Search

The anomalous X-ray pulsar 4U 0142+61 was observed with Suzaku on 2007 August 15 for a net exposure of -100 ks, and was detected in a 0.4 to ~70 keV energy band. The intrinsic pulse period was determined as 8.68878 \pm 0.00005 s, in agreement with an extrapolation from previous measurements. The broadband Suzaku spectra enabled a first simultaneous and accurate measurement of the soft and hard components of this object by a single satellite. The former can be reproduced by two blackbodies, or slightly better by a resonant cyclotron scattering model. The hard component can be approximated by a power-law of photon index \Gamma h ~0.9 when the soft component is represented by the resonant cyclotron scattering model, and its high-energy cutoff is constrained as >180 keV. Assuming an isotropic emission at a distance of 3.6 kpc, the unabsorbed 1-10 keV and 10-70 keV luminosities of the soft and hard components are calculated as 2.8e+35 erg s^{-1} and 6.8e+34 erg s^{-1}, respectively. Their sum becomes ~10^3 times as large as the estimated spin-down luminosity. On a time scale of 30 ks, the hard component exhibited evidence of variations either in its normalization or pulse shape., Comment: 24 pages, 8 figures, accepted for publication in Publications of the Astronomical Society of Japan

We have searched for pulsation of the anomalous X-ray pulsar (AXP) 4U 0142+61 in the K' band ($\lambda_{\rm eff} = 2.11$ $\mu$m) using the fast-readout mode of IRCS at the Subaru 8.2-m telescope. We found no significant signal at the pulse frequency expected by the precise ephemeris obtained by the X-ray monitoring observation with RXTE. Nonetheless, we obtained a best upper limit of 17% (90% C.L.) for the root-mean-square pulse fraction in the K' band. Combined with i' band pulsation (Dhillon et al. 2005), the slope of the pulsed component ($F_\nu \propto \nu^\alpha$) was constrained to $\alpha > -0.87$ (90% C.L.) for an interstellar extinction of $A_{V} = 3.5$., Comment: 11 pages, 3 figures, Accepted for publication in PASJ

We model thermal evolution of magnetars with a phenomenological heat source in a spherical internal layer and compare the results with observations of persistent thermal radiation from magnetars. We show that the heat source should be located in the outer magnetar’s crust, at densities ρ≲5×1011 g cm−3, and the heating rate should be ∼1020 erg cm−3 s−1. Heating deeper layers is extremely inefficient because the thermal energy is mainly radiated away by neutrinos and does not warm up the surface to the magnetar’s level. This deep heating requires too much energy; it is inconsistent with the energy budget of neutron stars.

We study thermal structure and evolution of magnetars as cooling neutron stars with a phenomenological heat source in a spherical internal layer. We explore the location of this layer as well as the heating rate that could explain high observable thermal luminosities of magnetars and would be consistent with the energy budget of neutron stars. We conclude that the heat source should be located in an outer magnetar's crust, at densities rho < 5e11 g/cm^3, and should have the heat intensity of the order of 1e20 erg/s/cm^3. Otherwise the heat energy is mainly emitted by neutrinos and cannot warm up the surface.

We carried out a deep subarcsecond BRI imaging of the two middle-aged pulsars to establish their properties in the optical range. Both pulsars are detected at >10 sigma level. Geminga is for the first time reliably detected in the I band with a magnitude of 25.10+/-0.14. We also reanalyze archival ESO/NTT and HST broadband data and find that some published fluxes for Geminga were estimated inaccurately. The resulting dereddened broadband spectra of both pulsars are remarkably similar to each other and show significant flux increases towards the far-UV and near-IR, and a wide flux excess in V-I bands. This suggests a multicomponent structure of the optical emission. The nonthermal power law component of the pulsar magnetospheric origin dominates in the most part of the optical range. For PSR B0656+14 it is compatible with a low energy extension of the power law tail seen in hard X-rays. For Geminga the respective extension overshoots by a factor of 100 the nonthermal optical flux, which has a less steep spectral slope than in X-rays. This implies a spectral break at a photon energy of about 1 keV. The flux increases towards the far-UV are compatible with contributions of the Rayleigh-Jeans parts of the blackbody components from whole surfaces of the neutron stars dominating in soft X-rays. The V-I excess, which is most significant for PSR B0656+14, suggests a third spectral component of still unidentified origin. Faint, a few arcseconds in size nebulae extended perpendicular to the proper motion directions of the pulsars, are seen around both objects in our deepest I band images. They can be optical counterparts of the bow-shock head of Geminga and of the tentative pulsar wind nebula of PSR B0656+14 observed in X-rays., 15 pages, 8 figures, A&A, accepted. For higher resolution images see http://www.ioffe.ru/astro/NSG/obs/map/

