AGILE detection of variable gamma-ray activity from the blazar S5 0716+714 during September-October 2007
F. D'Ammando, A. W. Chen, M. Villata, C. M. Raiteri, V. Vittorini, A. Bulgarelli, I. Donnarumma, A. Giuliani, F. Longo, L. Pacciani, G. Pucella, M. Tavani, S. Vercellone
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8 pages, 4 figures, "Workshop on Blazar Variability across the Electromagnetic Spectrum", 2008 April 22-25, Palaiseau, France
We report the gamma-ray activity from the Intermediate BL Lac S5 0716+714 during 2007 September-October observations by the AGILE satellite, coincident with a period of intense optical activity of the source monitored by GASP-WEBT. AGILE observed the source with its two co-aligned imagers, the Gamma-Ray Imaging Detector (GRID) and the hard X-ray imager (Super-AGILE) sensitive in the energy range 30 MeV-50 GeV and 18-60 keV respectively, in two different periods: the first between 4 and 23 September 2007, the second between 24 October and 1 November 2007. Over the period 7-12 September, AGILE detected gamma-ray emission from the source at a significance level of 9.6-sigma with an average flux (E>100 MeV) of (97+/-15) x 10^{-8} photons cm^{-2} s^{-1}, increasing by a factor of at least four within three days. No emission was detected by Super-AGILE in the energy range 18-60 keV, with a 3-sigma upper limit of 10 mCrab in 335 ksec. The gamma-ray flux of S5 0716+714 detected by AGILE is the highest ever detected for this blazar and one of the most intense gamma-ray fluxes detected from a BL Lac object. The Spectral Energy Distribution (SED) of mid-September seems to be consistent with the synchrotron self-Compton (SSC) emission model, but only by including two SSC components with different variability. In October 2007 AGILE repointed toward S5 0716+714 following an intense optical flare, measuring an average flux of (47+/-11) x 10^{-8} photons cm^{-2} s^{-1} at a significance level of 6.0-sigma. The gamma-ray flux during both AGILE pointings appears to be highly variable on timescales of 1 day.
A Second Intense Burst with Photospheric Radius Expansion from X2127+119 in M15
2000年9月，我们用Rossi X射线定时探测器观测到了来自X2127+119的明亮X射线爆发。这一爆发具有多峰轮廓，峰值亮度约为6.5x10^{38}尔格·秒^{-1}，总积分能量约为2x 10 ^{40}尔格，光球半径显著膨胀，最大范围为R=118+-5 km。从膨胀阶段的光度-温度关系，我们得到估计的引力红移在中子星表面，校正爱丁顿光度，和中子星质量。在爆发期间，我们没有检测到慢（~ 30 s）径向振荡或快（100-1200 Hz）相干振荡或QPO。2000年9月的事件只是从这个球状星团双星（M15 = NGC 7078）观测到的第二次爆发，它与Ginga在1988年10月探测到的事件（Dotani et al. 1990; van Paradijs et al. 1990）有许多共同的特征，关键的区别可能是热核闪光消耗的物质总量。
First detection of hard X-ray photons in the soft X-ray transient Narrow-Line Seyfert 1 galaxy WPVS 007: The X-ray photon distribution observed by Swift
本文报道了在ROSAT全天巡天期间首次探测到的X射线瞬态窄线Seyfert 1星系WPVS 007中的硬X射线光子（E> 2.5keV），该星系是X射线谱最软的活动星系核。在2007年9月的50 ks观测中，Swift在0.3-10.0 keV波段清晰地探测到了AGN，其能级约为2 x 10^{-17} W m^{-2}。这是自1990年ROSAT全天巡天观测以来第一次有可能通过将迄今为止进行的所有Swift观测结果（总共85.5 k s）相加得出X射线光子分布。这种光子分布与AGN的X射线光谱一致，该AGN具有部分覆盖吸收体，柱密度约为1 x 10^{23} cm^{-2}，覆盖率约为90%。与2002年的钱德拉数据相比，WPVS 007的亮度增加了约4倍。Swift的数据还表明，导致当前低状态的吸收体可能已经开始消失。这种消失是由一个显着的变化，在硬度比从一个非常软的X射线状态在2005年10月至2007年1月的观测到一个相当硬的X射线状态在2007年9月的观测。在紫外线中，WPVS 007在过去两年中似乎变得更暗，最高可达0.5等。由光谱能量分布得到的光学-X射线光谱斜率为α ox =2.5，将WPVS 007归类为X射线弱活动星系核。校正红化和X射线吸收后，α ox变为1.9，大蓝凸块中的光度为log LBBB=37.7 [W]，换算成爱丁顿比L/LEdd约为1.0。
