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21.
Chulhee Kim 《Journal of Astrophysics and Astronomy》2001,22(4):283-292
We present the results from ROSAT observations of 3C273 in the soft X-ray band. The light variation of 3C273 was investigated
for three different energy bands of soft, medium, and hard. The maximum variability with a factor of 2 for 551 days was confirmed
at all three different bands. This appears to be a periodic variation within the period of roughly 6 months. However, the
short-term or micro variation was not so distinct and the light variation of each band did not show any correlation between
them. The hardness ratio for hard and soft bands shows irregular variation but there was no correlation between them. There
is no distinct variation of the photon index in the case of simple power law model fitting. For power law + free absorption
model fitting, the average photon index (Γ) is 2.08. 相似文献
22.
邓铁如 《中国天文和天体物理学报》1996,(3)
围绕黑洞作开普勒运动的环状发光物所发射的光，将受到多普勒颇移和引力的综合作用．本文用光子输运方程方法，针对洛仑兹型发射谱线，求出在Schwarzschild度规下谱线轮廓的精确解，并讨论了Hercules星系团中类星体1604＋179光谱的认证． 相似文献
23.
韩金林 《中国天文和天体物理学报》1995,(2)
研究表明，高频射电源与低频射电源相比，前者中的类星体比例更大。３ＣＲ低频射电源（Ｓ１７８ＭＨｚ＞９Ｊｙ）中有１７．８％是类星体，而在２．７ＧＨｚ亮射电源样本中（Ｓ２．７ＧＨｚ≥２．０Ｊｙ），有３５．６％是类星体。更有趣的是，５１８个５ＧＨｚ亮射电源中（Ｓ５ＧＨｚ≥１．０Ｊｙ），至少有２９１个（≥５６％）是类星体。因此，我们认为高频亮射电源的证认是发现类星体的有效手段。 相似文献
24.
OJ 287 is a BL Lac object which exhibits intense activities of low peak-frequencies. Its energy spectrum in low frequency band is quite similar with those of two other TeV BL Lac objects (i.e., 0716+714 and BL Lacertae). However, the Cerenkov telescope did not detect its TeV rays. By using the observational data of these three heavenly bodies and comparing the discrepan- cies of their minimal periods of light variations and delays at 22 GHz, 37 GHz and B-waveband, we have further investigated the possible reason why the TeV gamma-rays of OJ 287 have not been observed. The results of analyses are as fol- lows. (1) For the minimal periods of light variations, the periods of OJ 287 at 37 GHZ and B-waveband are short. At 22 GHz the results of OJ 287 and 0716+714 are comparable, but the period of OJ 287 is much shorter in comparison with that of BL Lacertae, and this shows that its activity is more intense. However, the TeV gamma-rays of OJ 287 have not been detected, which implies that the radiation of OJ 287 in TeV waveband may have no connection with the minimal periods of light variations in these three low-energy wavebands. (2) In respect of delays, the delay of OJ 287 in the B waveband with respect to 37 GHz is longer than that of 0716+714, but shorter than that of BL Lacertae. Its delay at 37 GHz in respect to 22 GHz is shorter than that of 0716+714. Meanwhile, the delay of BL Lacertae at 37 GHz in respect to 22 GHz is negative, which implies that 22 GHz precedes 37 GHz. Via the comparison and analysis of delays, no obvious differences between OJ 287 and 0716+714 as well as BL Lacertae have been found. On the side of energy spectra, it is quite possible that due to the steep energy spectrum of OJ 287 in TeV waveband, the Cerenkov telescope has not detected the gamma radiation of OJ 287. However, nowadays it is still not clear whether the steep energy spectrum in TeV energy range has some influence on the light variations in low energy realm. 相似文献
25.
本文根据文[1，2]三个类星体表的3941个类星体作统计分析，发现在发射红移Zem1．4—3．2范围内吸收线较多，尤其在Zem1．8—2．4范围内明显增加；同时在Zem1．4—2．8范围内出现吸收线红移Zab＞Zem的现象．结果表明，在Zem1．8—2．2间隔内的类星体活动性加剧，似可以说反映了类星体与环境相互作用的演化效应． 相似文献
26.
We examine a Doppler theory of quasars in which it is assumed that a fraction of the total population of quasars are fired
from centres of explosion with moderate cosmological redshifts. It is argued that the substantial part of the redshift of
a typical high redshift quasar could be of Doppler origin. If Hoyle’s recent hypothesis that quasars emit the bulk of their
radiation in a narrow backward cone is given a quantitative form, it is shown that the kinematic and emission parameters of
this model can explain the observed features of the four aligned triplets of quasars discovered by Arp and Hazard (1980) and
by Saslaw (personal communication). The model predicts a small but nonzero fraction of quasars with blueshifts. Further observational
tests of the model are discussed. 相似文献
27.
基于斯隆数字化巡天(Sloan Digital Sky Survey,SDSS)第12期数据(data release 12,DR12)的光谱,分析引力透镜类星体SDSS J1001+5027的A, B两个像的光谱。两个像光谱的红移分别为1.84132±0.00024和1.84545±0.00012,透镜天体红移约为0.415。通过证认可靠的CⅣλλ1548, 1551或Mg Ⅱλλ2796, 2803窄吸收双线的方法,证认出A, B两个像的光谱中红移分别为1.60677±0.00012, 0.87140±0.00007和0.41455±0.00006的3个吸收系统。从3个吸收系统共证认出27条窄吸收线。测量27条窄吸收线的等值宽度,再通过分析、比较3个吸收系统在A, B两个像光谱中吸收线的数量及等值宽度的差异,给出了3个吸收系统在引力透镜类星体SDSS J1001+5027视线方向可能的分布示意图。 相似文献
28.
1997－1998年期间,使用2．16m望远镜对ROSATX射线源进行光学证认,证认出4个ROSATX射线源是新发现的类星体,2个ROSATX射线源是新发现的赛弗特星系． 相似文献
29.
The method of time delay correlation function (TDCF) is a new method for calculating the sequential time delays. This method is utilized to calculate the time delays in 3 radio wave bands (4.8 GHz, 8 GHz and 14.5 GHz) of the blazar 0316 + 413 (NGC 1275) and to make the multi-band correlation analysis for other 7 blazar sources. The calculated result of the blazar 0316 + 413 shows that its light curve at 4.8 GHz lags by 410 d behind that at 8 GHz, or τ4.8−8 = 410 d; the light curve at 4.8 GHz lags by 440 d behind that at 14.5 GHz, or τ4.8−14.5 = 440 d; and the light curve at 8 GHz lags by 30 d behind that at 14.5 GHz, or τ8−14.5 = 30 d. In comparison with the method of discrete correlation function (DCF), the time delay obtained by taking advantage of the TDCF method is much more rational for the multi-band correlation analysis of the 7 blazars. 相似文献
30.
The structures of faint high redshift galaxies cannot be observed directly. But if a luminous quasar is located farther along
their line of sight, high resolution absorption lines offer a valuable and reliable probe to their structure. GMRT is suited
to monitor the absorption spectra, if the redshifted neutral hydrogen or OH doublet fall in one of the windows of the telescope.
We present the OH doublet absorption spectra for the system B0218+357, taken at GMRT this year at resolution of approx. 9.5
km/sec with an rms noise of the order of 1 mJy. Based on our study of the OH doublet and 21cm neutral hydrogen line we infer
that, in the lensing spiral galaxy of B0218 + 357, neutral hydrogen and OH coexist in tenous clouds and there is possibly
a hole in the central part of the galaxy. In contrast, the gas is seen in high density clouds in the lens in an otherwise
similar system PKS1830-211. 相似文献