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Optical Luminosity Function of the QSOs Observed with the Sloan Digital Sky Survey Data Release Seven (SDSS DR7)
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作者 Salam Ajitkumar Singh Irom Ablu Meitei Kangujam Yugindro Singh 《International Journal of Astronomy and Astrophysics》 2014年第3期474-478,共5页
We have determined the Optical Luminosity Function (OLF) of a sample of 80946 Quasi Stellar Objects (QSOs) taken from the Sloan Digital Sky Survey Data Release Seven (SDSS DR7) with redshift range??0.3 z Mi < -22.5... We have determined the Optical Luminosity Function (OLF) of a sample of 80946 Quasi Stellar Objects (QSOs) taken from the Sloan Digital Sky Survey Data Release Seven (SDSS DR7) with redshift range??0.3 z Mi < -22.5. The Monte Carlo Technique of numerical integration is used. The sample of QSOs is divided into seven sub-samples with redshift in the ranges: 0.30 z z z < 1.05,?1.05 z z z < 1.80, and 1.80 z < 2.05. Each redshift interval is binned in absolute magnitude with bin width ΔMi = -0.5. A flat universe with cosmological parameters Ωm = 0.3, Ω∧ = 0.7, and Hubble constant Ho = 70.0 km·s-1·Mpc-1 is used. From the optical luminosity function a clear evidence of AGN downsizing is observed, i.e. the number density of the less luminous AGNs peaks at lower redshift than the number density of the more luminous AGNs. 展开更多
关键词 Quasi STELLAR Objects (qsos) LUMINOSITY Function
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Why the Central Monster in M87 Should Be a Massive DEO Rather than a SMBH?
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作者 Ahmad A. Hujeirat Mauritz Wicker 《Journal of Modern Physics》 2024年第5期537-549,共13页
In this paper, we show that massive envelopes made of highly compressed normal matter surrounding dark objects (DEOs) can curve the surrounding spacetime and make the systems observationally indistinguishable from the... In this paper, we show that massive envelopes made of highly compressed normal matter surrounding dark objects (DEOs) can curve the surrounding spacetime and make the systems observationally indistinguishable from their massive black hole counterparts. DEOs are new astrophysical objects that are made up of entropy-free incompressible supranuclear dense superfluid (SuSu-matter), embedded in flat spacetimes and invisible to outside observers, practically trapped in false vacua. Based on highly accurate numerical modelling of the internal structures of pulsars and massive neutron stars, and in combination with using a large variety of EOSs, we show that the mass range of DEOs is practically unbounded from above: it spans those of massive neutron stars, stellar and even supermassive black holes: thanks to the universal maximum density of normal matter, , beyond which normal matter converts into SuSu-matter. We apply the scenario to the Crab and Vela pulsars, the massive magnetar PSR J0740 6620, the presumably massive NS formed in GW170817, and the SMBHs in Sgr A* and M87*. Our numerical results also reveal that DEO-Envelope systems not only mimic massive BHs nicely but also indicate that massive DEOs can hide vast amounts of matter capable of turning our universe into a SuSu-matter-dominated one, essentially trapped in false vacua. 展开更多
关键词 General Relativity Big Bang Black Holes qsos Neutron Stars QCD Condensed Matter INCOMPRESSIBILITY SUPERFLUIDITY Super-Conductivity
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Luminosity function of optically-selected type II QSOs
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作者 BIAN WeiHao & ZHANG ShiYan Department of Physics,Nanjing Normal University,Nanjing 210097,China 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS 2010年第S1期191-195,共5页
For a sample of 411 type II QSOs with redshifts less then 0.3,we use the Balmer decrements to do the reddening correction of the [O III] luminosities and then derive the intrinsic [O III] luminosity function.We find t... For a sample of 411 type II QSOs with redshifts less then 0.3,we use the Balmer decrements to do the reddening correction of the [O III] luminosities and then derive the intrinsic [O III] luminosity function.We find that the host reddening correction of the [O III] 5007 luminosity for type II QSOs cannot be neglected.The median Balmer decrement of Hα/Hβ=4.0 corresponds to an extinction of 0.94 mag for the [O III] 5007 line,which is consistent with the result derived from the median Hβ/Hγ.Comparing the intrinsic luminosity function of type II QSOs with that of type I QSOs,we find that the upper limit of the type II QSO's fraction in the total QSOs is 80% for type II QSOs with z < 0.3 and 8.6≤log(L[O III]/L)≤9.4. 展开更多
关键词 type II qsos LUMINOSITY FUNCTION EMISSION LINES Balmer decrements
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Why the Energy Density of the Universe Is Lower and Upper-Bounded? Relaxing the Need for the Cosmological Constant
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作者 Ahmad A. Hujeirat 《Journal of Modern Physics》 CAS 2023年第6期790-801,共12页
