• The Bulletin of The Korean Astronomical Society
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• v.43 no.2
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• pp.55.2-55.2
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• 2018

The Wide-field Infrared Survey Explorer (WISE) mission enabled efficient selection of Active Galactic Nuclei (AGN) with high luminosities and large obscuration. According to the merger driven AGN powering scenarios, luminous and obscured AGN are in a stage where they go through feeding of gas accretion into the central black hole, and feedback to the host galaxy through outflows. We report the rest-frame UV-optical spectra of Hot Dust Obscured Galaxies (Hot DOGs) at z~2, WISE color-selected to be extremely reddened AGN. Most of the targets show blueshifted and broadened [OIII] line profiles indicative of ionized gas outflows. We present the occurrence and strength of the outflows, and discuss the impact of luminous, obscured AGN activity on their hosts.

• The Bulletin of The Korean Astronomical Society
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• v.45 no.1
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• pp.65.2-65.2
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• 2020

We present NIR spectroscopic data of young radio quasars obtained from Flamingos-2 (F2) at Gemini-South. The targets are originally selected from Wide-Field Infrared Survey Explorer survey in combination with radio survey data, such as FIRST and NVSS. Our goal is to find observational evidence of jet-driven outflows, which is expected to be present in young luminous quasars from the theoretical studies. While 16 targets were observed with F2, narrow emission lines ([O III] or Hα) were detected in 7 targets. FWHM of the emission lines (up to 2500 km/s) were remarkably broad compared to ordinary quasars, revealing the presence of strong outflows. The black hole mass estimated from Eddington limit ranges from ~108 to 109 solar mass, indicating that the target quasars are likely to be progenitors of massive galaxies. Finally, we present the comparisons between the outflow velocity and the physical properties of radio jets derived from the VLA radio imaging data, in order to investigate the physical connection between the ionized outflows and radio jets.

• Korea Trade Review
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• v.47 no.6
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• pp.173-187
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• 2022

Since the economic reform 1991, Indian has been implementing policies to promote trade and foreign direct investment (FDI). In particular, since the inauguration of the Modi government in 2014, India has created an economic environment in which more FDI can be launched and more jobs created in manufacturing sector. This study aims to analyze between FDI outflows and export from Korea to India. Using the quarter data from 2000 to 2021, this study examines panel regression. From the panel regression result, Korea's FDI outflows to India has a significantly positive impact on the Korea's export into India. Therefore, the relationship between FDI outflows and export from Korea to India is complementary. It is due that Korea's companies invest into India directly for the purpose of construction of production factors, and export capital goods and intermediate goods for producing in the factors. Therefore, for promoting FDI and export between Korea and India, Korean government should do continuous economic cooperation and discussion for the cooperation with Indian government.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.1
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• pp.35.2-35.2
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• 2016

We present a census of AGN-driven gas outflows based on the kinematics of ionized gas and stars, using a large sample of ~11,000 emission line galaxies at z < 0.3, selected from SDSS. First, a broad correlation between gas and stellar velocity dispersions indicates that the bulge gravitational potential plays a main role in determining the ionized gas kinematics. However, the velocity dispersion of the [OIII] emission line is larger than stellar velocity dispersion by a factor of 1.3-1.4, suggesting that the non-gravitational (non-virial) component, i.e., outflows, is almost comparable to the gravitational component. Second, gas-to-stellar velocity dispersion ratio increases with both AGN luminosity and Eddington ratio, suggesting that non-gravitational kinematics are clearly linked to AGN accretion. The distribution in the [OIII] velocity - velocity dispersion diagram dramatically expands toward large values with increasing AGN luminosity, implying that the launching velocity of gas outflows increases with AGN luminosity. Third, the fraction of AGNs with a signature of the non-gravitational kinematics, steeply increases with AGN luminosity and Eddington ratio, while the majority of luminous AGNs presents the non-gravitational kinematics in the [OIII] profile. These results suggest that ionized gas outflows are prevalent among type 2 AGNs. On the other hand, we find no strong trend of the [OIII] kinematics with radio luminosity, once we remove the effect of the bulge gravitational potential, indicating that ionized gas outflows are not directly related to radio activity for the majority of type 2 AGNs. We will discuss the implication of these results for AGN feedback in the local universe.

