A Detailed Analysis of the High-Resolution X-Ray Spectra of NGC 3516: Variability of the Ionized Absorbers

Abstract

The 1.5 Seyfert galaxy NGC 3516 presents a strong time variability in X-rays. We re-analyzed the 9 observations performed on October 2006 by XMM-Newton and Chandra in the 0.3 to 10 keV energy band. An acceptable model was found to the XMM-Newton data fitting EPIC-PN and RGS spectra simultaneously; later, this model was successfully applied to the contemporary Chandra high resolution data. The model consists of a continuum emission component (power law + blackbody) absorbed by four ionized components (warm absorbers), and ten narrow emission lines. Three absorbing components are warm, producing features only in the soft X-ray band. The fourth ionization component produces FeXXV and FeXXVI in the hard-energy band. We study the time response of the absorbing components to the well detect changes in the X-ray luminosity of this source, and find that the two components with the lower ionization state show clear opacity changes consistent with gas close to photoionization equilibrium. These changes are supported by the models and by differences in the spectral features among the nine observations. On the other hand, the two components with higher ionization state do not seem to respond to continuum variations. The response time of the ionized absorbers allows us to constrain their electron density and location. We find that one component (with intermediate ionization) must be located within the obscuring torus, at a distance 2.7×10 17 cm from the central engine. This outflowing component is likely originated in the accretion disk. The three remaining components are at distances larger than 10 16−17 cm. Two of the absorbing components in the soft X-rays have similar outflow velocities and locations. These components may be in pressure equilibrium, forming a multi-phase medium, if the gas has metallicity larger than the solar one (Z 5Z ). We also search for variations in the covering factor of the ionized absorbers (although partial covering is not required in our models). We find no correlation between the change in covering factor and the flux of the source. This, in connection with the observed variability of the ionized absorbers, suggests that the changes in flux are not produced by this material. If the variations are indeed produced by obscuring clumps of gas, these must be located much closer in to the central source.

AGN Torus Detectability at Submillimeter Wavelengths: What to Expect from ALMA Continuum Data

“…Kraemer et al (2002) found optical absorption features associated to eight distinctive kinematic components. This complex outflowing features can also be seen at X-rays (Netzer et al 2002;Turner et al 2005;Huerta et al 2014). Esparza-Arredondo et al (in prep.…”

A flare in the optical spotted in the changing-look Seyfert NGC 3516

“…NGC 3516 shows even more interesting properties in the high-energy band (e.g., Edelson et al 2000;Netzer et al 2002;Maoz et al 2002;Turner et al 2005;Mehdipour et al 2010;Liu et al 2014;Huerta et al 2014;Noda et al 2016). Edelson et al (2000) showed that there are uncorrelated trends on longer timescales between the X-ray and optical bands, which was supported with the later findings of Maoz et al (2002).…”

Ionized outflows from active galactic nuclei as the essential elements of feedback

“…In most cases, the WA clouds have been found to thrive in a multiphase medium with a range in ξ, N H and even in v, (Kaspi et al 2004;Behar et al 2017;Huerta et al 2014;Ebrero et al 2013;Krongold et al 2009;) and very rarely detected as a single cloud (see for e.g., theoretical works by Chakravorty et al 2009). To quantify this effect, an important parameter is the absorption measure distribution (AMD).…”