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BLACK HOLE MASS MEASUREMENTS WITH REST-FRAME OPTICAL QUASAR SPECTRA AT 3<z<
Jun, Hyunsung David,Im, Myungshin,Lee, Hyung Mok,AKARI QSONG team, AKARI QSONG team The Korean Astronomical Society 2012 天文學論叢 Vol.27 No.4
We summarize the progress on the rest-frame optical spectroscopy of quasars at 3<z<6, from the AKARI QSONG program. QSONG (Quasar Spectroscopic Observations with NIR Grism) is an AKARI space telescope mission program which utilizes the unique spectroscopic capability in the wavelength range of $2.5-5{\mu}m$. This spectral window has been utilized for detecting redshifted $H{\alpha}$ emission lines of our high redshift subsample of quasars. From the calculated emission line widths and luminosities we measured supermassive black hole masses using well calibrated optical mass estimators. Science topics regarding optical based black hole masses at high-z are discussed.
Kim, Dohyeong,Im, Myungshin,Kim, Ji Hoon,Jun, Hyunsung David,Woo, Jong-Hak,Lee, Hyung Mok,Lee, Myung Gyoon,Nakagawa, Takao,Matsuhara, Hideo,Wada, Takehiko,Oyabu, Shinki,Takagi, Toshinobu,Ohyama, Youic IOP Publishing 2015 The Astrophysical journal Supplement series Vol.216 No.1
<P>We present 2.5-5.0 mu m spectra of 83 nearby (0.002 <z <0.48) and bright (K <14 mag) type-1 active galactic nuclei (AGNs) taken with the Infrared Camera on board AKARI. The 2.5-5.0 mu m spectral region contains emission lines such as Br alpha (2.63 mu m), Bra (4.05 mu m), and polycyclic aromatic hydrocarbons (3.3 mu m), which can be used for studying the black hole (BH) masses and star formation activity in the host galaxies of AGNs. The spectral region also suffers less dust extinction than in the ultra violet (UV) or optical wavelengths, which may provide an unobscured view of dusty AGNs. Our sample is selected from bright quasar surveys of Palomar-Green and SNUQSO, and AGNs with reverberation-mapped BH masses from Peterson et al. Using 11 AGNs with reliable detection of Brackett lines, we derive the Brackett-line-based BH mass estimators. We also find that the observed Brackett line ratios can be explained with the commonly adopted physical conditions of the broad line region. Moreover, we fit the hot and warm dust components of the dust torus by adding photometric data of SDSS, 2MASS, WISE, and ISO to the AKARI spectra, finding hot and warm dust temperatures of similar to 1100K and similar to 220 K, respectively, rather than the commonly cited hot dust temperature of 1500 K.</P>
The Infrared Medium-deep Survey. III. Survey of Luminous Quasars at 4.7 ≤ <i>z</i> ≤ 5.4
Jeon, Yiseul,Im, Myungshin,Kim, Dohyeong,Kim, Yongjung,Jun, Hyunsung David,Pak, Soojong,Taak, Yoon Chan,Baek, Giseon,Choi, Changsu,Choi, Nahyun,Hong, Jueun,Hyun, Minhee,Ji, Tae-Geun,Karouzos, Marios,K Published by the University of Chicago Press for t 2017 The Astrophysical journal Supplement series Vol.231 No.2
<P>We present the first results of our survey for high-redshift quasars at 5 less than or similar to z less than or similar to 5.7. The search for quasars in this redshift range has been known to be challenging due to the limitations of the filter sets used in previous studies. We conducted a quasar survey for two specific redshift ranges, 4.60 <= z <= 5.40 and 5.50 <= z <= 6.05, using multi-wavelength data that include observations made with custom-designed filters, is and iz. Using these filters and a new selection technique, we were able to reduce the fraction of interlopers. Through optical spectroscopy, we confirmed six quasars at 4.7 <= z <= 5.4 with -27.4 < M-1450 < -26.4 that recently were discovered independently by another group. We estimated black hole masses and Eddington ratios of four of these quasars from optical and near-infrared spectra, and found that these quasars are undergoing nearly Eddington-limited accretion that is consistent with the rapid growth of supermassive black holes in luminous quasars at z similar to 5.</P>
