A5032662354- Galaxies: Formation, Evolution, Phenomena
- Gamma-ray bursts and supernovae
- Astronomy and Astrophysical Research
- Astrophysical Phenomena and Observations
- Stellar, planetary, and galactic studies
- Astrophysics and Cosmic Phenomena
- Astronomical Observations and Instrumentation
- Radio Astronomy Observations and Technology
- Astrophysics and Star Formation Studies
- CCD and CMOS Imaging Sensors
- Adaptive optics and wavefront sensing
- Astro and Planetary Science
- Geophysics and Gravity Measurements
- Calibration and Measurement Techniques
- Particle Accelerators and Free-Electron Lasers
- SAS software applications and methods
- Optical Systems and Laser Technology
- Advanced Optical Sensing Technologies
- Infrared Target Detection Methodologies
- Remote Sensing in Agriculture
- Soil Moisture and Remote Sensing
- Particle physics theoretical and experimental studies
- History and Developments in Astronomy
- earthquake and tectonic studies
- Seismology and Earthquake Studies
Seoul National University
2012-2024
Abstract We present the main results from a long-term reverberation mapping campaign carried out for Seoul National University AGN Monitoring Project (SAMP). High-quality data were obtained during 2015–2021 32 luminous active galactic nuclei (AGNs; i.e., continuum luminosity in range of 10 44–46 erg s −1 ) at regular cadence, 20–30 days spectroscopy and 3–5 photometry. obtain time lag measurements between variability H β emission AGNs; 25 those have best based on our quality assessment,...
We present ten medium-resolution, high signal-to-noise ratio near-infrared (NIR) spectra of SN 2011fe from SpeX on the NASA Infrared Telescope Facility (IRTF) and Gemini Near-Infrared Spectrograph (GNIRS) North, obtained as part Carnegie Supernova Project. This data set constitutes earliest time-series NIR spectroscopy a Type Ia supernova (SN Ia), with first spectrum at 2.58 days past explosion covering -14.6 to +17.3 relative B-band maximum. C I {\lambda}1.0693 {\mu}m is detected in...
We present the discovery and extensive early-time observations of Type Ic supernova (SN) PTF12gzk. Our finely sampled light curves show a rise 0.8mag within 2.5hr. Power-law fits [f(t)\sim(t-t_0)^n] to these data constrain explosion date one day. cannot rule out expected quadratic fireball model, but higher values n are possible as well for larger areas in fit parameter space. bolometric curve dense spectral sequence used estimate physical parameters exploding star explosion. that...
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 =...
GRB 090426 is a short duration burst detected by Swift ($T_{90}\sim 1.28$ s in the observer frame, and $T_{90}\sim 0.33$ frame at $z=2.609$). Its host galaxy properties some $\gamma$-ray related correlations are analogous to those seen long GRBs, which believed be of massive-star origin (so-called Type II GRBs). We present results its early optical observations with 0.8-m TNT telescope Xinglong observatory, 1-m LOAO Mt. Lemmon Optical Astronomy Observatory Arizona. Our well-sampled afterglow...
We present a photometric catalog of infrared (IR) sources based on the North Ecliptic PoleWide field (NEP-Wide) survey AKARI, which is an space telescope launched by Japan. The NEP-Wide covered 5.4 deg2 area, nearly circular shape centered Pole, using nine filter-bands from 2 - 25 {\mu}m Infrared Camera (IRC). Extensive efforts were made to reduce possible false objects due cosmic ray hits, multiplexer bleeding phenomena around bright sources, and other artifacts. number detected varied...
We present spectra of 1796 sources selected in the AKARI North Ecliptic Pole Wide Survey field, obtained with MMT/Hectospec and WIYN/Hydra, for which we measure 1645 redshifts. complemented generic flux-limited spectroscopic surveys at 11 μm 15 μm, additional based on MIR optical colors. In observations, redshift identification rates are ∼80% objects R < 21.5 mag. On other hand, WIYN/Hydra magnitudes brighter than 19 The observed were classified through visual inspection or from line...
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...
We present the characteristics of Seoul National University 4k Camera (SNUCAM) and report its performance on 1.5m telescope at Maidanak observatory in Uzbekistan. SNUCAM is a CCD camera with pixel scale 0.266" <TEX>$4096{\times}4096$</TEX> format, covering <TEX>$18.1'{\times}18.1'$</TEX> field view 1.5m. The currently equipped Bessell UBVRI, <TEX>$H{\alpha}$</TEX>, SDSS ugriz, Y-band filters, allowing us to carry out variety scientific programs ranging from exoplanet studies survey quasars...
