of the neutrino-cooled hyperaccreting torus around a black hole that powers the jet in gamma ray bursts. We focus on the influence of the black hole spin on the properties of the torus. Methods: The structure of a stationary torus around the Kerr black hole is solved numerically. We take into account the detailed treatment of the microphysics in the nuclear equation of state that includes the neutrino trapping effect. Results: We find that in the case of rapidly rotating black holes, the thermal instability discussed in our previous work is enhanced and is developed for much lower accretion rates. We also find the important role of the energy transfer from the rotating black hole to the torus via the magnetic coupling. |
BibTeX:
@article{aap509_55,
author = {Janiuk, A. and Yuan, Y.-F.},
title = {The role of black hole spin and magnetic field threading the unstable neutrino disk in gamma ray bursts},
journal = {Astron. Astrophys.},
year = {2010},
volume = {509},
pages = {A55+},
url = {http://ads.bao.ac.cn/abs/2010A%26A...509A..55J},
doi = {10.1051/0004-6361/200912725}
}
|
| Janiuk A, Yuan Y, Perna R and Di Matteo T (2007), "Instabilities in the Time-Dependent Neutrino Disk in Gamma-Ray Bursts", The Astrophysical Journal., August, 2007. Vol. 664, pp. 1011-1025. |
| Abstract: We investigate the properties and evolution of accretion tori formed after the coalescence of two compact objects. At these extreme densities and temperatures, the accreting torus is cooled mainly by neutrino emission produced primarily by electron and positron capture on nucleons ($-reactions). We solve for the disk structure and its time evolution by introducing a detailed treatment of the equation of state which includes photodisintegration of helium, the condition of $-equilibrium, and neutrino opacities. We self-consistently calculate the chemical equilibrium in the gas consisting of helium, free protons, neutrons, and electron-positron pairs and compute the chemical potentials of the species, as well as the electron fraction throughout the disk. We find that, for sufficiently large accretion rates (Mdotgt10 M_solar s^-1), the inner regions of the disk become opaque and develop a viscous and thermal instability. The identification of this instability might be relevant for GRB observations. |
BibTeX:
@article{apj664_1011,
author = {Janiuk, A. and Yuan, Y. and Perna, R. and Di Matteo, T.},
title = {Instabilities in the Time-Dependent Neutrino Disk in Gamma-Ray Bursts},
journal = {The Astrophysical Journal},
year = {2007},
volume = {664},
pages = {1011-1025},
url = {http://ads.bao.ac.cn/abs/2007ApJ...664.1011J},
doi = {10.1086/518761}
}
|
| Li G-X, Yuan Y-F and Cao X (2010), "Emergent Spectra from Disks Surrounding Kerr Black Holes: Effect of Photon Trapping and Disk Self-shadowing", The Astrophysical Journal., May, 2010. Vol. 715, pp. 623-635. |
| Abstract: Based on a new estimation of their thickness, the global properties of relativistic slim accretion disks are investigated in this work. The resulting emergent spectra are calculated using the relativistic ray-tracing method, in which we neglect the self-irradiation of the accretion disk. The angular dependence of the disk luminosity, the effects of the heat advection, and the disk thickness on the estimation of the black hole spin are discussed. Compared with the previous works, our improvements are that we use the self-consistent disk equations and we consider the disk self-shadowing effect. We find that at the moderate accretion rate, the radiation trapped in the outer region of the accretion disks will escape in the inner region of the accretion disk and contribute to the emergent spectra. At the high accretion rate, for the large inclination and large black hole spin, both the disk thickness and the heat advection have significant influence on the emergent spectra. Consequently, these effects will influence the measurement of the black hole spin based on the spectra fitting and influence the angular dependence of the luminosity. For the disks around Kerr black holes with a = 0.98, if the disk inclination is greater than 60deg, and their luminosity is beyond 0.2 Eddington luminosity, the spectral model which is based on the relativistic standard accretion disk is no longer applicable for the spectra fitting. We also confirm that the effect of the self-shadowing is significantly enhanced by the light bending, which implies that the non-relativistic treatment of the self-shadowing is inaccurate. According to our results, the observed luminosity dependence of the measured spin suggests that the disk self-shadowing significantly shapes the spectra of GRS 1915+105, which might lead to the underestimation of the black hole spin for the high luminosity states. |
