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The prospects for observations of gravitationally lensed extragalactic sources in the far-infrared and submillimeter ranges of the electromagnetic spectrum by the planned space observatories with active cooling of the telescope mirror to cryogenic temperatures are considered. The possibility of solving topical cosmological and astrophysical problems related to the observations of gravitationally lensed sources is discussed. The number counts of lensed sources have been performed for various wavelengths in the range from 70 to 2000 µm. The redshift and magnification distributions of lensed sources and the mass distribution of lenses have been obtained. We have constructed model photometric sky maps for which the contribution from lensed sources has been calculated for the first time.
相似文献3.
The use of cosmic rays for continuous monitoring and prediction of some dangerous phenomena for the earth's civilization 总被引：1，自引：0，他引：1
The main idea of the International Cosmic Ray Service (ICRS) is to combine satellite and spaceprobe cosmic rays, magnetic and plasma data with groundbased cosmic ray data (exchanged in real time) for obtaining continuous information on the electromagnetic and radiation situation in the interplanetary space and Earth's magnetosphere: prediction of great geomagnetic storms, big increases of radiation hazards and other dangerous phenomena in space and on the Earth for people and technology. ICRS can predict not only geomagnetic storms and unfavorable days in the environment (especially important for old people and people with some diseases), but, in combination with astrophysical methods, can predict big increases of radiation hazards very dangerous for the Earth's civilization and big changes in the environment due to extremely powerful solar flares and local supernova explosions. We hope that, after some additional investigation of high energy cosmic-ray distribution function outside the heliosphere, it could be possible to solve by ICRS more complicated problems: to determine in combination with astrophysical methods the location and velocity of nearest dust-molecular galactic clouds with frozen-in magnetic fields and predict the expected time of the Sun capturing by some clouds with possible changes of Earth's global climate. The foundation of ICRS could bring a new possibility of development to the cosmic ray observatories, release scientists from a lot of routine work and increase the fundamental and applied research efficiency. 相似文献
4.
宽带频谱序列干扰信号识别与统计方法 总被引：1，自引：0，他引：1
随着科学技术的不断进步,射电天文台站趋于自动化,各类电子设备的广泛使用使得射电天文台站的电磁环境变得尤为复杂,如何有效识别和统计复杂频谱中的干扰信号是当前射电天文台站亟需解决的问题,故提出一种宽带频谱序列干扰信号识别与统计方法.首先,对每组宽带频谱进行信噪分离、识别频谱中的干扰信号;然后,对第1组宽带频谱信号识别结果及信号特征建立模板库,后续每组频谱的信号识别结果与模板库中对应频率的信号进行相似性分析,根据相似性分析结果,统计信号次数,更新模板库;实现宽带频谱序列干扰信号的识别与统计.针对QTT (QiTai Radio Telescope)台站实测频谱,运用该方法进行干扰信号识别与统计,能够有效识别并标记频谱中的干扰信号,并统计干扰信号随时间、方向的变化趋势. 相似文献
5.
We list the principal stages of astroclimatic studies concerned with choosing the sites for astrophysical observatories in
Caucasus and Crimea. We chow that the sites for three observatories in Northern Caucasus (Kislovodsk Mountain Astronomical
Station of Pulkovo Main Astronomical Observatory of the Russian Academy of Sciences, Special Astrophysical Observatory of
the Russian Academy of Sciences, Terskol Observatory) were chosen without obtaining representative statistical data in terms
of the number of clear night hours and seeing. We report the data on the number of clear night hours and seeing for the 6-m
telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences based on results of long-term observations.
We discuss the possible causes of the discrepancies between experimental and forecast data and conclude that currently none
of the three observatories in the North Caucasus can be preferred because of the great variety of the methods employed and
limited statistics in terms of astroclimatic and meteorological parameters for some sites. 相似文献
6.
M. E. Sachkov 《Solar System Research》2014,48(7):480-484
7.
