A5013379740- Galaxies: Formation, Evolution, Phenomena
- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Astrophysics and Star Formation Studies
- Gamma-ray bursts and supernovae
- Astrophysics and Cosmic Phenomena
- Polymer Nanocomposites and Properties
- Cosmology and Gravitation Theories
- Polymer crystallization and properties
- Scientific Research and Discoveries
- Mental Health Research Topics
- Complex Network Analysis Techniques
- Space Science and Extraterrestrial Life
- Geological and Geochemical Analysis
- Material Dynamics and Properties
- Granular flow and fluidized beds
- Space Exploration and Technology
- Data Visualization and Analytics
- Big Data Technologies and Applications
- Spectroscopy and Chemometric Analyses
- Opportunistic and Delay-Tolerant Networks
- CCD and CMOS Imaging Sensors
- Surfactants and Colloidal Systems
- Dark Matter and Cosmic Phenomena
- Block Copolymer Self-Assembly
Korea Astronomy and Space Science Institute
2020-2022
Korea Institute for Advanced Study
2018-2020
The University of Texas at Austin
2016-2018
Kitt Peak National Observatory
2013-2016
University of Massachusetts Amherst
1975-2013
Spitzer data at 24, 70, and 160 μm ground-based Hα images are analyzed for a sample of 189 nearby star-forming starburst galaxies to investigate whether reliable star formation rate (SFR) indicators can be defined using the monochromatic infrared dust emission centered 70 μm. We compare recently published recipes SFR measures combinations 24 observed luminosities with those luminosity alone. From these comparisons, we derive reference indicator use in our analysis. Linear correlations...
We present new observations of the field containing z=3.786 protocluster, PC217.96+32.3. confirm that it is one largest and most overdense high-redshift structures known. Such are rare even in cosmological simulations. used Mayall/MOSAIC1.1 imaging camera to image a 1.2x0.6 deg area (~150x75 comoving Mpc) surrounding protocluster's core discovered 165 candidate Lyman Alpha emitting galaxies (LAEs) 788 Break (LBGs). There at least 2 regions traced by LAEs, which shows an areal overdensity its...
In this work, we test the conventional assumption that Lyman Alpha Emitting galaxies (LAEs) are experiencing their first major burst of star formation at time observation. To end, identify 74 LAEs from ODIN Survey with rest-UV-through-NIR photometry UVCANDELS. For each LAE, perform non-parametric history (SFH) reconstruction using Dense Basis Gaussian process-based method spectral energy distribution fitting. We find a strong majority (67%) our LAE SFHs align archetype burst, most modest...
Abstract We report the detection of diffuse Ly α emission, or halos (LAHs), around star-forming galaxies at z ≈ 3.78 and 2.66 in NOAO Deep Wide-Field Survey Boötes field. Our samples consist a total ∼1400 galaxies, within two separate regions containing spectroscopically confirmed galaxy overdensities. They provide unique opportunity to investigate how LAH characteristics vary with host large-scale environment physical properties. stack images different defined by these properties measure...
Compared to starburst galaxies, normal star forming galaxies have been shown display a much larger dispersion of the dust attenuation at fixed reddening through studies IRX-beta diagram (the IR/UV ratio "IRX" versus UV color "beta"). To investigate causes this and attempt isolate second parameters, we used GALEX UV, ground-based optical, Spitzer infrared imaging 8 nearby examined properties individual 24 micron selected regions. We concentrated on star-forming regions, in order simpler...
We report the discovery of a large-scale structure containing multiple protoclusters at z = 3.78 in Boötes field. The spectroscopic five galaxies 3.783 ± 0.002 lying within 1 Mpc one another led us to undertake deep narrow- and broadband imaging survey surrounding Within comoving volume 72 × 25 Mpc3, we have identified 65 Lyα emitter (LAE) candidates 3.795 0.015, four additional zspec 3.730, 3.753, 3.780, 3.835. galaxy distribution field is highly non-uniform, exhibiting three large (≈3–5 ×)...
We present Hubble Space Telescope/WFC3 narrow-band imaging of the starburst galaxy M83 targeting hydrogen recombination lines (Hβ, Hα, and Paβ), which we use to investigate dust extinction in H ii regions. derive maps with 6 pc spatial resolution from two combinations (Hα/Hβ Hα/Paβ), show that longer wavelengths probe larger optical depths, AV values by ≳1 mag than those derived shorter wavelengths. This difference leads a factor ≳2 discrepancy extinction-corrected Hα luminosity, significant...
We study the process of panspermia in Milky Way-like galaxies by modeling probability successful travel organic compounds between stars harboring potentially habitable planets. To this end, we apply modified habitability recipe Gobat & Hong (2016) to a model galaxy from MUGS suite zoom-in cosmological simulations. find that, unlike habitability, which only occupies narrow dynamic range over entire galaxy, can vary be orders magnitude inner ($R, b = 1-4 {\rm kpc}$) and outer disk. However,...
We use Spitzer 24 μm, 70 μm and ground-based Hα data for a sample of 40 SINGS galaxies to establish star formation rate (SFR) indicator using emission sub-galactic (∼0.05–2 kpc) line-emitting regions investigate limits in application. A linear correlation between SFR is found SFR(70) proposed as Σ(SFR)(M☉ yr-1 kpc−2) = 9.4 × 10−44 Σ(70)(erg s-1 kpc−2), with 12 + log(O/H) ≳ 8.4 Σ(SFR) 10−3(M☉ 1σ dispersion around the calibration ∼0.16 dex. also discuss influence metallicity on scatter data....
