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تسجيل مستخدم جديدSimultaneous XMM-textit{Newton} and HST-COS observation of 1H0419-577: II. Broadband spectral modeling of a variable Seyfert galaxy
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تأليف
L. Di Gesu
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In this paper we present the longest exposure (97 ks) XMM-Newton EPIC-pn spectrum ever obtained for the Seyfert 1.5 galaxy 1H 0419-577. With the aim of explaining the broadband emission of this source, we took advantage of the simultaneous coverage in the optical/UV that was provided in the present case by the XMM-Newton Optical Monitor and by a HST-COS observation. Archival FUSE flux measurements in the FUV were also used for the present analysis. We successfully modeled the X-ray spectrum together with the optical/UV fluxes data points using a Comptonization model. We found that a blackbody temperature of $T sim 56$ eV accounts for the optical/UV emission originating in the accretion disk. This temperature serves as input for the Comptonized components that model the X-ray continuum. Both a warm ($T_{rm wc} sim 0.7 $ keV, $tau_{rm wc} sim 7 $) and a hot corona ($T_{rm hc} sim 160 $ keV, $tau_{rm hc} sim 0.5$) intervene to upscatter the disk photons to X-ray wavelengths. With the addition of a partially covering ($C_vsim50%$) cold absorber with a variable opacity ($ {it N}_{rm H}sim [10^{19}- 10^{22}] ,rm cm^{-2}$), this model can well explain also the historical spectral variability of this source, with the present dataset presenting the lowest one (${it N}_{rm H}sim 10^{19} , rm cm^{-2} $). We discuss a scenario where the variable absorber, getting ionized in response to the variations of the X-ray continuum, becomes less opaque in the highest flux states. The lower limit for the absorber density derived in this scenario is typical for the broad line region clouds. Finally, we critically compare this scenario with all the different models (e.g. disk reflection) that have been used in the past to explain the variability of this source
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In this paper we analyze the X-ray, UV and optical data of the Seyfert 1.5 galaxy 1H0419-577, with the aim of detecting and studying an ionized-gas outflow. The source was observed simultaneously in the X-rays with XMM and in the UV with HST-COS. Opt
ical data were also acquired with the XMM Optical Monitor. We detected a thin, lowly ionized warm absorber (log xi ~ 0.03, log NH ~19.9 cm^-2) in the X-ray spectrum, consistent to be produced by the same outflow already detected in the UV. Provided the gas density estimated in the UV, the outflow is consistent to be located in the host galaxy, at ~ kpc scale. Narrow emission lines were detected in the X-rays, in the UV and also in the optical spectrum. A single photoionized-gas model cannot account for all the narrow lines emission, indicating that the narrow line region is probably a stratified environment, differing in density and ionization. X-ray lines are unambiguously produced in a more highly ionized gas phase than the one emitting the UV lines. The analysis suggests also that the X-ray emitter may be just a deeper portion of the same gas layer producing the UV lines. Optical lines are probably produced in another, disconnected gas system. The different ionization condition, and the ~ pc scale location suggested by the line width for the narrow lines emitters, argue against a connection between the warm absorber and the narrow line region in this source.
The preliminary results of the BeppoSAX observation of the radio-quiet AGN 1H0419-577 are presented. Despite its broad line optical spectrum, the intermediate X-ray spectrum (i.e. 2--10 keV) is flatter than typically observed in Seyfert 1s and no iro
n line is significantly detected. Even more intriguingly, a 1992 ROSAT pointed observation suggests a dramatic (~ 1) change in the spectral shape for E < 2 keV. Such behavior is briefly discussed in the framework of our current understanding of Comptonization scenarios in the nuclear regions of radio-quiet AGN.
We present a detailed analysis of the spectral properties of the Seyfert 1 galaxy 1H0419-577, based on the archival XMM-Newton, NuSTAR and simultaneous Swift observations taken between 2002-2015. All the observations show a broad emission line featur
e at the iron band. We demonstrate that the broad band spectral variability at different levels can be explained by the combination of light-bending effects in the vicinity of the central black hole plus a thin warm absorber. We obtain a black hole spin of a > 0.98 by fitting the multi-epoch spectra with the relativistic disc reflection model. 1H0419-577 is accreting at 40% of its Eddington limit and its X-ray band shows the hardest powerlaw continuum in the highest flux state, which was previously more commonly seen in AGNs with a low accretion rate (e.g. $L_{rm X} /L_{rm Edd} < 10^{-2}$). The NuSTAR observation shows a cool coronal temperature of $kT=30^{+22}_{-7}$keV in the high flux state.
In this paper we report on the first simultaneous optical and X-ray (Beppo-SAX) observations of the radio-quiet AGN 1H0419-577. The optical spectrum clearly leads us to classify this source as a Seyfert 1. The X-ray spectrum is, however, somewhat at
odds with this classification: a simple flat (Gamma ~ 1.55) and featureless power--law is a good description of the whole 1.8-40 keV spectrum, even if the upper limit to a broad iron line is not very tight. An analysis of a still unpublished ROSAT observation of the same target reveals that the soft X-ray spectrum has undergone a transition from a steep (Gamma ~ 2.5) to a flat (Gamma ~ 1.55) state, at least in the 0.7-2 keV band. If this difference is due to a remarkably variable soft excess, it is unlikely that a single component is responsible for the optical/UV/soft X-ray spectral distribution. The hypothesis that the difference is due to a change in the primary X-ray continuum and its implications for current Comptonization models are discussed.
We have extensively studied the broadband X-ray spectra of the source ESO~141--G055 using all available xmm{} and ustar{} observations. We detect a prominent soft excess below 2 keV, a narrow Fe line and a Compton hump (>10 keV). The origin of the s
oft excess is still debated. We used two models to describe the soft excess: the blurred reflection from the ionized accretion disk and the intrinsic thermal Comptonisation model. We find that both of these models explain the soft excess equally well. We confirm that we do not detect any broad Fe line in the X-ray spectra of this source, although both the physical models prefer a maximally spinning black hole scenario (a$>$0.96). This may mean that either the broad Fe line is absent or blurred beyond detection. The Eddington rate of the source is estimated to be $lambda_{Edd} sim 0.31$. In the reflection model, the Compton hump has a contribution from both ionized and neutral reflection components. The neutral reflector which simultaneously describes the narrow Fe K$alpha$ and the Compton hump has a column density of $rm N_{H} geq 7times 10^{24} rm cm^{-2} $. In addition, we detect a partially covering ionized absorption with ionization parameter $log xi/rm erg cm s^{-1}$ = $0.1^{+0.1}_{-0.1}$ and column density $rm N_{H} =20.6^{+1.0}_{-1.0}times 10^{22} rm cm^{-2}$ with a covering factor of $0.21^{+0.01}_{-0.01}$.
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