THE 3.3 μm POLYCYCLIC AROMATIC HYDROCARBON EMISSION AS A STAR FORMATION RATE INDICATOR
Kim, Ji Hoon,Im, Myungshin,Lee, Hyung Mok,Lee, Myung Gyoon,Jun, Hyunsung David,Nakagawa, Takao,Matsuhara, Hideo,Wada, Takehiko,Oyabu, Shinki,Takagi, Toshinobu,Inami, Hanae,Ohyama, Youichi,Yamada, Rika IOP Publishing 2012 The Astrophysical journal Vol.760 No.2
<P>Polycyclic aromatic hydrocarbon (PAH) emission features dominate the mid-infrared spectra of star-forming galaxies and can be useful to calibrate star formation rates (SFRs) and diagnose ionized states of grains. However, the PAH 3.3 mu m feature has not been studied as much as other PAH features since it is weaker than others and resides outside of Spitzer capability. In order to detect and calibrate the 3.3 mu m PAH emission and investigate its potential as an SFR indicator, we carried out an AKARI mission program, AKARI mJy Unbiased Survey of Extragalactic Sources (AMUSES), and compared its sample with various literature samples. We obtained 2-5 mu m low-resolution spectra of 20 flux-limited galaxies with mixed spectral energy distribution classes, which yielded the detection of the 3.3 mu m PAH emission from 3 out of 20 galaxies. For the combined sample of AMUSES and literature samples, the 3.3 mu m PAH luminosities correlate with the infrared luminosities of star-forming galaxies, albeit with a large scatter (1.5 dex). The correlation appears to break down at the domain of ultraluminous infrared galaxies (ULIRGs), and the power of the 3.3 mu m PAH luminosity as a proxy for the infrared luminosity is hampered at log[L-PAH3.3 erg(-1) s(-1)] > similar to 42.0. Possible origins for this deviation in the correlation are discussed, including contributions from active galactic nuclei and strongly obscured young stellar objects, and the destruction of PAH molecules in ULIRGs.</P>
DISCOVERY OF A FAINT QUASAR AT <i>z</i> ∼ 6 AND IMPLICATIONS FOR COSMIC REIONIZATION
Kim, Yongjung,Im, Myungshin,Jeon, Yiseul,Kim, Minjin,Choi, Changsu,Hong, Jueun,Hyun, Minhee,Jun, Hyunsung David,Karouzos, Marios,Kim, Dohyeong,Kim, Duho,Kim, Jae-Woo,Kim, Ji Hoon,Lee, Seong-Kook,Pak, IOP Publishing 2015 ASTROPHYSICAL JOURNAL LETTERS - Vol.813 No.2
<P>Recent studies suggest that faint active galactic nuclei may be responsible for the reionization of the universe. Confirmation of this scenario requires spectroscopic identification of faint quasars (M-1450 > -24 mag) at z greater than or similar to 6, but only a very small number of such quasars have been spectroscopically identified so far. Here, we report the discovery of a faint quasar IMS J220417.92+011144.8 at z similar to 6 in a 12.5 deg(2) region of the SA22 field of the Infrared Medium-deep Survey (IMS). The spectrum of the quasar shows a sharp break at similar to 8443 angstrom, with emission lines redshifted to z = 5.944 +/- 0.002 and rest-frame ultraviolet continuum magnitude M-1450 = -23.59 +/- 0.10 AB mag. The discovery of IMS J220417.92+011144.8 is consistent with the expected number of quasars at z similar to 6 estimated from quasar luminosity functions based on previous observations of spectroscopically identified low-luminosity quasars. This suggests that the number of M-1450 similar to 23 mag quasars at z similar to 6 may not be high enough to fully account for the reionization of the universe. In addition, our study demonstrates that faint quasars in the early universe can be identified effectively with a moderately wide and deep near-infrared survey such as the IMS.</P>
Discovery of a Faint Quasar at z ~ 6 and Implications for Cosmic Reionization
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 한국천문학회 2016 天文學會報 Vol.41 No.1