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        검색결과 26

        1.
        2020.10 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Donghoon Son, Jong-Hak Woo, Da-In Eun, Hojin Cho, Marios Karouzos, Songyeon Park
        We analyze the spatially resolved kinematics of gas and stars for a sample of ten hidden type 1 AGNs in order to investigate the nature of their central sources and the scaling relation with host galaxy stellar velocity dispersion. We select our sample from a large number of hidden type 1 AGNs, which are identified based on the presence of a broad (full width at half maximum ≳1000 kms-1) component in the Hα line profile and which are frequently mis-classified as type 2 AGNs 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 Multiple Mirror Telescope to obtain long-slit data with a spatial scale of 0.3 arcsec pixel-1. We detected broad Hβ lines for only two targets; however, the presence of strong broad Hα lines indicates that the AGNs we selected are all low-luminosity type 1 AGNs. We measured the velocity, velocity dispersion, and ux of stellar continuum and gas emission lines (i.e., Hβ and [OIII]) as a function of distance from the center. The spatially resolved gas kinematics traced by Hβ or [OIII] are generally similar to the stellar kinematics except for the inner center, where signatures of gas out ows are detected. We compare the luminosity-weighted effective stellar velocity dispersions with the black hole masses and find that our hidden type 1 AGNs, which have relatively low back hole masses, follow the same scaling relation as reverberation-mapped type 1 AGN and more massive inactive galaxies.
        4,500원
        2.
        2020.10 구독 인증기관·개인회원 무료
        Yongjung Kim, Myungshin Im, Yiseul Jeon, Minjin Kim, Soojong Pak, Minhee Hyun, Yoon Chan Taak, Suhyun Shin, Gu Lim, Gregory S. H. Paek, Insu Paek, Linhua Jiang, Changsu Choi, Jueun Hong, Tae-Geun Ji, Hyunsung D. Jun, Marios Karouzos, Dohyeong Kim, Duho Kim, Jae-Woo Kim, Ji Hoon Kim, Hye-In Lee, Seong-Kook Lee, Won-Kee Park, Yongmin Yoon, Seoyeon Byeon, Sungyong Hwang, Joonho Kim, Sophia Kim, Woojin Park
        3.
        2019.08 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Jong-Hak Woo, Donghoon Son, Elena Gallo, Edmund Hodges-Kluck, Yiseul Jeon, Jaejin Shin, Hyun-Jin Bae, Hojin Cho, Wanjin Cho, Daeun Kang, Wonseok Kang, Marios Karouzos, Minjin Kim, Taewoo Kim, Huynh Anh N. Le, Daeseong Park, Songyoun Park, Suvendu Rakshit, Hyun-il Sung
        While the reverberation mapping technique is the best available method for measuring black hole mass in active galactic nuclei (AGNs) beyond the local volume, this method has been mainly applied to relatively low-to-moderate luminosity AGNs at low redshift. We present the strategy of the Seoul National University AGN Monitoring Project, which aims at measuring the time delay of the Hβ line emission with respect to AGN continuum, using a sample of relatively high luminosity AGNs out to redshift z ∼ 0.5. We present simulated cross correlation results based on a number of mock light curves, in order to optimally determine monitoring duration and cadence. We describe our campaign strategy based on the simulation results and the availability of observing facilities. We present the sample selection, and the properties of the selected 100 AGNs, including the optical luminosity, expected time lag, black hole mass, and Eddington ratio.
        4,200원
        4.
        2019.04 구독 인증기관·개인회원 무료
        Rongxin Luo, Jong-Hak Woo, Jaejin Shin, Daeun Kang, Hyun-Jin Bae, Marios Karouzos
        5.
        2018.10 구독 인증기관·개인회원 무료
        Suhyun Shin, Myungshin Im, Yongjung Kim, Minhee Hyun, Yiseul Jeon, Tae-Geun Ji, Seoyeon Byeon, Woojin Park, Hojae Ahn, Yoon Chan Taak, Sophia Kim, Gu lim, Sungyong Hwang, Insu Paek, Gregory Paek, Minjin Kim, Dohyeong Kim, Jae-Woo Kim, Yongmin Yoon, Changsu Choi, Jueun Hong, Hyunsung David Jun, Marios Karouzos, Duho Kim, Ji Hoon Kim, Seong-Kook Lee, Soojong Pak, Won-Kee Park
        6.
