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The reionization of He II and the temperature evolution of the intergalactic medium 认领 引用
1
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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Part III: Explaining the “Extra” Heat of Intergalactic Hydrogen Clouds with Probabilistic Spacetime 认领 引用 被引量：1
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作者 Dennis Doren James Harasymiw 《Journal of High Energy Physics, Gravitation and Cosmology》 CAS 2023年第2期542-551,共10页
Recent observations have consistently shown a greater degree of heat in intergalactic hydrogen clouds when redshift z < 2 than what well-designed simulations have indicated. The reason for this “extra” energy has... Recent observations have consistently shown a greater degree of heat in intergalactic hydrogen clouds when redshift z < 2 than what well-designed simulations have indicated. The reason for this “extra” energy has not been established, with the latest hypothesis being the effect of a certain type of dark matter. This paper presents a contrasting straightforward non-dark explanation for the extra energy based on the Probabilistic Spacetime Theory (PST). Both the dark matter and PST models are shown to involve the creation of new photons to explain the thermal enigma, but with very different underlying mechanisms. As this is the third paper in a three-part series of articles on the utility of that theory, a discussion is offered at the end of this paper concerning what the collective set of three articles has shown. Despite dark entities being hypothesized as a cause of all three reviewed research findings, dark entities are not needed to explicate the excess energy documented in each paper. Instead, the PST offers explanations for the reviewed research findings based solely on its five tenets and no dark entities. When viewed from an even larger context of other studies’ unexpected results, the PST was found to be a comprehensive yet parsimonious cosmological theory worthy of further testing. 展开更多
关键词 Intergalactic Medium Absorption Lines Lyman-α Forest Probabilistic Spacetime Dark Photons Dark Matter
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Energetic Gamma Radiation from Blazar and Its Effect on Intergalactic Medium 认领 引用
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作者 Jayashri Medhi Hira Lal Duorah Anurup Gohain Barua Kalpana Duorah 《Journal of Earth Science and Engineering》 2013年第3期203-206,共4页
Blazars are subclass of AGN （active galactic nuclei） with relativistic jet that is pointing in the general direction of the earth. The energy flux in the jet is about （10^44-10^47） erg/s. The γ-rays in the energy... Blazars are subclass of AGN （active galactic nuclei） with relativistic jet that is pointing in the general direction of the earth. The energy flux in the jet is about （10^44-10^47） erg/s. The γ-rays in the energy range 10 GeV-10 TeV emanating from blazar are examined and their effect on the IGM （intergalactic medium） is studied. The γ-ray emission is considered as due to inverse Compton scattering of relativistic electrons. There appears to be a gamma ray flux from blazar above 10 GeV having a line intensity of 1.5 × 10^-4 cm^-2 s^-1 sr^-1. The IGM is measured to large distances and it is found to be clumpy. It is found that at higher redshifl the density of IGM increases. The cosmological density parameter measured is found to lie within the suggested limit of 0.03 at redshift z = 3 for background intensity of radiation 10^-24 W·m^-2·Hz^-1·sr^-1. The iso-ΩIGM curve shows a kink in its profile which might be significant at the particular value of z equal to 2. Some more detailed studies are required for understanding the distribution of intergalactic medium at the unstable point at z = 2 as shown in inverse Compton radiation. 展开更多
关键词 Active galactic nuclei gamma rays intergalactic medium.
