Research on the properties of neutron stars with dark energy is a particularly interesting yet unresolved problem in astrophysics.We analyze the influence of dark energy on the equation of state,the maximum mass,the s...Research on the properties of neutron stars with dark energy is a particularly interesting yet unresolved problem in astrophysics.We analyze the influence of dark energy on the equation of state,the maximum mass,the surface gravitational redshift and the Keplerian frequency for the traditional neutron star and the hyperon star matter within the relativistic mean field theory,using the GM1 and TM1 parameter sets by considering the two flavor symmetries of SU(6)and SU(3)combined with the observations of PSR J1614-2230,PSR J0348+0432,PSR J0030+0451,RX J0720.4-3125,and 1E 1207.4-5209.It is found that the existence of dark energy leads to the softened equations of the state of the traditional neutron star and the hyperon star.The radius of a fixed-mass traditional neutron star(or hyperon star)with dark energy becomes smaller,which leads to increased compactness.The existence of dark energy can also enhance the surface gravitational redshift and the Keplerian frequency of traditional neutron stars and hyperon stars.The growth of the Keplerian frequency may cause the spin rate to speed up,which may provide a possible way to understand and explain the pulsar glitch phenomenon.Specifically,we infer that the mass and the surface gravitational redshift of PSR J1748-2446ad without dark energy for the GM1(TM1)parameter set are 1.141 M_(☉)(1.309 M_(☉))and 0.095(0.105),respectively.The corresponding values for the GM1(TM1)parameter set are 0.901 M_(☉)(1.072M_(☉))and 0.079(0.091)if PSR J1748-2446ad contains dark energy withα=0.05.PSR J1748-2446ad may be a low-mass pulsar with a lower surface gravitational redshift under our selected models.展开更多
A team of researchers from the Beijing Normal University,the Institute of High Energy Physics(IHEP)under the Chinese Academy of Sciences(CAS),and the National Astronomical Observatories,CAS(NAOC),reported in Nature As...A team of researchers from the Beijing Normal University,the Institute of High Energy Physics(IHEP)under the Chinese Academy of Sciences(CAS),and the National Astronomical Observatories,CAS(NAOC),reported in Nature Astronomy on January 23,2025 their discovery of an X-ray flash about 12.5 billion lightyears away.The signals burst out only 1.2 billion years after the Big Bang,when our 13.8-billion-year-old universe was still in its infancy,and a science satellite swiftly recorded them.展开更多
The phenomenon that a clock at a higher gravitational potential ticks faster than one at a lower potential,also known as gravitational redshift,is one of the classical tests of Einstein’s theory of general relativity...The phenomenon that a clock at a higher gravitational potential ticks faster than one at a lower potential,also known as gravitational redshift,is one of the classical tests of Einstein’s theory of general relativity.Owing to their ultra-high accuracy and stability,state-of-the-art optical lattice clocks have enabled resolving the gravitational redshift with a millimeter-scale height difference.Further reducing the vertical inter-clock separation down to the sub-millimeter level and especially shortening the required measurement time may be achieved by employing spin squeezing.Here,we theoretically investigate the spin-squeezing-enhanced differential frequency comparison between two optical clocks within a lattice-trapped cloud of^(171)Yb atoms.The numerical results illustrate that for a sample of 10^(4)atoms,the atomic-collision-limited resolution of the vertical separation between two clocks can reach 0.48 mm,corresponding to a fractional gravitational redshift at the 10^(-20)level.In addition,the required averaging time may be reduced to less than one hundredth of that of conventional clocks with independent atoms.Our work opens a door to the future spin-squeezing-enhanced test of general relativity.展开更多
Through the analysis of representative samples of field galaxies,both local(z~0.027)and distant(z~0.7),we explore the barred galaxy fraction and its dependence on stellar mass,color,and morphology,aiming to understand...Through the analysis of representative samples of field galaxies,both local(z~0.027)and distant(z~0.7),we explore the barred galaxy fraction and its dependence on stellar mass,color,and morphology,aiming to understand the evolution of these structural components through cosmic time.To this end,two complementary bar detection techniques were employed:elliptical isophote fitting and two-dimensional Fourier analysis,both applied to deep optical images.The observational samples were drawn from previously established and calibrated catalogs to ensure a homogeneous selection in stellar mass,enabling a robust comparison between local galaxies(z~0.027)and those in the distant Universe(z~0.7).This study systematically applies both isophotal fitting and Fourier decomposition across a wide redshift range,offering a comprehensive view of the evolution of bar incidence as a function of stellar mass and morphology.The results indicate that the fraction of barred galaxies is significantly higher in the local Universe than at earlier epochs,particularly among spiral galaxies.Furthermore,a clear correlation is observed between the presence of bars and stellar mass,especially in the high-mass regime(log(M_*/M☉)>10.5).In distant galaxies,this fraction is lower across all mass ranges,which may be related to more active dynamical processes.Overall,the findings reinforce the idea that stellar bars emerge as a consequence of dynamical cooling and the progressive stabilization of galactic disks,playing a key role in gas transport and the internal structural evolution of galaxies from z~1 to the present day.展开更多
This report is about the graviton redshift theory (GRST) which hypothesises the redshift of the energy of gravitons traveling in fields. A new source of energy loss in galaxy dynamics is introduced. Due to the hypothe...This report is about the graviton redshift theory (GRST) which hypothesises the redshift of the energy of gravitons traveling in fields. A new source of energy loss in galaxy dynamics is introduced. Due to the hypothetical interactions of gravitons with the expansion of the universe, which causes an energy loss of the gravitons due to cosmological redshift, the rotation equation for galaxies, which previously had the Newtonian potential energy and the graviton gravitational redshift energy loss, is now updated with the graviton cosmological redshift energy loss. From the galaxy rotation equation, the baryonic Tully-Fisher relation (BTFR) and the modified Newtonian dynamics (MOND) are defined in radial distribution form. Fits to galaxy rotation motion are detailed. A cosmic connection for the BTFR is defined. The result is that galaxy rotation curves are fully accounted for with the GRST rotation equation and the BTFR and MOND theories are incorporated into a unified framework.展开更多