        2018.08 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Joonho Kim, Marios Karouzos, Myungshin Im, Changsu Choi, Dohyeong Kim, Hyunsung D. Jun, Joon Hyeop Lee, Mar Mezcua
        Active Galactic Nucleus (AGN) variability can be used to study the physics of the region in the vicinity of the central black hole. In this paper, we investigated intra-night optical variability of AGN in the COSMOS field in order to understand the AGN instability at the smallest scale. Observations were performed using the KMTNet on three separate nights for 2.5 to 5 hours at a cadence of 20 to 30 min. We find that the observation enables the detection of short-term variability as small as ∼ 0.02 and 0.1 mag for R ∼ 18 and 20 mag sources, respectively. Using four selection methods (X-rays, mid-infrared, radio, and matching with SDSS quasars), 394 AGN are detected in the 4 deg2 field of view. After differential photometry and X2−test, we classify intra-night variable AGN. The fraction of variable AGN (0–8%) is statistically consistent with a null result. Eight out of 394 AGN are found to be intra-night variable in two filters or two nights with a variability level of 0.1 mag, suggesting that they are strong candidates for intra-night variable AGN. Still they represent a small population (2%). There is no sub-category of AGN that shows a statistically significant intra-night variability.
        5,800원
        7.
        2018.04 구독 인증기관·개인회원 무료
        Suhyun Shin, Myungshin Im, Yongjung Kim, Minhee Hyun, Woojin Park, Tae-geun Ji, Yiseul Jeon, Minjin Kim, Dohyeong Kim, Jae-Woo Kim, Yoon Chan Taak, Yongmin Yoon, Changsu Choi, Jueun Hong, Hyunsung David Jun, Marios Karouzos, Duho Kim, Ji Hoon Kim, Seong-Kook Lee, Soojong Pak, Won-Kee Park
        8.
        2017.10 구독 인증기관·개인회원 무료
        Suhyun Shin, Myungshin Im, Yongjung Kim, Minhee Hyun, Yiseul Jeon, Minjin Kim, Dohyeong Kim, Jae-Woo Kim, Yoon Chan Taak, Yongmin Yoon, Changsu Choi, Jueun Hong, Hyunsung David Jun, Marios Karouzos, Duho Kim, Ji Hoon Kim, Seong-Kook Lee, Soojong Pak, Won-Kee Park
        9.
        2017.10 구독 인증기관·개인회원 무료
        Yongjung Kim, Myungshin Im, Yiseul Jeon, Minjin Kim, Minhee Hyun, Dohyeong Kim, Jae-Woo Kim, Yoon Chan Taak, Yongmin Yoon, Changsu Choi, Jueun Hong, Hyunsung David Jun, Marios Karouzos, Duho Kim, Ji Hoon Kim, Seong-Kook Lee, Soojong Pak, Won-Kee Park
        10.
        2017.04 구독 인증기관·개인회원 무료
        Joonho Kim, Marios Karouzos, Myungshin Im, Dohyeong Kim, Hyunsung David Jun, Joon Hyeop Lee, Mar Mezcua Pallerola
        11.
        2017.04 구독 인증기관·개인회원 무료
        Hyun-Jin Bae, Jong-Hak Woo, Marios Karouzos, Elena Gallo, Helene Flohic, Yue Shen, Suk-Jin Yoon
        12.
        2017.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Laia Barrufet de Soto, Glenn J. White, Chris Pearson, Stephen Serjeant, Tanya Lim, Hideo Matsuhara, Nagisa Oi, Marios Karouzos, AKARI-NEP Team
        The AKARI North Ecliptic Pole Deep Field is a natural location to accomplish deep extragalactic surveys. It is supported by comprehensive ancillary data extending from radio to X-ray wavelengths, which have been used to classify radio sources as radio-loud and radio-quiet objects and to create a catalogue of Active Galactic Nuclei (AGN). This has been achieved by using a radio-optical classification and colour- colour diagrams rather than the more usual way based on spectroscopy Furthermore, we explore whether this technique can be extended by using a far-Infrared (FIR) colour-colour diagram which has been used to identify 268 high redshift candidates.
        3,000원
        13.
        2017.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Laia Barrufet, Glenn J. White, Chris Pearson, Stephen Serjeant, Tanya Lim, Hideo Matsuhara, Nagisa Oi, Marios Karouzos, AKARI-NEP Team
        We report the results of a multi-wavelength study in the North Ecliptic Pole (NEP) deep field and examine the far infrared-radio correlation (FIRC) for high and low redshift objects. We have found a correlation between the GMRT data at 610 MHz and the Herschel data at 250μm that has been used to define a spectral index. This spectral index shows no evolution against redshift. As a result of the study, we show a radio colour-infrared diagram that can be used as a redshift indicator.
        3,000원
        14.
        2017.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Glenn J. White, Laia Barrufet de Soto, Chris Pearson, Stephen Serjeant, Tanya Lim, Hideo Matsuhara, S.K.Sirothia, S.Pal, Marios Karouzos, AKARI-NEP Team
        We have imaged the AKARI Deep Field with the GMRT radio telescope at 610 MHz, detecting 1224 radio components, which are optically identified with 455 optical galaxies having a mean r0 magnitude brighter of 22.5 (to a completeness limit of 25.4 mag), and an average redshift ~ 0.8.
        3,000원
        15.