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Probing Large-scale Structure and the Multi-phase IGM at the Cosmic Noon——Insights from a Joint Survey with Euclid,CSST,JPCam,and JUST 认领 引用
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作者 Jiang-Tao Li Renato A.Dupke +4 位作者 Yan Gong Zhijie Qu Weichen Wang Xiaohu Yang Xiaodi Yu 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2026年第6期281-306,共26页
We present scientific and technical justifications of a potential coordinated Euclid/CSST/JPCam/JUST survey of the Euclid Deep Field North(EDF-N),aimed at probing the multi-phase circumgalactic and intergalactic mediu... We present scientific and technical justifications of a potential coordinated Euclid/CSST/JPCam/JUST survey of the Euclid Deep Field North(EDF-N),aimed at probing the multi-phase circumgalactic and intergalactic medium(CGM/IGM)at the cosmic noon over~20 deg2.The survey is structured around three connected goals:(1)improving photometric redshift(photo-z)accuracy through the combination of broad-and narrow-band photometry,enabling reliable identification of large-scale structures;(2)probing extended CGM emission with dedicated narrow-band imaging;and(3)mapping foreground IGM via absorption-line spectroscopy of background galaxies.Together,these components establish an integrated observational framework to investigate galactic ecosystems—linking galaxies to their circumgalactic and intergalactic environments—at cosmic noon.We show that the J-PAS-like narrow-band system used in JPCam substantially improves photo-z accuracies from only the Euclid/CSST broad-band data,especially for star-forming galaxies at z~1.0–1.4.This enables the identification of galaxy groups and(proto-)clusters directly from photo-z measurements.Stacked JPCam narrowband imaging should also detect extended[O II]-emitting CGM halos.We then construct mock three-dimensional(3D)gas distribution model and realistic galaxy catalog,and further construct mock CSST and JUST background galaxy spectra adding Lyαand Mg II absorptions.The reconstructed 3D H I field from CSST Lyαforest reliably recovers large-scale structures;however,our simulations indicate that detecting diffuse IGM Mg II absorption with JUST is infeasible,either through spectral stacking or via the two-point correlation function method.We conclude that constraining the metallicity of the diffuse IGM will require significantly deeper and higherresolution spectroscopy expected from future facilities such as the 39 m E-ELT. 展开更多
关键词 (galaxies:)intergalactic medium Galaxy:evolution galaxies:high redshift (galaxies:)quasars:absorption lines
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Strong gravitational lensing of blazar gamma-radiation and intergalactic magnetic fields 认领 引用
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作者 Yu.N.Eroshenko 《Chinese Physics C》 SCIE CAS CSCD 2024年第1期184-191,共8页
The influence of intergalactic magnetic fields on the strong gravitational lensing of blazar secondary gamma radiation is discussed.Currently,two cases of strong gravitational lensing of blazar gamma-radiation are kno... The influence of intergalactic magnetic fields on the strong gravitational lensing of blazar secondary gamma radiation is discussed.Currently,two cases of strong gravitational lensing of blazar gamma-radiation are known,where radiation is deflected by galaxies on the line of sight between the blazars and Earth.The magnetic field can affect the movements of electron-positron pairs generated by primary radiation,thereby changing the directions of secondary gamma radiation.It modifies the equation of the gravitational lens and leads to the dependence of the observed signal in the secondary gamma radiation on the energy of photons and magnetic field.Accordingly,it is possible,in principle,to estimate the intergalactic magnetic fields from the time delay of signals,from the angular position of images(for future high-resolution gamma-ray telescopes)or from the shape of the observed energy spectrum.This method is demonstrated by the example of the blazar B0218+357.In this case,however,it is not possible to obtain useful constraints due to the large distances to the blazar and lens galaxy.The result is only a lower limit on the magnetic field B>2×10−17G,which is weaker than other existing constraints.However,future discoveries of lensed blazars may provide more favorable opportunities for measuring the magnetic fields,especially with the help of a new generation of gamma-ray telescopes such as e-ASTROGAM,GECAM,and SVOM as well as future gamma-ray telescopes with a high angular resolution,∼0.1″. 展开更多
