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This article summarizes the main activities of the Tsinghua Center for Astrophysics of Tsinghua University in Beijing, and the recent involvements on projects exploring the Dark Universe.

Relativity Theory (RT) incorporates serious inconsistencies:- (1) embracing the function of transverse e.m. (TEM) waves as perfect messengers but denying the presence of a Maxwell’s equations aether lest it might invalidate that perfection, despite it being essential for their existence; (2) assuming the physical absurdity that the external physical properties (mass, magnetic moment) of fundamental particles can be developed in zero volume (“spatially infinitesimal singularities”), despite powerful evidence that they are of finite size. It thereby overlooks that if two electromagnetically defined objects are of finite size the force communication between them is progressively velocity-limited, falling to zero at c [Heaviside 1889]. So this is what happens in electromagnetic accelerators, not massincrease. For more than a century these defects have hampered progress in understanding the physics of the mass property of particles, thus compelling it to be regarded as ‘intrinsic’ to those specific infinitesimal points in space. A rewarding substitute, Continuum Theory (CT), outlined here, (A) implements Maxwell’s aether as a massless all-pervasive quasi-superfluid elastic continuum of (negative) electric charge, and (B) follows others [Clerk Maxwell, both Thompsons, Larmor, Milner] in seeing mass-bearing fundamental particles as vortical constructs of aether in motion, not as dichotomously different from it. To encompass that motion, these cannot be infinitesimal singularities. Electron-positron scattering provides guidance as to that size. For oppositely-charged particles, one sort contains more aether and the other less, so particle-pair creation is ‘easy’, and abundantly observed, but has been attributed to ‘finding’. This electron-positron relationship defines mean aether density as >1030 coulomb.cm-3, thus constituting the near-irrotational reference frame of our directional devices. Its inherent self-repulsion also offers an unfathomable force capability should the means for displacing its local density exist; that, we show, is the nature of gravitational action and brings gravitation into the electromagnetic family of forces. Under (B) the particle mass is measured by the aether-sucking capability of its vortex, positiveonly gravitation being because the outward-diminishing force developed by each makes mutual convergence at any given point the statistically prevalent expectation. This activity maintains a radial aether (charge) density gradient - the Gravity-Electric (G-E) Field - around and within any gravitationally retained assemblage. So Newton’s is an incomplete description of gravitation; the corresponding G-E field is an inseparable facet of the action. The effect on c of that charge density gradient yields gravitational lensing. We find that G-E field action on plasma is astronomically ubiquitous. This strictly radial outward force on ions has the property of increasing the orbital angular momentum of material, by moving it outwards, but at constant tangential velocity. Spiral galaxies no longer require Cold Dark Matter (CDM) to explain this. The force (maybe 30 V.m-1 at solar surface) has comprehensive relevance to the high orbital a.m. achieved during solar planet formation, to their prograde spins and to exoplanet observations. The growth of high-mass stars is impossible if radiation pressure rules, whereas G-E field repulsion is low during dust-opaque infall, driving their prodigious mass loss rates when infall ceases and the star establishes an ionized environment. Its biggest force-effect (~1012 V.m-1) is developed at neutron stars, where it is likely the force of supernova explosions, and leads to a fertile model for pulsars and the acceleration of 1019 eV extreme-energy cosmic rays. Our only directly observed measure of the G-E field is recorded at about 1 V.m-1 in the ionosphere-to-Earth electric potential. And temporary local changes of ionosphere electron density, monitored by radio and satellite, have been discovered to act as earthquake precursors, presumably, we suggest, by recording change of G-E field and gravitational potential at Earth surface when its elastic deformation occurs, even when this is deep below electrically conducting ocean water. The paper concludes by noting experimental evidence of the irrelevance of the Lorentz transformations in CT and with a discussion of CT’s competence in such matters as perihelion advance and Sagnac effect, widely regarded as exclusively RT attributes. Finally we broach the notion that the aether is the site of inertia. This could explain the established equality of gravitational and inertial masses. In an accompanying paper we explore the cosmological and other aspects of ‘making particles out of aether’. This link undermines the expectation of fully distinct dynamical behaviour by particles and aether which motivated the Michelson-Morley experiment.

Type Ia supernovae (SNe Ia) have been used with remarkable success to map the expansion history of the Universe. These measurements dramatically changed our description of nature as they revealed cosmic acceleration, indicating the presence of new physics, dark energy, counteracting the effect of gravity at the largest scales. Understanding the source of the acceleration ranks among the most pressing undertakings in fundamental physics. Current and future surveys are challenged to accurately measure the equation state of dark energy, the parameter used to explore its nature. Distances measurements using SNe Ia remain among the most powerful techniques in observational cosmologists. The recent history of the field is reviewed, as well as current limitations and opportunities for the future.