BibTeX:
@article{apj715_623,
author = {Li, G.-X. and Yuan, Y.-F. and Cao, X.},
title = {Emergent Spectra from Disks Surrounding Kerr Black Holes: Effect of Photon Trapping and Disk Self-shadowing},
journal = {The Astrophysical Journal},
year = {2010},
volume = {715},
pages = {623-635},
url = {http://ads.bao.ac.cn/abs/2010ApJ...715..623L},
doi = {10.1088/0004-637X/715/1/623}
}
|
| Li Y-R, Wang J-M, Yuan Y-F, Hu C and Zhang S (2010), "Episodic Activities of Supermassive Black Holes at Redshift z lt= 2: Driven by Mergers?", The Astrophysical Journal., February, 2010. Vol. 710, pp. 878-885. |
| Abstract: It has been suggested for quite a long time that galaxy mergers trigger activities of supermassive black holes (SMBHs) on the grounds of imaging observations of individual galaxies. To quantitatively examine this hypothesis, we calculate quasar luminosity functions (LFs) by manipulating the observed galaxy LFs (z lt 2) and theoretical merger rates from semi-analytical formulations. We find that the model reproduces the observed quasar LFs provided that the mass ratio (q) of the secondary galaxy to the newly formed one changes with cosmic time. The results show that the fraction of major mergers decreases from f _maj 0.2 at z 2 to f _maj rarr 0 at z 0. As a consequence, the newly formed SMBHs from major mergers at z 2 may acquire a maximal spin due to the orbital angular momentum of the merging holes. Subsequently, random accretion led by minor mergers rapidly drives the SMBHs to spin down. Such an evolutionary trend of the SMBH spins is consistent with the fact that radiative efficiency of accreting SMBHs strongly declines with cosmic time, reported by Wang et al. This suggests that minor mergers are important in triggering activities of SMBHs at low redshift, while major mergers may dominate at high redshift. |
BibTeX:
@article{apj710_878,
author = {Li, Y.-R. and Wang, J.-M. and Yuan, Y.-F. and Hu, C. and Zhang, S.},
title = {Episodic Activities of Supermassive Black Holes at Redshift z lt= 2: Driven by Mergers?},
journal = {The Astrophysical Journal},
year = {2010},
volume = {710},
pages = {878-885},
url = {http://ads.bao.ac.cn/abs/2010ApJ...710..878L},
doi = {10.1088/0004-637X/710/1/878}
}
|
| Li Y-R, Yuan Y-F, Wang J-M, Wang J-C and Zhang S (2009), "Spins of Supermassive Black Holes in M87. II. Fully General Relativistic Calculations", The Astrophysical Journal., July, 2009. Vol. 699, pp. 513-524. |
| Abstract: The fast variability of energetic TeV photons from the center of M87 has been detected, offering a new clue to estimate spins of supermassive black holes (SMBHs). We extend the study of Wang et al. by including all of the general relativistic effects. We numerically solve the full set of relativistic hydrodynamical equations of the radiatively inefficient accretion flows (RIAFs) and then obtain the radiation fields around the black hole. The optical depth of the radiation fields to TeV photons due to pair productions is calculated in the Kerr metric. We find that the optical depth strongly depends on (1) accretion rates as $tau $$TeV$$$propto $dot$$M$$$$2.5$--5.0$$, (2) black hole spins, and (3) location of the TeV source. Jointly considering the optical depth and the spectral energy distribution radiated from the RIAFs, the strong degeneration of the spin with the other free parameters in the RIAF model can be largely relaxed. We apply the present model to M87, wherein the RIAFs are expected to be at work, and find that the minimum specific angular momentum of the hole is a 0.8. The present methodology is applicable to M87-like sources with future detection of TeV emissions to constrain the spins of SMBHs. |
BibTeX:
@article{apj699_513,
author = {Li, Y.-R. and Yuan, Y.-F. and Wang, J.-M. and Wang, J.-C. and Zhang, S.},
title = {Spins of Supermassive Black Holes in M87. II. Fully General Relativistic Calculations},
journal = {The Astrophysical Journal},
year = {2009},
volume = {699},
pages = {513-524},
url = {http://ads.bao.ac.cn/abs/2009ApJ...699..513L},
doi = {10.1088/0004-637X/699/1/513}
}
|
| Liu M-Q, Yuan Y-F and Zhang J (2009), "Effect of electron screening on the collapsing process of core-collapse supernovae", Monthly Notices of the Royal Astronomical Society., December, 2009. Vol. 400, pp. 815-819. |
