• The Bulletin of The Korean Astronomical Society
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• v.45 no.1
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• pp.32.3-33
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• 2020

Jellyfish galaxies show spectacular features such as star-forming knots and tails due to strong ram-pressure stripping in galaxy clusters. Thus, jellyfish galaxies are very useful targets to investigate the effects of ram-pressure stripping on the star formation activity in galaxies. Integral field spectroscopy (IFS) studies are the best way to study star formation in jellyfish galaxies, but they have been limited to those in low-mass galaxy clusters until now. In this study, we present a Gemini GMOS/IFU study of three jellyfish galaxies in very massive clusters (M_200 > 10^15 Mo). The host clusters (Abell 2744, MACSJ0916.1-0023, and MACSJ1752.0+4440) are X-ray luminous and dynamically unstable, suggesting that ram-pressure stripping in these clusters is much stronger than in low-mass clusters. We present preliminary results of star formation rates, kinematics, dynamical states, and ionization mechanisms of our sample galaxies and discuss how ram-pressure stripping relates with the star formation activity of jellyfish galaxies in massive clusters.

• The Bulletin of The Korean Astronomical Society
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• v.46 no.2
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• pp.43.2-43.2
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• 2021

Ram-pressure stripping (RPS) is known as the main driver of quenching the star formation (SF) activity in cluster galaxies. However, galaxies undergoing RPS in galaxy clusters often show blue star-forming knots in their disturbed disks and tails. The existence of these "jellyfish galaxies" implies that RPS can temporarily boost the SF activity of cluster galaxies. Thus, jellyfish galaxies are very unique and interesting targets to study the influence of RPS on their SF activity, in particular with integral field spectroscopy (IFS). While there have been many IFS studies of jellyfish galaxies in low-mass clusters (e.g., the GASP survey), IFS studies of those in massive clusters have been lacking. We present an IFS study of five jellyfish galaxies in massive clusters at intermediate redshifts using the Gemini GMOS/IFU. Their star formation rates (SFRs) are estimated to be up to 15 Mo/yr in the tails and 50 Mo/yr in the disks. These SFRs are by a factor of 10 higher than those of star-forming galaxies on the main sequence in the M*-SFR relation at similar redshifts. Our results suggest that the SF activity of jellyfish galaxies tends to be more enhanced in massive clusters than in low-mass clusters. This implies that strong RPS in massive clusters can trigger strong starbursts.

• The Bulletin of The Korean Astronomical Society
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• v.46 no.1
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• pp.55.1-55.1
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• 2021

Ram-pressure stripping (RPS) is known as a typical mechanism of quenching star formation (SF) of galaxies orbiting in clusters, but it can also boost the SF activity within a short period of time. Jellyfish galaxies, with eye-catching blue tails and knots, are such starburst galaxies undergoing strong RPS in galaxy clusters. Thus, they are very useful targets to understand their SF activity in relation to RPS. We study the SF activity of three jellyfish galaxies in massive clusters at z=0.3-0.4 (MACSJ1752-JFG2, MACSJ0916-JFG1, and A2744-F0083) with Gemini GMOS/IFU and compare our results to those of jellyfish galaxies in low-mass clusters. We obtain total star formation rates (SFRs) of up to 60 Mo/yr and SFRs in the tails of up to 15 Mo/yr, which are much higher than those of jellyfish galaxies in low-mass clusters with the median SFRs of 1.1 Mo/yr in total and 0.03 Mo/yr in tails. In addition, these SFRs are also significantly higher than the SF main sequence of galaxies at the redshifts of the three jellyfish galaxies. This implies that their SF activity is much more enhanced compared to jellyfish galaxies in low-mass clusters due to extreme RPS in massive clusters.