        2017.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Tomotsugu Goto, Yoshiki Toba, Yousuke Utsumi, Nagisa Oi, Toshinobu Takagi, Matt Malkan, Youichi Ohayma, Kazumi Murata, Paul Price, Marios Karouzos, Hideo Matsuhara, Takao Nakagawa, Takehiko Wada, Steve Serjeant, Denis Burgarella, Veronique Buat, Masahiro Takada, Satoshi Miyazaki, Masamune Oguri, Takamitsu Miyaji, Shinki Oyabu, Glenn White, Tsutomu Takeuchi, Hanae Inami, Chris Perason, Katarzyna Malek, Lucia Marchetti, Lee HyungMoK, Myung Im, Seong Jin Kim, Ekaterina Koptelova, Dani Chao, Yi-Han Wu, AKARI NEP Survey team, AKARI All Sky Survey Team
        The extragalactic background suggests half the energy generated by stars was reprocessed into the infrared (IR) by dust. At z1.3, 90% of star formation is obscured by dust. To fully understand the cosmic star formation history, it is critical to investigate infrared emission. AKARI has made deep mid-IR observation using its continuous 9-band filters in the NEP field (5.4 deg2), using 10% of the entire pointed observations available throughout its lifetime. However, there remain 11,000 AKARI infrared sources undetected with the previous CFHT/Megacam imaging (r ~25.9ABmag). Redshift and IR luminosity of these sources are unknown. These sources may contribute signi cantly to the cosmic star-formation rate density (CSFRD). For example, if they all lie at 1< z <2, the CSFRD will be twice as high at the epoch. We are carrying out deep imaging of the NEP eld in 5 broad bands (g; r; i; z; and y) using Hyper Suprime-Camera (HSC), which has 1.5 deg field of view in diameter on Subaru 8m telescope. This will provide photometric redshift information, and thereby IR luminosity for the previously-undetected 11,000 faint AKARI IR sources. Combined with AKARI's mid-IR AGN/SF diagnosis, and accurate mid- IR luminosity measurement, this will allow a complete census of cosmic star-formation/AGN accretion history obscured by dust.
        4,000원
        16.
        2017.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Marios Karouzos, Myungshin Im, Markos Trichas, Tomogotsu Goto, Matthew Malkan, Angel Ruiz, Yiseul Jeon, Ji Hoon Kim, Hyung Mok Lee, Seong Jin Kim, Nagisa Oi, Hideo Matsuhara, Toshinobu Takagi, Kazumi Murata, Takehiko Wada, Kensuke Wada, Hyunjin Shim, Hitoshi Hanami, Stephen Serjeant, Youichi Ohyama
        There exists strong evidence supporting the co-evolution of central supermassive black holes and their host galaxies; however it is still under debate how such a relation comes about and whether it is relevant for all or only a subset of galaxies. An important mechanism connecting AGN to their host galaxies is AGN feedback, potentially heating up or even expelling gas from galaxies. AGN feedback may hence be responsible for the eventual quenching of star formation and halting of galaxy growth. A rich multi- wavelength dataset ranging from the X-ray regime (Chandra), to far-IR (Herschel), and radio (WSRT) is available for the North Ecliptic Pole field, most notably surveyed by the AKARI infrared space telescope, covering a total area on the sky of 5.4 sq. degrees. We investigate the star formation properties and possible signatures of radio feedback mechanisms in the host galaxies of 237 radio sources below redshift z = 2 and at a radio 1.4 GHz ux density limit of 0.1 mJy. Using broadband SED modelling, the nuclear and host galaxy components of these sources are studied simultaneously as a function of their radio luminosity. Here we present results concerning the AGN content of the radio sources in this eld, while also offering evidence showcasing a link between AGN activity and host galaxy star formation. In particular, we show results supporting a maintenance type of feedback from powerful radio-jets.
        3,000원
        17.
        2016.10 구독 인증기관·개인회원 무료
        Joonho Kim, Marios Karouzos, Myungshin Im, Dohyeong Kim, Hyunsung Jun, Joon Hyeop Lee, Mar Mezcua Pallerola
        18.
        2016.04 구독 인증기관·개인회원 무료
        Joonho Kim, Marios Karouzos, Myungshin Im
        19.
        2016.04 구독 인증기관·개인회원 무료
        Marios Karouzos, Jong-Hak Woo, Hyun-Jin Bae
        20.
        2016.04 구독 인증기관·개인회원 무료
        Yongjung Kim, Myungshin Im, Yiseul Jeon, Minjin Kim, Changsu Choi, Jueun Hong, Minhee Hyun, Hyunsung David Jun, Marios Karouzos, Dohyeong Kim, Duho Kim, Jae-Woo Kim, Ji Hoon Kim, Seong-Kook Lee, Soojong Pak, Won-Kee Park, Yoon Chan Taak, Yongmin Yoon
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