Recently, it was argued that the energy density of the supranuclear dense matter inside the cores of massive neutron stars must have reached the , beyond which supranuclear dense matter becomes incompressible entropy-... Recently, it was argued that the energy density of the supranuclear dense matter inside the cores of massive neutron stars must have reached the , beyond which supranuclear dense matter becomes incompressible entropy-free gluon-quark superfluid. As this matter is also confined and embedded in flat spacetime, it is Lorentz invariant and could be treated as vacuum. The lower bound of matter in the universe may be derived using the following observational constraints: 1) The average energy density of the observable universe is erg/cc, 2) The observable universe is remarkably flat, and 3) the Hubble constant is a slowly decreasing function of cosmic time. Based thereon, I argue that the energy density in nature should be bounded from below by the average density of our vast and flat parent universe, , which is, in turn, comparable to the vacuum energy density , and amounts to erg/cc. When the total energy density is measured relative to , then both GR and Newtonian field equations may consistently model the gravitational potential of the parent universe without invoking cosmological constants. Relying on the recently proposed unicentric model of the observable universe, UNIMOUN, the big bang must have warped the initially flat spacetime into a curved one, though the expansion of the fireball doomed the excited energy state to diffuse out and return back to the ground energy state that governs the flat spacetime of our vast parent universe. 展开更多
关键词 General Relativity Big Bang Black Holes qsos Neutron Stars QCD Condensed Matter INCOMPRESSIBILITY SUPERFLUIDITY Super-Conductivity
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Foundation of the Unicentric Model of the Observable Universe—UNIMOUN
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作者 Ahmad A. Hujeirat 《Journal of Modern Physics》 CAS 2023年第4期415-431,共17页
In view of the growing difficulties of ΛCDM-cosmologies to compete with recent highly accurate cosmological observations, I propose the alternative model: the Unicentric Model of the Observable UNiverse (UNIMOUN). Th... In view of the growing difficulties of ΛCDM-cosmologies to compete with recent highly accurate cosmological observations, I propose the alternative model: the Unicentric Model of the Observable UNiverse (UNIMOUN). The model relies on employing a new time-dependent -metric for the GR field equations, which enables reversible phase transitions between normal compressible fluids and incompressible quantum superfluids, necessary for studying the cosmic evolution of the observable universe. The main properties of UNIMOUN read: 1) The observable universe was born in a flat spacetime environment, which is a tiny fraction of our infinitely large and flat parent universe, 2) Our big bang (BB) happened to occur in our neighbourhood, thereby endowing the universe the observed homogeneity and isotropy, 3) The energy density in the universe is upper-bounded by the universal critical density , beyond which matter becomes purely incompressible, rendering formation of physical singulareties, and in particular black holes, impossible, 4) Big bangs are neither singular events nor invoked by external forces, but rather, they are common self-sustaining events in our parent universe, 5) The progenitors of BBs are created through the merger of cosmically dead and inactive neutron stars and/or through “supermassive black holes” that are currently observed at the centres of most massive galaxies, 6) The progenitors are made up of purely incompressible entropy-free superconducting gluon- quark superfluids with (SuSu-matter), which endows these giant objects measurable sizes, 7) Spacetimes embedding SuSu-matter are conformally flat. It is shown that UNIMOUN is capable of dealing with or providing answers to several fundamental open questions in astrophysics and cosmology without invoking inflation, dark matter or dark energy. 展开更多
关键词 General Relativity: Big Bang Black Holes qsos Neutron Stars QCD Condensed Matter INCOMPRESSIBILITY SUPERFLUIDITY Super-Conductivity
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The Progenitor of the Big Bang and Its Connection to the Flatness and Acceleration of the Universe 被引量:1
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作者 Ahmad A. Hujeirat 《Journal of Modern Physics》 CAS 2022年第11期1474-1498,共25页