We report a glitch-like pulse frequency deviation from the simple spin-down law in an anomalous X-ray pulsar (AXP) 4U 0142+61 detected by ASCA observations. We also found a significant pulse profile change after the putative glitch. The glitch parameters resemble those found in another AXP 1RXS J170849.0$-$400910, in the Vela pulsar, and in other radio pulsars. This suggests that the radio pulsars and AXPs have the same internal structure and glitch mechanism. It must be noted, however, that the pulse frequency anomaly can also be explained by a gradual change of the spin-down rate ($\dot{P}$) without invoking a glitch., 14 pages, 4 figures, accepted by ApJ

PSR B1259-63 is a radio pulsar orbiting a Be star in a highly eccentric orbit. Soft and hard X-rays are observed from this unique system. We apply the shock powered emission model to this system. The collision of the pulsar and Be star winds forms a shock, which accelerates electrons and positrons to the relativistic energies. We derive the energy distribution of relativistic electrons and positrons as a function of the distance from the shock in the pulsar nebula. We calculate the X-rays and γ-rays emitted from the relativistic electrons and positrons in the nebula at various orbital phases, taking into account the Klein–Nishina effect fully. The shock powered emission model can explain the observed X-ray properties approximately. We obtain from the comparison with observations that a fraction of ∼0.1 of the pulsar spin-down luminosity should be transformed into the final energy of relativistic electrons and positrons. We find that the magnetization parameter of the pulsar wind, the ratio of the Poynting flux to the kinetic energy flux, is ∼0.1 and may decrease with distance from the pulsar. We predict the flux of 10 MeV–100 GeV γ-rays which may be nearly equal to the detection threshold in the future projects.

PSR 1259-63 is a radio pulsar orbiting a Be star in a highly eccentric orbit. Soft and hard X-rays are observed from this binary system. We apply the shock powered emission model to this system. The collision of the pulsar and Be star winds forms a shock, which accelerates electrons and positrons to the relativistic energies. We derive the energy distribution of relativistic electrons and positrons as a function of the distance from the shock in the pulsar nebula. We calculate the X-rays and $\gamma$-rays emitted from the relativistic electrons and positrons in the nebula at various orbital phases, taking into account the Klein-Nishina effect fully. The shock powered emission model can explain the observed X-ray properties approximately. We obtain from the comparison with observations that a fraction of $\sim 0.1$ of the pulsar spin-down luminosity should be transformed into the relativistic electrons and positrons. We find that the magnetization parameter of the pulsar wind, the ratio of the Poynting flux to the kinetic energy flux, is $\sim 0.1$ immediately upstream of the termination shock of the pulsar wind, and may decrease with distance from the pulsar. We predict the flux of 10 MeV - 100 GeV $\gamma$-rays which may be nearly equal to the detection threshold in the future projects., Comment: 18 pages, 9 figures, accepted for publication in PASJ

We observed two magnetars, 4U 0142+61 and 1E2259+568, with the Japanese infrared satellite AKARI to search for the time variability at wavelengths between 2-4 μm. We significantly detected 4U0142+61 in the 4μm band, and determined flux upper limits in the other two bands. We did not detect 1E 2259+586 in any of the bands, and determined upper limits. Comparing the detection of 4U 0142+61 in the 4μm band with the Spitzer observation from 2005, we found the flux was reduced to be 64%. We interpret this time variability in the infrared band as an increase of the inner radius of the dust disk around the neutron star, where the increase is due to the sublimation of the dust by the large flare of neutron star itself.

