Are James Webb Space Telescope Observations Consistent with Warm Dark Matter?

We compare observed with predicted distributions of galaxy stellar masses M* and galaxy rest-frame ultra-violet luminosities per unit bandwidth LUV, in the redshift range z=2 to 13. The comparison is presented as a function of the comoving warm dark matter free-streaming cut-off wavenumber kfs. For this comparison the theory is a minimal extension of the Press-Schechter formalism with only two parameters: the star formation efficiency, and a proportionality factor between the star formation rate per galaxy and LUV. These two parameters are fixed to their values obtained prior to the James Webb Space Telescope (JWST) data. The purpose of this comparison is to identify if, and where, detailed astrophysical evolution is needed to account for the new JWST observations.

Two suggested configurations for the Chinese space telescope

China will establish a 2-meter space-based astronomical telescope. Its main science goals are performing a sky survey for research about dark matter and dark energy, and high resolution observations. Some experts suggest that this space telescope should be installed inside the Chinese space station. In accord with this suggestion we put forward our first configuration, i.e., to adopt a coude system for this telescope. This coude system comes from the Chinese 2.16 m telescope＇s coude system, which includes a relay mirror so that excellent image quality can be obtained. In our second configuration, we suggest that the whole space telescope fly freely as an independent satellite outside the space station. When it needs servicing, for example, changing in- struments, refilling refrigerant or propellant, etc., this space telescope can fly near or even dock with the core space station. Although some space stations have had accom- panying satellites, the one we propose is a space telescope that will be much larger than other accompanying satellites in terms of weight and volume. On the basis of the second configuration, we also put forward the following idea： the space station can be composed of several large independent modules if necessary.

Korean Participation in the Galex Ultraviolet Space Telescope Project

The Center for Space Astrophysics at Yonsei university, Seoul, Korea, is actively participating in the development and operation of the Galaxy Evolution Explorer (GALEX), a NASA ultraviolet space telescope project to be launched in late 2001. As the first official case of NASA Korea cooperation on major space science program, this project will greatly expand the capability of Korean astronomy into space based operations.

Deployment dynamics for flexible deployable primary mirror of space telescope with paraboloidal and laminated structure by using absolute node coordinate method

A nonlinear dynamic modeling method for primary mirror of Flower-like Deployable Space Telescope(F-DST)undergoing large deployment motion is proposed in this paper.To ensure pointing accuracy and attitude stability of the paraboloidal primary mirror,the mirror is discretized into equal thickness shell elements by considering shell curvature.And the material nonlinear constitutive relation of flexible mirror is acquired using Absolute Nodal Coordinate Formulation(ANCF).Furthermore,the primary mirror of F-DST can be regarded as a clustered multi-body system,and its dynamic equations of elastic deformation and deployment motion are established by virtual work principle.Finally,the deployment motion of primary mirror by different driving conditions are simulated,the results show that the vibrations of mirrors that driven by elastic hinge device are more than that driven by servo motor.In addition,single sub-mirror deployment process will perturb the pointing accuracy of primary mirror,and the multiple sub-mirrors simultaneously deploying will seriously affect all the sub-mirrors surface accuracy because of the coupling effect.Thus,there are theoretical value and practical significance for the controlling surface accuracy and attitude accuracy of space telescope.

Active vibration control of a large space telescope truss based on unilateral saturated cable actuators

Due to obvious advantages,such as light weight,easy folding and deployment and high accuracy of optical imaging,the membrane diffraction large space telescope has currently been one of the hot research topics.Because of the influence of external disturbance and attitude adjustment,the large space telescope will occur a certain degree of vibration inevitably,affecting the imaging accuracy of the space telescope for Earth.Thus,to satisfy the requirement of imaging accuracy,it is necessary for the space telescope to adopt appropriate vibration control methods.In this paper,the active vibration control of the large space telescope is studied using cables as active actuators.Considering that cables can work under tension but not under pression and the tensile capacity is limited,the unilateral and saturated characteristics of cable actuators are taken into account during control design in this paper.Firstly,the dynamic model of the membrane diffraction space telescope is established using the finite element method(FEM).Secondly,in combination with the linear quadratic regulator(LQR)and the bang-bang regulator,a piecewise cost function is used to design the active vibration control law.Next,the controllability criterion and the genetic algorithm(GA)are adopted to determine the optimal positions of cable actuators.Finally,the validity of the proposed control method is verified by numerical simulations.Simulation results indicate that the vibration of the space telescope can be suppressed effectively using the proposed control method,and the imaging requirements of the telescope may be realized using the least cable actuators,whose minimum quantity and position distribution are determined in this paper.