| Abstract: By using an average heavy nuclei model, the effects of the electron screening on electron capture (EC) in core-collapse supernovae are investigated. A one-dimension code based on the Ws15M_solar progenitor model is utilized to test the effects of electron screening during the collapsing process. The results show that, at high densities, the effects of electron screening on EC become significant. During the collapsing stage, the EC rate is decreased, the collapse time-scale is prolonged and the leakage of the neutrino energy is increased. These effects lead to an appreciable decrease in the initial energy of the bounce shock wave. The effects of electron screening in the other progenitor models are also discussed. |
BibTeX:
@article{mnras400_815,
author = {Liu, M.-Q. and Yuan, Y.-F. and Zhang, J.},
title = {Effect of electron screening on the collapsing process of core-collapse supernovae},
journal = {Monthly Notices of the Royal Astronomical Society},
year = {2009},
volume = {400},
pages = {815-819},
url = {http://ads.bao.ac.cn/abs/2009MNRAS.400..815L},
doi = {10.1111/j.1365-2966.2009.15487.x}
}
|
| Pan Z and Yuan Y-F (2012), "Vertical Structure of Neutrino-dominated Accretion Disks and Neutrino Transport in the Disks", The Astrophysical Journal. Vol. 759(2), pp. 82. |
| Abstract: We investigate the vertical structure of neutrino-dominated accretion disks by self-consistently considering the detailed microphysics, such as the neutrino transport, the vertical hydrostatic equilibrium, the conservation of lepton number, as well as the balance between neutrino cooling, advection cooling, and viscosity heating. After obtaining the emitting spectra of neutrinos and antineutrinos by solving the one-dimensional Boltzmann equation of neutrino and antineutrino transport in the disk, we calculate the neutrino/antineutrino luminosity and their annihilation luminosity. We find that the total neutrino and antineutrino luminosity is about 10 54 erg s –1 and their annihilation luminosity is about 5 × 10 51 erg s –1 with an extreme accretion rate 10 M sun s –1 and an alpha viscosity α = 0.1. In addition, we find that the annihilation luminosity is sensitive to the accretion rate and will not exceed 10 50 erg s –1 , which is not sufficient to power the fireball of most energetic gamma-ray bursts (GRBs) if the accretion rate is lower than 1 M sun s –1 . Therefore, the effects of the spin of the black hole or/and the magnetic field in the accretion flow might play a role in powering the central engine of GRBs. |
BibTeX:
@article{apj759_82,
author = {Zhen Pan and Ye-Fei Yuan},
title = {Vertical Structure of Neutrino-dominated Accretion Disks and Neutrino Transport in the Disks},
journal = {The Astrophysical Journal},
year = {2012},
volume = {759},
number = {2},
pages = {82},
url = {http://adsabs.harvard.edu/abs/2012ApJ...759...82P},
doi = {10.1088/0004-637X/759/2/82}
}
|
| Pan Z and Yuan Y-F (2012), "Neutrino and anti-neutrino transport in accretion disks", Phys. Rev. D., Mar, 2012. Vol. 85, pp. 064004. American Physical Society. |
| Abstract: We numerically solve the one-dimensional Boltzmann equation of the neutrino and antineutrino transport in accretion disks and obtain the fully energy-dependent and direction-dependent neutrino- and antineutrino-emitting spectra, under the condition that the distribution of the mass density, temperature and chemical components are given. Then, we apply the resulting neutrino- and antineutrino-emitting spectra to calculate the corresponding annihilation rate of neutrino pairs above the neutrino-dominated accretion disk and find that the released energy resulting from the annihilation of neutrino pairs cannot provide sufficient energy for the most energetic short gamma ray bursts whose isotropic luminosity can be as high as 10$^52$ergs/s unless the high-temperature zone, where the temperature is beyond 10 MeV, can stretch over 200 km in the disk. We also compare the resulting luminosity of neutrinos and antineutrinos with the results from the two commonly used approximate treatments of the neutrino and antineutrino luminosity: the Fermi-Dirac black-body limit and a simplified model of neutrino transport, i.e., the gray-body model, and find that both of them overestimate the neutrino/antineutrino luminosity and their annihilation rate greatly. Additionally, as did in Sawyer (2003), we also check the validity of the two-stream approximation, and find that it is a good approximation to high accuracy. |
BibTeX:
@article{PhysRevD.85.064004,
author = {Pan, Zhen and Yuan, Ye-Fei},
title = {Neutrino and anti-neutrino transport in accretion disks},
journal = {Phys. Rev. D},