A simple and selective method for the determination of silver ions was developed by utilizing the red- shift in emission wavelength of the core-shell CdSe/Cd5 quantum dots （QDs） functionalized with rhodanine upon th...A simple and selective method for the determination of silver ions was developed by utilizing the red- shift in emission wavelength of the core-shell CdSe/Cd5 quantum dots （QDs） functionalized with rhodanine upon the addition of Ag＋. A linear relationship was observed between the shift and the increase in concentration of Ag＋ in the range of 0.0125-12.5 μmol/L. The mechanism of the red-shift was investigated and suggested that the coordination between Ag＋ and rhodanine on the QDs surface caused an increase of particle size, which resulted in the red-shift of the QDs＇ emission wavelength. A detection limit of 2 nmol/L was achieved. The developed method showed superior selectivity and was successfully applied to the determination of silver in environmental samples.展开更多
We investigate two training-set methods; support vector machines （SVMs） and Kernel Regression （KR） for photometric redshift estimation with the data from the databases of Sloan Digital Sky Survey Data Release 5 an...We investigate two training-set methods; support vector machines （SVMs） and Kernel Regression （KR） for photometric redshift estimation with the data from the databases of Sloan Digital Sky Survey Data Release 5 and Two Micron All Sky Survey. We probe the performances of SVMs and KR for different input patterns. Our experiments show that with more parameters considered, the accuracy does not always increase, and only when appropriate parameters are chosen, the accuracy can improve. For different approaches, the best input pattern is different. With different parameters as input, the optimal bandwidth is dissimilar for KR. The rms errors of photometric redshifts based on SVM and KR methods are less than 0.03 and 0.02, respectively. Strengths and weaknesses of the two approaches are summarized. Compared to other methods of estimating photometric redshifts, they show their superiorities, especially KR, in terms of accuracy.展开更多
This paper analyses the center-to-limb problem of the Sun encountered in the solar lines by using for the first time the New Tired Light theory based on photons of light losing energy due to interaction with electrons...This paper analyses the center-to-limb problem of the Sun encountered in the solar lines by using for the first time the New Tired Light theory based on photons of light losing energy due to interaction with electrons. For this scope, a detailed geometrical orbital model on the scale was created in order to trace back all physical characteristics of the Earth orbiting the Sun for three days in the year 1946, when the redshift measurements were taken. This paper suggests that, since the space between the Sun and the Earth consists of a high exponential distribution of electrons, it works out as a medium for the photons of light. Indeed, in the line of sight of a terrestrial observer, the distance between the Sun and the Earth is greater at the limb than in the center, valid for each orbital position. Accordingly, the interactions between photons and electrons cause a slight difference in redshift along the entire solar disk, matching the observational data. An important factor is the definition of objective criteria for the radial velocity component of the solar granules, whose variable values refer, in turn, to existing observational data, crucial for the success of the study. The redshift anomaly on the solar disk has been repeatedly detected in many scientific researches but only a few attempts so far, mostly based on parametrized models, have been done to give a reliable explanation to the measurements.展开更多
The Amati and Yonetoku relations are two of the main energy and luminosity correlations that currently exist for gamma-ray bursts (GRBs). The Amati relation is a correlation between the intrinsic peak energy, Epeak, i...The Amati and Yonetoku relations are two of the main energy and luminosity correlations that currently exist for gamma-ray bursts (GRBs). The Amati relation is a correlation between the intrinsic peak energy, Epeak, in the vFv spectrum of a burst and its equivalent isotropic energy, Eiso. The Yonetoku relation is a correlation between Epeak and the isotropic peak luminosity, Liso. In this paper, we use a recent data sample of 65 GRBs to investigate whether these two relations evolve with redshift, z. The z-correction and the?k-correction are both taken into account. Our method consists of binning the data in redshift, z, then applying (for each bin) a fit of the form:?log(Eiso) = A + Blog(Epeak/Epeak>) for the Amati relation, and of the form:?log(Liso) = A + Blog(Epeak/Epeak>) for the Yonetoku relation, where Epeak> is the mean value of the peak energy for the entire sample. The objective is to see whether the two fitting parameters, A and B, evolve systematically with z. Good least-squares fits were obtained with reasonable values for the linear regression coefficient, r. Our results indicate that the normalization, A, and the slope, B, do not evolve with redshift, and hence the Amati and Yonetoku relations seem to be redshift independent.展开更多
It is generally accepted that the history of the expansion of the universe can be exactly described by the concordance model, which makes specific predictions about the shape of the Hubble diagram. The redshift-magnit...It is generally accepted that the history of the expansion of the universe can be exactly described by the concordance model, which makes specific predictions about the shape of the Hubble diagram. The redshift-magnitude Hubble diagram in the redshift range z = 0.0104 - 1 seems to confirm this expectation, and it is believed that this conformity is also valid in the high redshift range. However, this belief is not undisputed. Recent work in the high redshift range of up to z = 8.1 has shown that the shape of the Hubble diagram deviates considerably from the predictions made by the Lambda cold dark matter model. These analyses, however, were based on mixed SN1a and gamma ray burst data, and some astronomers argue that this may have biased the results. In this paper, 109 cosmology-independent, calibrated gamma ray burst z/μdata points are used to calculate the Hubble diagram in the range z = 0.034 to z = 8.1. The outcome of this analysis confirms prior results: contrary to expectations, the shape of the Hubble diagram turns out to be exponential, and this is difficult to explain within the framework of the standard model. The cosmological implications of this unexpected result are discussed.展开更多