It was argued that old and massive neutron stars end up as black objects that are made of purely incompressible superconducting gluon-quark superfluid matter (henceforth SuSu-objects). Based on theoretical investigati... It was argued that old and massive neutron stars end up as black objects that are made of purely incompressible superconducting gluon-quark superfluid matter (henceforth SuSu-objects). Based on theoretical investigations and numerical solving of the field equations with time-dependent spacetime topologies, I argue that a dense cluster of SuSu-objects at the background of flat spacetime that merged smoothly is a reliable candidate for the progenitor of the big bang. Here, we present and use a new time-dependent spacetime metric, which unifies the metrics of Minkowski, Schwarzschild, and Friedmann as well as a modified TOV-equation for modeling dynamical contractions of relativistic objects. Had the progenitor undergone an abrupt decay, a hadronizing front forms at its surface and starts propagating from outside-to-inside, thereby hadronizing its entire content and changing the topology of the embedding spacetime from a flat into a dynamically expanding curved one. For an observer located at the center of the progenitor, H<sub>0</sub>, the universe would be seen as isotropic and homogeneous, implying therefore that the last big bang event must have occurred in our neighborhood. For the curved spacetime re-converges into a flat one, whereas the outward-propagation topological front, which separates the enclosed curved spacetime from the exterior flat one, would appear spatially and temporally accelerating outwards. The here-presented scenario suggests possible solutions to the flatness problem, the origin of acceleration of the universe and the pronounced activities of high redshift QSOs. We anticipate that future observations by the James-Webb-Telescope to support our scenario when active QSOs with z >12 would be detected. 展开更多
关键词 General Relativity: Big Bang Black Holes qsos Neutron Stars QCD Condensed Matter SUPERFLUIDITY
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The Origin of Power and Acceleration of High-Redshift Galaxies in the Unicentric Model of the Universe
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作者 Ahmad A. Hujeirat 《Journal of Modern Physics》 CAS 2022年第12期1581-1597,共17页
Recently, a unicentric model of our observable universe was proposed. Accordingly, the big bang was neither a singular event nor invoked by external forces, but rather a frequent event in cosmic life cycles that occur... Recently, a unicentric model of our observable universe was proposed. Accordingly, the big bang was neither a singular event nor invoked by external forces, but rather a frequent event in cosmic life cycles that occur sequentially or in parallel at the same and/or in different locations of our infinitely large, flat, homogeneous, and isotropic parent universe. The progenitor of our big bang is predicted to have been of a measurable size and happened to be in our neighbourhood. Based on theoretical arguments and general relativistic numerical calculations, it is argued that: 1) The surface of the progenitor is most appropriate for the hadron flash to run away;2) The structure of the progenitor is immune to self-collapse into a hyper-massive black hole;and 3) The power and acceleration of high-redshift galaxies may be connected to the BB-explosion. We conclude that the currently observed high-redshift galaxies must have been old and inactive in older times, but turned into life through matter and momentum transfer from the fireball and the collision of the locally curved spacetime embedding the galaxy with the expanding one embedding the fireball. With the present scenario, the origin of the monstrous black hole candidates with M<sub>BH</sub> &ge;10<sup>9</sup>M<sub>e</sub> , that are believed to have resided at the centre of galaxies when the observable universe was 400 Myr old, could be straightforwardly explained. This implies that QSOs with ever higher redshifts should exist, though their detection becomes increasingly harder. 展开更多
关键词 General Relativity Big Bang Black Holes qsos Neutron Stars QCD Condensed Matter INCOMPRESSIBILITY SUPERFLUIDITY Super-Conductivity
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新型反激变换器准谐振控制器ICE1QS01及其应用电路与设计
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作者 毛兴武 闫小娟 《电源技术应用》 2004年第5期270-274,共5页
ICE1QS01是一种支持低功率待机和功率因数校正(PFC)的开关电源准谐振控制器。介绍了 ICE1QS01的基本结构、工作原理及其应用电路与设计。
关键词 准谐振控制器 ICE1QSO1 反激变换器 设计
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Interstellar Refractive Scintillation and Intraday Polarization Angle Swings
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作者 Shan-JieQian Xi-ZhenZhang A.Kraus 《Chinese Journal of Astronomy and Astrophysics》 CSCD 2005年第1期27-40,共14页
Intraday polarization angle swings of ~180° observed in two sources (QSO0917+624 and QSO 1150+812) are discussed in the framework of refractive interstellar scintillationby a continuous interstellar medium. Mode... Intraday polarization angle swings of ~180° observed in two sources (QSO0917+624 and QSO 1150+812) are discussed in the framework of refractive interstellar scintillationby a continuous interstellar medium. Model-fits to the I-, Q- and U- light curves were made for bothsources. It is shown that for the case of 0917+624 both the intraday intensity variations and thepolarization angle swing of ~180° could be explained consistently in terms of a four-componentmodel, which comprises one steady and two scintillating polarized components and one furthernon-polarized scintillating component. The polarization angle swing of ~180° observed in 1150+812,which occurred when the polarized flux density was almost constant, could not be explained in termsof refractive scintillation by a continuous medium and might be due to other mechanisms (e.g.,scintillation by interstellar clouds). 展开更多