• The Bulletin of The Korean Astronomical Society
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• v.39 no.2
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• pp.58.1-58.1
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• 2014

Energetic gas outflows from active galactic nuclei (AGNs) may have a crucial role in galaxy evolution. In this contribution, we present a census of ionized gas outflows using a large sample (~23,000) of local (z < 0.1) type-2 AGNs selected from the Sloan Digital Sky Survey DR 7. By measuring the velocity offset of narrow emission lines, i.e., [O III] ${\lambda}5007$ and the Balmer lines, with respect to the systemic velocity measured from the stellar absorption lines, we find ~47% of AGNs showing an [O III] line-of-sight velocity offset ${\geq}20km\;s-1$. The fraction in type-2 AGNs is similar to that in type-1 AGNs after considering the projection effect. AGNs with larger [O III] velocity offsets, in particular with no or weak $H{\alpha}$ velocity offsets, tend to have higher Eddington ratios, implying that the [O III] velocity offset is related to on-going black hole activity. Also, we find the different distributions of the host galaxy inclination between the AGNs with blueshifted [O III] and the AGNs with redshifted [O III], supporting the model of biconical outflow with dust obscuration. Meanwhile, for ~3% of AGNs, [O III] and $H{\alpha}$ exhibit comparable large velocity offsets, suggesting a more complex gas kinematics than decelerating outflows in the narrow-line region.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.2
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• pp.72.1-72.1
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• 2017

Energetic ionized gas outflows driven by active galactic nuclei (AGN) have been studied as a key phenomenon related to AGN feedback. To probe the kinematics of the gas in the narrow line region, [O III] ${\lambda}5007$ has been utilized in a number of studies, showing non-virial kinematic properties due to AGN outflows. We statistically investigate whether the $H{\alpha}$ emission line is influenced by AGN driven outflows, by measuring the kinematic properties based on the $H{\alpha}$ line profile, and by comparing them with those of [O III]. Using the spatially integrated spectra of ~37,000 Type 2 AGNs at z < 0.3 selected from the SDSS DR7, we find a non-linear correlation between $H{\alpha}$ velocity dispersion and stellar velocity dispersion, which reveals the presence of the non-gravitational component, especially for AGNs with a wing component in $H{\alpha}$. The large $H{\alpha}$ velocity dispersion and velocity shift of luminous AGNs are clear evidence of AGN outflow impacts on $H{\alpha}$ emitting gas, while relatively smaller kinematic properties compared to those of [O III] imply that the observed outflow effect on the $H{\alpha}$ line is weaker than the case of [O III].

• The Bulletin of The Korean Astronomical Society
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• v.42 no.2
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• pp.81.1-81.1
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• 2017

L1251B is an excellent example of a small group of pre- and protostellar objects in low-mass star-forming region. Previous interferometer data with a high angular resolution resolved the outflows associated with L1251B into a few components. To understand the physical conditions of the protostellar outflows in L1251B, we mapped this region spectroscopically with Spitzer/IRS and obtained spectral line data from Herschel/PACS. Spitzer/IRS provides the S(0)-S(7) pure rotational lines of H2 as well as fine-structure emissions produced in shocks such as S, [Si II], and [Fe II] and it is a powerful tool for studying shocked interstellar gas. In addition, [O I] lines observed with Herschel/PACS are described well by J-type shock models expected in the outflows from protostars. We will present an analysis of the L1251B protostellar outflow in the H2 pure rotational lines and fine-structure emissions.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.2
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• pp.67.3-68
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• 2017