We compare the Hubble diagram calculated from the observed redshift (RS)/magnitude (μ) data of 280 Supernovae in the RS range of z = 0.0104 to 8.1 with Hubble diagrams inferred on the basis of the exponential tired l...We compare the Hubble diagram calculated from the observed redshift (RS)/magnitude (μ) data of 280 Supernovae in the RS range of z = 0.0104 to 8.1 with Hubble diagrams inferred on the basis of the exponential tired light and the Lambda Cold Dark Matter (ΛCDM) cosmological model. We show that the experimentally measured Hubble diagram follows clearly the exponential photon flight time (tS)/RS relation, whilst the data calculated on the basis of the ΛCDM model exhibit poor agreement with the observed data.展开更多
We study the growth of black holes and stellar population in spheroids at high redshift using several （sub）mm-loud QSO samples. Applying the same criteria established in an earlier work, we find that, similar to IR ...We study the growth of black holes and stellar population in spheroids at high redshift using several （sub）mm-loud QSO samples. Applying the same criteria established in an earlier work, we find that, similar to IR QSOs at low redshift, the far-infrared emission of these （sub）mm-loud QSOs mainly originates from dust heated by starbursts. By combining low-z IR QSOs and high-z （sub）mm-loud QSOs, we find a trend that the star formation rate （M＊） increases with the accretion rate （Mace）. We compare the values of M＊/Macc for submm emitting galaxies （SMGs）, far-infrared ultraluminous/hypeduminous QSOs and typical QSOs, and construct a likely evolution scenario for these objects. The （sub）mm-loud QSO transition phase has both high Macc and M＊ and hence is important for establishing the correlation between the masses of black holes and spheroids.展开更多
New data from FRB’s have provided an exciting new window on the cosmos. For the first time we have both Dispersion Measure (DM) from distant sources and their red-shift. This gives us the opportunity to determine the...New data from FRB’s have provided an exciting new window on the cosmos. For the first time we have both Dispersion Measure (DM) from distant sources and their red-shift. This gives us the opportunity to determine the average electron number density in intergalactic space and thus test New Tired Light predictions. Here, in an alternative cosmology, the universe is static and redshifts are produced by an interaction between photons and the electrons in the intergalactic medium. In a paper published in summer 2006 New Tired Light (NTL) predicted an average electron number density of n = 0.5 m<sup>-3</sup>. In 2016 a paper was published reporting that for the first time the DM of a FRB and the redshift of the host galaxy had been found. Using standard physics this confirmed the electron number density as n = 0.5 m<sup>-3</sup>. The prediction NTL made ten years earlier was proved to be correct. Using this measured electron number density enabled a definitive value of the Hubble constant to be made by New Tired Light and the value is 63 km/s per Mpc which compares well with currently accepted values. Importantly, since in NTL the redshift and dispersion are both due to the electrons in IG space, a relationship between DM’s and redshift can be predicted. NTL predicts that DM and LN(1 + z) will be directly proportional and related by the formula DM = mec/2hr<sub>e</sub>(3.086 × 1022) where me, re are the rest mass and classical radius of the electron, c is the speed of light in a vacuum and h is the plank constant. The numerical term is to change units from pccm<sup>-3</sup> to m<sup>-2</sup>. This reduces to DM = 2380LN(1 + z). Using data from five FRB’s this is tested and a linear relation is seen of the form DM = 1830LN(1 + z). The gradient of the plot from the observed data is within 23% of that predicted by NTL. Recently the Tolman Surface Brightness test has been applied to the HUDF and the results support a static universe whilst the possibility of two differing types of SN Ia whose distribution changes with distances means that tired light models can no longer be ruled out. Using SDF we know the distance to the Atlia galaxy cluster as 1.26 × 10<sup>24</sup> m. With the average electron number density of n = 0.5 m<sup>-3</sup> found from the Dispersion Measures of the FRB’s, from first principles, New Tired Light gives a calculated predicted redshift of 0.0086. This compares well with the value found spectroscopically of 0.0087—a difference of approximately 1%. It is shown that if the energy transferred to a recoiling electron when a UV photon of wavelength λ = 5 × 10<sup>-8</sup> m interacts with it is emitted as a secondary photon that photon will have a wavelength of 2.2 mm— the wavelength at which the CMB curve peaks.展开更多
We have collected a sample of 70 BL Lacs （33 radio-selected BL Lacs and 37 X-ray selected BL Lacs） with multi-waveband data for investigating the classifying criteria of BL Lacertae Objects. For each source, we esti...We have collected a sample of 70 BL Lacs （33 radio-selected BL Lacs and 37 X-ray selected BL Lacs） with multi-waveband data for investigating the classifying criteria of BL Lacertae Objects. For each source, we estimate its luminosities in radio, optical and X-ray, the broad-band spectral index from radio to X-ray and the peak frequency of the synchrotron emission, and make a statistical analysis of the data obtained. Our main results are as follows： （1） The broad-band spectral index and the peak frequency have no correlation with the redshift, while they are inversely correlated with each other and they could be regarded as equivalent classifying criteria of BL Lac objects. （2） There are significant effects of the luminosity/redshift relation on the observed luminosity distribution in our sample, hence, if the radio luminosity is to be used as a classifying criterion of BL Lac objects, it should not be regarded as equivalent to the broad-band spectral index or the peak frequency. （3） Our resuits supply a specific piece of evidence for the suggestion that the use of luminosities always introduces a redshift bias to the data and show that the location of the peak frequency is not always linked to the luminosity of any wave band.展开更多
