田代 信

Two bright quasars NRAO 140 (z = 1.258) and 4C 34.47 (z = 0.206) have been studied with Ginga. The observed spectra in the energy range 2-20 keV, in the observer rest frame, are well described by power-law models. The measured 2-10 keV luminosities and energy indices are L(x) = 3.8 x 10(46) ergs s-1 and alpha = 0.72 +/- 0.11 for NRAO 140, and L(x) = 5.3 x 10(44) ergs s-1 and alpha = 0.64(-0.14)+0.17 for 4C 34.47 (H-0 = 100 km s-1 Mpc-1; q0 = 0.5); the intensity variation was less than about 10% during the approximately 1 day observation for each source. Upper limits, in the source rest frame, for iron line emission are EW < 200 and EW < 120 eV for NRAO 140 and 4C 34.47, respectively. The featureless X-ray spectra, whose slopes are flatter than those of BL Lac objects, and the high X-ray luminosities in excess of the extension of the IR-optical continuum are consistent with the synchrotron self-Compton emission accompanied by a moderate beaming toward us.

Two bright quasars NRAO 140 (z = 1.258) and 4C 34.47 (z = 0.206) have been studied with Ginga. The observed spectra in the energy range 2-20 keV, in the observer rest frame, are well described by power-law models. The measured 2-10 keV luminosities and energy indices are L(x) = 3.8 x 10(46) ergs s-1 and alpha = 0.72 +/- 0.11 for NRAO 140, and L(x) = 5.3 x 10(44) ergs s-1 and alpha = 0.64(-0.14)+0.17 for 4C 34.47 (H-0 = 100 km s-1 Mpc-1; q0 = 0.5); the intensity variation was less than about 10% during the approximately 1 day observation for each source. Upper limits, in the source rest frame, for iron line emission are EW < 200 and EW < 120 eV for NRAO 140 and 4C 34.47, respectively. The featureless X-ray spectra, whose slopes are flatter than those of BL Lac objects, and the high X-ray luminosities in excess of the extension of the IR-optical continuum are consistent with the synchrotron self-Compton emission accompanied by a moderate beaming toward us.

Ginga observations of the X-ray binary pulsar GX301 - 2 are analysed for their temporal and spectral properties. We report the unambiguous detection of aperiodic intensity variations of 7-10 per cent rms relative amplitude over time-scales covering approximately 16 to 0.1 s. These variations are self-similar, being well fitted by a power law in power spectral density versus frequency space. The pulse period measured is 689.80 s, the shortest yet measured for this source. The fraction of X-rays which is pulsed is energy dependent, being greater at higher energies. The fractional aperiodic variability shows no such energy dependence, nor do they appear to be significantly dependent on source intensity, pulse phase or absorbing column measured. These facts strongly suggest that the aperiodic variations are not caused by absorption variations, but are intrinsic to the source. The iron-line intensity shows little pulsations, but surprisingly shows significant aperiodic variability down to a time-scale as short as several seconds, thus giving a constraint to the size of the line emission region.

「てんま」, 「ぎんが」のデータにもとづき, X線パルサーのスペクトル中に観測されたサイクロトロン吸収構造とその意義を論じる。おもな結果は以下のようにまとめられる。a. X線パルサー4U1538-52での発見に続き, 「ぎんが」により, トランジェントX線パルサーX0331+53のスペクトルの28keV付近に, 新たにサイクロトロン吸収構造が発見された。このようなサイクロトロン構造は, X線パルサーにひろく見られる現象であるらしい。b. X線パルサーHer X-1のスペクトル構造は輝線ではなく, エネルギーE∿34keVの吸収線と解釈できるとわかった。これにより, 永年の論争に決着がつけられた。c. X線パルサーのスペクトルのエネルギーE=10∿20keVに見られる急な「折れ曲り」が, サイクロトロン共鳴を直接に反映していること, 従って磁場強度のよい指標になることが確実になってきた。d.上の立場にもとづいて既知のスペクトルからX線パルサーの表面磁場強度を推定してみると, いずれも(1-4)×10^<12>Gときわめて良くそろった値となる。