Presentation on the Electronic Control System of Space Solar Telescope

This paper gives the brief view of the electronic control system of SPACE SOLAR TELESCOPE (SST), especially the On Board Data Handling unit (OBDH) on the SST which control the operation of the instrument, acquire data and make data analysis and storage. In OBDH, the Scientific Data Unit (SDU) is a special unit that requires high speed computer. In this paper gives a brief comparison of two possible choices and discuss selection of electronic parts in the space environment.

Photometric Calibration of the Lunar-based Ultraviolet Telescope for Its First Six Months of Operation on the Lunar Surface

We describe the photometric calibration of the Lunar-based Ultraviolet Telescope（LUT）, the first robotic astronomical telescope working on the lunar surface, for its first six months of operation on the lunar surface. Two spectral datasets（set A and B） from near-ultraviolet（NUV） to the optical band were constructed with 44 International Ultraviolet Explorer（IUE） standards, because of the LUT＇s relatively wide wavelength coverage. Set A was obtained by extrapolating the IUE NUV spectra（λ 〈 3200 ） to the optical band based upon the theoretical spectra of stellar atmosphere models. Set B was composed of theoretical spectra from 2000 to 8000 extracted from the same model grid. In total, seven standards have been observed in15 observational runs until May 2014. The calibration results show that the photometric performance of LUT is highly stable in its first six months of operation. The magnitude zero points obtained from the two spectral datasets are also consistent with each other, i.e., zp = 17.54 ± 0.09 mag（set A） and zp = 17.52 ± 0.07 mag（set B）.

The first comprehensive Milky Way stellar mock catalogue for the Chinese Space Station Telescope Survey Camera

The Chinese Space Station Telescope(CSST)is a cutting-edge two-meter astronomical space telescope currently under construction.Its primary Survey Camera(SC)is designed to conduct large-area imaging sky surveys using a sophisticated seven-band photometric system.The resulting data will provide unprecedented data for studying the structure and stellar populations of the Milky Way.To support the CSST development and scientific projects related to its survey data,we generate the first comprehensive Milky Way stellar mock catalogue for the CSST SC photometric system using the TRILEGAL stellar population synthesis tool.The catalogue includes approximately 12.6 billion stars,covering a wide range of stellar parameters,photometry,astrometry,and kinematics,with magnitude reaching down to g=27.5 mag in the AB magnitude system.The catalogue represents our benchmark understanding of the stellar populations in the Milky Way,enabling a direct comparison with the future CSST survey data.Particularly,it sheds light on faint stars hidden from current sky surveys.Our crowding limit analysis based on this catalogue provides compelling evidence for the extension of the CSST Optical Survey(OS)to cover low Galactic latitude regions.The strategic extension of the CSST-OS coverage,combined with this comprehensive mock catalogue,will enable transformative science with the CSST.

JWST Discoveries—Confirmation of World-Universe Model Predictions

In 1937, P. Dirac proposed the Large Number Hypothesis and Hypothesis of Variable Gravitational Constant [1], and later added notion of Continuous Creation of Matter in the World [2]. Developed Hypersphere World-Universe Model (WUM) follows these ideas, albeit introducing different mechanism of Matter creation. Most direct observational evidence of validity of WUM are: 1) Microwave Background Radiation and Intergalactic Plasma speak in favor of existence of Medium;2) Laniakea Supercluster with binding mass ~1017M⊙ is home to Milky Way (MW) galaxy and ~105 other nearby galaxies, which did not start their movement from Initial Singularity (see Figure 1);3) MW is gravitationally bounded with Virgo Supercluster (VSC) and has Orbital Angular Momentum calculated based on distance of 65 Mly from VSC and orbital speed of ~400 km·s-1, which far exceeds rotational angular momentum of MW;4) Mass-to-light ratio of VSC is ~300 times larger than that of Solar ratio. Similar ratios are obtained for other superclusters (see Figure 2). These ratios are main arguments in favor of the presence of tremendous amounts of Dark Matter (DM) in the World. JWST discoveries confirm the most important predictions of WUM in 2018: 1) Absolute Age of World is 14.22 Gyr;2) Dark Epoch (spanning for Laniakea Supercluster (LSC) from the Beginning of World for 0.45 Gyr) when only DM Macroobjects (MOs) form and evolve;3) Luminous Epoch (ever since, 13.77 Gyr for LSC) when Luminous MOs (superclusters, galaxies, extrasolar systems, etc.) emerge;4) Transition from Dark Epoch to Luminous Epoch is due to Explosive Rotational Fission of Overspinning (surface speed at equator exceeding escape velocity) DM Supercluster’s Cores and self-annihilation of DM Particles (DMPs);5) MOs of World form from top (Superclusters) down to Galaxies and Extrasolar systems in parallel around different Cores made up of different DMPs;6) 3D Finite Boundless World presents a Patchwork Quilt of different Luminous Superclusters, which emerged in different places of World at different Cosmological times.