he history of cosmic expansion can be accurately traced using Type Ia supernovae (SN Ia) as standard candles. Over the past 40 years, this effort has improved its precision and extended its reach in redshift. Recently, the distances to SN Ia have been measured to a precision of ~5% using luminosity information that is encoded in the shape of the supernova's rest frame optical light curve. By combining observations of supernova distances as measured from their light curves and redshifts measured from spectra, we can detect changes in the cosmic expansion rate. This empirical approach was successfully exploited by the High-Z Supernova Team and by the Supernova Cosmology Project to detect cosmic expansion and to infer the presence of dark energy. The 2011 Nobel Prize in Physics was awarded to Perlmutter, Schmidt and Riess for this discovery. The world's sample of well-observed SN Ia light curves at high redshift and low, approaching 1000 objects, is now large enough to make statistical errors due to sample size a thing of the past. Systematic errors are now the challenge. To learn the properties of dark energy and determine, for example, whether it has an equation-of-state that is different from the cosmological constant demands higher precision and better accuracy. The largest systematic uncertainties come from light curve fitters, photometric calibration errors, and from uncertain knowledge of the scattering properties of dust along the line of sight. Efforts to use SN Ia spectra as luminosity indicators have had some success, but have not yet produced a big step forward. Fortunately, observations of SN Ia in the near infrared (NIR), from 1 to 2 microns, offer a very promising path to better knowledge of the Hubble constant and to improved constraints on dark energy. In the NIR, SN Ia are better standard candles and the effects of dust absorption are smaller. We have begun an HST program dubbed RAISIN (SN IA in the IR) to tighten our grip on dark energy properties

This contribution is a review of some talks presented at the session ‘Magneto-Plasma Processes in Relativistic Astrophysics’ of the Thirteenth Marcel Grossmann Meeting MG13. We discuss the modern developments of relativistic astrophysics, connected with presence of plasma and magnetic fields. The influence of magneto-plasma processes on the structure of the compact objects and accretion processes is considered. We also discuss a crucial role of magnetic field for the mechanism of core-collapse supernova explosions. Gravitational lensing in plasma is also considered.

Compact binaries are important progenitors for gamma-ray bursts, they constitute the most promising sources of gravitational waves and form an interesting setting for dynamically important nuclear burning processes. Here we present simulations of the onset of mass transfer in compact binaries, focusing on systems containing a neutron star and a white dwarf. These systems are formed interestingly often. A significant fraction of them will come into contact in less than a Hubble time while still being interestingly eccentric. We realistically model the white dwarf by using the Helmholtz equation of state. We make use of a modified form of smoothed particle hydrodynamics, which enables us to model realistically low mass transfer rates for the first time. We use this code to investigate the stability of mass transfer.

For future surveys, spectroscopic follow-up for all supernovae will be extremely difficult. However, one can use light curve fitters, to obtain the probability that an object is a Type Ia. One may consider applying a probability cut to the data, but we show that the resulting non-Ia (nIa) contamination can lead to biases in the estimation of cosmological parameters. A different method, which allows the use of the full dataset and results in unbiased cosmological parameter estimation, is Bayesian Estimation Applied to Multiple Species (BEAMS). BEAMS is a Bayesian approach to the problem which includes the uncertainty in the types in the evaluation of the posterior. Here we outline the theory of BEAMS and demonstrate its effectiveness using both simulated datasets and SDSS-II data. We also show that it is possible to use BEAMS if the data are correlated, by introducing a numerical marginalisation over the types of the objects.

We discuss the identification of SGR/AXPs progenitors and associated birth events. We argue that a possible interval of 18 — 40M_⊙ of rotating progenitors is indicated, and that associated supernovae may be driven by the magnetar under certain conditions. This does not guarantee a super-energetic event, although it is shown that this may be the case of the recent identification CXOU J171405.7-381031/CTB37B. Magnetars are predicted to be massive, M ≥ 1.6M_⊙ right at their birth.

There are two new observational facts: the mass spectrum of neutron stars and black hole candidates (or collapsars) shows an evident absence of compact objects with masses within the interval from 2 M⊙ (with a peak for neutron stars about 1.4 M⊙) to about 6 M⊙, and in close binary stellar systems with a low-massive (about 0.6 M⊙) optical companion the most probable mass value (the peak in the masses distribution of black hole candidates) is close to 7 M⊙. The problem of the compact objects discrete mass spectra demands some solution both in the context of the supernovae and gamma-ray bursts relation, and in connection with the core-collapse supernovae explosion mechanism itself. In the totally non-metric scalar-tensor model of gravitational interaction (in a modified or extended Feynman field approach to gravitation) the total mass of a compact relativistic object with extremely strong gravitational field (an analog of black holes in General Relativity) is approximately equal to 6.7 M⊙ with radius of a region filled with a matter (quark-gluon plasma) ≈ 10 km. Polarized emission of long gamma-ray bursts, a black-body component in their spectrum and other observed properties could be explained by the direct manifestation of a surface of these collapsars.

A massive neutrino has nonzero magnetic moment and is involved in the electromagnetic interactions with external fields and photons. The electromagnetic neutrino moving in matter can emit the spin light (SLν) in the process of transition between two quantum states in matter. In quite resembling way an electron can emit spin light in moving background composed of neutrinos, that is “the spin light of an electron in neutrino flux” (SLe_ν). In this paper we obtain the exact solution for the wave function and energy spectrum for an electron moving in a neutrino flux and consider the SLe_ν as the transition process between two electron quantum states in the background. The SLe_ν radiation rate, power and emitted photon energy are calculated. Notably, the energy spectrum of the emitted SLe_ν photons can span up to gamma-rays. We argue that the considered SLe_ν can be of interest for astrophysical applications, for supernovae processes in particular.