Minhee Hyun
A5050438947- Galaxies: Formation, Evolution, Phenomena
- Astronomy and Astrophysical Research
- Gamma-ray bursts and supernovae
- Stellar, planetary, and galactic studies
- Astrophysical Phenomena and Observations
- Radio Astronomy Observations and Technology
- Astrophysics and Cosmic Phenomena
- Astronomical Observations and Instrumentation
- Adaptive optics and wavefront sensing
- Pulsars and Gravitational Waves Research
- CCD and CMOS Imaging Sensors
- Solar and Space Plasma Dynamics
- Particle Accelerators and Free-Electron Lasers
- Image and Signal Denoising Methods
- Seismic Imaging and Inversion Techniques
- Astrophysics and Star Formation Studies
- Particle accelerators and beam dynamics
- Advanced Vision and Imaging
- Geophysics and Gravity Measurements
- SAS software applications and methods
- Satellite Image Processing and Photogrammetry
- Remote Sensing in Agriculture
- GNSS positioning and interference
- Astro and Planetary Science
- Cosmology and Gravitation Theories
Korea Astronomy and Space Science Institute
2021-2024
Seoul National University
2014-2023
We give an overview and describe the rationale, methods, first results from NIRCam images of JWST "Prime Extragalactic Areas for Reionization Lensing Science" ("PEARLS") project. PEARLS uses up to eight filters survey several prime extragalactic areas: two fields at North Ecliptic Pole (NEP); seven gravitationally lensing clusters; high redshift proto-clusters; iconic backlit VV 191 galaxy system map its dust attenuation. also includes NIRISS spectra one NEP NIRSpec high-redshift quasars....
Abstract The James Webb Space Telescope (JWST) North Ecliptic Pole (NEP) Time-domain Field (TDF) is a >14′ diameter field optimized for multiwavelength time-domain science with JWST. It has been observed across the electromagnetic spectrum both from ground and space, including Hubble (HST). As part of HST observations over three cycles (the “TREASUREHUNT” program), deep images were obtained Wide Camera on Advanced Surveys in F435W F606W that cover almost entire JWST NEP TDF. Many...
Recent studies suggest that faint active galactic nuclei may be responsible for the reionization of universe. Confirmation this scenario requires spectroscopic identification quasars (M1450 > −24 mag) at z ≳ 6, but only a very small number such have been spectroscopically identified so far. Here, we report discovery quasar IMS J220417.92+011144.8 ∼ 6 in 12.5 deg2 region SA22 field Infrared Medium-deep Survey (IMS). The spectrum shows sharp break ∼8443 Å, with emission lines redshifted to =...
The James Webb Space Telescope Time-Domain Field (JWST-TDF) is an $\sim$14$'$ diameter field near the North Ecliptic Pole that will be targeted by one of JWST Guaranteed Time Observations programs. Here, we describe our Clerk Maxwell SCUBA-2 850 $\mu$m imaging JWST-TDF and present submillimeter source catalog properties. We also a radio sources from Karl J. Jansky Very Large Array 3 GHz observations field. These were obtained to aid JWST's study dust-obscured galaxies contribute...
Faint $z\sim5$ quasars with $M_{1450}\sim-23$ mag are known to be the potentially important contributors ultraviolet ionizing background in post-reionization era. However, their number density has not been well determined, making it difficult assess role early ionization of intergalactic medium (IGM). In this work, we present updated results our quasar survey using Infrared Medium-deep Survey (IMS), a near-infrared imaging covering an area 85 deg$^{2}$. From spectroscopic observations Gemini...
Abstract The faint quasars with M 1450 > −24 mag are known to hold the key determination of ultraviolet emissivity for cosmic reionization. But only a few have been identified so far because limitations on survey data. Here we present first results z ∼ 5 quasar Infrared Medium-deep Survey (IMS), which covers ∼100 deg 2 areas in J band depths AB 23 mag. To improve selection methods, medium-band follow-up imaging has carried out using SED camera QUasars Early uNiverse (SQUEAN) Otto Struve...