Cosmological redshift is commonly attributed to the continuous expansion of the universe starting from the Big-Bang. However, expansion models require simplifying assumptions and multiple parameters to get acceptable ...Cosmological redshift is commonly attributed to the continuous expansion of the universe starting from the Big-Bang. However, expansion models require simplifying assumptions and multiple parameters to get acceptable fit to the observed data. Here we consider the redshift to be a hybrid of two effects: recession of distant galaxies due to expansion of the universe, and resistance to light propagation due to cosmic drag. The weight factor determining the contribution of the two effects is the only parameter that is needed to fit the observed data. The cosmic drag considered phenomenologically yields mass of the universe ≈?2 × 1053 kg. This implicitly suggests that the mass of the whole universe is causing the cosmic drag. The databases of extragalactic objects containing redshift z and distance modulus μof galaxies up to z = 8.26 resulted in an excellent fit to the model. Also, the weight factor wD for expansion effect contribution to μobtained from the data sets containing progressively higher values of μ?can be nicely fitted with .展开更多
We analyse the possibility that the observed cosmological redshift may be cumulatively due to the expansion of the universe and the tired light phenomenon. Since the source of both the redshifts is the same, they both...We analyse the possibility that the observed cosmological redshift may be cumulatively due to the expansion of the universe and the tired light phenomenon. Since the source of both the redshifts is the same, they both independently relate to the same proper distance of the light source. Using this approach we have developed a hybrid model combining the Einstein de Sitter model and the tired light model that yields a slightly better fit to Supernovae Ia redshift data using one parameter than the standard ΛCDM model with two parameters. We have shown that the ratio of tired light component to the Einstein de Sitter component of redshift has evolved from 2.5 in the past, corresponding to redshift 1000, to its present value of 1.5. The hybrid model yields Hubble constant H0 =69.11(±0.53)km·s-1 ·Mpc-1 and the deceleration parameter q0 =-0.4. The component of Hubble constant responsible for expansion of the universe is 40% of H0 and for the tired light is 60% of H0. Consequently, the critical density is only 16% of its currently accepted value;a lot less dark matter is needed to make up the critical density. In addition, the best data fit yields the cosmological constant density parameter =0. The tired light effect may thus be considered equivalent to the cosmological constant in the hybrid model.展开更多
We investigate the spectral redshift of high-order harmonics of the H_2~＋（D_2~＋） molecule by numerically solving the non-Born–Oppenheimer time-dependent Schr ¨odinger equation（TDSE）. The results show that ...We investigate the spectral redshift of high-order harmonics of the H_2~＋（D_2~＋） molecule by numerically solving the non-Born–Oppenheimer time-dependent Schr ¨odinger equation（TDSE）. The results show that the spectral redshift of highorder harmonics can be observed by adding a weak pulse in the falling part of the trapezoidal laser pulses. Comparing with the H_2~＋ molecule, the shift of high-order harmonic generation（HHG） spectrum for the D_2~＋ molecule is more obvious.We employ the spatial distribution in HHG and time-frequency analysis to illustrate the physical mechanism of the spectral redshift of high-order harmonics.展开更多
The massive photometric data collected from multiple large-scale sky surveys offer significant opportunities for measuring distances of celestial objects by photometric redshifts. However, catastrophic failure is an u...The massive photometric data collected from multiple large-scale sky surveys offer significant opportunities for measuring distances of celestial objects by photometric redshifts. However, catastrophic failure is an unsolved problem with a long history and it still exists in the current photometric redshift estimation approaches （such as the k-nearest neighbor （KNN） algorithm）. In this paper, we propose a novel two-stage approach by integration of KNN and support vector machine （SVM） methods together. In the first stage, we apply the KNN algorithm to photometric data and estimate their corresponding Zphot. Our analysis has found two dense regions with catastrophic failure, one in the range of Zphot E [0.3, 1.2] and the other in the range of Zphot E [1.2, 2.1]. In the second stage, we map the photometric input pattern of points falling into the two ranges from their original attribute space into a high dimensional feature space by using a Gaussian kernel function from an SVM. In the high dimensional feature space, many outliers resulting from catastrophic failure by simple Euclidean distance computation in KNN can be identified by a classification hyperplane of SVM and can be further corrected. Experimental results based on the Sloan Digital Sky Survey （SDSS） quasar data show that the two-stage fusion approach can significantly mitigate catastrophic failure and improve the estimation accuracy of photometric redshifts of quasars. The percents in different /△z/ ranges and root mean square （rms） error by the integrated method are 83.47%, 89.83%, 90.90% and 0.192, respectively, compared to the results by KNN （71.96%, 83.78%, 89.73% and 0.204）.展开更多
Based on an analysis of 280 Type SNIa supernovae and gamma-ray bursts redshifts in the range of z = 0.0104 - 8.1 the Hubble diagram is shown to follow a strictly exponential slope predicting an exponentially expanding...Based on an analysis of 280 Type SNIa supernovae and gamma-ray bursts redshifts in the range of z = 0.0104 - 8.1 the Hubble diagram is shown to follow a strictly exponential slope predicting an exponentially expanding or static universe. At redshifts > 2 - 3 ΛCDM models show a poor agreement with the observed data. Based on the results presented in this paper, the Hubble diagram test does not necessarily support the idea of expansion according to the big-bang concordance model.展开更多
Quasars with redshifts greater than 4 are rare, and can be used to probe the structure and evolution of the early universe. Here we report the discovery of six new quasars with i-band magnitudes brighter than 19.5 and...Quasars with redshifts greater than 4 are rare, and can be used to probe the structure and evolution of the early universe. Here we report the discovery of six new quasars with i-band magnitudes brighter than 19.5 and redshifts between 2.4 and 4.6 from spectroscopy with the Yunnan Faint Object Spectrograph and Camera (YFOSC) at the Lijiang 2.4 m telescope in February, 2012. These quasars are in the list of z > 3.6 quasar candidates selected by using our proposed J K/i Y criterion and the photometric redshift estimations from the SDSS optical and UKIDSS near-IR photometric data. Nine candidates were observed by YFOSC, and five among six new quasars were identified as z > 3.6 quasars. One of the other three objects was identified as a star and the other two were unidentified due to the lower signal-to-noise ratio of their spectra. This is the first time that z > 4 quasars have been discovered using a telescope in China. Thanks to the Chinese Telescope Access Program (TAP), the redshift of 4.6 for one of these quasars was confirmed by the Multiple Mirror Telescope (MMT) Red Channel spectroscopy. The continuum and emission line properties of these six quasars, as well as their central black hole masses and Eddington ratios, were obtained.展开更多
