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Fluorescent H<sub>2</sub>Emission Lines from the Reflection Nebula NGC 7023 Observed with IGRINS
Le, Huynh Anh N.,Pak, Soojong,Kaplan, Kyle,Mace, Gregory,Lee, Sungho,Pavel, Michael,Jeong, Ueejeong,Oh, Heeyoung,Lee, Hye-In,Chun, Moo-Young,Yuk, In-Soo,Pyo, Tae-Soo,Hwang, Narae,Kim, Kang-Min,Park, C American Astronomical Society 2017 The Astrophysical journal Vol.841 No.1
<P>We have analyzed the temperature, velocity, and density of H-2 gas in NGC. 7023 with a high-resolution near-infrared spectrum of the northwestern filament of the reflection nebula. By observing NGC. 7023 in the H and K bands at R similar or equal to 45,000 with the Immersion GRating INfrared Spectrograph, we detected 68 H-2 emission lines within the 1 '' x 15 '' slit. The diagnostic ratio of 2-1 S(1)/1-0 S(1) is 0.41-0.56. In addition, the estimated ortho-to-para ratio (OPR) is 1.63-1.82, indicating that the H-2 emission transitions in the observed region arise mostly from gas excited by UV fluorescence. Gradients in the temperature, velocity, and OPR within the observed area imply motion of the photodissociation region (PDR) relative to the molecular cloud. In addition, we derive the column density of H-2 from the observed emission lines and compare these results with PDR models in the literature covering a range of densities and incident UV field intensities. The notable difference between PDR model predictions and the observed data, in high rotational J levels of v = 1, is that the predicted formation temperature for newly formed H-2 should be lower than that of the model predictions. To investigate the density distribution, we combine pixels in 1 '' x 1 '' areas and derive the density distribution at the 0.002 pc scale. The derived gradient of density suggests that NGC 7023 has a clumpy structure, including a high clump density of similar to 10(5) cm(-3) with a size smaller than similar to 5 x 10(- 3) pc embedded in lower-density regions of 10(3)-10(4) cm(-3).</P>
Ionized-gas Kinematics Along the Large-scale Radio Jets in Type-2 AGNs
Le, Huynh Anh N.,Woo, Jong-Hak,Son, Donghoon,Karouzos, Marios,Chung, Aeree,Jung, Taehyun,Tremou, Evangelia,Hwang, Narae,Park, Byeong-Gon American Astronomical Society 2017 The Astrophysical journal Vol.851 No.1
<P>To investigate the connection between radioactivity and active galactic nucleus (AGN) outflows, we present a study of ionized-gas kinematics based on an [O III] lambda 5007 emission line along the large-scale radio jet for six radio AGNs. These AGNs are selected based on the radioactivity (i.e., L-1.4 (GHz) >= 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 [[OIII]] 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 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.</P>
Calibration and Limitations of the Mg ii Line-based Black Hole Masses
Woo, Jong-Hak,Le, Huynh Anh N.,Karouzos, Marios,Park, Dawoo,Park, Daeseong,Malkan, Matthew A.,Treu, Tommaso,Bennert, Vardha N. American Astronomical Society 2018 The Astrophysical journal Vol.859 No.2
<P>We present single-epoch black hole mass (M-BH) calibrations based on the rest-frame ultraviolet (UV) and optical measurements of Mg II 2798 angstrom and H beta 4861 angstrom lines and the active galactic nucleus (AGN) continuum, using a sample of 52 moderate-luminosity AGNs at z similar to 0.4 and z similar to 0.6 with high-quality Keck spectra. We combine this sample with a large number of luminous AGNs from the Sloan Digital Sky Survey to increase the dynamic range for a better comparison of UV and optical velocity and luminosity measurements. With respect to the reference M-BH based on the line dispersion of H beta and continuum luminosity at 5100 angstrom, we calibrate the UV and optical mass estimators by determining the best-fit values of the coefficients in the mass equation. By investigating whether the UV estimators show a systematic trend with Eddington ratio, FWHM of H beta, Fe II strength, or UV/optical slope, we find no significant bias except for the slope. By fitting the systematic difference of Mg II-based and H beta-based masses with the L-3000/L-5100 ratio, we provide a correction term as a function of the spectral index as Delta C = 0.24 (1 + alpha(lambda)) + 0.17, which can be added to the Mg II-based mass estimators if the spectral slope can be well determined. The derived UV mass estimators typically show >similar to 0.2 dex intrinsic scatter with respect to the H beta-based MBH, suggesting that the UV-based mass has an additional uncertainty of similar to 0.2 dex, even if high-quality rest-frame UV spectra are available.</P>
Auto-guiding Performance from IGRINS Test Observations (Immersion GRating INfrared Spectrograph)
Hye-In Lee,Soojong Pak,Huynh Anh N.Le,Wonseok Kang,Gregory Mace,Michael Pavel,Daniel T.Jaffe,Jae-Joon Lee,Ueejeong Jeong,Michael Pavel,Daniel T.Jaffe,Jae-Joon Lee,Ueejeong Jeong,Moo-Young Chun,Chan Pa 한국천문학회 2014 天文學會報 Vol.39 No.2