To date, most of the luminous quasars known at $z\sim6$ have been found to be in maximal accretion with Eddington ratios, $\lambda_{\rm{Edd}}\sim1$, suggesting enhanced nuclear activities early universe. However, this may not whole picture supermassive black hole (SMBH) growth since previous studies reached on faint that are more likely harbor SMBHs low $\lambda_{\rm{Edd}}$. gain a better understanding universe, we obtained deep near-infrared (NIR) spectrum quasar, IMS J220417.92+011144.8...
ABSTRACT The ΛCDM cosmological model successfully reproduces many aspects of the galaxy and structure formation universe. However, growth large-scale structures (LSSs) in early universe is not well tested yet with observational data. Here, we have utilized wide deep optical–near-infrared data order to search for distant clusters superclusters (0.8 < z 1.2). From spectroscopic observation Inamori Magellan Areal Camera Spectrograph (IMACS) on telescope, three massive at ∼ 0.91 are confirmed...
Abstract The intergalactic medium (IGM) at z ∼ 5 to 6 is largely ionized, and yet the main source for IGM ionization in early universe uncertain. Of possible contributors are faint quasars with <?CDATA $-26\lesssim {M}_{1450}\lesssim -23$?> , but their number density poorly constrained 5. In this paper, we present our survey of European Large-Area Infrared Space Observatory Survey-North 1 (ELAIS-N1) field over a area 6.51 deg 2 examine if such can be dominant ionization. We use deep...
Black hole mass scaling relations suggest that extremely massive black holes (EMBHs) with $M_\mathrm{BH}\ge10^{9.4}\,M_{\odot}$ are found in the most galaxies $M_\mathrm{star}\ge10^{11.6}\,M_{\odot}$, which commonly dense environments, like galaxy clusters. Therefore, one can expect there is a close connection between active EMBHs and environments. Here, we study environments of 9461 2943 quasars at $0.24 \le z 0.40$, among 52 $\log(M_\mathrm{BH}/M_{\odot}) \ge 9.4$, using Sloan Digital Sky...
We present our first results of the survey for high redshift quasars at $5 \lesssim {\rm z} 5.7$. The search in this range has been known to be challenging due limitations filter sets used previous studies. conducted a quasar two specific ranges, 4.60 $\leq$ z 5.40 and 5.50 6.05, using multi-wavelength data that include observations custom-designed filters, $is$ $iz$. Using these filters new selection technique, we were able reduce fraction interlopers. Through optical spectroscopy,...
Activity at the centers of galaxies, during which central supermassive black hole is accreting material, nowadays accepted to be rather ubiquitous and most probably a phase every galaxy's evolution. It has been suggested that galactic mergers interactions may culprits behind triggering nuclear activity. We use near-infrared data from new Infrared Medium-Deep Survey (IMS) Deep eXtragalactic (DXS) VIMOS-SA22 field radio 1.4 GHz FIRST survey deep VLA study environments radio-AGN over an area...
Multiple color selection techniques are successful in identifying quasars from wide-field broadband imaging survey data. Among the that have been discovered so far, however, there is a redshift gap at 5 ≲ z 5.7 due to limitations of filter sets previous studies. In this work, we present new technique high using sequence medium-band filters: nine filters with central wavelengths 625 1025 nm and bandwidths 50 nm. Photometry these medium-bands traces spectral energy distribution (SED) source,...
We present the result of Infrared Medium-deep Survey (IMS) $z\sim6$ quasar survey, using combination IMS near-infrared images and Canada-France-Hawaii Telescope Legacy (CFHTLS) optical images. The traditional color-selection method results in 25 candidates over $86$ deg$^{2}$. introduce corrected Akaike Information Criterion (AICc) with high-redshift late-type star models to prioritize efficiently. Among color-selected candidates, seven plausible finally passed AICc selection which three are...