关键词 gravitational lensing blazar gamma-astronomy intergalactic magnetic fields
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Intensity distribution function and statistical properties of fast radio bursts 认领 引用 被引量：5
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作者 Long-Biao Li Yong-Feng Huang +2 位作者 Zhi-Bin Zhang Di Li Bing Li 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2017年第1期71-80,共10页
Fast Radio Bursts （FRBs） are intense radio flashes from the sky that are characterized by mil- lisecond durations and Jansky-level flux densities. We carried out a statistical analysis on FRBs that have been discove... Fast Radio Bursts （FRBs） are intense radio flashes from the sky that are characterized by mil- lisecond durations and Jansky-level flux densities. We carried out a statistical analysis on FRBs that have been discovered. Their mean dispersion measure, after subtracting the contribution from the interstellar medium of our Galaxy, is found to be ~ 660 pc cm-3, supporting their being from a cosmological origin. Their energy released in the radio band spans about two orders of magnitude, with a mean value of ~ 10-39 erg. More interestingly, although the study of FRBs is still in a very early phase, the published collection of FRBs enables us to derive a useful intensity distribution function. For the 16 non-repeating FRBs detected by the Parkes telescope and the Green Bank Telescope, the intensity distribution can be described as dN/dFobs = （4.1± 1.3） × 103 F-obs1.1±0.2 sky-1 d-l, where Fobs is the observed radio obs fluence in units of Jy ms. Here the power-law index is significantly flatter than the expected value of 2.5 for standard candles distributed homogeneously in a flat Euclidean space. Based on this intensity distribution function, the Five-hundred-meter Aperture Spherical radio Telescope （FAST） is predicted to be able to detect about five FRBs for every 1000 h of observation time. 展开更多
关键词 pulsars general - stars neutron - radio continuum general - intergalactic medium -methods statistical
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Combined limit on the photon mass with nine localized fast radio bursts 认领 引用 被引量：3
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作者 Jun-Jie Wei Xue-Feng Wu 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2020年第12期330-336,共7页
A nonzero-mass hypothesis for the photon can produce a frequency-dependent dispersion of light, which results in arrival-time differences of photons with different frequencies originating from a given transient source... A nonzero-mass hypothesis for the photon can produce a frequency-dependent dispersion of light, which results in arrival-time differences of photons with different frequencies originating from a given transient source. Extragalactic fast radio bursts(FRBs), with their low frequency emissions, short time durations, and long propagation distances, are excellent astrophysical probes to constrain the rest mass of the photon mγ. However, the derivation of a limit on mγis complicated by the similar frequency dependences of dispersion expected from the plasma and nonzero photon mass effects. If a handful measurements of redshift for FRBs are available, then the different redshift dependences of the plasma and photon mass contributions to the dispersion measure(DM) might be able to break dispersion degeneracy in testing the photon mass. For now, nine FRBs with redshift measurements have been reported, which can turn this idea into reality. Taking into account the DM contributions from both the plasma and a possible photon mass,we use the data on the nine FRBs to derive a combined limit of mγ≤ 7.1 × 10^-51 kg, or equivalently mγ≤ 4.0 × 10^-15 e V/c2 at 68% confidence level, which is essentially as good as or represents a factor of 7 improvement over previous limits obtained by the single FRBs. Additionally, a reasonable estimation for the DM contribution from the host galaxy, DMhost, can be simultaneously achieved in our analysis. The rapid progress in localizing FRBs will further tighten the constraints on both mγ and DMhost. 展开更多
关键词 radio continuum:general intergalactic medium astroparticle physics
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Alternative kind of hydrogen atoms as a possible explanation for the latest puzzling observation of the 21 cm radio line from the early Universe 认领 引用 被引量：2
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作者 Eugene Oks 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2020年第7期172-176,共5页