We present the source catalog and properties of $B-, R-$, $I-$band images obtained to support {\it AKARI} North Ecliptic Pole Wide (NEP-Wide) survey. The NEP-Wide is an infrared imaging survey north ecliptic pole covering a 5.8 deg$^2$ area over 2.5 -- 6 $\micron$ wavelengths. optical data were at Maidanak Observatory in Uzbekistan using Seoul National University 4k $\times$ Camera on 1.5m telescope. These cover 4.9 where no deep are available. Our reach depths $\sim$23.4, $\sim$23.1,...
Several lines of argument support the existence a link between activity at nuclei galaxies, in form an accreting supermassive black hole, and star formation these galaxies. Radio jets have long been argued to be ideal mechanism that allows active galactic (AGNs) interact with their host galaxies affect formation. We use sample radio sources North Ecliptic Pole (NEP) field study nature this putative link, by means spectral energy distribution (SED) fitting. employ excellent coverage AKARI...
Abstract The broad-line region (BLR) size–luminosity relation has paramount importance for estimating the mass of black holes in active galactic nuclei (AGNs). Traditionally, size H β BLR is often estimated from optical continuum luminosity at 5100 Å, while α and its correlation with much less constrained. As a part Seoul National University AGN Monitoring Project, which provides 6 yr photometric spectroscopic monitoring data, we present our measurements lags high-luminosity AGNs. Combined...
We present our successful Chandra program designed to identify, with subarcsecond accuracy, the X-ray afterglow of short GRB 111117A, which was discovered by Swift and Fermi. Thanks rapid target opportunity request, clearly detected afterglow, though no optical found in deep observations. The host galaxy near-infrared band, best photometric redshift (90% confidence), making it one highest known gamma-ray burst (GRB) redshifts. Furthermore, we see an offset 1.0 ± 0.2 arcsec, corresponds 8.4...
We present the J- and H-band source catalog covering AKARI North Ecliptic Pole field. Filling gap between optical data from other follow-up observations mid-infrared (MIR) AKARI, our near-infrared (NIR) provides contiguous wavelength coverage to MIR. For imaging, we used FLoridA Multi-object Imaging Near-ir Grism Observational Spectrometer on Kitt Peak National Observatory 2.1 m telescope a 5.1 deg2 area down 5σ depth of ∼21.6 mag ∼21.3 (AB) for J H bands with an astrometric accuracy 014 017...
We describe the overall characteristics and performance of an optical CCD camera system, Camera for QUasars in EArly uNiverse (CQUEAN), which is being used at 2.1 m Otto Struve Telescope McDonald Observatory since 2010 August. CQUEAN was developed follow-up imaging observations red sources such as high redshift quasar candidates (z >= 5), Gamma Ray Bursts, brown dwarfs, young stellar objects. For efficient objects, has a science with deep depletion chip boasts higher quantum efficiency 0.7 -...
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...
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...
We present the mid-infrared (MIR) properties of galaxies within a supercluster in north ecliptic pole region at z ∼ 0.087 observed with AKARI satellite. use data from NEP-Wide (5.4 deg2) IR survey and CLusters EVoLution studies (CLEVL) mission program. show that near-IR (3 μm)–mid-IR (11 μm) color can be used as an indicator specific star formation rate presence intermediate-age stellar populations. From MIR observations, we find red-sequence consist not only passively evolving red...
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...
We present a wide dataset of gamma-ray, X-ray, UVOIR, and radio observations the Swift GRB100814A. At end slow decline phase X-ray optical afterglow, this burst shows sudden prominent rebrightening in band only, followed by fast decay both bands. The also chromatic evolution. Such puzzling behaviour cannot be explained single component model. discuss other possible interpretations, we find that model incorporates long-lived reverse shock forward fits temporal spectral properties GRB100814A best.
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,...
We present the detection of day-timescale periodic variability in r-band lightcurve newly outbursting FU Orionis-type object HBC 722, taken from > 42 nights observation with CQUEAN instrument on McDonald Observatory 2.1m telescope. The optical/near-IR 722 shows a complex array variability, clustering around 5.8 day (0.044 mag amplitude) and 1.28 (0.016 periods, after removal overall baseline variation. attribute unusual number comparable strength signals to phenomenon related temporary...
We study the host galaxy properties of tidal disruption object Swift J164449.3+573451 using long-term optical to near-infrared (NIR) data. First, we decompose surface brightness distribution and analyze morphology high-resolution Hubble Space Telescope WFC3 images. conclude that is bulge-dominant well described by a single Sérsic model with index . Adding disk component, bulge total flux ratio (B/ T) 0.83 ± 0.03, which still indicates galaxy. Second, estimate multi-band fluxes through light...