We perform the NuSTAR and Swift/XRT joint energy spectral fitting of simultaneous observations from the broad-line Seyfert 1.5 galaxy NGC 5273. When fitted with the combination of an exponential cut-off power-law and a reflection model, a high energy cut-off is detected at 143$^{+96}_{-40}$ keV with 2-sigma significance. Existence of such cut-off is also consistent with the observed Comptonizing electron temperature when fitted with a Comptonization model independently. We observe a moderate hard X-ray variability of the source over the time-scale of ~12 years using INTEGRAL/ISGRI observations in the energy range of 20-100 keV. When the hard band count rate (6-20 keV) is plotted against the soft band count rate (3-6 keV), a hard offset is observed. Our results indicate that the cut-off energy may not correlate with the coronal X-ray luminosity in a simple manner. Similarities in parameters that describe coronal properties indicate that the coronal structure of NGC 5273 may be similar to that of the broad-line radio galaxy 3C 390.3 and another galaxy MCG-5-23-16 where the coronal plasma is dominated by electrons, rather than electron-positron pairs. Therefore, the coronal cooling is equally efficient to the heating mechanism keeping the cut-off energy at low even at the low accretion rate.
Seyfert galaxy targets for KM3NeT neutrino telescope
Université Paris Cité（巴黎西岱大学）；CNRS（法国国家科学研究中心）；Astroparticule et Cosmologie（粒子物理与宇宙学）；Laboratory of Astrophysics, École Polytechnique Fédérale de Lausanne（洛桑联邦理工学院天体物理学实验室）；Bogolyubov Institute for Theoretical Physics of the NAS of Ukraine（乌克兰国家科学院博戈留博夫理论物理研究所）；Kyiv Academic University（基辅学术大学）
Probing the physics of the accretion flow around active galactic nuclei (AGN) is crucial to understanding their emission mechanisms as well as being able to constrain the geometrical and variability properties of the different regions around them. The soft X-ray excess -- usually observed below $\sim2\,\mathrm{keV}$ in excess of the dominant X-ray powerlaw continuum -- is one prominent feature that is commonly seen in type 1 Seyfert AGN and therefore readily provides a useful diagnostic of the accretion flow mechanism around these systems. NGC 5940 is a Seyfert 1 AGN which reveals strong, prom…
NGC 5033 is an intriguing Seyfert galaxy because its sub-classification may change with time, and because optical and sub-mm observations find that the massive black hole does not sit at the dynamical center of the galaxy, pointing to a past merger. We obtained a new optical spectrum of NGC 5033 using the 200'' Hale telescope at Palomar that clearly reveals a broad H$β$ line (FWHM$=5400\pm 300~{\rm km}~{\rm s}^{-1}$). This signals a clear view of the optical broad line region (BLR) and requires Seyfert-1.5 designation. Some spectra obtained in the past suggest a Seyfert-1.9 classification, pot…
We study accretion disk-corona connection in Seyfert 1 galaxies using simultaneous UV/X-ray observations of NGC 4593 (July 14-18, 2016) and NGC 7469 (October 15-19, 2017) performed with AstroSat. We use the X-ray (0.5-7.0 keV) data acquired with the Soft X-ray Telescope (SXT) and the UV (FUV: 130-180 nm, NUV: 200-300 nm) data obtained with the Ultra-Violet Imaging Telescope (UVIT). We also use the contemporaneous Swift observations of NGC 4593 and demonstrate AstroSat's capability for X-ray/UV correlation studies. We performed UV/X-ray cross-correlation analysis using the Interpolated and the …
我们分析了2013年拍摄的Seyfert 2星系NGC 4388的3-79 keV能带的NuSTAR X射线观测结果。NuSTAR的宽带灵敏度覆盖了Fe K $α$线和康普顿反射峰，能够对活动星系核X射线谱中的反射特征进行严格的约束，从而提供对环核物质几何结构的深入了解。在这次观测中，我们发现NGC 4388的X射线光谱可以很好地用非相对论反射的适度吸收幂律来描述。我们拟合光谱与现象学反射模型和物理环面模型，并找到源被吸收的康普顿薄材料（N $_{H} = (6.5\pm0.8)\times10^{23}$ cm $^{-2}$）具有非常弱的康普顿反射峰（R $<$ 0.09）和异常大的Fe K $α$线（EW $= 368^{+56}_{-53}$ eV）的源具有弱反射或无反射。使用薄壳近似的预期Fe K $α$ EW的计算表明，一个Fe K $α$线起源于康普顿薄材料提出了一个可能的解释。
We present an analysis of the time-averaged spectrum of the Seyfert-2 active galaxy NGC 4388, obtained by NICER. The intrinsic strength of the reflection spectrum in NGC 4388, the large collecting area and favorable pass band of NICER, and a net exposure of 105.6 ks yielded an exceptionally sensitive spectrum. Using two independent families of models, the intrinsic spectrum from the central engine is found to be highly obscured but not Compton-thick. Enforcing physical self-consistency within each model, the independent treatments give formally consistent results: N_H = 2.67 (-0.03,+0.02) E+23…
