SUZAKUMONITORING OF THE SEYFERT 1 GALAXY NGC 5548: WARM ABSORBER LOCATION AND ITS IMPLICATION FOR COSMIC FEEDBACK

Abstract

We present a two month Suzaku X-ray monitoring of the Seyfert 1 galaxy NGC 5548. The campaign consists of 7 observations (with exposure time ∼ 30 ks each), separated by ∼1 week. This paper focus on the XIS data of NGC 5548. We analyze the response in the opacity of the gas that forms the well known ionized absorber in this source to ionizing flux variations. Despite variations by a factor ∼ 4 in the impinging continuum, the soft X-ray spectra of the source show little spectral variations, suggesting no response from the ionized absorber. A detailed time modeling of the spectra confirms the lack of opacity variations for an absorbing component with high ionization (U X ≈ −0.85), and high outflow velocity (v out ≈ 1040 km s −1 ), as the ionization parameter was found to be consistent with a constant value during the whole campaign. Instead, the models suggest that the ionization parameter of a low ionization (U X ≈ −2.8), low velocity (v out ≈ 590 km s −1 ) absorbing component might be changing linearly with the ionizing flux, as expected for gas in photoionization equilibrium.-2 -However, given the lack of spectral variations among observations, we consider the variations in this component as tentative. Using the lack of variations, we set an upper limit of n e <2.0×10 7 cm −3 for the electron density of the gas forming the high ionization, high velocity component. This implies a large distance from the continuum source (R > 0.033 pc; R > 5000 R S ). If the variations in the low ionization, low velocity component are real, they imply n e >9.8×10 4 cm −3 and R < 3 pc. We discuss our results in terms of two different scenarios: a large scale outflow originating in the inner parts of the accretion disk, or a thermally driven wind originating much farther out. Given the large distance of the wind, the implied mass outflow rate is also large (Ṁ w > 0.08Ṁ accr ) (the mass outflow is dominated by the high ionization component). The associated total kinetic energy deployed by the wind in the host galaxy (> 1.2 × 10 56 erg) can be enough to disrupt the interstellar medium, possibly quenching or regulating large scale star formation. However, the total mass and energy ejected by the wind may still be lower than the one required for cosmic feedback, even when extrapolated to quasar luminosities. Such feedback would require that we are observing the wind before it is fully accelerated.

SimultaneousXMM-Newtonand HST-COS observation of 1H0419-577

“…As argued in Krongold et al (2010), this value may in principle be sufficient to evaporate the interstellar environment out of the host galaxy. However, it is not trivial to couple this energy effectively to the galaxy (e.g.…”

Anatomy of the AGN in NGC 5548

“…This component absorbs only the baseline underlying continuum model, and not the soft emission lines introduced below (which are already corrected for absorption from the WA, as discussed below), and it accounts for the historical multi A27, page 8 of 18 components highly ionized warm absorber that is clearly seen when the source is in its typical unobscured state (Kaastra et al 2002(Kaastra et al , 2004Steenbrugge et al 2003Steenbrugge et al , 2005Krongold et al 2010;Andrade-Velazquez et al 2010;Paper VI). Absorption from this warm absorber component was clearly detected during the unobscured archival observations and, given the pn low energy resolution, its six WA ionization components could be approximated by only two warm absorber ionization components with ionization parameters 2 log ξ 1-2.7 erg cm s −1 and low column density (log N H 21-22 cm −2 ), which is consistent with previous literature results .…”

“…NGC 5548 exhibits all the typical components seen in type 1 Seyfert galaxies, that is: a steep (Γ ∼ 1.8-1.9) powerlaw spectrum plus a reflection component with associated FeK line, a soft-excess emerging below a few keV, evidence for warm ionized gas along the LOS, and typical soft X-ray variability, as shown in the CAIXAvar sample by Ponti et al (2012a). Recently, detailed studies of either the time-average or variability properties of the WA, the reflection component, and the softexcess component have been made using either low-(CCD-type) or higher-(grating-type) energy resolution instrumentation available from Chandra, XMM-Newton and Suzaku (Pounds et al 2003a,b;Steenbrugge et al 2003Steenbrugge et al , 2005Crenshaw et al 2003a,b;Andrade-Velazquez et al 2010;Krongold et al 2010;Liu et al 2010;Brenneman et al 2012;McHardy et al 2014).…”

XMM-NewtonRGS observation of the warm absorber in Mrk 279

“…Given these L KE values, the kinetic energy injected into the medium would be E KE ∼ L KE t ∼ 10 55 erg, assuming that the average AGN lifetime is of the order of t ∼ 10 8−9 years (Ebrero et al 2009;Gilli et al 2009). For instance, the energy needed to disrupt the ISM of a typical galaxy is estimated to be ∼10 57 erg (Krongold et al 2010), which means that the outflows in Mrk 279 are not powerful enough to critically affect the ISM of the host galaxy.…”

“…MCG-6-30-15, Gibson et al 2007;Miller et al 2008;NGC 4051, Krongold et al 2007;NGC 1365, Risaliti et al 2009) and also on longer timescales (e.g. NGC 5548, Krongold et al 2010). …”