J.-P. Berger F. Malbet F. Baron A. Chiavassa G. Duvert M. Elitzur B. Freytag F. Gueth S. H?nig J. Hron H. Jang-Condell J.-B. Le Bouquin J.-L. Monin J. D. Monnier G. Perrin B. Plez T. Ratzka S. Renard S. Stefl E. Thiébaut K. R. W. Tristram T. Verhoelst S. Wolf J. Young 《Astronomy and Astrophysics Review》2012,20(1):1-55
The number of publications of aperture-synthesis images based on optical long-baseline interferometry measurements has recently increased due to easier access to visible and infrared interferometers. The interferometry technique has now reached a technical maturity level that opens new avenues for numerous astrophysical topics requiring milli-arcsecond model-independent imaging. In writing this paper our motivation was twofold: (1) review and publicize emblematic excerpts of the impressive corpus accumulated in the field of optical interferometry image reconstruction; (2) discuss future prospects for this technique by selecting four representative astrophysical science cases in order to review the potential benefits of using optical long-baseline interferometers. For this second goal we have simulated interferometric data from those selected astrophysical environments and used state-of-the-art codes to provide the reconstructed images that are reachable with current or soon-to-be facilities. The image-reconstruction process was ??blind?? in the sense that reconstructors had no knowledge of the input brightness distributions. We discuss the impact of optical interferometry in those four astrophysical fields. We show that image-reconstruction software successfully provides accurate morphological information on a variety of astrophysical topics and review the current strengths and weaknesses of such reconstructions. We investigate how to improve image reconstruction and the quality of the image possibly by upgrading the current facilities. We finally argue that optical interferometers and their corresponding instrumentation, existing or to come, with six to ten telescopes, should be well suited to provide images of complex sceneries. 相似文献
8.
Anthony L. Peratt 《Astrophysics and Space Science》1996,242(1-2):93-163
Plasma science is rich in distinguishable scales ranging from the atomic to the galactic to the meta-galactic, i.e., themesoscale. Thus plasma science has an important contribution to make in understanding the connection between microscopic and macroscopic phenomena. Plasma is a system composed of a large number of particles which interact primarily, but not exclusively, through the electromagnetic field. The problem of understanding the linkages and couplings in multi-scale processes is a frontier problem of modern science involving fields as diverse as plasma phenomena in the laboratory to galactic dynamics.Unlike the first three states of matter, plasma, often called the fourth state of matter, involves the mesoscale and its interdisciplinary founding have drawn upon various subfields of physics including engineering, astronomy, and chemistry. Basic plasma research is now posed to provide, with major developments in instrumentation and large-scale computational resources, fundamental insights into the properties of matter on scales ranging from the atomic to the galactic. In all cases, these are treated as mesoscale systems. Thus, basic plasma research, when applied to the study of astrophysical and space plasmas, recognizes that the behavior of the near-earth plasma environment may depend to some extent on the behavior of the stellar plasma, that may in turn be governed by galactic plasmas. However, unlike laboratory plasmas, astrophysical plasmas will forever be inaccessible to in situ observation. The inability to test concepts and theories of large-scale plasmas leaves only virtual testing as a means to understand the universe. Advances in in computer technology and the capability of performing physics first principles, fully three-dimensional, particle-in-cell simulations, are making virtual testing a viable alternative to verify our predictions about the far universe.The first part of this paper explores the dynamical and fluid properties of the plasma state, plasma kinetics, and the radiation emitted from plasmas. The second part of this paper outlines the formulation for the particle-in-cell simulation of astrophysical plasmas and advances in simulational techniques and algorithms, as-well-as the advances that may be expected as the computational resource grows to petaflop speed/memory capabilities.Dedicated to the memories of Hannes Alfvén and Oscar Buneman; Founders of the Subject. 相似文献
9.
Solutions in the form of cylindrical magnetosonic solitons of compression and rarefaction were obtained within the scope of
the three-species electromagnetic gas-dynamic model of an electron-positron-ion plasma. These solutions can describe formation
of cylindrical structures in accretion disks and jets in the vicinity of compact astrophysical objects. 相似文献
10.
Douglas A. Simons Paola Amico Dietrich Baade Sam Barden Randall Campbell Gert Finger Kirk Gilmore Roland Gredel Paul Hickson Steve Howell Norbert Hubin Andreas Kaufer Ralf Kohley Philip MacQueen Sergej Markelov Mike Merrill Satoshi Miyazaki Hidehiko Nakaya Darragh O'Donoghue Tino Oliva Andrea Richichi Derrick Salmon Ricardo Schmidt Hongjun Su Simon Tulloch Maria Luisa García Vargas R. Mark Wagner Olivier Wiecha Binxun Ye 《Experimental Astronomy》2005,19(1-3):15-44
Results of a survey of instrumentation and detector systems, either currently deployed or planned for use at telescopes larger than 3.5 m, in ground based observatories world-wide, are presented. This survey revealed a number of instrumentation design trends at optical, near, and mid-infrared wavelengths. Some of the most prominent trends include the development of vastly larger optical detector systems (> 109 pixels) than anything built to date, and the frequent use of mosaics of near-infrared detectors – something that was quite rare only a decade ago in astronomy. Some future science applications for detectors are then explored, in an attempt to build a bridge between current detectors and what will be needed to support the research ambitions of astronomers in the future. 相似文献
11.