We report B, V, and R band CCD photometry of the Seyfert galaxy NGC 4151 obtained with the 1.0-m telescope at Weihai Observatory of Shandong University and the 1.56-m telescope at Shanghai Astronomical Observatory from 2005 December to 2013 February. Combining all available data from literature, we have constructed a historical light curve from 1910 to 2013 to study the periodicity of the source using three different methods (the Jurkevich method, the Lomb-Scargle periodogram method and the Discrete Correlation Function method). We find possible periods of P_1=4\pm0.1, P_2=7.5\pm0.3 and P_3=15…
We present Atacama Large Millimeter/submillimeter Array observations at $\approx100$ GHz with $0.05$ arcsec (3 pc) resolution of the kiloparsec-scale jet seen in the nearby Seyfert galaxy NGC 1068, and we report the presence of parsec-scale blobs at the head of the jet. The combination of the detected radio flux ($\approx0.8$ mJy), spectral index ($\approx0.5$), and the blob size ($\approx10$ pc) suggests a strong magnetic field of $B\approx240\,μ$G. Such a strong magnetic field most likely implies magnetic field amplification by streaming cosmic rays. The estimated cosmic-ray power by the jet…
We present optical photometric observations of SN 2018aoq from 2 to 100 days after explosion, and 7 spectra at epochs from 11 to 71 days. The light curves and spectra are typical for SNe II-P. As previously reported, SN 2018aoq appears to be of intermediate brightness between subluminous and normal SNe II-P. SN 2018aoq was discovered in Seyfert galaxy NGC 4151, for which the distance is uncertain. We utilised the Expanding Photosphere Method using three sets of filter combinations and velocities derived from the absorption minima of FeII lines and obtained a distance of 20.0 +-1.6 Mpc. The Sta…
We present results of a long-term optical, UV and X-ray study of variability of the nearby changing-look (CL) Seyfert NGC 1566 which was observed with the Swift Observatory from 2007 to 2020. We summarize our previously published spectroscopic and photometric results and present new observations. We reported on the alteration in the spectral type of NGC 1566 in 2018 (REF1). Moreover, we focused on the exceptional postmaximum behavior after 2018 July, when all bands dropped with some fluctuations (REF2). We observed four significant re-brightenings in the post-maximum period. We have found diff…
Active galactic nuclei (AGN) are powered by accreting supermassive black holes, surrounded by a torus of obscuring material. Recent studies have shown how the torus structure, formerly thought to be homogeneous, appears to be 'patchy': the detection of variability in the line-of-sight hydrogen column density, in fact, matches the description of an obscurer with a complex structure made of clouds with different column density. In this work, we perform a multi-epoch analysis of the X-ray spectra of the Seyfert 2 galaxy NGC 7479 in order to estimate its torus properties, such as the average colum…
The shape of the ambient circumnuclear medium (ACM) density profile can probe the history of accretion onto the central supermassive black hole in galaxies and the circumnuclear environment. However, due to the limitation of the instrument resolution, the density profiles of the ACM for most of galaxies remain largely unknown. In this work, we propose a novel method to measure the ACM density profile of active galactic nucleus (AGN) by the equilibrium between the radiation pressure on the warm absorbers (WAs, a type of AGN outflows) and the drag pressure from the ACM. We study the correlation …
Discovery of a deep Seyfert-2 galaxy at z = 0.222 behind NGC 300
我们使用哈勃太空望远镜的数据，新的光谱双子座观测和可用的XMM-牛顿和钱德拉数据，报告揭开了身份不明的X射线源3XMM J005450.3-373849作为位于螺旋星系NGC 300后面的Seyfert-2星系的性质。我们表明，X射线源的位置是一致的扩展的光源，由一个边缘解决核/凸起，椭圆盘状特征和两个对称的外环包围。光谱是典型的塞弗特-2星系红移到z=0.222 +/- 0.001，这证实了该源与NGC 300没有物理关系。在这个红移下，源将位于909+/-4 Mpc（标准模型中的同向距离）。源的X射线谱符合吸收幂律模型。通过将$N_\mathrm{H}$与六个可用光谱联系起来，我们发现了一个可变指数$Γ$，从2000-2001年的2到2005-2014年的1.4-1.6。或者，通过连接$Γ$，我们发现2000-2001年的N_H ~ 0.34 x $10^{-22}$ cm $^{-2}$的可变吸收柱，以及2005-2014年期间的0.54-0.75 x $10^{-22}$ cm $^{-2}$。虽然我们不能区分光谱或吸收来源，从衍生的未吸收的X射线通量，我们能够确保长期的X射线变异的存在。此外，在X射线波段导出的0.8-2 × 10 ~（-1）$^{43}$ erg s $^{-1}$的未吸收X射线光度值与$z \approx 0.22$上弱遮蔽的Seyfert-2活动星系…
