118010707
The origin of the WMAP quadrupole
The cosmic microwave background (CMB) temperature maps from the Wilkinson Microwave Anisotropy Probe (WMAP) are of great importance for cosmology. In previous work we had developed a pipeline for map-making independently of the WMAP team. The new maps produced from the WMAP raw data by our pipeline are notably different to the official ones, and the power spectrum as well as the best-fit cosmological parameters are significantly different too. What's more, by revealing the inconsistency between the WMAP raw data and their official map, we had pointed out that there must exist an unexpected problem in the WMAP team's pipeline. In this work, we find that the trouble comes from the inaccuracy of antenna pointing direction caused by a systematical time drift between the attitude data and the science data in the WMAP raw time-order data (TOD). The CMB quadrupole in the WMAP release can be exactly generated from a differential dipole field which is completely determined by the spacecraft velocity and the antenna directions without using any CMB signal. After correcting the WMAP team's error, the CMB quadrupole component disappears. Therefore, the released WMAP CMB quadrupole is almost completely artificial and the real quadrupole of the CMB anisotropy should be near zero. Our finding is important for understanding the early universe.
121381895
Abnormal correlation in WMAP data: parity violation or data flaw?
The cosmic microwave background (CMB) temperature maps and the corresponding results published by the Wilkinson Microwave Anisotropy Probe (WMAP) team are the basis of precision cosmology. However, in our previous work, they have been questioned: it is discovered that the WMAP CMB temperatures are correlated with the number of observations (N-obs) (Li et al 2009 Mon. Not. R. Astron. Soc. 398 47). We have repeated this finding with a much simpler method and found more interesting attributes of the temperature-N-obs correlation. What is more, with our method, we have also found significant correlations between the CMB intensity and polarization components. With these results, either the law of parity conservation may be violated in the early universe or there may be a flaw in the WMAP data.
16231433
Temporal and spectral properties of gamma-ray flashes
[1] The temporal and spectral properties of terrestrial gamma-ray flashes (TGFs) are studied. The delay of low energy photons relative to high energy ones in the γ-ray variations of the TGFs with high signal to noise ratio has been revealed by an approach of correlation analysis in the time domain on different time scales. The temporal structures of the TGFs in high energy band are usually narrower than that in low energy band. The spectral hardness has a general trend of decreasing with time in a flash. The observed temporal and spectral characteristics give constraints and valuable hints on the flash production mechanism.
118555439
Attraction-repulsion coupled and energy conserved universe
The discovery of accelerated cosmic expansion implies that, in addition to the attractive gravity of matter, there exists in our universe some other form of energy (dark energy or cosmological constant) producing a repulsive force. The natural interpretation of dark energy is the vacuum energy. However, the density of vacuum energy expected by the quantum field theory is 120 orders of magnitude larger than what is allowed by cosmological observations, which is called the cosmological constant problem and remains one of the most significant unsolved problems in fundamental physics. Here we show that the huge discrepancy can be resolved by assuming that our universe is an attraction-repulsion coupled system with energy conservation, and that the pre-inflation vacuum is in equilibrium between attraction and repulsion (in flat Minkowski spacetime, not de Sitter or anti de Sitter). The attraction-repulsion coupling picture can also easily explain why both kinds of energy in our universe have similar magnitude today, and avoid singularity problems in general relativity and cosmology.
17242777
TEMPORAL AND SPECTRAL CORRELATIONS OF CYGNUS X-1
Temporal and spectral properties of X-ray rapid variability of Cyg X-l are studied through correlation analysis in the time domain on different timescales. The correlation coefficients between the total intensity in the 2-60 keV band and the hardness ratio of the 13-60 keV to the 2-6 keV band on the timescale of similar to 1 ms are always negative in all states. For soft states, the correlation coefficients are positive on all timescales from similar to 0.01 to similar to 100 s, which is significantly different from those for transition and low states. The temporal structures in the high-energy band are narrower than those in low-energy band in quite a few cases. The delay of high-energy photons relative to low-energy ones in the X-ray variations has also been revealed by the correlation analysis. The implications of the observed temporal and spectral characteristics for the production region and mechanism of Cyg X-l X-ray variations are discussed.
56439385
On the relation of hard X-ray peak flux and outburst waiting time in the black hole transient GX 339-4
Aims. We reinvestigate the empirical relation between the hard X-ray peak flux and the outburst waiting time found previously in the black hole transient GX 339-4. We verify the relation using the observed hard X-ray peak flux of the 2007 outburst of GX 339-4, we clarify the nature of faint flares, and we estimate the lower limit to hard X-ray peak flux of the next outburst.
