Circumnuclear Multi-phase Gas in Circinus Galaxy IV: Absorption Owing to High-J CO Rotational Transitions

Taisei, Uzuo,; Wada, Keiichi; Izumi, Teruo; Baba, Shigeo; Matsumoto, K.; Kudoh, Yuki

doi:10.3847/1538-4357/ac013d

Cited by 10 publications

(21 citation statements)

References 51 publications

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“…The observed spectrum and the best-fit model folded with the energy responses of the Circinus galaxy are plotted in Figure A2. We obtain the best-fit inclination angle of ∼87 • , which is consistent with the previous studies, in which the infrared SED, molecular lines in radio, and X-ray continuum spectra are compared with observed ones (Wada et al 2016;Izumi et al 2018;Uzuo et al 2021;Buchner et al 2021). Our model gives a reasonably good description of observed spectrum except the intensities of the emission lines.…”

Section: A2 X-ray Spectrum: Comparison With Circinus Galaxysupporting

confidence: 89%

“…Wada et al (2016) applied this radiation-driven fountain model to the Circinus galaxy, which is one of the closest (4.2 Mpc: Freeman et al 1977) type-2 AGN. The model is consistent with several observed features, such as the infrared spectral energy distribution (SED, Wada et al 2016), the dynamics of atomic/molecular gas (Wada et al 2018a;Izumi et al 2018;Uzuo et al 2021), distribution of ionized gas in the NLR (Wada et al 2018b), and broadband X-ray spectra (Buchner et al 2021). Mizumoto et al (2019) also suggested that this kind of dust driven wind may play an important role to the warm absorber acceleration.…”

Section: Introductionsupporting

confidence: 82%

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Warm Absorbers in the Radiation-driven Fountain Model of Low-mass Active Galactic Nuclei

Ogawa,

Ueda,

Wada

et al. 2021

Preprint

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To investigate the origins of the warm absorbers in active galactic nuclei (AGNs), we study the ionizationstate structure of the radiation-driven fountain model in a low-mass AGN (Wada et al. 2016) and calculate the predicted X-ray spectra, utilizing the spectral synthesis code Cloudy (Ferland et al. 2017). The spectra show many absorption and emission line features originated in the outflowing ionized gas. The O VIII 0.654 keV lines are produced mainly in the polar region much closer to the SMBH than the optical narrow line regions. The absorption measure distribution of the ionization parameter (ξ) at a low inclination spreads over 4 orders of magnitude in ξ, indicating multi-phase ionization structure of the outflow, as actually observed in many type-1 AGNs. We compare our simulated spectra with the high energy-resolution spectrum of the narrow line Seyfert 1 galaxy, NGC 4051. The model reproduces slowly outflowing (a few hundreds km s −1 ) warm absorbers. However, the faster components with a few thousands km s −1 observed in NGC 4051 are not reproduced. The simulation also underproduces the intensity and width of the O VIII 0.654 keV line. These results suggest that the ionized gas launched from sub-parsec or smaller regions inside the torus, which are not included in the current fountain model, must be important ingredients of the warm absorbers with a few thousands km s −1 . The model also consistently explains the Chandra/HETG spectrum of the Seyfert 2 galaxy, the Circinus galaxy.

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Section: A2 X-ray Spectrum: Comparison With Circinus Galaxysupporting

confidence: 89%

Section: Introductionsupporting

confidence: 82%

Warm Absorbers in the Radiation-driven Fountain Model of Low-mass Active Galactic Nuclei

Ogawa,

Ueda,

Wada

et al. 2021

Preprint

Self Cite

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“…The radiation-driven fountain model (Wada et al 2016) suggested a picture that AGN tori are naturally formed by gas circulation around the AGN, and this picture is consistent with multiwavelength observations of low luminosity AGNs, such as the Circinus galaxy (Wada et al 2018a(Wada et al , 2018bIzumi et al 2018;Buchner et al 2021;Ogawa et al 2022). However, these previous studies have not directly verified the gas circulation inside the torus (see also Uzuo et al 2021). In this paper, we propose that CO rovibrational absorption lines can be used to infer the internal motion of the molecular tori and focus on the following four questions: (1) What is the source of continuum radiation at the back of the CO absorption gas in near-infrared observations, especially at the wavelength 4.7 μm?…”

Section: Discussionmentioning

confidence: 94%

Probing Dynamics and Thermal Properties Inside Molecular Tori with CO Rovibrational Absorption Lines