关键词 radio continuum GALAXIES polarization intraday variability SCATTERING refractive scintillation QUASARS individual: QSO 0917+624 and 1150+812
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An Intrinsic Model for the Polarization Position Angle Swing Observed in QSO 1150+812
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作者 Shan-JieQian Xi-ZhenZhang 《Chinese Journal of Astronomy and Astrophysics》 CSCD 北大核心 2004年第1期37-50,共14页
The rapid polarization position angle swing of ~ 180° observed in QSO 1150+812 at 2cm by Kochenov and Gabuzda is quite a regular event. One interesting property of the event is that, during the time of the swing ... The rapid polarization position angle swing of ~ 180° observed in QSO 1150+812 at 2cm by Kochenov and Gabuzda is quite a regular event. One interesting property of the event is that, during the time of the swing the polarized flux density remained almost constant. We suggest that such an event can be explained in terms of a relativistic thin shock propagating through a uniform helical magnetic field, giving rise to relativistic aberration effects as the transverse field component rotates. The model may also be applicable to other similar events in which variations in polarization are not accompanied by variations in total flux density. 展开更多
关键词 radio continuum: galaxies POLARIZATION quasars: individual: QSO 1150+812
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The reionization of He II and the temperature evolution of the intergalactic medium
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作者 Yun-Chuan Yu Chang-Shuo Yan You-Jun Lu 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2014年第4期373-389,共17页
A number of observations suggest that He II in the intergalactic medium (IGM) was fully ionized at z-3, probably by quasi-stellar objects (QSOs). Here we construct a simple model of a QSO to study the reionization... A number of observations suggest that He II in the intergalactic medium (IGM) was fully ionized at z-3, probably by quasi-stellar objects (QSOs). Here we construct a simple model of a QSO to study the reionization of He II and the corre- sponding thermal evolution of the IGM. We assume that QSOs are triggered by major mergers of dark matter halos, and the luminosity evolution of individual QSOs is de- scribed by an initial accretion stage with a constant Eddington ratio and then a power- law decay driven by long term disk evolution or fueling. Once a QSO is triggered, it immediately ionizes its surrounding area as an ionized bubble. The resulting changes in size and volume of the bubble are determined by the luminosity evolution of the central QSO. With the emergence of more and more bubbles, they eventually over- lap each other and finally permeate the whole universe. During the He II reionization, the IGM temperature increases due to the photoheating by the ionization processes. Applying the bubble model and considering various heating and cooling mechanisms, we trace the thermal evolution of the IGM and obtain the average IGM temperature as a function of redshift, which is very consistent with observations. The increase in IGM temperature due to the reionization of He II may be determined more accurately in the future, which may put robust constraints on the QSO model and the physics of He II reionization. 展开更多
关键词 cosmology: theory -- intergalactic medium: QSO
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Multifrequency Polarization Variations in the Quasar 0917+624
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作者 Shan-JieQian A.Kraus 《Chinese Journal of Astronomy and Astrophysics》 CSCD 北大核心 2002年第4期325-346,共22页
We present a detailed analysis of multi-frequency observations of linear polarization in the intraday variable quasar 0917+624 (z = 1.44). The observations were made in May 1989 at five frequencies (1.4, 2.7, 5.0, 8.3... We present a detailed analysis of multi-frequency observations of linear polarization in the intraday variable quasar 0917+624 (z = 1.44). The observations were made in May 1989 at five frequencies (1.4, 2.7, 5.0, 8.3 and 15GHz) with the VLA and the Effelsberg 100 m-telescope and in December 1988 at two frequencies (2.7 and 5.0 GHz) with the latter. It is shown that the relationship between the variations of the polarized and total flux density is highly wavelength dependent, and the multi-frequency polarization behavior may be essential for investigating the mechanisms causing these variations. It is shown that the variations observed at 20 cm can be interpreted in terms of refractive interstellar scintillation. However, after subtracting the variation due to scintillation, three 'features' emerged in the light-curve of the polarized