A short summary of recent progress in measuring and understanding turbulence during magnetic reconnection in laboratory plasmas
is given. Magnetic reconnection is considered as a primary process to dissipate magnetic energy in laboratory and astrophysical
plasmas. A central question concerns why the observed reconnection rates are much faster than predictions made by classical
theories, such as the Sweet–Parker model based on MHD with classical Spitzer resistivity. Often, the local resistivity is
conjectured to be enhanced by turbulence to accelerate reconnection rates either in the context of the Sweet–Parker model
or by facilitating setup of the Pestchek model. Measurements at a dedicated laboratory experiment, called MRX or Magnetic
Reconnection Experiment, have indicated existence of strong electromagnetic turbulence in current sheets undergoing fast reconnection.
The origin of the turbulence has been identified as right-hand polarized whistler waves, propagating obliquely to the reconnecting
field, with a phase velocity comparable to the relative drift velocity. These waves are consistent with an obliquely propagating
electromagnetic lower-hybrid drift instability driven by drift speeds large compared to the Alfven speed in high-beta plasmas.
Interestingly, this instability may explain electromagnetic turbulence also observed in collisionless shocks, which are common
in energetic astrophysical phenomena. 相似文献
12.
A close temporal and spatial association has been found between erupting filaments/coronal transients and radio noise storm continua. The three transients studied occurred away from active regions and are members of a class not usually accompanied by chromospheric emission. The data analyzed were from the S-054 soft X-ray telescope on Skylab and from one- and two-dimensional interferometers at meter and decameter wavelengths at Nançay and Clark Lake observatories. Calculations confirmed that observed microwave radiation from the transients is due to thermal bremsstrahlung. The results are consistent with an interpretation of heating of an increased amount of coronal plasma by nonthermal, 10–100 keV electrons. Three possibilities for the source of the material are described: (1) The filament material; (2) evaporation from the chromosphere or transition region; and (3) via a long-lived reconnection process. 相似文献
13.
Bruny Baret Imre Bartos Boutayeb Bouhou Alessandra Corsi Irene Di Palma Corinne Donzaud Vronique Van Elewyck Chad Finley Gareth Jones Antoine Kouchner Szabolcs Mrka Zsuzsa Mrka Luciano Moscoso Eric Chassande-Mottin Maria Alessandra Papa Thierry Pradier Peter Raffai Jameson Rollins Patrick Sutton 《Astroparticle Physics》2011,35(1):1-7
We derive a conservative coincidence time window for joint searches of gravitational-wave (GW) transients and high-energy neutrinos (HENs, with energies ?100 GeV), emitted by gamma-ray bursts (GRBs). The last are among the most interesting astrophysical sources for coincident detections with current and near-future detectors. We take into account a broad range of emission mechanisms. We take the upper limit of GRB durations as the 95% quantile of the T90’s of GRBs observed by BATSE, obtaining a GRB duration upper limit of ∼150 s. Using published results on high-energy (>100 MeV) photon light curves for 8 GRBs detected by Fermi LAT, we verify that most high-energy photons are expected to be observed within the first ∼150 s of the GRB. Taking into account the breakout-time of the relativistic jet produced by the central engine, we allow GW and HEN emission to begin up to 100 s before the onset of observable gamma photon production. Using published precursor time differences, we calculate a time upper bound for precursor activity, obtaining that 95% of precursors occur within ∼250 s prior to the onset of the GRB. Taking the above different processes into account, we arrive at a time window of tHEN − tGW ∈ [−500 s, +500 s]. Considering the above processes, an upper bound can also be determined for the expected time window of GW and/or HEN signals coincident with a detected GRB, tGW − tGRB ≈ tHEN − tGRB ∈ [−350 s, +150 s]. These upper bounds can be used to limit the coincidence time window in multimessenger searches, as well as aiding the interpretation of the times of arrival of measured signals. 相似文献
14.
E. Pace A. Gherardi L. Gambicorti M. Pancrazzi I. Pagano S. Scuderi C. Pontoni M. Munari G. Piotto S. Villanova D. Magrin M. Uslenghi M. Fiorini M. Trifoglio E. Cavazzuti M. Miccolis 《Astrophysics and Space Science》2009,320(1-3):197-202
The WSO-UV space observatory, an UV-optimized 1.7 m Ritchey-Chretien telescope, will investigate many astrophysical phenomena from planetary science to cosmology. The Field Camera Unit is a multi-spectral radial instrument on the focal plane of WSO-UV. It will have three channels covering the wide spectral range from 115 nm to 800 nm and it will be operated in imaging, low-resolution spectroscopic, polarimetric and spectro-polarimetric modes. This paper will discuss and review the main characteristics and the present status of this instrument. 相似文献
15.