publisher = {American Physical Society},
year = {2012},
volume = {85},
pages = {064004},
url = {http://adsabs.harvard.edu/abs/2012PhRvD..85f4004P},
doi = {10.1103/PhysRevD.85.064004}
}
|
| Wang J-M, Yuan Y-F, Wu M and Kusunose M (2000), "Blob Ejection from Advection-dominated Accretion Flow: Observational Consequences", Astrophysical Journal Letters., October, 2000. Vol. 541, pp. L41-L44. |
| Abstract: There is increasing evidence for the presence of an optically thin advection-dominated accretion flow (ADAF) in low-luminosity active galactic nuclei and radio-loud quasars. The present Letter is devoted to exploring the fate of a blob ejected from an ADAF and to discussing its observational consequences. It is inevitable for the ejected blob to drastically expand into its surroundings. Consequently, it is expected that a group of relativistic electrons will be accelerated, which may lead to nonthermal flares since a strong shock will be formed by the interaction between the blob and its surroundings. Then the blob cools down efficiently, leading to the appearance of recombination lines about 10^5 s after its ejection from an ADAF. We apply this model to NGC 4258 for some observational prediction and to PKS 2149-306 for the explanation of observational evidence. Future simultaneous observations of recombination X-ray lines and continuum emission are strongly desired for testing the present model. |
BibTeX:
@article{apjl541_41,
author = {Wang, J.-M. and Yuan, Y.-F. and Wu, M. and Kusunose, M. },
title = {Blob Ejection from Advection-dominated Accretion Flow: Observational Consequences},
journal = {Astrophysical Journal Letters},
year = {2000},
volume = {541},
pages = {L41-L44},
url = {http://ads.bao.ac.cn/abs/2000ApJ...541L..41W},
doi = {10.1086/312896}
}
|
| Wang J-M, Zhou Y-Y, Yuan Y-F, Cao X and Wu M (2000), "Profile of an Emission Line from Relativistic Outflows around a Black Hole", Astrophysical Journal., November, 2000. Vol. 544, pp. 381-389. |
| Abstract: Recent observations show strong evidence for the presence of Doppler-shifted emission lines in the spectrum of both black hole candidates and active galactic nuclei. These lines are likely to originate from relativistic outflows (or jets) in the vicinity of the central black hole. Consequently, the profile of such a line should be distorted by strong gravitational effects near the black hole, as well as special relativistic effects. In this paper, we present results from a detailed study on how each process affects the observed line profile. We found that the profile is sensitive to the intrinsic properties of the jets (Lorentz factor, velocity profile, and emissivity law), as well as to the spin of the black hole and the viewing angle (with respect to the axis of the jets). More specifically, in the case of approaching jets, an intrinsically narrow line (blueshifted) is seen as simply broadened at small viewing angles, but it shows a doubly peaked profile at large viewing angles for extreme Kerr black holes (due to the combination of gravitational focusing and Doppler effects) the profile is always singly peaked for Schwarzschild black holes. For receding jets, however, the line profile becomes quite complicated owing to complicated photon trajectories. To facilitate comparison with observations, we searched a large parameter space to derive representative line profiles. We show the results and discuss how to use emission lines as a potential tool for probing the inner region of a black hole jet system. |
BibTeX:
@article{apj544_381,
author = {Wang, J.-M. and Zhou, Y.-Y. and Yuan, Y.-F. and Cao, X. and Wu, M.},
title = {Profile of an Emission Line from Relativistic Outflows around a Black Hole},
journal = {Astrophysical Journal},
year = {2000},
volume = {544},
pages = {381-389},
url = {http://ads.bao.ac.cn/abs/2000ApJ...544..381W},
doi = {10.1086/317214}
}
|
| Wang L, Mao J, Xiang S and Yuan Y-F (2009), "Negative feedback effects on star formation history and cosmic reionization", Astron. Astrophys.., February, 2009. Vol. 494, pp. 817-827. |
