123083834
Can Current Detectors Detect Gravitational Radiation from Newborn Pulsars
973744
Wave Effects in the Gravitational Lensing of Gravitational Waves from Chirping Binaries
In the gravitational lensing of gravitational waves, wave optics should be used instead of geometrical optics when the wavelength λ of the gravitational waves is longer than the Schwarzschild radius of the lens mass ML. For gravitational lensing of chirp signals from the coalescence of supermassive black holes at redshift zS ~ 1 relative to the Laser Interferometer Space Antenna, the wave effects become important for a lens mass smaller than ~108 M☉. For such cases, we compute how accurately we can extract the mass of the lens and the source position from the lensed signal. We consider two simple lens models: the point-mass lens and the SIS (singular isothermal sphere). We find that the lens mass and the source position can be determined to within ~0.1% of [(S/N)/103]-1 for a lens mass larger than 108 M☉ and 10% of [(S/N)/103]-1 for a lens mass smaller than 107 M☉ because of the diffraction effect, where S/N is the signal-to-noise ratio of the unlensed chirp signals. For the SIS model, if the source position is outside the Einstein radius, only a single image exists in the geometrical optics approximation, so that the lens parameters cannot be determined, while in the wave optics cases we find that the lens mass can be determined even for ML < 108 M☉. For the point-mass lens, one can extract the lens parameters even if the source position is far outside the Einstein radius. As a result, the lensing cross section is an order of magnitude larger than that for the usual strong lensing of light.
2890887
Microlensing of Collimated Gamma-Ray Burst Afterglows
We investigate the stellar microlensing of collimated gamma-ray burst afterglows. A spherical afterglow appears on the sky as a superluminally expanding thin ring (a "ringlike" image), which is maximally amplified as it crosses a lens. We find that the image of the collimated afterglow becomes quite uniform (a "disklike" image) after the jet-break time (after the Lorentz factor of the jet drops below the inverse of the jet opening angle). Consequently, the amplification peak in the light curve after the break time is lower and broader. Therefore, detailed monitoring of the amplification history will be able to test whether afterglows are jets or not, i.e., disklike or not, if lensing occurs after the break time. We also show that some proper motion and polarization is expected, peaking around the maximum amplification. The simultaneous detection of proper motion and polarization will indicate that the brightening of the light curve is due to microlensing.
120027595
Gravitational radiation from an extreme Kerr black hole
We analytically investigate gravitational radiation induced by a test particle falling into an extreme Kerr black hole. Assuming the radiation is dominated by the infinite sequence of quasi-normal modes which has the limiting frequencym/(2M), wherem is an azimuthal eigenvalue andM is the mass of the black hole. we find the radiated energy diverges logarithmically in time. Then we evaluate the back reaction to the black hole by appealing to the energy and angular momentum conservation laws. We find the radiation has a tendency to increase the ratio of the angular momentum to mass of the black hole, which is completely different from the non-extreme case, while the contribution of the test particle is to decrease it.
96043155
Measurements of Activation Cross Sections on Spallation Reactions for 59Co and natCu at Incident Neutron Energies of 40 to 120 MeV
In our previous work, we have measured the neutron spallation cross sections of 12C and 209Bi in the 20-to 150-MeV energy range. Here in this succeeding study, the neutron activation cross sections on spallation reactions for 59Co and natCu have been measured in the quasi-monoenergetic p-7Li neutron fields in the 40-to 120-MeV energy range which have been established at two cyclotron facilities of Takasaki Research Establishment of Japan Atomic Energy Research institute (TIARA) and the Institute of Physical and Chemical Research (RIKEN). The neutron spectrum has been measured with the TOF (Time of Flight) method using an organic liquid scintillator, and the absolute value of peak neutron fluence has been determined from the proton recoil counter telescope at TIARA and the activation method of lithium target at RIKEN. In this study, the following seventeen neutron activation cross section data are reported which produce 56Mn, 54Mn, 52Mn, 58Co, 57Co, 56Co, 55Co, 59Fe from 59Co reactions and 56Mn, 59Fe, 60Co...