There is a puzzling astrophysical result concerning the latest observation of the absorption profile of the redshifted radio line 21 cm from the early Universe(as described in Bowman et al.). The amplitude of the prof... There is a puzzling astrophysical result concerning the latest observation of the absorption profile of the redshifted radio line 21 cm from the early Universe(as described in Bowman et al.). The amplitude of the profile was more than a factor of two greater than the largest predictions. This could mean that the primordial hydrogen gas was much cooler than expected. Some explanations in the literature suggested a possible cooling of baryons either by unspecified dark matter particles or by some exotic dark matter particles with a charge a million times smaller than the electron charge. Other explanations required an additional radio background. In the present paper, we entertain a possible different explanation for the above puzzling observational result: the explanation is based on the alternative kind of hydrogen atoms(AKHA),whose existence was previously demonstrated theoretically, as well as by the analysis of atomic experiments. Namely, the AKHA are expected to decouple from the cosmic microwave background(CMB) much earlier(in the course of the Universe expansion) than usual hydrogen atoms, so that the AKHA temperature is significantly lower than that of usual hydrogen atoms. This seems to lower the excitation(spin) temperature of the hyperfine doublet(responsible for the 21 cm line) sufficiently enough for explaining the above puzzling observational result. This possible explanation appears to be more specific and natural than the previous possible explanations. Further observational studies of the redshifted 21 cm radio line from the early Universe could help to verify which explanation is the most relevant. 展开更多
关键词 Cosmology:Early Universe explanation of the puzzle of 21cm radio line Galaxies:intergalactic medium Cosmology:observations Cosmology:theory
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A Deprojection Analysis of Abell 1650 with XMM-Newton 认领 引用 被引量：2
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作者 Shu-Mei Jia Yong Chen Li Chen 《Chinese Journal of Astronomy and Astrophysics》 2006年第2期181-196,共16页
We revisit the XMM-Newton observation of the galaxy cluster Abell 1650 with a deprojection technique. We find that the radial deprojected spectra of Abell 1650 can be marginally fitted by a single-temperature model. I... We revisit the XMM-Newton observation of the galaxy cluster Abell 1650 with a deprojection technique. We find that the radial deprojected spectra of Abell 1650 can be marginally fitted by a single-temperature model. In order to study the properties of the central gas, we fit the spectra of the central two regions with a two- temperature model. The fits then become significantly better and the cool gas about 1～2 keV can be connected with the gas cooling. Fitting the central spectrum （r≤1′） by using a cooling flow model with an isothermal component yields a small mass deposition rate of 10-7^＋11 M. yr^-1, while the standard cooling flow model can not fit this spectrum satisfactorily except that there exists a cut-off temperature having a level of about 3 keV. From the isothermal model we derive the deprojected electron density profile ne（r）, and then together with the deprojected temperature profile the total mass and gas mass fraction of cluster are also determined. We compare the properties of Abell 1650 with those of Abell 1835 （a large cooling flow cluster） and some other clusters, to explore the difference in properties between large and small cooling flow cluster, and what causes the difference in the cooling flow of different clusters. It has been shown that Abell 1835 has a steeper potential well and thus a higher electron density and a lower temperature in its center, indicating that the shape of the gravitational potential well in central region determines the cooling flow rates of clusters. We calculate the potential, internal and radiated energies of these two clusters, and find that the gas energies in both clusters are conserved during the collapsing stage. 展开更多
关键词 galaxies： clusters： individual： Abell 1650 -galaxies： cooling flowsgalaxies： evolution - galaxies： intergalactic medium - X-rays： galaxies： clusters
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Constraining the Temperature-density Relation of the Inter-galactic Medium from Analytically Modeling LyαForest Absorbers 认领 引用
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作者 Li Yang Zheng Zheng T.-S.Kim 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2023年第4期72-84,共13页
