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Register a new userMulti-wavelength campaign on NGC 7469 IV. The broad-band X-ray spectrum
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We conducted a multi-wavelength six-month campaign to observe the Seyfert galaxy NGC~7469, using the space-based observatories textit{HST}, textit{Swift}, textit{XMM-Newton} and textit{NuSTAR}. Here we report the results of the spectral analysis of the 7 simultaneous textit{XMM-Newton} and textit{NuSTAR} observations. The sources shows significant flux variability within each observation, but the average flux is less variable among the different pointings of our campaign. Our spectral analysis reveals a prominent narrow neutral ion{Fe} K$alpha$ emission line in all the spectra, with weaker contributions from Fe K$beta$, neutral Ni K$alpha$ and ionised iron. We find no evidence for variability or relativistic effects acting on the emission lines, which indicates that they originate from distant material. Analysing jointly textit{XMM-Newton} and textit{NuSTAR} data a constant photon index is found ($Gamma$=$1.78pm0.02$), together with a high energy cut-off $E_{rm{cut}}=170^{+60}_{-40}$ keV. Adopting a self-consistent Comptonization model, these values correspond to an average coronal electron temperature of kT=$45^{+15}_{-12}$ keV and, assuming a spherical geometry, an optical depth $tau=2.6pm0.9$. The reflection component is consistent with being constant, with a reflection fraction in the range $R=0.3-0.6$. A prominent soft excess dominates the spectra below 4 keV. This is best fit with a second Comptonization component, arising from a virg{warm corona} with an average $kT=0.67pm0.03$ keV and a corresponding optical depth $tau=9.2pm0.2$.
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Aims. We aim to investigate and characterise the photoionised X-ray emission line regions within NGC 7469. Methods. We apply the photoionisation model, PION, within the spectral fitting code SPEX to analyse the 640 ks RGS spectrum of NGC 7469 gathered during an XMM-Newton observing campaign in 2015. Results. We find the emission line region in NGC 7469 to be multiphased, consisting of two narrow components with ionisation parameters of $log xi = 0.4$ and 1.6. A third, broad emission component, with a broadening velocity of $v_b sim 1400$ km stextsuperscript{-1} and an outflow velocity of $v_{out} sim -4500$ km stextsuperscript{-1}, is required to fit the residuals in the O VII triplet, at around 22 AA. Assuming a volume filling factor of 0.1, the lower distance limits of the narrow emission line region components are estimated for the first time at 2.6 and 2.5 pc from the central black hole, whereas the broad component has an estimated lower bound distance between 0.004 to 0.03 pc, depending on the assumed plasma parameters. The collisionally ionised plasma from the star burst region in NGC 7469 has a plasma temperature of 0.32 keV and outflow velocity of $-280$ km stextsuperscript{-1}, consistent with previous results in this campaign. In addition, we model the photoionised plasma of the warm absorber (WA) in NGC 7469, and find that it consists of three photoionised phases, with different values of $xi$, $N_H$ and $v_{out}$. The upper bound distances of these WA components are 1.9, 0.3 and 0.6 pc, respectively, consistent with archival results. Conclusions. The environment of NGC 7469 is a complex mix of plasma winds absorbing and emitting X-rays. We find the picture painted by our results can be attributed to line emitting plasma located at distances ranging from near the black hole to the torus and beyond the ionised outflows.
Aims. Our aim is to determine the distance of the UV outflow components from the central source, their abundances and total column density, and the mechanism responsible for their observed absorption variability. Methods. We studied the UV spectra acquired during the campaign as well as from three previous epochs (2002-2010). Our main analysis tools are ionic column-density extraction techniques and photoionization models (both equilibrium and time-dependent models) based on the code Cloudy. Results. For component 1 (at -600 km/s) our findings include the following: metallicity that is roughly twice solar; a simple model based on a fixed total column-density absorber, reacting to changes in ionizing illumination that matches the different ionic column densities derived from four spectroscopic epochs spanning 13 years; and a distance of R=6+2.5-1.5 pc from the central source. Component 2 (at -1430 km/s) has shallow troughs and is at a much larger R. For component 3 (at -1880 km/s) our findings include: a similar metallicity to component 1; a photoionization-based model can explain the major features of its complicated absorption trough variability and an upper limit of 60 or 150 pc on R. This upper limit is consistent and complementary to the X-ray derived lower limit of 12 or 31 pc for R. The total column density of the UV phase is roughly 1% and 0.1% of the lower and upper ionization components of the warm absorber, respectively. Conclusions. The NGC 7469 outflow shows super-solar metallicity similar to the outflow in Mrk 279, carbon and nitrogen are twice and four times more abundant than their solar values, respectively. Similar to the NGC 5548 case, a simple model can explain the physical characteristics and the variability observed in the outflow.