We describe the characteristics and performance of a camera system, Spectral energy distribution Camera for Quasars in Early Universe (SQUEAN). It was developed to measure SEDs high redshift quasar candidates (z $\gtrsim$ 5) other targets, e.g., young stellar objects, supernovae, gamma-ray bursts, trace time variability objects such as active galactic nuclei (AGNs). SQUEAN consists an on-axis focal plane module, auto-guiding mechanical supporting structures. The science module is composed...
ABSTRACT High-redshift galaxy clusters, unlike local counterparts, show diverse star formation activities. However, it is still unclear what keeps some of the high-redshift clusters active in formation. To address this issue, we performed a multiobject spectroscopic observation 226 (0.8 < z 1.3) galaxies cluster candidates and areas surrounding them. Our reveals six to eight clusters/groups at ∼ 0.9 1.3. The redshift measurements demonstrate reliability our photometric measurements, which...
Abstract We present near-infrared (NIR) ground-based Y , J H and K imaging obtained in the James Webb Space Telescope (JWST) North Ecliptic Pole Time Domain Field (NEP TDF) using MMT-Magellan Infrared Imager Spectrometer on MMT. These new observations cover a field of approximately 230 arcmin 2 K, 313 . Using Monte Carlo simulations, we estimate 1 σ depth relative to background sky ( Y, J, H, ) = (23.80, 23.53, 23.13, 23.28) AB magnitudes for point sources at 95% completeness level. are part...
Abstract The Time Domain Field (TDF) near the North Ecliptic Pole in JWST’s continuous-viewing zone will become a premier “blank field” for extragalactic science. JWST/NIRCam data 16 arcmin 2 portion of TDF identify 4.4 μ m counterparts 62 63 3 GHz sources with S (3 GHz) > 5 Jy. one unidentified radio source may be lobe nearby Seyfert galaxy, or it an infrared-faint source. bulk properties radio-host galaxies are consistent those found by previous work: redshifts range from 0.14–4.4...
The JWST North Ecliptic Pole (NEP) Time Domain Field (TDF) is a $>$14 arcmin diameter field optimized for multi-wavelength time-domain science with JWST. Its location within JWST's northern continuous viewing zone offers optimal conditions studies JWST, ensuring year-round observability, absence of bright stars, and minimal Zodiacal foreground interference. It has been observed across the electromagnetic spectrum both from ground space, including Hubble Space Telescope (HST). As part HST...
Abstract While galaxy clusters are dominated by quiescent galaxies in the local Universe, they show a wide range fraction (QF) at higher redshifts. Here we present discovery of two z ∼ 0.95 with contrasting QFs despite having similar masses (log ( M 200 / ⊙ ) 14) and spectra redshifts 29 these 76 surrounding area. The found Ultra Deep Survey field confirmed through multiobject spectroscopic observation using Inamori Magellan Areal Camera Spectrograph on telescope. exhibit <mml:math...
Abstract The first public 0.9–4.4 μ m NIRCam images of the North Ecliptic Pole Time Domain Field uncovered galaxies displaying point-source features in their cores as seen longer-wavelength filters. We visually identified a sample 66 (∼1 galaxy arcmin –2 ) with pointlike and have modeled two-dimensional light profiles GalFit , identifying 16 galactic nuclei measurable components. suggests that visual is mix both compact stellar bulge cores. This core classification complemented by spectral...
Multiple color selection techniques have been successful in identifying quasars from wide-field broad-band imaging survey data. Among the that discovered so far, however, there is a redshift gap at $5 \lesssim {\rm z} 5.7$ due to limitations of filter sets previous studies. In this work, we present new technique high using sequence medium-band filters: nine filters with central wavelengths 625 1025 nm and bandwidths 50 nm. Photometry these medium-bands traces spectral energy distribution...
It has been suggested that only the most luminous AGNs (<TEX>$L{\gtrsim}10^{45}erg/s$</TEX>) are triggered by galaxy mergers, while less (<TEX>$L{\sim}10^{43}erg/s$</TEX>) driven other internal processes. The lack of merging features in low luminosity AGN host galaxies a primary argument against idea merger triggering AGNs. But merger, especially rather minor one, might still have played an important role AGNs, as at luminosities more difficult to identify than major features. Using SNUCAM...