117068481
Phenomenology of a Low-Energy Neutrino Factory and Related Experiments
The discovery of neutrino oscillations is one of the most important in the recent history of particle physics, being the first evidence of physics beyond the Standard Model. We describe the theoretical framework of the neutrino oscillation model, motivate the necessity for a new generation of neutrino oscillation experiments and study the phenomenological factors which influence the design of these experiments. 
 
We perform the first detailed study of a European super-beam setup using the CERN to Pyhasalmi baseline of 2285 km, analysing the physics reach of this setup with a 100 kiloton liquid argon detector and comparing its performance to that of a 50 kiloton liquid scintillator detector and a 440 kiloton water Cerenkov detector. The liquid argon and liquid scintillator detectors are found to perform best, providing sensitivity to theta_{13}, delta and the mass hierarchy for sin^{2}2theta_{13} > 10^{-2}. 
 
A potential successor to super-beam experiments is a neutrino factory. We study a low-energy neutrino factory, a setup which has so far not been analysed in any detail, performing optimisation studies and an analysis of its sensitivity to oscillation parameters and non-standard matter interactions. We show that for sin^{2}2theta_{13} > 4x10^{-3}, a low-energy neutrino factory using a 20 kiloton totally active scintillating detector has 100% CP coverage for hierarchy sensitivity and theta_{13} discovery, and has greater sensitivity to CP violation than the high-energy neutrino factory. We consider the novel concept of including the `platinum channels' in addition to the `golden channels', showing that this is a powerful way of resolving the degeneracies between the oscillation and non-standard parameters. This enhances the sensitivity, such that the low-energy neutrino factory can put upper bounds \gtrsim10^{-2} on the non-standard interaction parameters epsilon_{e\mu} and epsilon_{e\tau}.
123983687
Extracting Physics from Gravitational Waves: Testing the Strong-field Dynamics of General Relativity and Inferring the Large-scale Structure of the Universe
23581346
Demonstrating the feasibility of probing the neutron-star equation of state with second-generation gravitational-wave detectors.
Fisher matrix and related studies have suggested that, with second-generation gravitational-wave detectors, it may be possible to infer the equation of state of neutron stars using tidal effects in a binary inspiral. Here, we present the first fully Bayesian investigation of this problem. We simulate a realistic data analysis setting by performing a series of numerical experiments of binary neutron-star signals hidden in detector noise, assuming the projected final design sensitivity of the Advanced LIGO-Virgo network. With an astrophysical distribution of events (in particular, uniform in comoving volume), we find that only a few tens of detections will be required to arrive at strong constraints, even for some of the softest equations of state in the literature. Thus, direct gravitational-wave detection will provide a unique probe of neutron-star structure.
119203391
Mock data challenge for the Einstein Gravitational-Wave Telescope
The Einstein Telescope (ET) is conceived to be a third generation gravitational-wave (GW) observatory. Its amplitude sensitivity would be a factor 10 better than advanced LIGO and Virgo and it could also extend the low-frequency sensitivity down to 1\char21{}3 Hz, compared to the 10\char21{}20 Hz of advanced detectors. Such an observatory will have the potential to observe a variety of different GW sources, including compact binary systems at cosmological distances. ET's expected reach for binary neutron star (BNS) coalescences is out to redshift $z\ensuremath{\simeq}2$ and the rate of detectable BNS coalescences could be as high as one every few tens or hundreds of seconds, each lasting up to several days. With such a signal-rich environment, a key question in data analysis is whether overlapping signals can be discriminated. In this paper we simulate the GW signals from a cosmological population of BNS and ask the following questions: Does this population create a confusion background that limits ET's ability to detect foreground sources? How efficient are current algorithms in discriminating overlapping BNS signals? Is it possible to discern the presence of a population of signals in the data by cross correlating data from different detectors in the ET observatory? We find that algorithms currently used to analyze LIGO and Virgo data are already powerful enough to detect the sources expected in ET, but new algorithms are required to fully exploit ET data.
1506194
TIGER: A data analysis pipeline for testing the strong-field dynamics of general relativity with gravitational wave signals from coalescing compact binaries
The direct detection of gravitational waves with upcoming second-generation gravitational wave observatories such as Advanced LIGO and Advanced Virgo will allow us to probe the genuinely strong-field dynamics of general relativity (GR) for the first time. We have developed a data analysis pipeline called TIGER (test infrastructure for general relativity), which uses signals from compact binary coalescences to perform a model-independent test of GR. In this paper we focus on signals from coalescing binary neutron stars, for which sufficiently accurate waveform models are already available which can be generated fast enough on a computer that they can be used in Bayesian inference. By performing numerical experiments in stationary, Gaussian noise, we show that for such systems, TIGER is robust against a number of unmodeled fundamental, astrophysical, and instrumental effects, such as differences between waveform approximants, a limited number of post-Newtonian phase contributions being known, the effects of neutron star tidal deformability on the orbital motion, neutron star spins, and instrumental calibration errors.