Bright rays are often observed after coronal mass ejections (CMEs) erupt. These rays are dynamical structures along which plasmas move outward. We investigated the outflows along the post-CME rays observed by the COR2 on board STEREO Behind on 2013 September 21 and 22. We tracked two CMEs, two ray tips, and seven blobs using the NAVE optical flow technique. As a result, we found that the departure times of blobs and ray tips from the optimally chosen starting height of 0.5 $R{\odot}$ coincided with the occurrence times of the corresponding recurrent small flares within 10 minutes. These small flares took place many hours after the major flares. This result supports a magnetic reconnection origin of the outward flows along the post-CME ray and the importance of magnetic islands for understanding the process of magnetic reconnection. The total energy of magnetic reconnection maintaining the outflows for 40 hr is estimated at 1.4' 1030 erg. Further investigations of plasma outflows along post-CME rays will shed much light on the physical properties of magnetic reconnection occurring in the solar corona.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.1
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• pp.28.1-28.1
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• 2017

To investigate AGN outflows as a tracer of AGN feedback on the host galaxies, we perform integral-field spectroscopy of 20 type 2 AGNs at z<0.1 using the Magellan/IMACS and the VLT/VIMOS. The observed objects are luminous AGNs with the [O III] luminosity >$10^{41.5}erg/s$, and exhibit strong outflow signatures in the [O III] kinematics. We obtain the maps of the narrow and broad components of [O III] and $H{\alpha}$ lines by decomposing the emission-line profile. The broad components in both [O III] and $H{\alpha}$ represent the non-gravitational kinematics, (i.e., gas outflows), while the narrow components represent the gravitational kinematics (i.e., rotational disks), especially in $H{\alpha}$. By using the spatially integrated spectra within the flux-weighted size of the narrow-line region, we estimate the outflow energetics. The ionized gas mass is $(1.0-38.5){\times}10^5M_{\odot}$, and the mean mass outflow rate is $4.6{\pm}4.3M_{\odot}/yr$, which is a factor of ~260 higher than the mean mass accretion rate $0.02{\pm}0.01M_{\odot}/yr$. The mean energy injection rate is $0.8{\pm}0.6%$ of the AGN bolometric luminosity Lbol, while the mean momentum flux is $(5.4{\pm}3.6){\times}L_{bol}/c$, except for two most kinematically energetic AGNs. The estimated energetics are consistent with the expectations for energy-conserving outflows from AGNs, yet we do not find any supporting evidence of instantaneous star-formation quenching due to the outflows.

• Journal of The Korean Astronomical Society
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• v.48 no.6
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• pp.365-380
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• 2015

We map 6 massive young stellar objects (YSOs) in the CO J=2-1 line and survey 18 massive YSOs, including the six, in the HCO⁺ J=1−0, SiO J=2−1, H₂O 6₁₆ − 5₂₃ maser, and CH₃OH 7₀ − 6₁ A⁺ maser lines. We detect CO bipolar outflows in all the six mapped sources. Four of them are newly discovered (07299−1651, 21306+5540, 22308+5812, 23133+6050), while 05490+2658 is mapped in the CO J=2-1 line for the first time. The detected outflows are much more massive and energetic than outflows from low-mass YSOs with masses >20 M_⊙ and momenta >300 M_⊙ km s⁻¹. They have mass outflow rates (3−6)×10⁻⁴ M_⊙ yr⁻¹, which are at least one order of magnitude greater than those observed in low-mass YSOs. We detect HCO⁺ and SiO line emission in 18 (100%) and 4 (22%) sources, respectively. The HCO⁺ spectra show high-velocity wings in 11 (61%) sources. We detect H₂O maser emission in 13 (72%) sources and 44 GHz CH₃OH maser emission in 8 (44%) sources. Of the detected sources, 5 H₂O and 6 CH₃OH maser sources are new discoveries. 20081+3122 shows high-velocity (>30 km s⁻¹) H₂O maser lines. We find good correlations of the bolometric luminosity of the central (proto)star with the mechanical force, mechanical luminosity, and mass outflow rate of molecular outflow in the bolometric luminosity range of 10⁻¹−10⁶ L_⊙, and identified 3 intermediate- or high-mass counterparts of Class O objects.