基金partially funded by the Horizontal Scientific Research Project of the National Astronomical Observatories of CAS(Grant No.E0900501)and the Theoretical Fundamental Research Special Project of the Changchun Observatory,National Astronomical Observatories,CAS(Grant No.Y990000205)。
文摘Research on the properties of neutron stars with dark energy is a particularly interesting yet unresolved problem in astrophysics.We analyze the influence of dark energy on the equation of state,the maximum mass,the surface gravitational redshift and the Keplerian frequency for the traditional neutron star and the hyperon star matter within the relativistic mean field theory,using the GM1 and TM1 parameter sets by considering the two flavor symmetries of SU(6)and SU(3)combined with the observations of PSR J1614-2230,PSR J0348+0432,PSR J0030+0451,RX J0720.4-3125,and 1E 1207.4-5209.It is found that the existence of dark energy leads to the softened equations of the state of the traditional neutron star and the hyperon star.The radius of a fixed-mass traditional neutron star(or hyperon star)with dark energy becomes smaller,which leads to increased compactness.The existence of dark energy can also enhance the surface gravitational redshift and the Keplerian frequency of traditional neutron stars and hyperon stars.The growth of the Keplerian frequency may cause the spin rate to speed up,which may provide a possible way to understand and explain the pulsar glitch phenomenon.Specifically,we infer that the mass and the surface gravitational redshift of PSR J1748-2446ad without dark energy for the GM1(TM1)parameter set are 1.141 M_(☉)(1.309 M_(☉))and 0.095(0.105),respectively.The corresponding values for the GM1(TM1)parameter set are 0.901 M_(☉)(1.072M_(☉))and 0.079(0.091)if PSR J1748-2446ad contains dark energy withα=0.05.PSR J1748-2446ad may be a low-mass pulsar with a lower surface gravitational redshift under our selected models.
文摘A team of researchers from the Beijing Normal University,the Institute of High Energy Physics(IHEP)under the Chinese Academy of Sciences(CAS),and the National Astronomical Observatories,CAS(NAOC),reported in Nature Astronomy on January 23,2025 their discovery of an X-ray flash about 12.5 billion lightyears away.The signals burst out only 1.2 billion years after the Big Bang,when our 13.8-billion-year-old universe was still in its infancy,and a science satellite swiftly recorded them.
基金supported by CAS Project for Young Scientists in Basic Research(Grant No.YSBR-085)the National Time Service Center(Grant No.E239SC1101)+1 种基金Innovation Program for Quantum Science and Technology(Grant No.2021ZD0303200)China Postdoctoral Science Foundation(Grant No.BX2021020).
文摘The phenomenon that a clock at a higher gravitational potential ticks faster than one at a lower potential,also known as gravitational redshift,is one of the classical tests of Einstein’s theory of general relativity.Owing to their ultra-high accuracy and stability,state-of-the-art optical lattice clocks have enabled resolving the gravitational redshift with a millimeter-scale height difference.Further reducing the vertical inter-clock separation down to the sub-millimeter level and especially shortening the required measurement time may be achieved by employing spin squeezing.Here,we theoretically investigate the spin-squeezing-enhanced differential frequency comparison between two optical clocks within a lattice-trapped cloud of^(171)Yb atoms.The numerical results illustrate that for a sample of 10^(4)atoms,the atomic-collision-limited resolution of the vertical separation between two clocks can reach 0.48 mm,corresponding to a fractional gravitational redshift at the 10^(-20)level.In addition,the required averaging time may be reduced to less than one hundredth of that of conventional clocks with independent atoms.Our work opens a door to the future spin-squeezing-enhanced test of general relativity.
基金financial support from the Secretaría Nacional de Ciencia,Tecnologia e Innovacion(SENACYT),through the Departamento de Fortalecimiento a los Posgrados Nacionalesthe coordination of the program"MOVILIDAD DE INVESTIGACION."+3 种基金the financial support provided by PAPIIT projects IN108323 and IN111825 from DGAPA-UNAMsupport from the Agencia Nacional de Investigación y Desarrollo(ANID)through Basal project FB210003FONDECYT Regular projects 1241426 and 123044Millennium Science Initiative Program NCN2024_112。
文摘Through the analysis of representative samples of field galaxies,both local(z~0.027)and distant(z~0.7),we explore the barred galaxy fraction and its dependence on stellar mass,color,and morphology,aiming to understand the evolution of these structural components through cosmic time.To this end,two complementary bar detection techniques were employed:elliptical isophote fitting and two-dimensional Fourier analysis,both applied to deep optical images.The observational samples were drawn from previously established and calibrated catalogs to ensure a homogeneous selection in stellar mass,enabling a robust comparison between local galaxies(z~0.027)and those in the distant Universe(z~0.7).This study systematically applies both isophotal fitting and Fourier decomposition across a wide redshift range,offering a comprehensive view of the evolution of bar incidence as a function of stellar mass and morphology.The results indicate that the fraction of barred galaxies is significantly higher in the local Universe than at earlier epochs,particularly among spiral galaxies.Furthermore,a clear correlation is observed between the presence of bars and stellar mass,especially in the high-mass regime(log(M_*/M☉)>10.5).In distant galaxies,this fraction is lower across all mass ranges,which may be related to more active dynamical processes.Overall,the findings reinforce the idea that stellar bars emerge as a consequence of dynamical cooling and the progressive stabilization of galactic disks,playing a key role in gas transport and the internal structural evolution of galaxies from z~1 to the present day.