We report the B band optical observations of an old (17.5 Myr) radiopulsar PSR B0950+08 obtained with the Suprime-Cam at the Subaru telescope. We detected a faint object, B=27.07(16). Within our astrometrical accuracy it coincides with the radio position of the pulsar and with the object detected earlier by Pavlov et al. (1996) in UV with the HST/FOC/F130LP. The positional coincidence and spectral properties of the object suggest that it is the optical counterpart of PSR B0950+08. Its flux in the B band is two times higher than one would expect from the suggested earlier Rayleigh-Jeans interpretation of the only available HST observations in the adjacent F130LP band. Based on the B and F130LP photometry of the suggested counterpart and on the available X-ray data we argue in favour of nonthermal origin of the broad-band optical spectrum of PSR B0950+08, as it is observed for the optical emission of the younger, middle-aged pulsars PSR B0656+14 and Geminga. At the same time, the optical efficiency of PSR B0950+08, estimated from its spin-down power and the detected optical flux, is by several orders of magnitude higher than for these pulsars, and comparable with that for the much younger and more energetic Crab pulsar. We cannot exclude the presence of a compact, about 1'', faint pulsar nebula around PSR B0950+08, elongated perpendicular to the vector of its proper motion, unless it is not a projection of a faint extended object on the pulsar position., Comment: 8 pages, LaTeX, aa.cls style, 5 PS figures, submitted to A&A. Image is available in FITS format at http://www.ioffe.rssi.ru/astro/NSG/obs/0950-subaru

The Chandra X-ray Observatory observed the Crab Nebula and Pulsar using the Low-Energy Transmission Grating (LETG) with the High-Resolution Camera (HRC). Time-resolved zeroth-order images reveal that the pulsar emits x rays at all pulse phases. Analysis of the flux at minimum -- most likely nonthermal in origin -- places an upper limit (T(sub infinity) < 2.1 MK) on the surface temperature of the underlying neutron star. In addition, analysis of the pulse profile appears to confirm the absolute timing of the Observatory to within about 0.2 ms.

The Advanced Satellite for Cosmology and Astrophysics (ASCA) observed the soft gamma repeater SGR 1900+14 on 1998 April 30-May 1 and discovered a pulsar with a period of 5.1589715(8) s from the known X-ray source of RX J190714.2+0919.3. Four months later, on September 16-17, ASCA observed SGR 1900+14 again just after the giant burst on 1998 August 27. Comparing the observations in September with those in April, there are several changes in characteristics. The pulse period changed to 5.160295(3) s, and thus the long-term period derivative is 1.1 × 10-10 s s-1. This strongly supports a magnetar model. The folded pulse profile in 2-10 keV largely changed from three peaks in April to one simple peak, while the steady intensity increased by a factor of 2. Finally, we successfully determined the accurate location of SGR 1900+14 by the bursts with an accuracy of 15 in diameter.

In a glitch, some energy must be liberated in the neutron star interior. We examine the thermal response of a neutron star to a sudden energy release in the interior. A part of the released energy diffuses outward and is emitted promptly as thermal afterglow from the surface of the star. The appearance of the thermal afterglow exhibits significant variations depending on the magnitude and depth of the energy release and on the equation of state for dense matter. We especially show how the thermal response varies according to whether the released energies are a small or large fraction of the heat content of the star. We also discuss how observations of thermal afterglow can be used to set constraints on the transient energy release and on the equation of state.