Matsumoto

Wada

Baba

et al. 2022

ApJ

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A recent hydrodynamic model, the radiation-driven fountain model (Wada et al. 2016), presented a dynamical picture that active galactic nuclei (AGNs) tori sustain their geometrical thickness by gas circulation around AGNs, and previous papers have confirmed that this picture is consistent with multiwavelength observations of nearby Seyfert galaxies. Recent near-infrared observations implied that CO rovibrational absorption lines (ΔJ = ± 1, v = 0 − 1, λ ∼ 4.7 μm) could probe the physical properties of the inside tori. However, the origin of the CO absorption lines has been under debate. In this paper, we investigate the origin of the absorption lines and conditions for detecting them by performing line radiative transfer calculations based on the radiation-driven fountain model. We find that CO rovibrational absorption lines are detected at inclination angles θ obs = 50°–80°. At the inclination angle θ obs = 77°, we observe multi-velocity components: inflow (v LOS = 30 km s−1), systemic (v LOS = 0 km s−1), and outflows (v LOS = −75, − 95, and −105 km s−1). The inflow and outflow components (v LOS = 30 and −95 km s−1) are collisionally excited at the excitation temperatures of 186 and 380 K up to J = 12 and 4, respectively. The inflow and outflow components originate from the accreting gas on the equatorial plane at 1.5 pc from the AGN center and the outflowing gas driven by AGN radiation pressure at 1.0 pc, respectively. These results suggest that CO rovibrational absorption lines can provide us with the velocities and kinetic temperatures of the inflow and outflow in the inner few parsec region of AGN tori, and the observations can probe the gas circulation inside the tori.

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“…Therefore, we conclude that CO rovibrational absorption lines can be detected in only the case with inclination angles θ obs = 50 − 80 • , but the detectability of outflow and inflow components depends on the azimuthal angles. (in Appendix A, we discuss differences in observational conditions between our results in the nearinfrared wavelength with a previous theoretical study in the submillimeter wavelengths (Uzuo et al 2021)).…”

Section: Conditions For Detecting Co Absorption Linesmentioning

confidence: 74%

“…We can use molecular absorption lines to know the physical condition of the molecular gas on the line of sight. Uzuo et al (2021) investigated the CO rotational absorption lines in submillimeter wavelength based on the model. The detected CO absorption line profiles for the rotational levels J = 7-6 or higher were affected by those of the CO emission lines, especially if the beam size was not fine enough, and it was difficult to derive the kinematics and level population of the molecular gas inside the torus.…”

Section: Introductionmentioning

confidence: 99%

Probing dynamics and thermal properties inside molecular tori with CO rovibrational absorption lines

Matsumoto,

Nakagawa,

Wada

et al. 2022

Preprint

Self Cite

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A recent hydrodynamic model, "radiation-driven fountain model" (Wada et al. 2016), presented a dynamical picture that active galactic nuclei (AGNs) tori sustain their geometrical thickness by gas circulation around AGNs, and previous papers confirmed that this picture is consistent with multiwavelength observations of nearby Seyfert galaxies. Recent near-infrared observations implied that CO rovibrational absorption lines (∆J = ±1, v = 0 − 1, λ ∼ 4.7 µm) could probe physical properties of the inside tori. However, the origin of the CO absorption lines has been under debate. In this paper, we investigate the origin of the absorption lines and conditions for detecting them by performing line radiative transfer calculations based on the radiation-driven fountain model. We find that CO rovibrational absorption lines are detected at inclination angles θ obs = 50 − 80 • . At the inclination angle θ obs = 77 • , we observe multi-velocity components: inflow (v LOS = 30 km s −1 ), systemic (v LOS = 0 km s −1 ), and outflows (v LOS = −75, −95, and −105 km s −1 ). The inflow and outflow components (v LOS = 30 and −95 km s −1 ) are collisionally excited at the excitation temperature of 186 and 380 K up to J = 12 and 4, respectively. The inflow and outflow components originate from the accreting gas on the equatorial plane at 1.5 pc from the AGN center and the outflowing gas driven by AGN radiation pressure at 1.0 pc, respectively. These results suggest that CO rovibrational absorption lines can provide us with the velocities and kinetic temperatures of the inflow and outflow in the inner a-few-pc regions of AGN tori, and the observations can probe the gas circulation inside the tori.

show abstract

Circumnuclear Multi-phase Gas in Circinus Galaxy IV: Absorption Owing to High-J CO Rotational Transitions

Cited by 10 publications

References 51 publications

Warm Absorbers in the Radiation-driven Fountain Model of Low-mass Active Galactic Nuclei

Warm Absorbers in the Radiation-driven Fountain Model of Low-mass Active Galactic Nuclei

Probing Dynamics and Thermal Properties Inside Molecular Tori with CO Rovibrational Absorption Lines

Probing dynamics and thermal properties inside molecular tori with CO rovibrational absorption lines

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