118461357
First stage of LISA data processing: Clock synchronization and arm-length determination via a hybrid-extended Kalman filter
In this paper, we describe a hybrid-extended Kalman filter algorithm to synchronize the clocks and to precisely determine the inter-spacecraft distances for space-based gravitational wave detectors, such as (e)LISA. According to the simulation, the algorithm has significantly improved the ranging accuracy and synchronized the clocks, making the phase-meter raw measurements qualified for time- delay interferometry algorithms.
119110055
EMRI data analysis with a phenomenological waveform
Extreme mass ratio inspirals (EMRIs) (capture and inspiral of a compact stellar mass object into a Massive Black Hole (MBH)) are among the most interesting objects for the gravitational wave astronomy. It is a very challenging task to detect those sources with the accurate estimation parameters of binaries primarily due to a large number of the secondary maxima on the likelihood surface. Search algorithms based on the matched filtering require computation of the gravitational waveform hundreds of thousands of times, which is currently not feasible with the most accurate (faithful) models of EMRIs. Here we propose to use a phenomenological template family which covers a large range of EMRIs parameter space. We use these phenomenological templates to detect the signal in the simulated data and then, assuming a particular EMRI model, estimate the physical parameters of the binary. We have separated the detection problem, which is done in a model-independent way, from the parameter estimation. For the latter one, we need to adopt the model for inspiral in order to map phenomenological parameters onto the physical parameter characterizing EMRIs.
14088655
The Mock LISA data challenges: from challenge 1B to challenge 3
The Mock LISA Data Challenges are a programme to demonstrate and encourage the development of LISA data-analysis capabilities, tools and techniques. At the time of this workshop, three rounds of challenges had been completed, and the next was about to start. In this paper we provide a critical analysis of the entries to the latest completed round, Challenge 1B. The entries confirm the consolidation of a range of data-analysis techniques for galactic and massive-black-hole binaries, and they include the first convincing examples of detection and parameter estimation of extreme-mass-ratio inspiral sources. In this paper we also introduce the next round, Challenge 3. Its data sets feature more realistic waveform models (e.g., galactic binaries may now chirp, and massive-black-hole binaries may precess due to spin interactions), as well as new source classes (bursts from cosmic strings, isotropic stochastic backgrounds) and more complicated nonsymmetric instrument noise.
41820397
Fast detection and automatic parameter estimation of a gravitational wave signal with a novel method
The detection of gravitational wave usually requires to match the measurement data with a large number of templates, which is computationally very expensive. Compressed sensing methods allow one to match the data with a small number of templates and interpolate the rest. However, the interpolation process is still computationally expensive. In this article, we designed a novel method that only requires to match the data with a few templates, yet without needing any interpolation process. The algorithm worked well for signals with relatively high SNRs. It also showed promise for low SNRs signals.
54877389
A scientific case study of an advanced LISA mission
A brief status report of an ongoing scientific case study of the Advanced Laser Interferometer Antenna (ALIA) mission is presented. Key technology requirements and primary science objectives of the mission are covered in the study. Possible descope options for the mission and the corresponding compromise in science are also considered and compared. Our preliminary study indicates that ALIA holds promise in mapping out the mass and spin distribution of intermediate mass black holes possibly present in dense star clusters at low redshift as well as in shedding important light on the structure formation in the early Universe.
118811248
DUSTY DISKS AROUND WHITE DWARFS. I. ORIGIN OF DEBRIS DISKS
A significant fraction of the mature FGK stars have cool dusty disks at least an order of magnitude brighter than the solar system's outer zodiacal light. Since such dusts must be continually replenished, they are generally assumed to be the collisional fragments of residual planetesimals analogous to the Kuiper-Belt objects. At least 10% of solar-type stars also bear gas giant planets. The fraction of stars with known gas giants or detectable debris disks (or both) appears to increase with the stellar mass. Here, we examine the dynamical evolution of systems of long-period gas giant planets and residual planetesimals as their host stars evolve off the main sequence, lose mass, and form planetary nebula around remnant white dwarf cores. The orbits of distant gas giant planets and super-km-size planetesimals expand adiabatically. During the most intense asymptotic giant branch mass-loss phase, sub-meter-size particles migrate toward their host stars due to the strong hydrodynamical drag by the intense stellar wind. Along their migration paths, gas giant planets capture and sweep up sub-km-size planetesimals onto their mean-motion resonances. These planetesimals also acquire modest eccentricities which are determined by the mass of the perturbing planets, and the rate and speed of stellar mass loss. The swept-up planetesimals undergo disruptive collisions which lead to the production of grains with an extended size range. The radiation drag on these particles is ineffective against the planets' resonant barrier and they form 30-50 AU size rings which can effectively reprocess the stellar irradiation in the form of FIR continuum. We identify the recently discovered dust ring around the white dwarf WD 2226-210 at the center of the Helix nebula as a prototype of such disks and suggest such rings may be common.