| Abstract: Context: The mechanical and radiative feedback that exists in the star formation history affects the subsequent star formation rate. Aims: After considering the effects of negative feedback on the process of star formation, we explore the relationship between star formation process and the associated feedback, by investigating how the mechanical feedback from supernovae(SNe) and radiative feedback from luminous objects regulate the star formation rate and therefore affect the cosmic reionization. Methods: Based on our present knowledge of the negative feedback theory and some numerical simulations, we construct an analytic model in the framework of the Lambda cold dark matter model. In certain parameter regions, our model can explain some observational results properly. Results: In large halos (Tvirgt10^4 K), both mechanical and radiative feedback have a similar behavior: the relative strength of negative feedback reduces as the redshift decreases. In contrast, in small halos (Tvirlt10^4 K) that are thought to breed the first stars at early time, the radiative feedback gets stronger when the redshift decreases. And the star formation rate in these small halos depends very weakly on the star-formation efficiency. Conclusions: Our results show that the radiative feedback is important for the early generation stars. It can suppress the star formation rate considerably. But the mechanical feedback from the SNe explosions is not able to affect the early star formation significantly. The early star formation in small-halo objects is likely to be self-regulated. The radiative and mechanical feedback dominates the star formation rate of the PopII/I stars all along. The feedback from first generation stars is very strong and should not be neglected. However, their effects on the cosmic reionization are not significant, which results in a small contribution to the optical depth of Thomson scattering. |
BibTeX:
@article{aap494_817,
author = {Wang, L. and Mao, J. and Xiang, S. and Yuan, Y.-F.},
title = {Negative feedback effects on star formation history and cosmic reionization},
journal = {Astron. Astrophys.},
year = {2009},
volume = {494},
pages = {817-827},
url = {http://ads.bao.ac.cn/abs/2009A%26A...494..817W},
doi = {10.1051/0004-6361/200809916}
}
|
| Wang X-W and Yuan Y-F (2012), "Dynamics of dual active galactic nuclei at kpc scales: observational consequences", Monthly Notices of the Royal Astronomical Society. Vol. 427, pp. L1-L5. |
| Abstract: Dual active galactic nuclei (AGNs) at kpc scales that originated from galaxy mergers have been found, but the dynamics of the mergers are insufficiently understood, especially the relevant observational consequences. We present evolutionary models of dual AGNs in two cases driven by different friction laws with their surroundings, which are characterized by forces with F∝V* and inline image. The evolutionary behaviours show that there is a minimum time-scale of ∼108 yr to accomplish a merger. Since the total friction and moment acting on dual AGNs with unequal masses do not vanish, the centre of mass moves with a velocity of Vc∼ a few ten km s−1 and makes an offset of ΔS∼ sub-kpc of the merged AGNs with respect to the centre of their host galaxies. The relative motion of the two cores along the line joining the centre of mass is of VR∼ a few ten km s−1, which determines the merger time-scales. Dissipation of the orbital kinetic energy of dual AGNs either enhances stellar velocity dispersion or heats up the interstellar medium in its revirialization to form a soft X-ray cocoon enshrouding them with a typical luminosity of ∼1042 erg s−1. We predict that galaxies with offset AGNs are likely to host binary supermassive black holes at sub-kpc scales, shedding light on searching candidates from AGNs. |
BibTeX:
@article{mnras427_L1,
author = {Wang, X.-W. and Yuan, Y.-F.},
title = {Dynamics of dual active galactic nuclei at kpc scales: observational consequences},
journal = {Monthly Notices of the Royal Astronomical Society},
year = {2012},
volume = {427},
pages = {L1-L5},
url = {http://adsabs.harvard.edu/abs/2012MNRAS.427L...1W},
doi = {10.1111/j.1745-3933.2012.01325.x}
}
|
| You B, Cao X and Yuan Y-F (2012), "A General Relativistic Model of Accretion Disks with Coronae Surrounding Kerr Black Holes", The Astrophysical Journal. Vol. 761(2), pp. 109. |
| Abstract: We calculate the structure of a standard accretion disk with a corona surrounding a massive Kerr black hole in the general relativistic frame, in which the corona is assumed to be heated by the reconnection of the strongly buoyant magnetic fields generated in the cold accretion disk. The emergent spectra of accretion disk-corona systems are calculated by using the relativistic ray-tracing method. We propose a new method to calculate the emergent Comptonized spectra from the coronae. The spectra of disk-corona systems with a modified α-magnetic stress show that both the hard X-ray spectral index and the hard X-ray bolometric correction factor L bol / L X, 2-10 keV increase with the dimensionless mass accretion