118464873
A Comparative Study of Long-Baseline Superbeams within LAGUNA for large $\theta_{13}$
The Daya Bay and RENO experiments have recently observed a non-zero $\theta_{13}$ at more than $5\sigma$ CL. This has important consequences for future neutrino oscillation experiments. We analyze these within the LAGUNA design study which considers seven possible locations for a European neutrino observatory for proton decay, neutrino, and astroparticle physics. The megaton-scale detector would be an ideal target for a CERN-based neutrino beam with baselines ranging from 130 km to 2300 km. We perform a detailed study to assess the physics reach of the three detector options - a 440 kton water \v{C}erenkov, a 100 kton liquid argon and a 50 kton liquid scintillator detector - at each of the possible locations, taking into account the recent measurement of $\theta_{13}$. We study the impact of the beam properties and detector performances on the sensitivity to CP-violation and the mass hierarchy. We find that a liquid argon or water \v{C}erenkov detector can make a $3\sigma$ discovery of CP violation for $60%-70%$ of the parameter space for any of the baselines under consideration, although the results for the liquid argon detector placed at 130 km are slightly worse and only $40%-50%$ is achieved in this case. The performance of the liquid scintillator detector is affected by its level of neutral-current background at all baselines. A $3\sigma$ determination of the mass hierarchy is possible for all values of $\delta$, for the values of $\theta_{13}$ favoured at $3\sigma$ by Daya Bay and RENO, for almost all setups with $L\gtrsim 650$ km.
118633851
Long-baseline super-beam experiments in Europe within LAGUNA
We explore the physics reach of several possible configurations for a Super-Beam experiment in Europe, focusing on the possibilities of discovering θ13, CP violation in the leptonic sector and the ordering of neutrino mass eigenstates. We consider the three different detector technologies: Water Cerenkov, Liquid Argon and Liquid Scintillator, and seven possible sites in Europe which would be able to host such a detector underground. The distances to these sites from CERN, where the beam would be originated, go from 130 km to 2300 km. The neutrino flux is optimized in each case as to match the first oscillation peak for each of the baselines under consideration. We also study the impact of several experimental factors in the performance of each detector technology.
15819864
Power Spectra of X-Ray Binaries
The interpretation of Fourier spectra in the time domain is critically examined. Power density spectra defined and calculated in the time domain are compared with Fourier spectra in the frequency domain for three different types of variability: periodic signals, Markov processes, and random shots. The power density spectra for a sample of neutron stars and black hole binaries are analyzed in both the time and the frequency domains. For broadband noise, the two kinds of power spectra in accreting neutron stars are usually consistent with each other, but the time domain power spectra for black hole candidates are significantly higher than corresponding Fourier spectra in the high-frequency range (10-1000 Hz). Comparing the two kinds of power density spectra may help to probe the intrinsic nature of timing phenomena in compact objects.
121504005
HXMT: A Chinese High-Energy Astrophysics Mission
The Hard X-ray Modulation Telescope mission HXMT is mainly devoted to performing a hard X-ray all-sky imaging survey with both high sensitivity and high spatial resolution In the energy range of 20 - 250 keV HXMT can perform full-sky hard X-ray survey with angular resolution 5 prime position accuracy 1 prime and sensitivity better than Integral IBIS and Swift BAT HXMT can also make high signal-to-noise ratio pointing observations of scientific hot spot sources with sensitivity sim 3 0 times 10 -7 ph cm -2 s -1 keV -1 3 100keV 10 5 s for detailed temporal and spectral studies HXMT was selected in 2000 as a project under the Major State Basic Research Program of China for its feasibility and technical demonstration study and in October 2005 HXMT entered the full design phase and was listed as a candidate for the first dedicated astronomy satellite around 2010
14550049
Timescale-Resolved Spectroscopy of Cyg X-1
We propose the timescale-resolved spectroscopy (TRS) as a new method to combine the timing and spectral study. The TRS is based on the time domain power spectrum and reflects the variable amplitudes of spectral components on different timescales. We produce the TRS with the RXTE PCA data for Cyg X-1 and study the spectral parameters (the power-law photon index and the equivalent width of the iron fluorescent line) as a function of timescale. The results of TRS and frequency-resolved spectra have been compared, and similarities have been found for the two methods with the identical motivations. We also discover the correspondences between the evolution of photon index with timescale and the evolution of the equivalent width with timescale. The observations can be divided into three types according to the correspondences and different type is connected with different spectral state.
119110521
LOW-FREQUENCY OSCILLATIONS IN XTE J1550–564
We present the results of a timing analysis of the low-frequency quasi-periodic oscillation (QPO) in the Rossi X-Ray Timing Explorer data of the black hole binary XTE J1550-564 during its 1998 outburst. The QPO frequency is observed to vary on timescales between {approx}100 s and days, correlated with the count rate contribution from the optically thick accretion disk: we studied this correlation and discuss its influence on the QPO width. In all observations, the quality factors ({nu}{sub 0}/FWHM) of the fundamental and second harmonic peaks were observed to be consistent, suggesting that the quasi-periodic nature of the oscillation is due to frequency modulation. In addition to the QPO and its harmonic peaks, a new 1.5{nu} component was detected in the power spectra. This component is broad, with a quality factor of {approx}0.6. From this, we argue that the peak observed at half the QPO frequency, usually referred to as 'sub-harmonic', could be the fundamental frequency, leading to the sequence 1:2:3:4. We also studied the energy dependence of the timing features and conclude that the two continuum components observed in the power spectrum, although both more intense at high energies, show a different dependence on energy. At low energies, the lowest-frequencymore » component dominates, while at high energies the higher-frequency one has a higher fractional rms. An interplay between these two components was also observed as a function of their characteristic frequency. In this source, the transition between the low/hard state and the hard-intermediate state appears to be a smooth process.« less
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.