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Register a new userIonized Gas Kinematics along the Large-Scale Radio Jets in Type 2 AGNs
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Huynh Anh Le Nguyen
Publication date
2017
fields
Physics
and research's language is
English
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To investigate the connection between radio activity and AGN outflows, we present a study of ionized gas kinematics based on [O III] $lambda$5007 emission line along the large-scale radio jet for six radio AGNs. These AGNs are selected based on the radio activity (i.e., $mathrm{L_{1.4GHz}}$ $geqslant$ 10$^{39.8}$ erg s$^{-1}$) as well as optical emission line properties as type 2 AGNs. Using the Red Channel Cross Dispersed Echellette Spectrograph at the Multiple Mirror Telescope, we investigate in detail the [O III] and stellar kinematics. We spatially resolve and probe the central AGN-photoionization sizes, which is important in understanding the structures and evolutions of galaxies. We find that the typical central AGN-photoionization radius of our targets are in range of 0.9$-$1.6 kpc, consistent with the size-luminosity relation of [O III] in the previous studies. We investigate the [O III] kinematics along the large-scale radio jets to test whether there is a link between gas outflows in the narrow-line region and extended radio jet emissions. Contrary to our expectation, we find no evidence that the gas outflows are directly connected to the large scale radio jets.
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We present a systematic study of ionized gas outflows based on the velocity shift and dispersion of the [O III] {lambda}5007 $AA$ emission line, using a sample of ~ 5000 Type 1 AGNs at z < 0.3 selected from Sloan Digital Sky Survey. This analysis is supplemented by the gas kinematics of Type 2 AGNs from Woo et al. (2016). For the majority of Type 1 AGNs (i.e., ~ 89%), the [O III] line profile is best represented by a double Gaussian model, presenting the kinematic signature of the non-virial motion. Blueshifted [O III] is more frequently detected than redshifted [O III] by a factor of 3.6 in Type 1 AGNs, while the ratio between blueshifted to redshifted [O III] is only 1.08 in Type 2 AGNs due to the projection and orientation effect. The fraction of AGNs with outflow signatures is found to increase steeply with [O III] luminosity and Eddington ratio, while Type 1 AGNs have larger velocity dispersion and more negative velocity shift than Type 2 AGNs. The [O III] velocity - velocity dispersion (VVD) diagram of Type 1 AGNs expands towards higher values with increasing luminosity and Eddington ratio, suggesting that the radiation pressure or wind is the main driver of gas outflows, as similarly found in Type 2 AGNs. In contrast, the kinematics of gas outflows is not directly linked to the radio activity of AGN.
We present the spatially resolved gas and stellar kinematics of a sample of ten hidden type 1 AGNs in order to investigate the true nature of the central source and the scaling relation with host galaxy stellar velocity dispersion. The sample is selected from a large number of hidden type 1 AGN, which are identified based on the presence of a broad component in the ha line profile (i.e., full-width-at-half-maximum $>$ $sim$1000 kms), while they are often mis-classified as type 2 AGN because AGN continuum and broad emission lines are weak or obscured in the optical spectral range. We used the Blue Channel Spectrograph at the 6.5-m MMT (Multiple Mirror Telescope) to obtain long-slit data. We detected a broad hb for only two targets, however, the presence of a strong broad ha indicates that these AGNs are low-luminosity type 1 AGNs. We measured the velocity, velocity dispersion and flux of stellar continuum and gas emission lines (i.e., hb and oiii) as a function of distance from the center with a spatial scale of 0.3 arcsec pixel$^{-1}$. Spatially resolved gas kinematics traced by hb or oiii are generally similar to stellar kinematics except for the very center, where signatures of gas outflows are detected. We compare the luminosity-weighted effective stellar velocity dispersion with black hole mass, finding that these hidden type 1 AGN with relatively low back hole mass follow the scaling relation of the reverberation-mapped type 1 AGN and more massive inactive galaxies. }
We investigate the ionization structure of the nebular gas in M83 using the line diagnostic diagram, [O III](5007 degA)/H{beta} vs. [S II](6716 deg A+6731 deg A)/H{alpha} with the newly available narrowband images from the Wide Field Camera 3 (WFC3) of the Hubble Space Telescope (HST). We produce the diagnostic diagram on a pixel-by-pixel (0.2 x 0.2) basis and compare it with several photo- and shock-ionization models. For the photo-ionized gas, we observe a gradual increase of the log([O III]/H{beta}) ratios from the center to the spiral arm, consistent with the metallicity gradient, as the H II regions go from super solar abundance to roughly solar abundance from the center out. Using the diagnostic diagram, we separate the photo-ionized from the shock-ionized component of the gas. We find that the shock-ionized H{alpha} emission ranges from ~2% to about 15-33% of the total, depending on the separation criteria used. An interesting feature in the diagnostic diagram is an horizontal distribution around log([O III]/H{beta}) ~ 0. This feature is well fit by a shock-ionization model with 2.0 Zodot metallicity and shock velocities in the range of 250 km/s to 350 km/s. A low velocity shock component, < 200 km/s, is also detected, and is spatially located at the boundary between the outer ring and the spiral arm. The low velocity shock component can be due to : 1) supernova remnants located nearby, 2) dynamical interaction between the outer ring and the spiral arm, 3) abnormal line ratios from extreme local dust extinction. The current data do not enable us to distinguish among those three possible interpretations. Our main conclusion is that, even at the HST resolution, the shocked gas represents a small fraction of the total ionized gas emission at less than 33% of the total. However, it accounts for virtually all of the mechanical energy produced by the central starburst in M83.
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The morphological, spectroscopic and kinematical properties of the warm interstellar medium (wim) in early-type galaxies (ETGs) hold key observational constraints to nuclear activity and the buildup history of these massive, quiescent systems. High-quality integral field spectroscopy (IFS) data with a wide spectral and spatial coverage, such as those from the CALIFA survey, offer an unprecedented opportunity for advancing our understanding of the wim in ETGs. This article centers on a 2D investigation of the wim component in 32 nearby (<~150Mpc) ETGs from CALIFA, complementing a previous 1D analysis of the same sample (Papaderos et al. 2013; P13). We include here Halpha intensity and equivalent width (EW) maps and radial profiles, diagnostic emission-line ratios, besides ionized-gas and stellar kinematics. This study is supplemented by tau-ratio maps as an efficient means to quantify the role of photoionization by pAGB stars, as compared to other mechanisms (e.g., AGN, low-level star formation). Additionally, we extend the tentative classification proposed in P13 by the type i+, which is assigned to a subset of type i ETGs exhibiting ongoing low-level star-formation (SF) in their periphery. This finding along with faint traces of localized SF in the extranuclear component of several of our sample ETGs points to a non-negligible contribution by OB stars to the total ionizing budget. We also demonstrate that, at the typical emission-line detection threshold of ~2AA in previous studies, most of the extranuclear wim emission in an ETG may evade detection, which could in turn prompt its classification as an entirely gas-devoid system. This study adds further observational evidence for a considerable heterogeneity among ETGs with regard to the physical properties and 2D kinematics of the wim component, and underscores the importance of IFS studies over their entire optical extent.
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