Recent observation of GRBs (Gamma Ray Burst) by GRO (Gamma Ray observatory) raised puzzling questions on what GRBs are. At first look of the observational results, the galactic disk origin may be denied due to apparent isotropy and inhomogeneity of the distribution of the source. However, if one takes the lower bound for the quadrupole moment of the distribution of the sources, sourcess can still be anisotropic. That is, for example, a homogeneous spheroidal distribution of the sources with eccentricity of 0.7 can be compatibler with the quadrupole moment and V/V max test within statistical error on 2 to 3σ level

Spectral studies of quiescent emission and bursts of magnetar candidates using XMM-Newton, Chandra and Swift data are presented. Spectra of both the quiescent emission and the bursts for most magnetar candidates are reproduced by a photoelectrically absorbed two blackbody function (2BB). There is a strong correlation between lower and higher temperatures of 2BB (kT_LT and kT_HT) for the magnetar candidates of which the spectra are well reproduced by 2BB. In addition, a square of radius for kT_T (R_LT^2) is well correlated with a square of radius for kT_HT (R_HT^2). A ratio kT_LT/kT_HT ~ 0.4 is nearly constant irrespective of objects and/or emission types (i.e., the quiescent emission and the bursts). This would imply a common emission mechanism among the magnetar candidates. The relation between the quiescent emission and the bursts might be analogous to a relation between microflares and solar flares of the sun. Three AXPs (4U 0142+614, 1RXS J170849.0-400910 and 1E 2259+586) seem to have an excess above ~7 keV which well agrees with a non-thermal hard component discovered by INTEGRAL., 17 pages, 5 figures, 12 tables, Accepted for publication in PASJ

The rotating neutron superfluid in the inner crust of a neutron star is threaded by quantized vortex lines. The pinning force from lattice nuclei and the Magnus force from neutron superfluid act onto a vortex line that has a finite tension. The configuration of a vortex line in equilibrium comprises a number of pinned straight lengths separated by unpinned kinks when the rotation axis is slightly inclined to the major axis of a crystal lattice and the Magnus force is not so strong. Energy of $\sim 4 {MeV}$ is required to form a kink at densities of $\sim 3.4 \times 10^{13}{g cm}^{-3}$. Magnus force makes the vortex line parabolic on global scale. There exist two modes, rotational and helical (Kelvin), for oscillations allowed on a vortex line. The vortex oscillations in the pinned straight segments are possible only above a minimum frequency. We find no unstable mode that grows with time. Hence, the vortex configurations with kinks may be stable and yield the strongly pinned state. The essence of our results may not be altered even when we consider the vortex behaviors in a polycrystalline structure. Our studies suggest that pinning of a vortex line in a polycrystalline structure would be still strong enough to explain the large glitches., Comment: 17 pages, 6 figures, aastex, accepted for publication in the Astrophysical Journal

It has been suggested that the frictional interaction of neutron superfluids with normal matter in the inner crust of neutron stars dissipates rotational energy of superfluids and generates heat. Incorporating a general formula of internal heating into the detailed numerical codes of thermal evolution, we examine the effects of the internal heating on thermal evolution of neutron stars. We find that when a very stiff equation of state is used, it takes as long as about 2 x 10 exp 4 yr for the interior of a neutron star to reach the isothermal state, even if a strong heat source is placed in a thin layer of the inner crust. This time scale reduces to a few hundred years or less when medium to soft equations of state are used. A neutron star cools by neutrino emissions during the earlier stages referred to as the neutrino cooling era, while during the later photon cooling era it cools primarily by emission of photons from its surface. We show that heating rates expected in the current superfluid-crust interaction model can greatly increase the surface temperature in the photon cooling era, significantly changing the thermal evolution of relatively old neutron stars if a stiff equation of state is adopted.

Dynamical collapse of the intracluster gas in clusters of galaxies is studied numerically by taking account of both the gravity of background galaxies and the self-gravity. The adiabatic case, the case with the thermal bremsstrahlung cooling and the case with both the heat conduction and thermal bremsstrahlung cooling have been calculated. In the first two cases, a hot plasma which is formed after the bounce reaches an equilib­ rium state if the initial density po is lower than a certain critical value. In the last case, the gas secularly contracts. The results are compared with X-ray observation of the Coma cluster.