Space solar telescope in soft X-ray and EUV band

In this paper we have reviewed our achievements in soft X-ray and extreme ultraviolet (EUV) optics. Up to now, the research system of soft X-ray and EUV optics has been established, including light sources, detectors, calibrations, optical testing and machining of super smooth mirrors, and fabrications of multilayer film mirrors. Based on our achievements, we have developed two types of solar space telescopes for the soft X-ray and EUV space solar observations. One is an EUV multilayer normal incident telescope array including 4 different operation wavelength telescopes. The operation wavelengths of the EUV telescope are 13.0, 17.1, 19.5 and 30.4 nm. The other is a complex space solar telescope, which is composed of an EUV multilayer normal incident telescope and a soft X-ray grazing incident telescope. The EUV multilayer normal incident telescope stands in the central part of the soft X-ray grazing incident telescope. The normal incident telescope and the grazing incident telescope have a common detector. The different operation wavelengths can be changed by rotating a filter wheel.

Design of Central Management & Control Unit for Onboard High-Speed Data Handling System

The Main Optical Telescope (MOT) is an important payload of the Space Solar Telescope (SST) with various instruments and observation modes. Its real-time data handling and management and control tasks are arduous. Based on the advanced techniques of foreign countries, an improved structure of onboard data handling systems feasible for SST, is proposed. This article concentrated on the development of a Central Management & Control Unit (MCU) based on FPGA and DSP. Through reconfigurating the FPGA and DSP programs, the prototype could perform different tasks. Thus the inheritability of the whole system is improved. The completed dual-channel prototype proves that the system meets all requirements of the MOT. Its high reliability and safety features also meet the requirements under harsh conditions such as mine detection.

Black holes as the source of dark energy:A stringent test with high-redshift JWST AGNs

Studies have proposed that there is evidence for cosmological coupling of black holes(BHs)with an index of k≈3;hence,BHs serve as the astrophysical source of dark energy.However,the data sample is limited for the redshifts of≤2.5.In recent years,the James Webb Space Telescope(JWST)has detected many high-redshift active galactic nuclei(AGNs)and quasars.Among the JWST NIRSpec-/NIRCam-resolved AGNs,three are determined to be in early-type host galaxies with a redshift of z~4.5-7.However,their M_(*)and MBH are in tension with the predicted cosmological coupling of black holes with k=3 at a confidence level of~2σ,which challenges the hypothesis that BHs serve as the origin of dark energy.Future work on high-redshift AGNs using the JWST will further assess such a hypothesis by identifying more early-type host galaxies in the higher mass range.

The nanohertz stochastic gravitational wave background from cosmic string loops and the abundant high redshift massive galaxies

Recently,pulsar timing array(PTA)experiments have provided compelling evidence for the existence of the nanohertz stochastic gravitational wave background(SGWB).In this work,we demonstrated that cosmic string loops generated from cosmic global strings offer a viable explanation for the observed nanohertz SGWB data,requiring a cosmic string tension parameter of log(Gμ)~-12 and a loop number density of log N~4.Additionally,we revisited the impact of cosmic string loops on the abundance of massive galaxies at high redshifts.However,our analysis revealed challenges in identifying a consistent parameter space that can concurrently explain both the SGWB data and observations from the James Webb Space Telescope.This indicates the necessity for either extending the existing model employed in this research or acknowledging distinct physical origins for these two phenomena.