The absorption by neutral hydrogen in the intergalactic medium(IGM)produces the Lya forest in the spectra of quasars.The Lya forest absorbers have a broad distribution of neutral hydrogen column density NHⅠ and Do... The absorption by neutral hydrogen in the intergalactic medium(IGM)produces the Lya forest in the spectra of quasars.The Lya forest absorbers have a broad distribution of neutral hydrogen column density NHⅠ and Doppler b parameter.The narrowest Lya absorption lines(of lowest b)with neutral hydrogen column density above~1013cm-2 are dominated by thermal broadening,which can be used to constrain the thermal state of the IGM.Here we constrain the temperature-density relation T=T0(ρ/■)γ-1 of the IGM at 1.6<z<3.6 by using NHⅠ and b parameters measured from 24 high-resolution and high-signal-to-noise quasar spectra and by employing an analytic model to model the NHⅠ -dependent low-b cutoff in the b distribution.In each NHⅠ bin,the b cutoff is estimated using two methods,one non-parametric method from computing the cumulative b distribution and a parametric method from fitting the full b distribution.We find that the IGM temperature T0 at the mean gas densityρshows a peak of~1.5×104 K at z~2.7-2.9.At redshift higher than this,the indexγapproximately remains constant,and it starts to increase toward lower redshifts.The evolution in both parameters is in good agreement with constraints from completely different approaches,which signals that HeⅡreionization completes around z~3. 展开更多
关键词 (galaxies:)intergalactic medium-(galaxies:)quasars absorption lines-radiation mechanisms thermal
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X-ray spectroscopy of clusters of galaxies 认领 引用
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作者 Naomi Ota 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2012年第8期973-994,共22页
Clusters of galaxies are the most massive objects in the Universe and precise knowledge of their mass structure is important to understand the history of structure formation and constrain still unknown types of dark c... Clusters of galaxies are the most massive objects in the Universe and precise knowledge of their mass structure is important to understand the history of structure formation and constrain still unknown types of dark contents of the Universe. X-ray spectroscopy of galaxy clusters provides rich information about the physical state of hot intracluster gas and the underlying potential structure. In this paper, starting from the basic description of clusters under equilibrium conditions, we review properties of clusters revealed primarily through X-ray observations considering their thermal and dynamical evolutions. The future prospects of cluster studies using upcoming X-ray missions are also mentioned. 展开更多
关键词 galaxies： clusters： general -- galaxies： intergalactic medium -- X-rays：galaxies： clusters -- cosmology： observations -- cosmology： dark matter
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Metal enrichment via ram pressure stripping in the IGM of the compact galaxy group RGH 80 认领 引用 被引量：1
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作者 Hai-Juan Cui Hai-Guang Xu +5 位作者 Jun-Hua Gu Jing-Ying Wang Li-Yi Gu Yu Wang Zhen-Zhen Qin Tao An 《Research in Astronomy and Astrophysics》 SCIE CAS 2010年第4期301-308,共8页
By creating and analyzing two dimensional gas temperature and abundance maps of the RGH 80 compact galaxy group with high-quality Chandra data,we detect a high-abundance （ 0.7 Z⊙） arc,where the metal abundance is s... By creating and analyzing two dimensional gas temperature and abundance maps of the RGH 80 compact galaxy group with high-quality Chandra data,we detect a high-abundance （ 0.7 Z⊙） arc,where the metal abundance is significantly higher than the surrounding regions by 0.3Z⊙.This structure shows tight spatial correlations with the member galaxy PGC 046529,as well as with the arm-like feature identified on the X-ray image in the previous work of Randall et al.（2009）.Since no apparent signature of AGN activity is found to be associated with PGC 046529 in multi-band observations,and the gas temperature,metallicity,and mass of the high-abundance arc resemble those of the ISM of typical early-type galaxies,we conclude that this high-abundance structure is the remnant of the ISM of PGC 046529,which was stripped out of the galaxy by ram pressure stripping due to the motion of PGC 046529 in RGH 80.This novel case shows that ram pressure stripping can work as efficiently in the metal enrichment process in galaxy groups as it can in galaxy clusters. 展开更多
关键词 galaxies：clusters：individual （RGH 80） - galaxy：abundance - intergalactic medium - X-rays：galaxies：clusters