Hydrostatic equilibrium solutions for the hot gas in a cluster of galaxies have been studied assuming the polytropic relation. The final equilibrium state is related to the initial state of the gas in the cluster using the mass and energy conservation laws between the above two states. Results are applied to the X-ray source in Coma cluster. We have obtained the central temperature, the central density and the mass of the intracluster gas such as 1.8X10' OK, 2.8X10- 27 gm/cm' and 5.7X10"1'vf0, respectively. As for the X-ray emission mechanism of these sources, inverse compton and thermal bremsstrahlung theories have been proposed. However, recent spectral analyses of soft X-ray data2l tend to show a strong preference for the thermal model. Moreover, tailed radio sources3l and the excess of SO galaxies4l found in these clusters may be well interpreted, if hot intracluster gases exist. Concerning the thermal model, a wind model, sl infall models6l, 7) and static modelsn,sl have been studied. Lea8l has calculated the hydrostatic equilibrium solu­ tion for a polytropic gas in a cluster of galaxies under the boundary condition that the temperature of the gas approaches to zero at infinity. By comparing that solution with observations for the Coma cluster, she shows that the intracluster gas is distributed more widely than the galaxies by a factor of about 2"--'2.5 and the temperature of the gas given from a best-fit model is 1.5 X 108 oK. Takahara et al. 9l have investigated the dynamical collapse of gas in a cluster of galaxies. As a result of numerical calculations, they find that a hot plasma is formed after the bounce and it attains an equilibrium state. In § 2 the hydrostatic equilibrium solution for a polytropic gas in a cluster of galaxies is derived. In § 3 the hydrostatic equilibrium state which is attained after the dynamical collapse is discussed using the energy and mass conservation laws which relate the final state of the gas to the initial state. In § 4 the central temperature, the central density and the mass of the intracluster gas are obtained

著者人数：29名, Accepted: 1984-02-28, 資料番号: SA1001355000

Structure and stability of a stationary thin-disk formed around a black-hole are studied using the conventional formula for the viscous stress. The disk is classified into an optically thick case, an optically thin case and an intermediat.e case in which the comptonization plays an important role. Thermal and ·secular stabilities are examined in each of the above three cases. High temperatures . in excess of 10°'K are expected in the optically thin case and in the comptonization dominant case. However, it is shown that in these case_s the disk is unstable for the thermal perturbation. § I. Introduction It has been known that some of Xcray sources consist close binary systems. Among these X-ray sources, especially Cyg X-1 is of great interest since it is believed as a black-hole candidate. Boltonn anaiysed spectroscopic and photometric data of HD 226868, which was highly believed to be associated with Cyg X-1, and found that the mass of the invisible component was greater than 7.4 M®. Even if the lower limit of the above mass is assumed for Cyg X-1, it is far massive than the upper limit of a stable neutron star ( r-.../2M®). Moreover, recently Roths­ child et a1. 2' and Oda et al. 3' presented evidence for millisecond pulses from Cyg X-1. It seems that these short time variations also indicate the existence of a black-hole. In a close binary system the material overflowing from the primary star. has a considerable amount of angular momentum against the secondary star, probably a black-hole for Cyg X-1. As a result the centrifugal force prevents the infall of the material toward the secondary star when it balances with the gravitational force; The material rotates in a circular orbit. If there exists an effective outward trans­ porting mechanism for angular momentum, the material keeping nearly Keplerian motion falls gradually toward the secondary star. A gaseous disk is formed around the secondary star and X-ray emission is expected since gravitational energy is released by the infalling material. Pringle and Rees,4' Shakura and Sunyaev5' and Novikov and Thorne 6' studied the structure of such a disk, and discussed the X-ray spectrum emitted from the surface of the disk. As for the transporting mechanisms for angular momentum Shakura et al. assumed turbulent and magnetic viscous forces. Tn terms· of them the tan­ gential viscous stress Pr6 is expressed as

Quasiperiodic oscillations with frequencies in the range 5-50 Hz have recently been discovered in X-rays from two bright galactic-bulge sources and Sco X-1. These sources are weakly magnetic neutron stars accreting from disks which the plasma is clumped. The interaction of the magnetosphere with clumps in the inner disk causes oscillations in the X-ray flux with many of the properties observed.