rate, which is qualitatively consistent with the observations of active galactic nuclei. The fraction of the power dissipated in the corona decreases with increasing black hole spin parameter a , which leads to lower electron temperatures of the coronae for rapidly spinning black holes. The X-ray emission from the coronae surrounding rapidly spinning black holes becomes weak and soft. The ratio of the X-ray luminosity to the optical/UV luminosity increases with the viewing angle, while the spectral shape in the X-ray band is insensitive to the viewing angle. We find that the spectral index in the infrared waveband depends on the mass accretion rate and the black hole spin a , which deviates from the f ν ##IMG## [http://ej.iop.org/icons/Entities/vprop.gif] vprop ν 1/3 relation expected by the standard thin disk model. |
BibTeX:
@article{apj761_109,
author = {Bei You and Xinwu Cao and Ye-Fei Yuan},
title = {A General Relativistic Model of Accretion Disks with Coronae Surrounding Kerr Black Holes},
journal = {The Astrophysical Journal},
year = {2012},
volume = {761},
number = {2},
pages = {109},
url = {http://ads.bao.ac.cn/abs/2012ApJ...761..109Y},
doi = {10.1088/0004-637X/761/2/109}
}
|
| Yuan Y-F (2005), "Electron-positron capture rates and a steady state equilibrium condition for an electron-positron plasma with nucleons", Physical Review D., July, 2005. Vol. 72(1), pp. 013007-+. |
| Abstract: The reaction rates of the beta processes for all particles at arbitrary degeneracy are derived, and an analytic steady state equilibrium condition $_n=$_p+2$_e which results from the equality of electron and positron capture rates in the hot electron-positron plasma with nucleons is also found, if the matter is transparent to neutrinos. This simple analytic formula is valid only if electrons are nondegenerate or mildly degenerate, which is generally satisfied in the hot electron-positron plasma. Therefore, it can be used to efficiently determine the steady state of the hot matter with plenty of positrons. Based on this analytic condition, given the baryon number density and the temperature, if the nucleons are nondegenerate, only one algebraic equation for determining the electron fraction is obtained, which shows the great advantage of the analytic equilibrium condition. |
BibTeX:
@article{prd72_13007,
author = {Yuan, Y.-F.},
title = {Electron-positron capture rates and a steady state equilibrium condition for an electron-positron plasma with nucleons},
journal = {Physical Review D},
year = {2005},
volume = {72},
number = {1},
pages = {013007-+},
url = {http://ads.bao.ac.cn/abs/2005PhRvD..72a3007Y},
doi = {10.1103/PhysRevD.72.013007}
}
|
| Yuan Y-F, Cao X, Huang L and Shen Z-Q (2009), "Images of the Radiatively Inefficient Accretion Flow Surrounding a Kerr Black Hole: Application in Sgr A*", The Astrophysical Journal., July, 2009. Vol. 699, pp. 722-731. |
| Abstract: In fully general relativity, we calculate the images of the radiatively inefficient accretion flow (RIAF) surrounding a Kerr black hole (BH) with arbitrary spins, inclination angles, and observational wavelengths. For the same initial conditions, such as the fixed accretion rate, it is found that the intrinsic size and radiation intensity of the images become larger, but the images become more compact in the inner region, while the size of the BH shadow decreases with the increase of the BH spin. With the increase of the inclination angles, the shapes of the BH shadows change and become smaller, even disappear completely due to the obscuration by the thick disks. For median inclination angles, the radial velocity observed at infinity is larger because of both the rotation and radial motion of the fluid in the disk, which results in the luminous part of the images being much brighter. For larger inclination angles, such as the disk is edge-on, the emission becomes dimmer at longer observational wavelengths (such as at 7.0 mm and 3.5 mm wavelengths), or brighter at shorter observational wavelengths (such as at 1.3 mm wavelength) than that of the face on case, except for the high-spin and high-inclination images. These complex behaviors are due to the combination of the Lorentz boosting effect and the radiative absorption in the disk. We hope our results are helpful to determine the spin parameter of the BH in low-luminosity sources, such as the Galactic center. A primary analysis by comparison with the observed sizes of Sgr A* at millimeter wavelengths strongly suggests that the disk around the central BH at Sgr A* is highly inclined or the central BH is rotating fast. |