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Central gas entropy excess as direct evidence for AGN feedback in galaxy groups and clusters 认领 引用
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作者 Yu Wang Hai-Guang Xu +3 位作者 Jun-Hua Gu Li-Yi Gu Jing-Ying Wang Zhong-Li Zhang 《Research in Astronomy and Astrophysics》 SCIE CAS 2010年第10期1013-1022,共10页
By analyzing Chandra X-ray data of a sample of 21 galaxy groups and 19 galaxy clusters, we find that in 31 sample systems there exists a significant central （R ≤ 10 h^-171 kpc） gas entropy excess （AK0）, which cor... By analyzing Chandra X-ray data of a sample of 21 galaxy groups and 19 galaxy clusters, we find that in 31 sample systems there exists a significant central （R ≤ 10 h^-171 kpc） gas entropy excess （AK0）, which corresponds to = 0.1 - 0.5 keV per gas particle, beyond the power-law model that best fits the radial entropy profile of the outer regions. We also find a distinct correlation between the central entropy excess △K0 and K-band luminosity LK of the central dominating galaxies （CDGs）, which is scaled as △K0 ∝ L K 1.6±04, where LK is tightly associated with the mass of the supermassive black hole hosted in the CDG. In fact, if an effective mass-to-energy conversionefficiency of 0.02 is assumed for the accretion process, the cumulative AGN feedback E AGN feedack=ηMBHc2 yields an extra heating of = 0.5 - 17.0keV per particle, which feedback is sufficient to explain the central entropy excess. In most cases, the AGN contribution can compensate the radiative loss of the X-ray gas within the cooling radius （= 0.002 - 2.2 keV per particle）, and apparently exceeds the energy required to cause the scaling relations to deviate from the self-similar predictions （=0.2 - 1.0 keV per particle）. In contrast to the AGN feedback, the extra heating provided by supernova explosions accounts for = 0.01 - 0.08 keV per particle in groups and is almost negligible in clusters. Therefore, the observed correlation between △K0 and Lx can be considered as direct evidence for AGN feedback in galaxy groups and clusters. 展开更多
关键词 galaxies active- galaxies clusters general -- X-rays galaxies clus-ters -- （galaxies ） intergalactic medium
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Reionizing Islands with Inhomogeneous Recombinations 认领 引用
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作者 朱润玉 徐怡冬 +1 位作者 岳斌 陈学雷 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2023年第6期172-186,共15页
Observations are beginning to constrain the history of the epoch of reionization(EoR).Modeling the reionization process is indispensable to interpret the observations,to infer the properties of ionizing sources,and to... Observations are beginning to constrain the history of the epoch of reionization(EoR).Modeling the reionization process is indispensable to interpret the observations,to infer the properties of ionizing sources,and to probe the various astrophysical processes from the observational data.Here we present an improved version of the seminumerical simulation islandFAST,by incorporating inhomogeneous recombinations and a corresponding inhomogeneous ionizing background,and simulate the reionization process of neutral islands during the late EoR.We find that the islands are more fragmented in models with inhomogeneous recombinations than the case with a homogeneous recombination number.In order to investigate the effects of basic assumptions in the reionization modeling,we compare the results from islandFAST with those from 21cmFAST for the same assumptions on the ionizing photon sources and sinks,to find how the morphology of the ionization field and the reionization history depend on the different treatments of these two models.Such systematic bias should be noted when interpreting the upcoming observations. 展开更多
关键词 (cosmology:)dark ages reionization first stars (galaxies:)intergalactic medium (cosmology:)large-scale structure of universe galaxies:high-redshift
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Mock X-Ray Observations of Hot Gas with L-Galaxies Semi-analytic Models of Galaxy Formation 认领 引用
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作者 Wenxin Zhong Jian Fu +1 位作者 Shiyin Shen Feng Yuan 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2023年第7期37-51,共15页