53361927
Resummation prediction on the jet mass spectrum in one-jet inclusive production at the LHC
A bstractWe study the factorization and resummation prediction on the jet mass spectrum in one-jet inclusive production at the LHC based on soft-collinear effective theory. The soft function with anti-kT algorithm is calculated at next-to-leading order and its validity is demonstrated by checking the agreement between the expanded leading singular terms with the exact fixed-order result. The large logarithms lnn(mJ2/pT2) and the global logarithms lnn(s4/pT2) in the process are resummed to all order at next-to-leading logarithmic and next-to-next-to-leading logarithmic level, respectively. The cross section is enhanced by about 23% from the next-to-leading logarithmic level to next-to-next-to- leading logarithmic level. Comparing our resummation predictions with those from Monte Carlo tool PYTHIA and ATLAS data at the 7 TeV LHC, we find that the peak positions of the jet mass spectra agree with those from PYTHIA at parton level, and the predictions of the jet mass spectra with non-perturbative effects are in coincidence with the ATLAS data. We also show the predictions at the future 13 TeV LHC.
120127236
Systematic study of tensor effects in shell evolution
In the framework of the Hartree-Fock-Bogoliubov approach with the Skyrme interactions SLy5, SLy5+T, SLy5+T{sub w}, and several sets of the TIJ parametrizations (Skyrme effective interaction parametrizations including the tensor terms), the effect of the tensor force on the shell evolution at Z,N=8, 20, and 28 is investigated. It is shown that the evolution of the gap (defined as the energy difference between the last occupied and first unoccupied single-particle orbits) with SLy5+T is similar to that with SLy5+T{sub w}, and the gap values with SLy5+T are smaller than those with SLy5+T{sub w} in the cases of Z,N=8, 20. At Z, N = 28, the gap values with SLy5 are smaller than those with SLy5+T and larger than those with SLy5+T{sub w}. To understand these features, we analyze the spin-orbit potentials with and without the tensor contributions and the radial wave functions of relevant orbits. Meanwhile, we find that the deviation of the calculated gaps with SLy5+T{sub w} from the experimental ones is larger than that with SLy5+T. This indicates that SLy5+T{sub w} is not suitable for investigating the properties of the ground-state gap evolution. Finally, it is seen that the gap evolutions with different sets of the TIJ parametrizations aremore » similar to each other except for the ones with T22, and there is almost no difference between the tensor effect in gap evolution with the perturbative method and the one with the complete fitting method.« less
110807481
Development of a high power 1.2 MW CW L-band klystron
The high power CW L-band klystron has been developed as the RF source of the PNC high power CW electron linac (10 MeV, 100 mA). CW power of 1.2 MW at 1.249135 GHz and efficiencies over 65% were the design goals. RF analysis of the windows using high-frequency simulation codes provided information about power loss distribution in the ceramic and optimizing properties of the RF structure. The prototype klystron window was replaced with a long pill-box type beryllia window as a result of the simulation and hardware tests. The klystron has reached CW power of 885 kW with efficiency above 45%. This paper describes key points of the designs and results of the high power RF tests.
122786385
Recent results from E802 and E859
Abstract Recent single-particle inclusive measurements and two-particle correlation data from E802 and its succesor, E859, are presented. The K + / π + ratio observed for collisions of 14.6 A·GeV 28 Si ions on various targets is presented as a function of both forward and transverse energy. Source sizes are determined via interferometry using π + , π − , K + and proton pairs.
121446966
The Muon Filter of the L3 detector
Abstract In this article we describe the outer part (Muon Filter) of the Hadron Calorimeter of the L3 detector. Construction and performance of the brass chambers, which form the sensitive part of the detector, are reviewed. We also report the results from data taken on two beam tests, at CERN.