BibTeX:
@article{apj699_722,
author = {Yuan, Y.-F. and Cao, X. and Huang, L. and Shen, Z.-Q.},
title = {Images of the Radiatively Inefficient Accretion Flow Surrounding a Kerr Black Hole: Application in Sgr A*},
journal = {The Astrophysical Journal},
year = {2009},
volume = {699},
pages = {722-731},
url = {http://ads.bao.ac.cn/abs/2009ApJ...699..722Y},
doi = {10.1088/0004-637X/699/1/722}
}
|
| Yuan Y-F and Heyl JS (2005), "Rotational evolution of protoneutron stars with hyperons: spin up or not?", Monthly Notices of the Royal Astronomical Society., July, 2005. Vol. 360, pp. 1493-1505. |
| Abstract: We study the evolution of a rigidly rotating protoneutron star (PNS) with hyperons and nucleons or solely nucleons in its core due to the escape of trapped neutrinos. As the neutrinos escape, the core nucleonic neutron star (NS) expands and the stellar rotation slows. After the neutrinos escape, the range of the spin periods is narrower than the initial one, but the distribution is still nearly uniform. A PNS with hyperons, at the late stage of its evolution, keeps shrinking and spinning up until all the trapped neutrinos escape. Consequently, the distribution of the stellar initial spin periods is skewed towards shorter periods. If the hyperonic star is metastable, its rotational frequency accelerates distinguishedly before it collapses to a black hole. |
BibTeX:
@article{mnras360_1493,
author = {Yuan, Y.-F. and Heyl, J.~S.},
title = {Rotational evolution of protoneutron stars with hyperons: spin up or not?},
journal = {Monthly Notices of the Royal Astronomical Society},
year = {2005},
volume = {360},
pages = {1493-1505},
url = {http://ads.bao.ac.cn/abs/2005MNRAS.360.1493Y},
doi = {10.1111/j.1365-2966.2005.09142.x}
}
|
| Yuan Y-F, Narayan R and Rees MJ (2004), "Constraining Alternate Models of Black Holes: Type I X-Ray Bursts on Accreting Fermion-Fermion and Boson-Fermion Stars", The Astrophysical Journal., May, 2004. Vol. 606, pp. 1112-1124. |
| Abstract: The existence of black holes remains open to doubt until other conceivable options are excluded. With this motivation, we consider a model of a compact star in which most of the mass consists of dark particles of some kind and a small fraction of the mass is in the form of ordinary nucleonic gas. The gas does not interact with the dark matter other than via gravity, but collects at the center as a separate fermionic fluid component. Depending on whether the dark mass is made of fermions or bosons, the objects may be called fermion-fermion stars or boson-fermion stars, respectively. For appropriate choices of the mass of the dark matter particles, these objects are viable models of black hole candidates in X-ray binaries. We consider models with a dark mass of 10 M_solar and a range of gas mass from 10^-6 to 1 M_solar, and analyze the bursting properties of the models when they accrete gas. We show that all the models would experience thermonuclear type I X-ray bursts at appropriate mass-accretion rates. Since no type I bursts have been reported from black hole candidates, the models are ruled out. The case for identifying black hole candidates in X-ray binaries as true black holes is thus strengthened. |
BibTeX:
@article{apj606_1112,
author = {Yuan, Y.-F. and Narayan, R. and Rees, M.~J.},
title = {Constraining Alternate Models of Black Holes: Type I X-Ray Bursts on Accreting Fermion-Fermion and Boson-Fermion Stars},
journal = {The Astrophysical Journal},
year = {2004},
volume = {606},
pages = {1112-1124},
url = {http://ads.bao.ac.cn/abs/2004ApJ...606.1112Y},
doi = {10.1086/383185}
}
|
| Yuan YF and Zhang JL (1999), "Cooling of a rotating strange star with a crust", Astron. Astrophys.., April, 1999. Vol. 344, pp. 371-375. |
| Abstract: As a strange star spins down, the nuclear matter in its crust contracts continuously into the quark core. The confined nuclear matter is dissolved into quark matter, liberating a lot of thermal energy. This process is called deconfinement heating. It is found that deconfinement heating dramatically changes the thermal evolution of a strange star. For a strange star with a strong surface magnetic field ( 10(12) Gauss), the star heats instead of cooling during the first 10 years. Therefore, contrary to the previous studies, we conclude that there is evidence for strange quark matter, if a heating period is observed for a very young pulsar. For a strange star with a weaker magnetic field, the surface temperature is higher than that of a neutron star in the photon cooling era. This could also signal the existence of strange quark matter. |
