IONIZATION-DRIVEN FRAGMENTATION OF GAS OUTFLOWS RESPONSIBLE FOR FeLoBALs IN QUASARS

Bautista, M. A.; Dunn, Jay P.

doi:10.1088/2041-8205/717/2/l98

Cited by 4 publications

(4 citation statements)

References 22 publications

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“…On the other hand, if the thermal front moves supersonically the gas has no time to adjust itself and strong pressure imbalances, like those seen in Figure 7, will appear. Thus, shocks will be formed in the slab, which can ultimately result in the fragmentation of the cloud (Bautista and Dunn 2010). Either way, variations in the ionizing flux will have important kinematic effects on the cloud.…”

Section: Step Flux Function On a Slab In Pressure Equilibriummentioning

confidence: 99%

“…There are many astrophysical systems in which time-dependent photoionization (TDP) modeling has been discussed. Some examples include the interstellar medium (Lyu & Bruhweiler 1996;Joulain et al 1998), H II regions (Rodriguez-Gaspar & Tenorio-Tagle 1998;Richling & Yorke 2000), planetary nebulae (Harrington & Marionni 1976;Harrington 1977;Schmidt-Voigt & Koeppen 1987;Frank & Mellema 1994;Marten & Szczerba 1997), novae and supernovae (Hauschildt et al 1992;Beck et al 1995;Kozma & Fransson 1998;Dessart & Hillier 2008), the reionization of the intergalactic medium (Ikeuchi & Ostriker 1986;Shapiro & Kang 1987;Shapiro et al 1994;Ferrara & Giallongo 1996;Giroux & Shapiro 1996;Ricotti et al 2001), ionization of the solar chromosphere (Carlsson & Stein 2002), Gamma ray bursts (Perna & Loeb 1998;Böttcher et al 1999), accretion discs (Woods et al 1996), active galactic nuclei (Nicastro et al 1997(Nicastro et al , 1999Krongold et al 2007), the evolution of the early Universe (Seager et al 2011), and quasar FeLoBALs (Bautista & Dunn 2010). However, there is as yet no general tool to model non-equilibrium photoionized plasmas.…”

Section: Introductionmentioning

confidence: 99%

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Time-Dependent Photoionization of Gaseous Nebulae: The Pure Hydrogen Case

García¹,

Bautista²,

Kallman³

2013

ApJ

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We study the problem of time-dependent photoionization of low density gaseous nebulae subjected to sudden changes in the intensity of ionizing radiation. To this end, we write a computer code that solves the full time-dependent energy balance, ionization balance, and radiation transfer equations in a selfconsistent fashion for a simplified pure hydrogen case. It is shown that changes in the ionizing radiation yield ionization/thermal fronts that propagate through the cloud, but the propagation times and response times to such fronts vary widely and non-linearly from the illuminated face of the cloud to the ionization front (IF). Ionization/thermal fronts are often supersonic, and in slabs initially in pressure equilibrium such fronts yield large pressure imbalances that are likely to produce important dynamical effects in the cloud.Further, we studied the case of periodic variations in the ionizing flux. It is found that the physical conditions of the plasma have complex behaviors that differ from any steady-state solutions. Moreover, even the time average ionization and temperature is different from any steady-state case. This time average is characterized by over-ionization and a broader IF with respect to the steadystate solution for a mean value of the radiation flux. Around the time average of physical conditions there is large dispersion in instantaneous conditions, particularly across the IF, which increases with the period of radiation flux variations.Moreover, the variations in physical conditions are asynchronous along the slab due to the combination of non-linear propagation times for thermal/ionization fronts and equilibration times.

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Section: Step Flux Function On a Slab In Pressure Equilibriummentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Time-Dependent Photoionization of Gaseous Nebulae: The Pure Hydrogen Case

García¹,

Bautista²,

Kallman³

2013

ApJ

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“…AGN variability has been extensively observed and reveals significant variability (20%) on timescales as short as ∼10 3 s. (Silva et al 2016). Time-dependent photoionization has been explored previously in models for the interstellar medium (Lyu & Bruhweiler 1996;Joulain et al 1998), H II regions (Rodriguez-Gaspar & Tenorio-Tagle 1998; Richling & Yorke 2000), planetary nebulae (Harrington & Marionni 1976;Harrington 1977;Schmidt-Voigt & Koeppen 1987;Frank & Mellema 1994;Marten & Szczerba 1997), novae, and supernovae (Hauschildt et al 1992;Beck et al 1995;Kozma & Fransson 1998), reionization of the intergalactic medium (Ikeuchi & Ostriker 1986;Shapiro & Kang 1987;Ferrara & Giallongo 1996;Giroux & Shapiro 1996), ionization of the solar chromosphere (Carlsson & Stein 2002), gamma-ray bursts (Perna & Loeb 1998;Böttcher et al 1999), accretion disks (Woods et al 1996), AGNs (Nicastro et al 1997;Krongold 2007), the evolution of the early universe (Seager et al 2011), and quasar FeLoBALs (Bautista & Dunn 2010). Gnat (2017) calculated the time-dependent cooling in photoionized plasma in the context of intergalactic gas.…”