• Proceedings of the KSME Conference
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• 2005.11a
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• pp.225.2-225.2
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• 2005

• Proceedings of the IEEK Conference
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• 2002.07b
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• pp.1346-1349
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• 2002

This paper presents the design and implementation of 16-QAM modem that can be applied to fixed broadband wireless access systenm. It is implemented in the hardware prototype that consist of FPGA(Field Programmable Gate Array) for digital signal processing and analog front end module for analog signal processing. We provide 20.48Mbps data rate using implemented modem and test the modem in KOREA 26㎓ broadband wireless local loop system including IFU(Intermediate Frequency Unit) and RFU(Radio Frequency Unit) via air interface.

• The Bulletin of The Korean Astronomical Society
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• v.45 no.1
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• pp.53.1-53.1
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• 2020

We present Herschel Space Observatory far-IR observations of the supernova remnant(SNR) G21.5-0.9. We search PACS-IFU data for 63um [O I], 88um [O III], 157um [C II] emission lines and detect the [O II] and the [C II]. We then produce emission line maps to check the spatial distribution of the elements. We compare the maps to Radio, IR-photometrics, and X-ray images in order to understand interaction of the ejecta with the Pulsar Wind Nebula(PWN) and physical environment in the SNR.

• The Bulletin of The Korean Astronomical Society
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• v.46 no.1
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• pp.30.4-31
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• 2021

We will present a scenario of the presence of a second AGN in a nearby Seyfert galaxy, NGC 1068. Using VLT/MUSE IFU data, we investigated the complex kinematics of ionized gas in the central region of NGC 1068. Interestingly, at a distance of 180 pc to the northeast from the nucleus of NGC 1068, we detected a kinematical signature of the launching point of AGN gas outflows, which suggests that there would be a second AGN. We will also discuss another supporting evidence of the second AGN based on previous spectropolarimetric results.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.2
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• pp.29.5-30
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• 2016

(1) The correlation between the mass of supermassive black holes (SMBHs) and the properties of their host galaxies suggests that SMBHs and host galaxies are closely linked in their formation and evolution. While the exact origin of their relationship is still under debate, theoretical models often invoke feedback from active galactic nuclei as a crucial mechanism for establishing the BH-host correlation. In the first part of my talk, I will present our efforts to find observational sign of the AGN feedback in young luminous AGNs. (2) While intermediate-mass black hole (IMBH) is thought be cosmologically important class to understand the link between stellar mass black holes and SMBHs, it is extremely rare in the present-day Universe. In the second part of this talk, I will report a Gemini/GMOS-N IFU study of an ultraluminous X-ray source in NGC 5252, which is a possible candidate of an off-nuclear non-stellar black hole.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.1
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• pp.27.4-27.4
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• 2017

(1) The correlation between the mass of supermassive black holes (SMBHs) and the properties of their host galaxies suggests that SMBHs and host galaxies are closely linked in their formation and evolution. While the exact origin of their relationship is still under debate, theoretical models often invoke feedback from active galactic nuclei as a crucial mechanism for establishing the BH-host correlation. In the first part of my talk, I will present possible observational biases in the BH-host relation, and methods to overcome these biases. I will also report our efforts to find observational sign of the AGN feedback in high-z young luminous AGNs. (2) While intermediate-mass black hole (IMBH) is thought be cosmologically important class to understand the link between stellar mass black holes and SMBHs, it is extremely rare in the present-day Universe. In the second part of this talk, I will report a Gemini/GMOS-N IFU study of an ultraluminous X-ray source in NGC 5252, which is a possible candidate of an off-nuclear non-stellar black hole.

• Publications of The Korean Astronomical Society
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• v.30 no.2
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• pp.163-167
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• 2015

We have carried out integral field unit (IFU) spectroscopy of $H{\alpha}$, [$N{\small{II}}$] and [$O{\small{III}}$] emission lines for a sample of Galactic planetary nebulae (PNe) with Wolf-Rayet (WR) stars and weak emission-line stars (wels). Comparing their spatially-resolved kinematic observations with morpho-kinematic models allowed us to disentangle their three-dimensional gaseous structures. Our results indicate that these PNe have axisymmetric morphologies, either bipolar or elliptical. In many cases the associated kinematic maps for the PNe around hot central stars also reveal the presence of so-called fast low-ionization emission regions.