Photoionization Calculations of the Radiation Force Due To Spectral Lines in AGNs

Dannen, Randall; Proga, Daniel; Kallman, Timothy R.; Waters, Tim

doi:10.3847/1538-4357/ab340b

Cited by 36 publications

(37 citation statements)

References 74 publications

(93 reference statements)

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“…In the other case, it acts as an ionisation state regulator of UV line-driven BEL winds. We notice though that recent photoionisation and radiative transfer calculations by Dannen et al (2019) suggest that the line driving mechanisms may not be relevant in plasma with high ionisation parameters typical of UFOs (i.e. ξ > 1000; e.g.…”

Section: Relationmentioning

confidence: 74%

The WISSH quasars project

Zappacosta

Piconcelli

Giustini

et al. 2020

A&A

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Hyper-luminous quasars (Lbol ≳ 1047 erg s−1) are ideal laboratories to study the interaction and impact of the extreme radiative field and the most powerful winds in the active galactic nuclei (AGN) nuclear regions. They typically exhibit low coronal X-ray luminosity (LX) compared to the ultraviolet (UV) and mid-infrared (MIR) radiative outputs (LUV and LUV); a non-negligible fraction of them report even ∼1 dex weaker LX compared to the prediction of the well established LX–LUV and LX–LUV relations followed by the bulk of the AGN population. In our WISE/SDSS-selected Hyper-luminous (WISSH) z = 2 − 4 broad-line quasar sample, we report on the discovery of a dependence between the intrinsic 2–10 keV luminosity (L2 − 10) and the blueshifted velocity of the CIV emission line (vCIV) that is indicative of accretion disc winds. In particular, sources with the fastest winds (vCIV ≳ 3000 km s−1) possess ∼0.5–1 dex lower L2 − 10 than sources with negligible vCIV. No similar dependence is found on LUV, LUV, Lbol, the photon index, or the absorption column density. We interpret these findings in the context of accretion disc wind models. Both magnetohydrodynamic and line-driven models can qualitatively explain the reported relations as a consequence of X-ray shielding from the inner wind regions. In case of line-driven winds, the launch of fast winds is favoured by a reduced X-ray emission, and we speculate that these winds may play a role in directly limiting the coronal hard X-ray production.

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Section: Relationmentioning

confidence: 74%

The WISSH quasars project

Zappacosta

Piconcelli

Giustini

et al. 2020

A&A

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“…The parameter M is known as the force multiplier, and we use the same parametrisation as Q20 (Stevens & Kallman 1990) (hereafter SK90). A limitation of our assumed parametrisation is that we do not take into account the dependence of the force multiplier on the particular spectral energy distribution (SED) of the accretion disc (Dannen et al 2019). Furthermore, the force multiplier is also expected to depend on the metallicity of the gas (Nomura et al 2021).…”

Section: Radiation Forcementioning

confidence: 99%

Qwind3: UV line-driven accretion disc wind models for AGN feedback

Quera-Bofarull¹,

Done²,

Lacey³

et al. 2021

Preprint

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The ultraviolet (UV) bright accretion disc in active galactic nuclei (AGN) should give rise to line driving, producing a powerful wind which may play an important role in AGN feedback as well as in producing structures like the broad line region. However, coupled radiationhydrodynamics codes are complex and expensive, so we calculate the winds instead using a non-hydrodynamical approach (the Q framework). The original Q model assumed the initial conditions in the wind, and had only simple radiation transport. Here, we present an improved version which derives the wind initial conditions and has significantly improved ray-tracing to calculate the wind absorption self consistently given the extended nature of the UV emission. We also correct the radiation flux for relativistic effects, and assess the impact of this on the wind velocity. These changes mean the model is more physical, so its predictions are more robust. We find that, even when accounting for relativistic effects, winds can regularly achieve velocities (0.1 − 0.5) 𝑐, and carry mass loss rates which can be up to 30% of the accreted mass for black hole masses of 10 7−9 M , and mass accretion rates of 50% of the Eddington rate. Overall, the wind power scales as a power law with the black hole mass accretion rate, unlike the weaker scaling generally assumed in current cosmological simulations that include AGN feedback. The updated code, Q 3, is publicly available in GitHub †.

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“…To complete the specification of a thermal wind model, we must determine the heating and cooling rates corresponding to the radiation field. In recent years, we have developed methods to compute these from the observationally inferred intrinsic SED as self-consistently as is currently possible (Dyda et al 2017;Dannen et al 2019) using the photoionization code XSTAR (Bautista & Kallman 2001). These calculations require introducing the density ionization parameter, ξ = L X /n H r 2 , where n H = (µ H /µ)n is the hydrogen number density (with µm p ≡ ρ/n and µ H m p ≡ ρ/n H for mass density ρ).…”

Section: Modeling Frameworkmentioning

confidence: 99%

Multiphase AGN winds from X-ray irradiated disk atmospheres

Waters,

Proga,

Dannen

2021

Preprint

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The mechanism of thermal driving for launching accretion disk winds is interconnected with classical thermal instability (TI). Indeed, the effective scale height of irradiated accretion disk atmospheres is determined by the extent of the cold branch of the S-curve demarcating thermally unstable zones. In a recent paper, we demonstrated that as a result of this interconnectedness, radial wind solutions of X-ray heated flows are prone to becoming clumpy. In over two decades of numerical work, however, only smooth thermally driven disk wind solutions that approach a steady state have been found. In this paper, we show that the Bernoulli function determines whether or not the entropy mode can grow due to TI in dynamical flows. Based on this finding, we identify a critical radius, R u , beyond which TI should accompany thermal driving, resulting in clumpy disk wind solutions. Our numerical simulations reveal that clumpiness is a consequence of buoyancy disrupting the stratified structure of smooth solutions. Namely, instead of a thin transition layer separating the highly ionized disk wind from the cold phase atmosphere below, TI seeds the formation of hot spots below the transition layer that rise up, fragmenting the atmosphere. We find that these hot spots first appear within large scale vortices that form within R u . This results in the continual production of characteristic cold phase structures that we refer to as irradiated atmospheric fragments (IAFs). These IAFs resemble tsunamis upon interacting with the disk wind, as crests develop as they are advected outwards. The multiphase character of these solutions results from the subsequent disintegration of the IAFs, which takes place within a turbulent wake that reaches high enough elevations in the wind so as to be observable from sightlines as high as 45• . We discuss the properties of the absorption measure distribution (AMD) in detail, showing that dips in the AMD are not expected within TI zones. We also compute synthetic X-ray absorption lines to show that this complicated dynamics should result in spectral signatures such as a less sudden desaturation of Oviii Lyα and multiple absorption troughs in Fe xxv Kα.

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Photoionization Calculations of the Radiation Force Due To Spectral Lines in AGNs

Cited by 36 publications

References 74 publications

The WISSH quasars project

The WISSH quasars project

Qwind3: UV line-driven accretion disc wind models for AGN feedback

Multiphase AGN winds from X-ray irradiated disk atmospheres

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