文摘This report is about the graviton redshift theory (GRST) which hypothesises the redshift of the energy of gravitons traveling in fields. A new source of energy loss in galaxy dynamics is introduced. Due to the hypothetical interactions of gravitons with the expansion of the universe, which causes an energy loss of the gravitons due to cosmological redshift, the rotation equation for galaxies, which previously had the Newtonian potential energy and the graviton gravitational redshift energy loss, is now updated with the graviton cosmological redshift energy loss. From the galaxy rotation equation, the baryonic Tully-Fisher relation (BTFR) and the modified Newtonian dynamics (MOND) are defined in radial distribution form. Fits to galaxy rotation motion are detailed. A cosmic connection for the BTFR is defined. The result is that galaxy rotation curves are fully accounted for with the GRST rotation equation and the BTFR and MOND theories are incorporated into a unified framework.
基金The National Natural Science Foundation of China is thanked for financial support(Nos.20345006 and 20575043)
文摘A simple and selective method for the determination of silver ions was developed by utilizing the red- shift in emission wavelength of the core-shell CdSe/Cd5 quantum dots （QDs） functionalized with rhodanine upon the addition of Ag＋. A linear relationship was observed between the shift and the increase in concentration of Ag＋ in the range of 0.0125-12.5 μmol/L. The mechanism of the red-shift was investigated and suggested that the coordination between Ag＋ and rhodanine on the QDs surface caused an increase of particle size, which resulted in the red-shift of the QDs＇ emission wavelength. A detection limit of 2 nmol/L was achieved. The developed method showed superior selectivity and was successfully applied to the determination of silver in environmental samples.
基金Supported by the National Natural Science Foundation of China.
文摘We investigate two training-set methods; support vector machines （SVMs） and Kernel Regression （KR） for photometric redshift estimation with the data from the databases of Sloan Digital Sky Survey Data Release 5 and Two Micron All Sky Survey. We probe the performances of SVMs and KR for different input patterns. Our experiments show that with more parameters considered, the accuracy does not always increase, and only when appropriate parameters are chosen, the accuracy can improve. For different approaches, the best input pattern is different. With different parameters as input, the optimal bandwidth is dissimilar for KR. The rms errors of photometric redshifts based on SVM and KR methods are less than 0.03 and 0.02, respectively. Strengths and weaknesses of the two approaches are summarized. Compared to other methods of estimating photometric redshifts, they show their superiorities, especially KR, in terms of accuracy.
文摘This paper analyses the center-to-limb problem of the Sun encountered in the solar lines by using for the first time the New Tired Light theory based on photons of light losing energy due to interaction with electrons. For this scope, a detailed geometrical orbital model on the scale was created in order to trace back all physical characteristics of the Earth orbiting the Sun for three days in the year 1946, when the redshift measurements were taken. This paper suggests that, since the space between the Sun and the Earth consists of a high exponential distribution of electrons, it works out as a medium for the photons of light. Indeed, in the line of sight of a terrestrial observer, the distance between the Sun and the Earth is greater at the limb than in the center, valid for each orbital position. Accordingly, the interactions between photons and electrons cause a slight difference in redshift along the entire solar disk, matching the observational data. An important factor is the definition of objective criteria for the radial velocity component of the solar granules, whose variable values refer, in turn, to existing observational data, crucial for the success of the study. The redshift anomaly on the solar disk has been repeatedly detected in many scientific researches but only a few attempts so far, mostly based on parametrized models, have been done to give a reliable explanation to the measurements.
文摘The Amati and Yonetoku relations are two of the main energy and luminosity correlations that currently exist for gamma-ray bursts (GRBs). The Amati relation is a correlation between the intrinsic peak energy, Epeak, in the vFv spectrum of a burst and its equivalent isotropic energy, Eiso. The Yonetoku relation is a correlation between Epeak and the isotropic peak luminosity, Liso. In this paper, we use a recent data sample of 65 GRBs to investigate whether these two relations evolve with redshift, z. The z-correction and the?k-correction are both taken into account. Our method consists of binning the data in redshift, z, then applying (for each bin) a fit of the form:?log(Eiso) = A + Blog(Epeak/Epeak>) for the Amati relation, and of the form:?log(Liso) = A + Blog(Epeak/Epeak>) for the Yonetoku relation, where Epeak> is the mean value of the peak energy for the entire sample. The objective is to see whether the two fitting parameters, A and B, evolve systematically with z. Good least-squares fits were obtained with reasonable values for the linear regression coefficient, r. Our results indicate that the normalization, A, and the slope, B, do not evolve with redshift, and hence the Amati and Yonetoku relations seem to be redshift independent.