flux density, indicating an additional variable component. Interestingly, these features are shown to be correlated with the variations at 2-6 cm, thus indicating that these features and the associated variations are due to some intrinsic causes. Moreover, a very rapid polarization angle swing of - 180° observed in December 1988 which cannot be explained by refractive interstellar scintillation, may also be produced by an intrinsic mechanism. Accordingly, we use a shock model to explain the polarization variations observed at the higher frequencies, although scintillation could also exist. The shock model can explain not only the variation of intensity, but also the time variation of its degree and angle of polarization, including the rapid swing of the polarization angle. It is shown that the degree and angle of polarization of the shock need only vary slightly in order to account for the observed complicated behaviour of polarization. 展开更多
关键词 radio continuum: galaxies - polarization - quasars: individual (QSO0917+624)
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Refractive Focusing of Interstellar Clouds and Intraday Polarization Angle Swings
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作者 Shan-Jie Qian T. E Krichbaum +3 位作者 Long Gao Xi-Zhen Zhang A. Witzel J. A. Zensus 《Chinese Journal of Astronomy and Astrophysics》 CSCD 2007年第2期215-223,共9页
Intraday variations of compact extragalactic radio sources in flux density and polarization are generally interpreted in terms of refractive scintillation from the continuous interstellar medium of our Galaxy. However... Intraday variations of compact extragalactic radio sources in flux density and polarization are generally interpreted in terms of refractive scintillation from the continuous interstellar medium of our Galaxy. However, continuous polarization angle swings of - 180° (for example, the one observed in the QSO 0917+624) could not be interpreted in this way. Qian et al. have shown that the polarization angle swing observed in the QSO 1150+812 can be explained in terms of focusing-defocusing effect by an interstellar cloud, which occults two closely-placed polarized components. Here we further show that the polarization angle swing event observed in the QSO 0917+624 can also be explained in this way. We also found evidence for the cloud eclipsing a non-polarized (core) component during a short period out- side the swing. A particular (and specific) plasma-lens model is proposed to model-fit the polarization swing event of 0917+624. Some physical parameters related to the plasma-lens and the source components are estimated. The brightness temperatures of the two lensed components are estimated to be -1.6× 10^13 K. Thus bulk relativistic motion with a Lorentz factor less than -20 may be sufficient to avoid the inverse - Compton catastrophe. 展开更多
关键词 radio continuum galaxies - polarization intraday variability - scattering refractive focusing - quasars Individual QSO 0917+624
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业余无线电台比赛操作技巧——结尾篇
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作者 吴国光 《无线电》 2003年第12期42-42,共1页
关键词 业余无线电台 操作技巧 CW QSO
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有朋自远方来 玉林HAM愉快的“五五节”
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作者 苏晓姗 黄良章 《现代通信》 2014年第3期36-36,共1页
常言道:习武之人以武会友,秀拳头。那么对我们玩无线电的HAM来说则是以电波会友,秀天线。今年的“五五节”,对玉林HAM而言确实是验证了此话,因一位未曾谋面的老朋友BG7SMP途径玉林,在电波的引导下被我们“劫持”到电磁环境优良的... 常言道:习武之人以武会友,秀拳头。那么对我们玩无线电的HAM来说则是以电波会友,秀天线。今年的“五五节”,对玉林HAM而言确实是验证了此话,因一位未曾谋面的老朋友BG7SMP途径玉林,在电波的引导下被我们“劫持”到电磁环境优良的佛子山景区,共度属于我们无线电爱好者的节日。 展开更多
关键词 眼球QSO HAM专享房车
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A high-order target phase approach for the station-keeping of periodic orbits
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作者 Xiaoyu Fu Nicola Baresi Roberto Armellin 《Astrodynamics》 EI 2024年第1期61-75,共15页
A novel high-order target phase approach(TPhA)for the station-keeping of periodic orbits is proposed in this work.The key elements of the TPhA method,the phase-angle Poincare map and high-order maneuver map,are constr... A novel high-order target phase approach(TPhA)for the station-keeping of periodic orbits is proposed in this work.The key elements of the TPhA method,the phase-angle Poincare map and high-order maneuver map,are constructed using differential algebra(DA)techniques to determine station-keeping epochs and calculate correction maneuvers.A stochastic optimization framework tailored for the TPhA-based station-keeping process is leveraged to search for fuel-optimal and error-robust TPhA parameters.Quasi-satellite orbits(QSOs)around Phobos are investigated to demonstrate the efficacy of TPhA in mutli-fidelity dynamical models.Monte Carlo simulations demonstrated that the baseline QSO of JAXA’s Martian Moons eXploration(MMX)mission could be maintained with a monthly maneuver budget of approximately 1 m/s. 展开更多
关键词 target phase approach(TPhA) station-keeping Poincarémap differential algebra(DA) quasi-satellite orbit(QSO)
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