We investigate the ionic column density variability of the ionized outflows associated with NGC$sim$7469, to estimate their location and power. This could allow a better understanding of galactic feedback of AGNs to their host galaxies. Analysis of seven XMM-Newton grating observations from 2015 is reported. We use an individual-ion spectral fitting approach, and compare different epochs to accurately determine variability on time-scales of years, months, and days. We find no significant column density variability in a 10 year period implying that the outflow is far from the ionizing source. The implied lower bound on the ionization equilibrium time, 10 years, constrains the lower limit on the distance to be at least 12 pc, and up to 31 pc, much less but consistent with the 1 kpc wide starburst ring. The ionization distribution of column density is reconstructed from measured column densities, nicely matching results of two 2004 observations, with one large high ionization parameter ($xi$) component at $2<log xi<3.5$, and one at $0.5<log xi<1$ in cgs units. The strong dependence of the expression for kinetic power, $propto1/xi$, hampers tight constraints on the feedback mechanism of outflows with a large range in ionization parameter, which is often observed and indicates a non-conical outflow. The kinetic power of the outflow is estimated here to be within 0.4 and 60 % of the Eddington luminosity, depending on the ion used to estimate $xi$.
We present our analysis of X-ray spectral properties observed from the Seyfrert 1 galactic nucleus NGC~7469 using the RXTE and ASCA observations. We demonstrate strong observational evidence that NGC~7469 undergoes spectral transitions from the low hard state (LHS) to the intermediate state (IS) during these observations. The RXTE observations (1996--2009) show that the source was in the IS ~ 75 % of the time only, ~ 25 % of the time in the LHS. The spectra of NGC~7469 are well fitted by the so-called bulk motion Comptonization (BMC) model for all spectral states. We have established the photon index saturation level, Gamma_{sat}+2.1+/-0.1, in the Gamma versus mass accretion rate, Mdot correlation. This Gamma- Mdot correlation allows us to estimate the black hole (BH) mass in NGC~7469 to be M__BH> 3 x 10^6 solar masses assuming the distance to NGC~7469 of 70 Mpc. For this BH mass estimate, we use the scaling method taking Galactic BHs, GRO~J1655--40, Cyg~ X--1 and an extragalactic BH source, NGC~4051 as reference sources. The Gamma versus Mdot correlation revealed in NGC~7469 is similar to those in a number of Galactic and extragalactic BHs and it clearly shows the correlation along with the strong Gamma saturation at ~2.1. This is robust observational evidence for the presence of a BH in NGC~7469. We also find that the seed photon temperatures are quite low, of the order of 140-200 eV, which are consistent with a high BH mass in NGC~7469 that is more than 3x10^6 solar masses.
Outflows in active galaxies (AGNs) are common, although their launching mechanism, location, and physical impact on the host galaxy remain controversial. We conducted a multiwavelength six-month campaign to observe the nearby Seyfert galaxy NGC 7469 with several observatories in order to better understand and quantify the outflow in this AGN. We report on the time-integrated line-resolved X-ray spectrum of NGC 7469 obtained with the Reflection Grating Spectrometer (RGS) on board XMM-Newton. We use the RGS spectrum to discern the many AGN outflow components. A global fit is applied to obtain their physical parameters. We find that the AGN wind can be well described by three narrow velocity components at -650, -950, and -2050 km/s. The RGS clearly resolves the -20 50 km/s component in C5+ Ly$alpha$, while the -650 km/s and -950 km/s velocities are blended. Similar velocities are resolved in the UV. The H-equivalent column densities of these components are, respectively, NH = 7x10^20, 2.2x10^21, and 10^20 cm^-2, for a total of 3x10^21 cm^-2. The -650 km/s component shows a broad ionisation distribution. We identify a photo-ionised emission component blue-shifted by -450 km/s which we ascribe to the same outflow that produces the absorption lines. The elemental abundance ratios of C, N, Ne, S, and Fe to O in the outflow tend to be between 1 - 2 times solar. Preliminary estimates of the absorber distance from the AGN center suggest it is at least a few pc away from the center, but more advanced methods need to be applied in order to obtain better constraints. The complex X-ray spectrum of NGC 7469 demonstrates the richness of high energy phenomena taking place in AGN cores. The subtle spectroscopic differences between the various components require deep, high-resolution observations, such as the present RGS spectrum, if one is to resolve them and perform quantitative plasma diagnostics.
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