Emission Line Ratios of FE III as Astrophysical Plasma Diagnostics

Laha, Sibasish; Tyndall, N. B.; Keenan, F. P.; Ballance, C. P.; Ramsbottom, Catherine; Ferland, Gary J.; Hibbert, A

doi:10.3847/1538-4357/aa7071

Cited by 17 publications

(11 citation statements)

References 25 publications

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“…We note that we did not find any statistically significant neutral or ionized absorption intrinsic to the source. On addition of an ionized absorption model generated using the latest atomic data with the photo-ionization modeling code CLOUDY (Ferland et al 2013;Laha et al 2016cLaha et al ,b, 2017Laha et al , 2019b, we did not detect any improvement in the fit, as also found in previous works on this source (Rivers et al 2011). Two black body components were necessary to describe the soft excess.…”

Section: The Phenomenological Modelssupporting

confidence: 72%

A Weakening Compton Hump and Soft X-Ray Excess Detected in the Seyfert 1 Galaxy MCG –02–58–22

Laha

Ghosh

2021

ApJ

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We have carried out an extensive X-ray spectral study of the bare Seyfert-1 galaxy MCG -02-58-22 to ascertain the nature of the X-ray reprocessing media, using observations from Suzaku (2009) and simultaneous observations from XMM-Newton and NuSTAR (2016) . The most significant results of our investigation are: 1. The primary X-ray emission from the corona is constant in these observations, both in terms of the power law slope (Γ = 1.80) and luminosity (L 2−10 keV = 2.55 × 10 44 erg s −1 ). 2. The soft excess flux decreased by a factor of two in 2016, the Compton hump weakened/vanished in 2016, and the narrow FeKα emission line became marginally broad (σ = 0.35 ± 0.08 keV) and its flux doubled in 2016. 3. From physical model fits we find that the normalization of the narrow component of the FeKα line does not change in the two epochs, although the Compton hump vanishes in the same time span. Since the primary X-ray continuum does not change, we presume that any changes in the reprocessed emission must arise due to changes in the reprocessing media. Our primary conclusions are: A. The vanishing of the Compton hump in 2016 can probably be explained by a dynamic clumpy torus which is infalling/outflowing, or by a polar torus wind. B. The torus in this AGN possibly has two structures: an equatorial toroidal disk (producing the narrow FeKα emission) and a polar component (producing the variable Compton hump), C. The reduction of the soft-excess flux by half and increase in the FeKα flux by a factor of two in the same period cannot be adequately explained by ionized disk reflection model alone.

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Section: The Phenomenological Modelssupporting

confidence: 72%

A Weakening Compton Hump and Soft X-Ray Excess Detected in the Seyfert 1 Galaxy MCG –02–58–22

Laha

Ghosh

2021

ApJ

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“…On the other hand, the [O i] λ6300 line, which is detected by Henry but not in Bohigas's data, is marginally detected in our IFU data with half of the intensity measured by Henry et al (2010) and very low S/N Figure 2. The theoretical [Fe iii] λλ5270/4658 line ratio as a function of electronic density for two different electronic temperatures at 9000 K(solid line) and 15000 K (dotted line) derived from (Laha et al 2017). The black square with error bars indicates the value 0.95±0.33 we found for Abell 14.…”

Section: D Approach: Integrated Spectrummentioning

confidence: 94%

Exploring the differences of integrated and spatially resolved analysis using integral field unit data: the case of Abell 14

Akras

Monteiro

Aleman

et al. 2020

Monthly Notices of the Royal Astronomical Society

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We present a new approach to study planetary nebulae using integral field spectroscopy. VLT@VIMOS datacube of the planetary nebula Abell 14 is analysed in three different ways by extracting: (i) the integrated spectrum, (ii) 1-dimensional simulated long slit spectra for different position angles and (iii) spaxel-by-spaxel spectra. These data are used to built emission-line diagnostic diagrams and explore the ionization structure and excitation mechanisms combining data from 1-and 3-dimensional photoionization models. The integrated and 1D simulated spectra are suitable for developing diagnostic diagrams, while the spaxel spectra can lead to misinterpretation of the observations. We find that the emission-line ratios of Abell 14 are consistent with UV photo-ionized emission; however, there are some pieces of evidence of an additional thermal mechanism. The chemical abundances confirm its previous classification as a Type I planetary nebula, without spatial variation. We find, though, variation in the ionization correction factors (ICFs) as a function of the slit position angle. The star at the geometric centre of Abell 14 has an A5 spectral type with an effective temperature of T eff = 7909±135 K and surface gravity log(g) = 1.4±0.1 cm s −2 . Hence, this star cannot be responsible for the ionization state of the nebula. Gaia parallaxes of this star yield distances between 3.6 and 4.5 kpc in good agreement with the distance derived from a 3-dimensional photoionization modelling of Abell 14, indicating the presence of a binary system at the centre of the planetary nebula.

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“…However, until recently the electronic energy structure of the Fe 2+ ion was poorly known and so theoretical predictions for the Fe iii line ratios and strengths were not accurate. Within the past few years, work by Badnell & Ballance (2014) has produced improved atomic data for Fe iii which, for the first time, allows predictions to be made for the full emission-line spectrum of this ion (Laha et al 2017). Previous observational studies of Fe iii have focused on the complex of lines at ∼2075Å, which is relatively isolated and measurements are thus relatively straightforward.…”

Section: Introductionmentioning

confidence: 99%

Fe iii emission in quasars: evidence for a dense turbulent medium

Temple

Ferland

Rankine

et al. 2020

Monthly Notices of the Royal Astronomical Society

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ABSTRACT Recent improvements to atomic energy-level data allow, for the first time, accurate predictions to be made for the Fe iii line emission strengths in the spectra of luminous, $L_\text{bol}\simeq 10^{46}\!-\!10^{48}\mbox{${\rm \, erg}{\rm \, s}^{-1}\, $}$, active galactic nuclei. The Fe iii emitting gas must be primarily photoionized, consistent with observations of line reverberation. We use cloudy models exploring a wide range of parameter space, together with ≃26 000 rest-frame ultraviolet spectra from the Sloan Digital Sky Survey, to constrain the physical conditions of the line emitting gas. The observed Fe iii emission is best accounted for by dense (nH ≃ 1014 cm−3) gas which is microturbulent, leading to smaller line optical depths and fluorescent excitation. Such high density gas appears to be present in the central regions of the majority of luminous quasars. Using our favoured model, we present theoretical predictions for the relative strengths of the Fe iii UV34 λλ1895, 1914, 1926 multiplet. This multiplet is blended with the Si iii] λ1892 and C iii] λ1909 emission lines and an accurate subtraction of UV34 is essential when using these lines to infer information about the physics of the broad line region in quasars.

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Emission Line Ratios of FE III as Astrophysical Plasma Diagnostics

Cited by 17 publications

References 25 publications

A Weakening Compton Hump and Soft X-Ray Excess Detected in the Seyfert 1 Galaxy MCG –02–58–22

A Weakening Compton Hump and Soft X-Ray Excess Detected in the Seyfert 1 Galaxy MCG –02–58–22

Exploring the differences of integrated and spatially resolved analysis using integral field unit data: the case of Abell 14

Fe iii emission in quasars: evidence for a dense turbulent medium

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