We report here on the unusual behaviour of MXB1730–335, the rapid burster1 as observed by the X-ray astronomy satellite Hakucho between 8 and 22 August 19792. MXB1730–335 is a unique burst source which generates rapidly repetitive bursts lasting between a few and tens of seconds. In the present observations, however, its behaviour was very different to that previously observed, in that the bursts of a trapezoidal profile were dominant. The profile is characterised by a flat top lasting between 30s and 10 min. A long train of such trapezoidal bursts was seen for the first time and clearly revealed a new mode of the rapid burster.

The recent discovery of cyclotron lines from gamma-ray bursts indicates that the strong magnetic fields of isolated neutron stars might not decay. The possible inverse correlation between the strength of the magnetic field and the mass accreted by the neutron star suggests that mass accretion itself may lead to the decay of the magnetic field. The spin and magnetic field evolution of the neutron star was calculated under the hypothesis of the accretion-induced field decay. It is shown that the calculated results are consistent with the observations of binary and millisecond radio pulsars.

The orbital period change due to unstable binary orbit has been examined for 6 binary x‐ray pulsars. It is shown that the orbital period decrease in Cen X‐3 is interpreted by this mechanism. SMCX‐1 is the next candidate for the unstable orbit, but more observations are necessary to reach the conclusion.

Results are presented on observations by HAKUCHO and TENMA satellites on the galactic bulge X‐ray sources. Most of the sources observed showed a positive correlation between intensity and spectral hardness. GX5‐1 has been found to have two characteristic states. Quasi‐periodic pulsations with 106 to 205 seconds have been observed from GX 349+2. Observational results are interpreted in terms of mass accretion onto an unmagnetized neutron star.

Since the discovery1 of a 283-s pulsation of an X-ray binary Vela X-1, several observations2–8 between 1975 and 1978 have revealed that its pulse period P was decreasing with an average value of Ṗ/P ≍ −1.5 × 10−4 yr−1. The long-term spin-up which is considered to be caused by the angular torque of accreting matter, is a common feature of X-ray pulsars. The pulse periods of Vela X-1 were measured by the Japanese satellite Hakucho in March 1979 and March 1980, and the period in the latter was found to be significantly greater than in the earlier period despite the general spin-up between early 1976 and early 1979. Moreover, we have measured for the first time the spin-down rate Ṗ/P = (2.6 ± 0.2)× 10−3 yr−1 in March 1980. This spin-down phenomenon is of great importance, as it is considered to be a manifestation of the dynamical behaviour caused by the internal structure of a neutron star.

The X-ray and gamma-ray emissions expected from SN 1987A have been calculated, taking into account mixing of material in the ejecta. Nuclear gamma rays emitted by Co-56 are scattered down to the hard X-ray band by multiple Compton scatterings. Nomoto's 11E1Y6 model for the ejecta of SN 1987A is used. X-ray light curves in the 10-30 keV band and spectra above 20 keV calculated with an inner mixed region of 5 + or - 1 solar mass are consistent with the observations performed with the Ginga satellite and the Kvant/Roentgen mission. On the basis of this comparison, further evolutions of the hard X-ray, gamma-ray, and optical/infrared emissions are discussed.

Shot-noise models provide a useful mathematical representation for some physical models for the quasi-periodic oscillations (QPOs) recently observed from several bright Galactic bulge and burst X-ray sources. Expressions are calculated for the first three moments for several versions of QPO shot-noise models that have appeared in the literature. It is shown that measurement of the third moment, together with measurement of the mean intensity and the power spectrum, can provide model-dependent constraints on important parameters of QPO shot-noise models, including the fraction of the X-ray intensity in shots and the shot rate. Under certain condtitions, a complete solution for all the shot-model parameters is possible.

