اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدA combined timing/spectral study of IRAS 13224-3809 using XMM-Newton data
108
0
0.0
(
0
)
تأليف
M. D. Caballero-Garcia
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
We present the results from an X-ray variability study of IRAS 13224-3809. This is probably the best source for X-ray reverberation studies since it is X-ray bright, extremely variable, and it has been extensively observed with XMM-Newton. We used all the archival XMM-Newton data from the three EPIC cameras (to increase the signal-to-noise) and, given the many observations of the source, we were able to compute the time-lags spectra in three different flux levels/periods. We fitted the time-lags and energy spectra, simultaneously, using a new X-ray reverberation code which computes the time dependent reflection spectra of the disc as a response to an X-ray flash from a point source located on the axis of the black-hole (BH) accretion disc (lamp-post geometry). To the best of our knowledge, this is the first time for an AGN that both time-lags and energy spectra are fitted by a model simultaneously in different flux periods. The model fits in the case when the BH is rapidly rotating are significantly better than the model fits in the case of a Schwarzschild BH. This result strongly favours the hypothesis of a rotating central BH in this source. We also detect significant variations in the height of the X-ray corona. The X-ray height appears to increase from 3-5 gravitational radii when the X-ray luminosity is of the order of 1.5-3 percent of the Eddington limit, up to 10 gravitational radii, when the luminosity doubles.
قيم البحث
اقرأ أيضاً
The discovery of an ultrafast outflow has been reported in the z=0.0658 narrow line Seyfert galaxy IRAS 13224-3809 (Parker et al. 2017a). The ultrafast outflow was first inferred through the detection of highly blueshifted absorption lines (Parker et
al. 2017a) and then confirmed with a principal component analysis (PCA) (Parker et al. 2017b). Two of the reported properties of this outflow differed from those typically detected in other AGN with ultrafast outflows. First, the outflow velocity was found not to vary with v=0.236c +/- 0.006c. Second, the equivalent width of the highly blueshifted absorption line was reported to be anti-correlated with the 3-10 keV flux of this source. We present a re-analysis of the XMM-Newton observations of IRAS 13224-3809 considering the influence of background. We also undertook a different analysis approach in combining the spectra and investigated the change of the properties of the outflow as a function of 3-10 keV flux and time. We confirm the presence of an ultrafast outflow in IRAS 13224-3809, however, we find that the background spectra used in the Parker et al. analyses dominate the source spectra for energies near the blueshifted iron lines. By reducing the source extraction regions to improve the signal-to-noise ratio we discover larger than previously reported outflow velocities and find that the outflow velocity varies from ~0.2c to ~0.3c and increases with 3-10~keV flux. The previously reported anti-correlation between equivalent width of the iron line and 3-10 keV flux disappears when the background spectra are reduced by optimizing the source extraction regions.
We present results from the optical, ultraviolet and X-ray monitoring of the NLS1 galaxy IRAS 13224-3809 taken with Swift and XMM-Newton during 2016. IRAS 13224-3809 is the most variable bright AGN in the X-ray sky and shows strong X-ray reflection,
implying that the X-rays strongly illuminate the inner disc. Therefore, it is a good candidate to study the relationship between coronal X-ray and disc UV emission. However, we find no correlation between the X-ray and UV flux over the available ~40 day monitoring, despite the presence of strong X-ray variability and the variable part of the UV spectrum being consistent with irradiation of a standard thin disc. This means either that the X-ray flux which irradiates the UV emitting outer disc does not correlate with the X-ray flux in our line of sight and/or that another process drives the majority of the UV variability. The former case may be due to changes in coronal geometry, absorption or scattering between the corona and the disc.
We present a detailed spectral analysis of the recent 1.5,Ms XMM-Newton observing campaign on the narrow line Seyfert 1 galaxy IRAS~13224$-$3809, taken simultaneously with 500,ks of NuSTAR data. The X-ray lightcurve shows three flux peaks, registerin
g at about 100 times the minimum flux seen during the campaign, and rapid variability with a time scale of kiloseconds. The spectra are well fit with a primary powerlaw continuum, two relativistic-blurred reflection components from the inner accretion disk with very high iron abundance, and a simple blackbody-shaped model for the remaining soft excess. The spectral variability is dominated by the power law continuum from a corona region within a few gravitational radii from the black hole. Additionally, blueshifted Ne textsc{x}, Mg textsc{xii}, Si textsc{xiv} and S textsc{xvi} absorption lines are identified in the stacked low-flux spectrum, confirming the presence of a highly ionized outflow with velocity up to $v= 0.267$ and $0.225$,c. We fit the absorption features with texttt{xstar} models and find a relatively constant velocity outflow through the whole observation. Finally, we replace the texttt{bbody} and supersolar abundance reflection models by fitting the soft excess successfully with the extended reflection model texttt{relxillD}, which allows for higher densities than the standard texttt{relxill} model. This returns a disk electron density $n_{rm e}>10^{18.7}$,cm$^{-3}$ and lowers the iron abundance from $Z_{rm Fe}=24^{+3}_{-4}Z_odot$ with $n_{rm e}equiv10^{15}$,cm$^{-3}$ to $Z_{rm Fe}=6.6^{+0.8}_{-2.1}Z_odot$.
We study the soft excess variability of the narrow line Seyfert 1 galaxy IRAS 13224-3809. We considered all five archival XMM-Newton observations, and we applied the flux-flux plot (FFP) method. We found that the flux-flux plots were highly affected
by the choice of the light curves time bin size, most probably because of the fast and large amplitude variations, and the intrinsic non-linear flux--flux relations in this source. Therefore, we recommend that the smallest bin-size should be used in such cases. Hence, We constructed FFPs in 11 energy bands below 1.7 keV, and we considered the 1.7-3 keV band, as being representative of the primary emission. The FFPs are reasonably well fitted by a power-law plus a constant model. We detected significant positive constants in three out of five observations. The best-fit slopes are flatter than unity at energies below $sim 0.9$ keV, where the soft excess is strongest. This suggests the presence of intrinsic spectral variability. A power-law-like primary component, which is variable in flux and spectral slope (as $Gammapropto N_{rm PL}^{0.1}$) and a soft-excess component, which varies with the primary continuum (as $F_{rm excess}propto F_{rm primary}^{0.46}$), can broadly explain the FFPs. In fact, this can create positive `constants, even when a stable spectral component does not exist. Nevertheless, the possibility of a stable, soft--band constant component cannot be ruled out, but its contribution to the observed 0.2-1 keV band flux should be less than $sim 15$ %. The model constants in the FFPs were consistent with zero in one observation, and negative at energies below 1 keV in another. It is hard to explain these results in the context of any spectral variability scenario, but they may signify the presence of a variable, warm absorber in the source.
We explore a disc origin for the highly-blueshifted, variable absorption lines seen in the X-ray spectrum of the Narrow Line Seyfert 1 galaxy IRAS13224-3809. The blueshift corresponds to a velocity of about 0.25c. Such features in other Active Galact
ic Nuclei are often interpreted as UltraFast Outflows (UFOs). The velocity is of course present in the orbital motions of the inner disk. The absorption lines in IRAS13224-3809 are best seen when the flux is low and the reflection component of the disk is strong relative to the power-law continuum. The spectra are consistent with a model in which the reflection component passes through a thin, highly-ionized absorbing layer at the surface of the inner disc, the blue-shifted side of which dominates the flux due to relativistic aberration (the disc inclination is about 70 deg). No fast outflow need occur beyond the disc.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