Section: Introductionmentioning

confidence: 99%

Time-dependent Photoionization Modeling of Warm Absorbers in Active Galactic Nuclei

Bautista

Garcia

et al. 2023

ApJ

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Warm absorber spectra contain bound-bound and bound-free absorption features seen in the X-ray and UV spectra from many active galactic nuclei. The widths and centroid energies of these features indicate they occur in outflowing gas, and the outflow can affect the gas within the host galaxy. Thus, the warm absorber mass and energy budgets are of great interest. Estimates for these properties depend on models that connect the observed strengths of the absorption features with the density, composition, and ionization state of the absorbing gas. Such models assume that the ionization and heating of the gas come primarily from the strong continuum near the central black hole. They also assume that the various heating, cooling, ionization, and recombination processes are in a time-steady balance. This assumption may not be valid, owing to the intrinsic time variability of the illuminating continuum or other factors that change the cloud environment. This paper presents models for warm absorbers that follow the time dependence of the ionization, temperature, and radiation field in warm absorber gas clouds in response to a changing continuum illumination. We show that the effects of time variability are important over a range of parameter values, that time-dependent models differ from equilibrium models in meaningful ways, and that these effects should be included in models that derive properties of warm absorber outflows.

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“…(Silva et al 2016). Time dependent photoionization has been explored previously in models for the interstellar medium (Lyu & Bruhweiler 1996;Joulain et al 1998), H II regions (Rodriguez-Gaspar & Tenorio-Tagle 1998;Richling & Yorke 2000), planetary nebulae (Harrington & Marionni 1976;Harrington 1977;Schmidt-Voigt & Koeppen 1987;Frank & Mellema 1994;Marten & Szczerba 1997), novae and supernovae (Hauschildt et al 1992;Beck et al 1995;Kozma & Fransson 1998), reionization of the intergalactic medium (Ikeuchi & Ostriker 1986;Shapiro & Kang 1987;Ferrara & Giallongo 1996;Giroux & Shapiro 1996), ionization of the solar chromosphere (Carlsson & Stein 2002), gamma-ray bursts (Perna & Loeb 1998;Böttcher et al 1999), accretion disks (Woods et al 1996), active galactic nuclei (Nicastro et al 1997;Krongold 2007), evolution of the early universe (Seager et al 2011), and quasar FeLoBALs (Bautista & Dunn 2010). Gnat (2017) calculated the time dependent cooling in photoionized plasma in the context of intergalactic gas.…”

Section: Introductionmentioning

confidence: 99%

Time Dependent Photoionization Modeling of Warm Absorbers in Active Galactic Nuclei

R¹,

Bautista²,

García³

et al. 2022

Preprint

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Warm absorber spectra contain bound-bound and bound-free absorption features seen in the Xray and UV spectra from many active galactic nuclei (AGN). The widths and centroid energies of these features indicate they occur in outflowing gas, and the outflow can affect the gas within the host galaxy. Thus the warm absorber mass and energy budgets are of great interest. Estimates for these properties depend on models which connect the observed strengths of the absorption features with the density, composition, and ionization state of the absorbing gas. Such models assume that the ionization and heating of the gas come primarily from the strong continuum from near the central black hole. They also assume that the various heating, cooling, ionization, and recombination processes are in a time-steady balance. This assumption may not be valid, owing to the intrinsic time-variability of the illuminating continuum, or other factors which change the cloud environment. This paper presents models for warm absorbers which follow the time dependence of the ionization, temperature, and radiation field in warm absorber gas clouds in response to a changing continuum illumination. We show that the effects of time variability are important over a range of parameter values, that time dependent models differ from equilibrium models in important ways, and that these effects should be included in models which derive properties of warm absorber outflows.

show abstract

IONIZATION-DRIVEN FRAGMENTATION OF GAS OUTFLOWS RESPONSIBLE FOR FeLoBALs IN QUASARS

Cited by 4 publications

References 22 publications

Time-Dependent Photoionization of Gaseous Nebulae: The Pure Hydrogen Case

Time-Dependent Photoionization of Gaseous Nebulae: The Pure Hydrogen Case

Time-dependent Photoionization Modeling of Warm Absorbers in Active Galactic Nuclei

Time Dependent Photoionization Modeling of Warm Absorbers in Active Galactic Nuclei

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