We create mock X-ray observations of hot gas in galaxy clusters with a new extension of the L-Galaxies semianalytic model of galaxy formation,which includes the radial distribution of hot gas in each halo.Based on the... We create mock X-ray observations of hot gas in galaxy clusters with a new extension of the L-Galaxies semianalytic model of galaxy formation,which includes the radial distribution of hot gas in each halo.Based on the model outputs,we first build some mock light cones,then generate mock spectra with the SOXS package and derive the mock images in the light cones.Using the mock data,we simulate mock X-ray spectra for the ROSAT all-sky survey,and compare the mock spectra with the observational results.Then,we consider the design parameters of the HUBS mission and simulate the observation of the halo hot gas for HUBS as an important application of our mock work.We find:(1)our mock data match the observations by current X-ray telescopes.(2)The survey of hot baryons in resolved clusters by HUBS is effective below redshift 0.5,and the observations of the emission lines in point-like sources at z>0.5 by HUBS help us understand the hot baryons in the early universe.(3)By taking advantage of the large simulation box and flexibility in semi-analytic models,our mock X-ray observations provide the opportunity to select targets and observation strategies for forthcoming X-ray facilities. 展开更多
关键词 X-rays:galaxies:clusters galaxies:clusters:intracluster medium galaxies:groups:general galaxies:halos (galaxies:)intergalactic medium
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Gamma-ray bursts and their links with supernovae and cosmology 认领 引用 被引量：1
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作者 Peter Mszros Neil Gehrels 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2012年第8期1139-1161,共23页
Gamma-ray bursts are the most luminous explosions in the Universe, whose origin and mechanism are the focus of intense interest. They appear connected to su- pernova remnants from massive stars or the merger of their ... Gamma-ray bursts are the most luminous explosions in the Universe, whose origin and mechanism are the focus of intense interest. They appear connected to su- pernova remnants from massive stars or the merger of their remnants, and their bright- ness makes them temporarily detectable out to the largest distances yet explored in the universe. After pioneering breakthroughs from space and ground experiments, their study is entering a new phase with observations from the recently launched Fermi satellite, as well as the prospect of detections or limits from large neutrino and gravitational wave detectors. The interplay between such observations and theoretical models of gamma-ray bursts is reviewed, and cosmology. as well as their connections to supernovae 展开更多
关键词 gamma-ray sources -- gamma-ray bursts -- cosmic rays -- neutrinos-- supernovae -- cosmology -- intergalactic medium
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The continuous wavelet derived by smoothing function and its application in cosmology 认领 引用
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作者 Yun Wang Ping He 《Communications in Theoretical Physics》 SCIE CAS CSCD 2021年第9期95-104,共10页
The wavelet analysis technique is a powerful tool and is widely used in broad disciplines of engineering,technology,and sciences.In this work,we present a novel scheme of constructing continuous wavelet functions,in w... The wavelet analysis technique is a powerful tool and is widely used in broad disciplines of engineering,technology,and sciences.In this work,we present a novel scheme of constructing continuous wavelet functions,in which the wavelet functions are obtained by taking the first derivative of smoothing functions with respect to the scale parameter.Due to this wavelet constructing scheme,the inverse transforms are only one-dimensional integrations with respect to the scale parameter,and hence the continuous wavelet transforms(CWTs)constructed in this way are more ready to use than the usual scheme.We then apply the Gaussian-derived wavelet constructed by our scheme to computations of the density power spectrum for dark matter,the velocity power spectrum and the kinetic energy spectrum for baryonic fluid.These computations exhibit the convenience and strength of the CWTs.The transforms are very easy to perform,and we believe that the simplicity of our wavelet scheme will make CWTs very useful in practice. 展开更多
关键词 wavelet analysis intergalactic medium large-scale structure of Universe
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5D World-Universe Model Space-Time-Energy 认领 引用 被引量：14
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作者 Vladimir S. Netchitailo 《Journal of High Energy Physics, Gravitation and Cosmology》 CAS 2015年第1期25-34,共10页
