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تسجيل مستخدم جديدTime lags in Narrow-line Seyfert 1 galaxies and the origin of their soft excess emission
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G. C. Dewangan
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The origin of soft X-ray excess emission from type 1 active galactic nuclei has remained a major problem for the last two decades. It has not been possible to distinguish alternative models for the soft excess emission despite the excellent data quality provided by XMM-Newton and Chandra. Here we present observations of time lags between the soft and hard band X-ray emission and discuss the implications to the models for the soft excess. We also device a method to distinguish the models for the soft excess using Suzakus broadband capability.
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We investigate the origin of the soft X-ray excess emission from narrow-line Seyfert 1 galaxies Akn564 and Mrk1044 using XMM-Newton observations. We find clear evidence for time delays between the soft and hard X-ray emission from Akn564 based on a 1
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We present for the first time the timing and spectral analyses for a narrow-line Seyfert 1 galaxy, SBS 1353+564, using it{XMM-Newton} and it{Swift} multi-band observations from 2007 to 2019. Our main results are as follows: 1) The temporal variabilit
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Narrow-line Seyfert 1 galaxies (NLS1s) exhibit extreme soft X-ray excess and large variability. We argue that both features can be basically accounted for by the slim disk model. We assume that a central black-hole mass in NLS1 is relatively small, $
M sim 10^{5-7}M_odot$, and that a disk shines nearly at the Eddington luminosity, $L_{rm E}$. Then, the disk becomes a slim disk and exhibits the following distinctive signatures: (1) The disk luminosity (particularly of X-rays) is insensitive to mass-flow rates, $dot M$, since the generated energy is partly carried away to the black hole by trapped photons in accretion flow. (2) The spectra are multi-color blackbody. The maximum blackbody temperature is $T_{rm bb} simeq 0.2(M/10^5 M_odot)^{-1/4}$ keV, and the size of the blackbody emitting region is small, $r_{rm bb} lsim 3 r_{rm S}$ (with $r_{rm S}$ being Schwarzschild radius) even for a Schwarzschild black hole. (3) All the ASCA observation data of NLS1s fall onto the region of $dot M/(L_{rm E}/c^2)>10$ (with $L_{rm E}$ being the Eddington luminosity) on the ($r_{rm bb},T_{rm bb}$) plane, supporting our view that a slim disk emits soft X-rays at $sim L_{rm E}$ in NLS1s. (4) Magnetic energy can be amplified, at most, up to the equipartition value with the trapped radiation energy which greatly exceeds radiation energy emitted from the disk. Hence, energy release by consecutive magnetic reconnection will give rise to substantial variability in soft X-ray emission.
Narrow-line Seyfert 1 (NLS1) galaxies are believed to be active galactic nuclei (AGN) in the early stages of their evolution. Some dozens of them have been found to host relativistic jets, whilst the majority has not even been detected in radio, emph
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I provide a short review of the properties of Narrow-line Seyfert 1 (NLS1) galaxies across the electromagnetic spectrum and of the models to explain them. Their continuum and emission-line properties manifest one extreme form of Seyfert activity. As
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