P. Padovani D. M. Alexander R. J. Assef B. De Marco P. Giommi R. C. Hickox G. T. Richards V. Smolčić E. Hatziminaoglou V. Mainieri M. Salvato 《Astronomy and Astrophysics Review》2017,25(1):2
Active galactic nuclei (AGN) are energetic astrophysical sources powered by accretion onto supermassive black holes in galaxies, and present unique observational signatures that cover the full electromagnetic spectrum over more than twenty orders of magnitude in frequency. The rich phenomenology of AGN has resulted in a large number of different “flavours” in the literature that now comprise a complex and confusing AGN “zoo”. It is increasingly clear that these classifications are only partially related to intrinsic differences between AGN and primarily reflect variations in a relatively small number of astrophysical parameters as well the method by which each class of AGN is selected. Taken together, observations in different electromagnetic bands as well as variations over time provide complementary windows on the physics of different sub-structures in the AGN. In this review, we present an overview of AGN multi-wavelength properties with the aim of painting their “big picture” through observations in each electromagnetic band from radio to \(\gamma \)-rays as well as AGN variability. We address what we can learn from each observational method, the impact of selection effects, the physics behind the emission at each wavelength, and the potential for future studies. To conclude, we use these observations to piece together the basic architecture of AGN, discuss our current understanding of unification models, and highlight some open questions that present opportunities for future observational and theoretical progress. 相似文献
16.
In this paper we examine the possibility of adopting standards within the context of radio astronomy and the benefits to be derived thereby. In particular we consider the application of standards within the three areas of the receiver hardware, the control and communication between different parts of the observing system, and the interface with the astronomer. The adoption of such standards will increase flexibility of observing systems, allow the easy interchange of equipment between observatories and greatly simplify guest observing. In this paper we will only consider the application of standards within the field of millimetre-wave and sub-millimetre-wave single dish astronomy. However, the principle can be easily extended to other astronomical wavebands. We describe some current developments at the Onsala Space Observatory which illustrate the proposed philosophy and show how such standards may be implemented. Naturally, the detailed definition of such standards would have to be agreed in conjunction with other interested astronomical institutions. 相似文献
17.
The “Spektr-UF” project (“World Space Observatory-Ultraviolet” (WSO-UV)) will be the largest space observatory for observations in the UV band. In this paper we briefly outline the key science issues that the WSO-UV will address during its lifetime with the help of its instrumentation: spectrographs and a field camera unit. Of special interest are early Universe physics (reionization and search for baryonic matter), star formation, chemical evolution of galaxies, astrophysical accretion processes, stellar atmosphere physics, and planetary atmosphere studies. 相似文献
18.
在无碰撞等离子体中,波粒相互作用会引起电磁场与粒子之间能量转移,其结果之一是重塑粒子速度分布函数.因而,如何定量化波粒相互作用是日球层和天体等离子体研究中的一个基础问题.近年来,在定量化波粒相互作用问题的研究中,取得了很多重要成果.将主要介绍相关理论研究上的进展,特别是,将重点介绍新近提出的度量共振和非共振波粒相互作用的理论方法.还将介绍该方法在度量内日球层阿尔文模式波、质子束流不稳定性和电子热流不稳定性中波粒相互作用上的应用. 相似文献
19.
A set of three nonlinearly coupled equations governing the interaction between electromagnetic ion-cyclotron and magnetosonic waves is derived. In appropriate limiting cases, the set yields simplified equations. On the other hand, the full set of equations is used to derive a general dispersion relation for the parametric interaction of electromagnetically modulated ion-cyclotron wave packets. An analytical expression for the growth rate of the electromagnetic modulational instability is presented. The relevance of our investigation to non-thermal electromagnetic fluctuations in astrophysical and cometary plasmas is pointed out. 相似文献
20.
In 1998–1999, the X-ray transients XTE J2012+381 and XTE J1550-564 were observed with the TTM X-ray telescope onboard the Mir-Kvant astrophysical module. Spectral properties of these sources on the descent of the light curve after the secondary maxima of their outbursts are studied. Upper limits on the off-state flux are given. Comparison with other X-ray novae observed with the TTM telescope leads us to conclude that XTE J2012+381 and XTE J 1550-564 are soft X-ray novae. XTE J2012+381 probably belongs to the subclass of long-period X-ray transients. 相似文献