5D Space-Time-Energy World-Universe Model is a unified model of the World built around the concept of Medium, composed of massive particles (protons, electrons, photons, neutrinos, and dark matter particles). The Mode... 5D Space-Time-Energy World-Universe Model is a unified model of the World built around the concept of Medium, composed of massive particles (protons, electrons, photons, neutrinos, and dark matter particles). The Model provides a mathematical framework that enables precise calculation of medium-bound physical parameters: Hubble’s parameter, intergalactic plasma parameters, temperature of microwave background radiation and the rest mass of photons. This paper aligns the World-Universe Model (WUM) with the theoretical framework developed by Prof. P. S. Wesson, albeit assigning a new physical meaning to the fifth coordinate. In the World-Universe Model, the fifth dimension is associated with the total energy of the Medium of the World, and the gravitomagnetic parameter of the Medium serves as the dimension-transposing parameter. 展开更多
关键词 5D World-Universe Model Space-Time-Energy Medium of the World Intergalactic Plasma Microwave Background Radiation Mass Varying Photons
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Burst Astrophysics 认领 引用 被引量：12
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作者 Vladimir S. Netchitailo 《Journal of High Energy Physics, Gravitation and Cosmology》 CAS 2017年第2期157-166,共10页
This article proposes an explanation for Fast Radio Bursts (FRBs) and Gamma Ray Bursts (GRBs) through the frames of Hypersphere World-Universe Model (WUM). WUM predicts that the concentration of protons and electrons ... This article proposes an explanation for Fast Radio Bursts (FRBs) and Gamma Ray Bursts (GRBs) through the frames of Hypersphere World-Universe Model (WUM). WUM predicts that the concentration of protons and electrons in Intergalactic Plasma decreases inversely proportional to time and in present epoch equals to . The energy density of Intergalactic Plasma relative to the critical energy density equals to . Time delay of FRBs is calculated through these characteristics. A number of experimental results, including the redshift for FRB 150418, remarkable brightness for FRB 150807, and transient gamma-ray counterpart for FRB 131104 are explained. The distance to FRB 150807 object is predicted to be ~800 Mpc. WUM holds that all macroobjects (galaxies, stars, and planets) contain a core composed of Dark Matter Particles. GRBs are explained as a sum of contributions of multicomponent dark matter annihilation. The spectra of such bursts depend on the composition of the Cores. 展开更多
关键词 Hypersphere World-Universe Model Medium of the World Intergalactic Plasma Macroobjects Structure Dark Matter Particles Gamma-Ray Bursts Fast Radio Bursts FRB Time Delay
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Mathematical Overview of Hypersphere World-Universe Model 认领 引用 被引量：14
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作者 Vladimir S. Netchitailo 《Journal of High Energy Physics, Gravitation and Cosmology》 CAS 2017年第3期415-437,共23页
The Hypersphere World-Universe Model (WUM) provides a mathematical framework that allows calculating the primary cosmological parameters of the World which are in good agreement with the most recent measurements and o... The Hypersphere World-Universe Model (WUM) provides a mathematical framework that allows calculating the primary cosmological parameters of the World which are in good agreement with the most recent measurements and observations. WUM explains the experimental data accumulated in the field of Cosmology and Astroparticle Physics over the last decades: the age of the World and critical energy density;the gravitational parameter and Hubble’s parameter;temperatures of the cosmic microwave background radiation and the peak of the far-infrared background radiation;the concentration of intergalactic plasma and time delay of Fast Radio Bursts. Additionally, the model predicts masses of dark matter particles, photons, and neutrinos;proposes new types of particle interactions (Super Weak and Extremely Weak);shows inter-connectivity of primary cosmological parameters of the World. WUM proposes to introduce a new fundamental parameter Q in the CODATA internationally recommended values. This paper is the summary of the mathematical results obtained in [1]-[4]. 展开更多
关键词 Hypersphere World-Universe Model Primary Cosmological Parameters Medium of the World Macroobjects Structure Gravitoelectromagnetism Dark Matter Particles Intergalactic Plasma Microwave Background Radiation Far-Infrared Background Radiation Fast Radio Bursts Emergent Phenomena CODATA
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