5492160
Low-Luminosity GRB 060218: A Collapsar Jet from a Neutron Star, Leaving a Magnetar as a Remnant?
The gamma-ray burst (GRB) 060218 has a luminosity ~105 times lower than that of typical long GRBs and is associated with a supernova (SN). The radio afterglow displays no jet break, so this burst might arise from a mildly relativistic spherical outflow produced by the SN shock sweeping the stellar surface. Since this model is energetically difficult, we propose that the radio afterglow is produced by a nonrelativistic phase of an initially collimated outflow (jet). Our jet model is supported by the detection of optical linear polarization in the SN component. We also show analytically that the jet can penetrate a progenitor star. We analyzed the observational data of the prompt emission of this burst and obtained a smooth power-law light curve which might last longer than 106 s. This behavior contrasts with the long intermittent activities of the X-ray flares of typical GRBs, implying that the central engine of this burst is different from those of typical GRBs. This argument is consistent with the analysis of the SN component of this burst, which suggests that the progenitor star was less massive and collapsed to a neutron star instead of a black hole. The collimation-corrected event rate of such low-luminosity GRBs is estimated to be ~10 times higher than that of typical long GRBs, and they might form a different GRB population: low-luminosity GRBs are produced by mildly relativistic jets from neutron stars at the collapses of massive stars, while typical long GRBs are produced by highly relativistic jets from black holes. We suggest that the central engine of GRB 060218 is a pulsar (or a magnetar) with initial rotation period P0 ~ 10 ms and magnetic field B ~ 1016 G. A giant flare from the magnetar might be observed in future.
55094258
Three Views of a Secret in Relativistic Thermodynamics
It has been shown three different views in relativistic thermodynamics can be derived from the basic formulation proposed by van Kampen and Israel. The way to decompose energy-momentum into work and heat is not uniquely determined; the different choices result in different views. Also the definition of three dimensional volume causes ambiguity of thermodynamical quantities. The present paper shows various theories are obtained depending on the choice of these two factors. Subject Index: 070
15956163
Factor Two Discrepancy of Hawking Radiation Temperature
The possibility of an alternative way to formulate the Hawking radiation in a static Schwarzschild spacetime has been explored. To calculate the Hawking radiation, there can be two possible choices of the spacetime wedge pairs in the Krucal-Szekeres coordinates. One is the wedge pair consists of exterior spacetime of a black hole and the exterior spacetime of a white hole, and the other is that of exterior and interior spacetimes of one black hole. The radiation from the former is the Hawking's original one. Though the the latter has been often regarded as the same phenomena as the former, the result here suggests it is not; its radiation has a temperature twice as high as the Hawking temperature.
15093684
Lorentz transform of black-body radiation temperature
The Lorentz transform of black-body radiation has been investigated from the viewpoint of relativistic statistical mechanics. The result shows that the well-known expression with the directional temperature can be derived based on the inverse-temperature four-vector. The directional temperature in the past literature was the result of mathematical manipulation and its physical meaning is not clear. The inverse-temperature four-vector has, in contrast, clear meaning to understand relativistic thermodynamical processes.
54195703
Rotating Unruh-DeWitt Detector in Minkowski Vacuum
Response of a circularly rotating Unruh-DeWitt detector to the Minkowski vacuum is investigated. What the detector observes depends on the surface (three volume) to define it by the Hamiltonian. Detectors in the past literature were defined on a surface of a constant Minkowski time, and this is the reason why rotating detectors investigated so far resister particles. No particle is detected by a detector defined by the Hamiltonian on a surface normal to the detector's orbit, in agreement with the global analysis of vacua. A detector with drift motion superposed on the linear acceleration is also examined, to find the same effect. c