BibTeX:
@article{aap344_371,
author = {Yuan, Y.~F. and Zhang, J.~L.},
title = {Cooling of a rotating strange star with a crust},
journal = {Astron. Astrophys.},
year = {1999},
volume = {344},
pages = {371-375},
url = {http://ads.bao.ac.cn/abs/1999A%26A...344..371Y}
}
|
| Yuan YF and Zhang JL (1999), "The Effects of Interior Magnetic Fields on the Properties of Neutron Stars in the Relativistic Mean-Field Theory", Astrophysical Journal., November, 1999. Vol. 525, pp. 950-958. |
| Abstract: We investigate the gross properties of the dense neutron star matter and the structure of the stars under the influence of strong magnetic fields, based on two nonlinear $-$ models of nuclear matter, i.e., the BB and the ZM models, within the relativistic mean-field approximation. Contrary to the results obtained in the linear $-$ model and the BB model, we find that the influence of the magnetic field on the effective nucleon mass m^* is not significant in the ZM model; therefore, we predict that the neutrons in the interior of a neutron star might be superfluid according to the ZM model, if there is a strong magnetic field in the interior of the star. Moreover, the equations of state (EOSs) will become softer and softer with the increase of the strength of the magnetic field B. We show the effects of the interior magnetic fields on the gross properties of neutron stars, such as the critical masses, their corresponding radii, the moment of inertia, the crust masses, the crust moment of inertia, and the gravitational redshift in both nonlinear $-$ models. |
BibTeX:
@article{apj525_950,
author = {Yuan, Y.~F. and Zhang, J.~L.},
title = {The Effects of Interior Magnetic Fields on the Properties of Neutron Stars in the Relativistic Mean-Field Theory},
journal = {Astrophysical Journal},
year = {1999},
volume = {525},
pages = {950-958},
url = {http://ads.bao.ac.cn/abs/1999ApJ...525..950Y},
doi = {10.1086/307921}
}
|
| Yuan YF and Zhang JL (1998), "The effect of interior magnetic field on the modified URCA process and the cooling of neutron stars", Astron. Astrophys.., July, 1998. Vol. 335, pp. 969-972. |
| Abstract: The effect of a strong magnetic field on the modified Urca process in neutron star cores is considered in this paper. It is found that this effect is significant when the interior magnetic field is greater than 10(18) G, especially at some resonant states. In these situations, the strong magnetic field will significantly increase the rate of neutrino emission and influence the cooling of neutron stars. Comparing with the observational data, we provide information about the order of the strength of interior magnetic field for the first time. The strength we obtained is about 10(19) G. This work is supported by the National Natural Science Foundation and National Climbing Programme on Fundamental Researches |
BibTeX:
@article{aap335_969,
author = {Yuan, Y.~F. and Zhang, J.~L.},
title = {The effect of interior magnetic field on the modified URCA process and the cooling of neutron stars},
journal = {Astron. Astrophys.},
year = {1998},
volume = {335},
pages = {969-972},
url = {http://ads.bao.ac.cn/abs/1998A%26A...335..969Y}
}
|
| Zhang JL and Yuan YF (1998), "The Quantum Radiation Formulae of a New Radiation Mechanism in Curved Magnetic Fields", The Astrophysical Journal., January, 1998. Vol. 493, pp. 826-+. |
| Abstract: A new radiation mechanism for relativistic charged particles moving in curved magnetic fields has been put forward recently by Zhang amp Cheng. This radiation mechanism generalizes all the classical results of ordinary synchrotron and curvature radiation and reveals the inherent linkage and unification between them. Since the magnitude of the pulsar magnetic field is generally 1011-1013 G, the quantum effects must be taken into account. Applying the generalized method of equivalent photon scattering developed recently by Lieu amp Axford, we present the quantum-limited synchrocurvature radiation formulae in this paper, which elaborates the essence of this new radiation mechanism in a deeper sense. The formulae we present could be extensively applied to various kinds of practical curved magnetic fields, including those of pulsars. |
BibTeX:
@article{apj493_826,
author = {Zhang, J.~L. and Yuan, Y.~F.},
title = {The Quantum Radiation Formulae of a New Radiation Mechanism in Curved Magnetic Fields},
journal = {The Astrophysical Journal},
year = {1998},
volume = {493},
pages = {826-+},
url = {http://ads.bao.ac.cn/abs/1998ApJ...493..826Z},
doi = {10.1086/305138}
}
|