Random process models provide a useful mathematical framework for analysis of the quasi-periodic oscillations (QPO) recently discovered in the X-ray emission from certain luminous Galactic X-ray stars. In this paper, consideration is given to the effects of the power spectrum of the decay of the amplitude of oscillation that is expected in some physical models for the QPO phenomena. The resulting changes in the power spectrum depend on the ratio of the decay time of the amplitude of oscillation to the lifetime of the shot envelope. For values of this ratio less than about 10, it is found that incoherent QPO peaks in the power spectrum are significantly reduced in height and total power and are broadened in width, making them more difficult to detect. Coherent terms in the power spectrum, if present, are reduced in height and total power, but their width is unaffected. The red noise component remains unchanged. The present results are applied to the beat-frequency modulated accretion model in order to set constraints on the physical properties of the boundary layer between the inner edge of the accretion disk and the neutron star magnetosphere.

The recurrent X-ray transient 1608--522 was observed from the X-ray astronomy satellite Hakucho through the high- and low-luminosity states of its persistent flux. 1608--522 is identified to be a burst source from which 22 X-ray bursts were recorded. The burst peak intensity is found to fluctuate by a factor as large as 7. 1608--522 exhibited two distinctly different burst modes with respect to the burst profile and the peak luminosity distribution. The burst mode seems to have changed in correlation with the persistent flux, whereas the burst frequency as well as the time-averaged burst luminosity were essentially constant despite a large change in the persistent flux.

Shot noise models provide a useful mathematical representation for some physical models for the quasi-periodic oscillations recently observed from several Galactic bulge and burst X-ray sources. For such models, correlations between the shot onset times and oscillation phases can have important effects on the expected autocorrelation function and power spectrum, with important consequences for the interpretation of observed power spectra. Making use of analytic and Monte Carlo techniques, two physically plausible correlations of this kind, one corresponding to drift and jitter in the oscillation phase and the other to a random walk in the oscillation phase, are examined.

著者人数：29名, Accepted: 1982-05-19, 資料番号: SA1001353000

The thermal evolution predicted by current models of the superfluid-crust interaction is noted to differ substantially from the thermal evolution predicted by models without internal heating as well as previous models of heating. Heating rates approaching the maximum predicted by current models enhance the photon luminosity of the star in the neutrino cooling era, and dramatically alter the thermal evolution in the photon cooling era. Standard cooling models are consistent with current pulsar temperature estimates and upper limits, except those for the Vela pulsar, which are lower than predicted.

The X-ray satellite Hakucho detected an X-ray burst from a nova-like transient Cen X-4 on 1979 May 31. The time profile and the spectral softening of the burst show the same properties as those of a type I X-ray burst. The peak intensity of approx.25 times the Crab in the energy range 1.5--12 keV is the strongest X-ray burst observed so far. The burst occurred during a nova-like outburst which is similar to one observed in 1969. The present discovery suggests that a soft transient source such as Cen X-4 comprises a neutron star and a late dwarf and can be an x-ray burster.

The Fe-56 nuclei excited by the inelastic collision of protons with the energy of around 10 MeV emit gamma rays in the same nuclear gamma-ray lines as those from the radioactive decay of Co-56. Since a very young supernova remnant like SN 1987A is most likely to accelerate cosmic rays by the shock and a possible pulsar embedded in the ejecta, this process may account for the gamma-ray lines observed from SN 1987A. The conditions required to explain the observed flux of the gamma-ray lines were investigated. It was found that this jet having a large fraction of the total kinetic energy of the supernova explosion.

Le satellite Hakucho a observe le 20 juillet 1982 un tres long sursaut RX de XB 1715-321. Le precurseur a precede le debut du sursaut principal dans le domaine 1-9 keV d'environ 7 s et a dure quelques secondes. Le sursaut principal a dure 300 s environ. L'evenement est considere comme etant un sursaut unique avec expansion et contraction de l'enveloppe