文摘It is generally accepted that the history of the expansion of the universe can be exactly described by the concordance model, which makes specific predictions about the shape of the Hubble diagram. The redshift-magnitude Hubble diagram in the redshift range z = 0.0104 - 1 seems to confirm this expectation, and it is believed that this conformity is also valid in the high redshift range. However, this belief is not undisputed. Recent work in the high redshift range of up to z = 8.1 has shown that the shape of the Hubble diagram deviates considerably from the predictions made by the Lambda cold dark matter model. These analyses, however, were based on mixed SN1a and gamma ray burst data, and some astronomers argue that this may have biased the results. In this paper, 109 cosmology-independent, calibrated gamma ray burst z/μdata points are used to calculate the Hubble diagram in the range z = 0.034 to z = 8.1. The outcome of this analysis confirms prior results: contrary to expectations, the shape of the Hubble diagram turns out to be exponential, and this is difficult to explain within the framework of the standard model. The cosmological implications of this unexpected result are discussed.
文摘We compare the Hubble diagram calculated from the observed redshift (RS)/magnitude (μ) data of 280 Supernovae in the RS range of z = 0.0104 to 8.1 with Hubble diagrams inferred on the basis of the exponential tired light and the Lambda Cold Dark Matter (ΛCDM) cosmological model. We show that the experimentally measured Hubble diagram follows clearly the exponential photon flight time (tS)/RS relation, whilst the data calculated on the basis of the ΛCDM model exhibit poor agreement with the observed data.
基金Supported by the National Natural Science Foundation of China.
文摘We study the growth of black holes and stellar population in spheroids at high redshift using several （sub）mm-loud QSO samples. Applying the same criteria established in an earlier work, we find that, similar to IR QSOs at low redshift, the far-infrared emission of these （sub）mm-loud QSOs mainly originates from dust heated by starbursts. By combining low-z IR QSOs and high-z （sub）mm-loud QSOs, we find a trend that the star formation rate （M＊） increases with the accretion rate （Mace）. We compare the values of M＊/Macc for submm emitting galaxies （SMGs）, far-infrared ultraluminous/hypeduminous QSOs and typical QSOs, and construct a likely evolution scenario for these objects. The （sub）mm-loud QSO transition phase has both high Macc and M＊ and hence is important for establishing the correlation between the masses of black holes and spheroids.
文摘New data from FRB’s have provided an exciting new window on the cosmos. For the first time we have both Dispersion Measure (DM) from distant sources and their red-shift. This gives us the opportunity to determine the average electron number density in intergalactic space and thus test New Tired Light predictions. Here, in an alternative cosmology, the universe is static and redshifts are produced by an interaction between photons and the electrons in the intergalactic medium. In a paper published in summer 2006 New Tired Light (NTL) predicted an average electron number density of n = 0.5 m<sup>-3</sup>. In 2016 a paper was published reporting that for the first time the DM of a FRB and the redshift of the host galaxy had been found. Using standard physics this confirmed the electron number density as n = 0.5 m<sup>-3</sup>. The prediction NTL made ten years earlier was proved to be correct. Using this measured electron number density enabled a definitive value of the Hubble constant to be made by New Tired Light and the value is 63 km/s per Mpc which compares well with currently accepted values. Importantly, since in NTL the redshift and dispersion are both due to the electrons in IG space, a relationship between DM’s and redshift can be predicted. NTL predicts that DM and LN(1 + z) will be directly proportional and related by the formula DM = mec/2hr<sub>e</sub>(3.086 × 1022) where me, re are the rest mass and classical radius of the electron, c is the speed of light in a vacuum and h is the plank constant. The numerical term is to change units from pccm<sup>-3</sup> to m<sup>-2</sup>. This reduces to DM = 2380LN(1 + z). Using data from five FRB’s this is tested and a linear relation is seen of the form DM = 1830LN(1 + z). The gradient of the plot from the observed data is within 23% of that predicted by NTL. Recently the Tolman Surface Brightness test has been applied to the HUDF and the results support a static universe whilst the possibility of two differing types of SN Ia whose distribution changes with distances means that tired light models can no longer be ruled out. Using SDF we know the distance to the Atlia galaxy cluster as 1.26 × 10<sup>24</sup> m. With the average electron number density of n = 0.5 m<sup>-3</sup> found from the Dispersion Measures of the FRB’s, from first principles, New Tired Light gives a calculated predicted redshift of 0.0086. This compares well with the value found spectroscopically of 0.0087—a difference of approximately 1%. It is shown that if the energy transferred to a recoiling electron when a UV photon of wavelength λ = 5 × 10<sup>-8</sup> m interacts with it is emitted as a secondary photon that photon will have a wavelength of 2.2 mm— the wavelength at which the CMB curve peaks.
基金the National Natural Science Foundation of China
文摘We have collected a sample of 70 BL Lacs （33 radio-selected BL Lacs and 37 X-ray selected BL Lacs） with multi-waveband data for investigating the classifying criteria of BL Lacertae Objects. For each source, we estimate its luminosities in radio, optical and X-ray, the broad-band spectral index from radio to X-ray and the peak frequency of the synchrotron emission, and make a statistical analysis of the data obtained. Our main results are as follows： （1） The broad-band spectral index and the peak frequency have no correlation with the redshift, while they are inversely correlated with each other and they could be regarded as equivalent classifying criteria of BL Lac objects. （2） There are significant effects of the luminosity/redshift relation on the observed luminosity distribution in our sample, hence, if the radio luminosity is to be used as a classifying criterion of BL Lac objects, it should not be regarded as equivalent to the broad-band spectral index or the peak frequency. （3） Our resuits supply a specific piece of evidence for the suggestion that the use of luminosities always introduces a redshift bias to the data and show that the location of the peak frequency is not always linked to the luminosity of any wave band.
文摘Cosmological redshift is commonly attributed to the continuous expansion of the universe starting from the Big-Bang. However, expansion models require simplifying assumptions and multiple parameters to get acceptable fit to the observed data. Here we consider the redshift to be a hybrid of two effects: recession of distant galaxies due to expansion of the universe, and resistance to light propagation due to cosmic drag. The weight factor determining the contribution of the two effects is the only parameter that is needed to fit the observed data. The cosmic drag considered phenomenologically yields mass of the universe ≈?2 × 1053 kg. This implicitly suggests that the mass of the whole universe is causing the cosmic drag. The databases of extragalactic objects containing redshift z and distance modulus μof galaxies up to z = 8.26 resulted in an excellent fit to the model. Also, the weight factor wD for expansion effect contribution to μobtained from the data sets containing progressively higher values of μ?can be nicely fitted with .
文摘We analyse the possibility that the observed cosmological redshift may be cumulatively due to the expansion of the universe and the tired light phenomenon. Since the source of both the redshifts is the same, they both independently relate to the same proper distance of the light source. Using this approach we have developed a hybrid model combining the Einstein de Sitter model and the tired light model that yields a slightly better fit to Supernovae Ia redshift data using one parameter than the standard ΛCDM model with two parameters. We have shown that the ratio of tired light component to the Einstein de Sitter component of redshift has evolved from 2.5 in the past, corresponding to redshift 1000, to its present value of 1.5. The hybrid model yields Hubble constant H0 =69.11(±0.53)km·s-1 ·Mpc-1 and the deceleration parameter q0 =-0.4. The component of Hubble constant responsible for expansion of the universe is 40% of H0 and for the tired light is 60% of H0. Consequently, the critical density is only 16% of its currently accepted value;a lot less dark matter is needed to make up the critical density. In addition, the best data fit yields the cosmological constant density parameter =0. The tired light effect may thus be considered equivalent to the cosmological constant in the hybrid model.
基金Project supported by the National Natural Science Foundation of China(Grant No.61575077)the Graduate Innovation Fund of Jilin University(Grant No.2017107)
文摘We investigate the spectral redshift of high-order harmonics of the H_2~＋（D_2~＋） molecule by numerically solving the non-Born–Oppenheimer time-dependent Schr ¨odinger equation（TDSE）. The results show that the spectral redshift of highorder harmonics can be observed by adding a weak pulse in the falling part of the trapezoidal laser pulses. Comparing with the H_2~＋ molecule, the shift of high-order harmonic generation（HHG） spectrum for the D_2~＋ molecule is more obvious.We employ the spatial distribution in HHG and time-frequency analysis to illustrate the physical mechanism of the spectral redshift of high-order harmonics.
基金supported by the National Natural Science Foundation of China (Grant Nos. 61272272 and U1531122)the Natural Science Foundation of Hubei province (Grant2015CFA058)+1 种基金the National Key Basic Research Program of China (2014CB845700)the NSFC-Texas A&M University Joint Research Program (No.11411120219)
文摘The massive photometric data collected from multiple large-scale sky surveys offer significant opportunities for measuring distances of celestial objects by photometric redshifts. However, catastrophic failure is an unsolved problem with a long history and it still exists in the current photometric redshift estimation approaches （such as the k-nearest neighbor （KNN） algorithm）. In this paper, we propose a novel two-stage approach by integration of KNN and support vector machine （SVM） methods together. In the first stage, we apply the KNN algorithm to photometric data and estimate their corresponding Zphot. Our analysis has found two dense regions with catastrophic failure, one in the range of Zphot E [0.3, 1.2] and the other in the range of Zphot E [1.2, 2.1]. In the second stage, we map the photometric input pattern of points falling into the two ranges from their original attribute space into a high dimensional feature space by using a Gaussian kernel function from an SVM. In the high dimensional feature space, many outliers resulting from catastrophic failure by simple Euclidean distance computation in KNN can be identified by a classification hyperplane of SVM and can be further corrected. Experimental results based on the Sloan Digital Sky Survey （SDSS） quasar data show that the two-stage fusion approach can significantly mitigate catastrophic failure and improve the estimation accuracy of photometric redshifts of quasars. The percents in different /△z/ ranges and root mean square （rms） error by the integrated method are 83.47%, 89.83%, 90.90% and 0.192, respectively, compared to the results by KNN （71.96%, 83.78%, 89.73% and 0.204）.
文摘Based on an analysis of 280 Type SNIa supernovae and gamma-ray bursts redshifts in the range of z = 0.0104 - 8.1 the Hubble diagram is shown to follow a strictly exponential slope predicting an exponentially expanding or static universe. At redshifts > 2 - 3 ΛCDM models show a poor agreement with the observed data. Based on the results presented in this paper, the Hubble diagram test does not necessarily support the idea of expansion according to the big-bang concordance model.
基金the National Natural Science Foundation of China (Grant No. 11033001)
文摘Quasars with redshifts greater than 4 are rare, and can be used to probe the structure and evolution of the early universe. Here we report the discovery of six new quasars with i-band magnitudes brighter than 19.5 and redshifts between 2.4 and 4.6 from spectroscopy with the Yunnan Faint Object Spectrograph and Camera (YFOSC) at the Lijiang 2.4 m telescope in February, 2012. These quasars are in the list of z > 3.6 quasar candidates selected by using our proposed J K/i Y criterion and the photometric redshift estimations from the SDSS optical and UKIDSS near-IR photometric data. Nine candidates were observed by YFOSC, and five among six new quasars were identified as z > 3.6 quasars. One of the other three objects was identified as a star and the other two were unidentified due to the lower signal-to-noise ratio of their spectra. This is the first time that z > 4 quasars have been discovered using a telescope in China. Thanks to the Chinese Telescope Access Program (TAP), the redshift of 4.6 for one of these quasars was confirmed by the Multiple Mirror Telescope (MMT) Red Channel spectroscopy. The continuum and emission line properties of these six quasars, as well as their central black hole masses and Eddington ratios, were obtained.