We investigate the properties of feedback-driven shocks in eight nearby starburst galaxies using narrow-band imaging data from Hubble Space Telescope. identify shock-ionized component via line diagnostic diagram [O iii] (λ5007)/Hβ versus [S ii] (λλ6716, 6731) (or [N (λ6583))/Hα, applied to resolved regions 3–15 pc size. divide our sample into three sub-samples: sub-solar, solar, and super-solar, for consistent shock measurements. For sub-solar sub-sample, we derive scaling relations: (1)...
(abridged) The large-scale distribution of galaxies is generally analyzed using the two-point correlation function. However, this statistic does not capture topology distribution, and it necessary to resort higher order correlations break degeneracies. We demonstrate that an alternate approach network analysis can discriminate between topologically different distributions have similar correlations. investigate two galaxy point distributions, one produced by a cosmological simulation other...
Abstract We present a detailed census of galaxies in and around PC 217.96+32.3, spectroscopically confirmed Coma analog at z = 3.78. Diverse galaxy types identified the field include Ly α emitters (LAEs), massive star-forming galaxies, ultramassive ( <?CDATA $\gtrsim {10}^{11}\,{M}_{\odot }$?> ) which may have already halted their star formation. The sky distribution suggests presence significant overdensity δ SFG ≈ 8 ± 2), is spatially offset from previously members by 3–4 Mpc to west....
By utilizing large-scale graph analytic tools implemented in the modern Big Data platform, Apache Spark, we investigate topological structure of gravitational clustering five different universes produced by cosmological $N$-body simulations with varying parameters: (1) a WMAP 5-year compatible $\Lambda$CDM cosmology, (2) two dark energy equation state variants, and (3) cosmic matter density variants. For calculations, use custom build stand-alone Spark/Hadoop cluster at Korea Institute for...
Abstract We investigate the effects of stellar populations and sizes on Ly α escape in 27 spectroscopically confirmed 35 photometric emitters (LAEs) at z ≈ 2.65 seven fields Boötes region NOAO Deep Wide-Field Survey. use deep HST/WFC3 imaging to supplement ground-based observations infer key galaxy properties. Compared typical star-forming galaxies (SFGs) similar redshifts, LAEs are less massive ( M ⋆ 10 7 –10 9 ⊙ ), younger (ages ≲1 Gyr), smaller r e < 1 kpc), dust-attenuated E B − V ) ≤...
We apply simple analyses techniques developed for the study of complex networks to cosmic web, large scale galaxy distribution. In this paper, we measure three network centralities (ranks topological importance), Degree Centrality (DC), Closeness (CL), and Betweenness (BC) from a built Cosmological Evolution Survey (COSMOS) catalog. define 8 populations according centrality measures; Void, Wall, Cluster by DC, Main Branch Dangling Leaf BC, Kernel, Backbone, Fracture CL. also voronoi...
Abstract Values of the anisotropy polarizability methylene groups deduced from refractive indexes n ‐paraffin crystals differ appreciably those obtained gas‐ or liquid‐phase measurements. The differences is attributed to erroneous application Lorenz—Lorentz internal field anisotropic crystal. A more detailed calculation carried out by summation dipolar over an idealized crystal in which molecular chains are replaced rods. With reasonable values parameters and assumed shape, discrepancy resolved.
We investigate the ionization structure of nebular gas in M83 using line diagnostic diagram, [O iii](5007 Å)/Hβ versus [S ii](6716 Å+6731 Å)/Hα, with newly available narrowband images from Wide Field Camera 3 (WFC3) Hubble Space Telescope (HST). produce diagram on a pixel-by-pixel (02 × 02) basis and compare it several photo- shock-ionization models. select four regions center to outer spiral arm them diagram. For photoionized gas, we observe gradual increase log ([O iii]/Hβ) ratios arm,...
The concept of the cosmic web, viewing Universe as a set discrete galaxies held together by gravity, is deeply engrained in cosmology. Yet, little known about most effective construction and characteristics underlying network. Here we explore seven network algorithms that use various galaxy properties, from their location, to size relative velocity, assign distributions provided both simulations observations. We find model relying only on spatial proximity offers best correlations between...
The kinematics of damped Lyman alpha absorbers (DLAs) are difficult to reproduce in hierarchical galaxy formation models, particularly the preponderance wide systems. We investigate DLA at z=3 using high-resolution cosmological hydrodynamical simulations that include a heuristic model for galactic outflows. Without outflows, our fail yield enough DLAs, as previous studies. With predicted much better agreement with observations. Comparing two outflow we find based on momentum-driven wind...
Abstract The calculated stress-optical coefficients obtained using the rotational isomer model and principle of additivity bond polarizability tensors give values segment anisotropy, Δ TSin reasonable agreement with experimental for swollen rubber networks. Furthermore, these agree well those from streaming birefringence studies. Estimates effect ordering in amorphous state upon TS lead to appreciably excess found experimentally. swelling solvent on can be interpreted terms its role...
Abstract A theory is presented to account for the effect of impingement growing spherulites on their H v small‐angle light scattering patterns. The developed basis results computer‐simulated two‐dimensional spherulite growth and calculated scattered intensities. produces a lowering intensity maximum diminishing overall sharpness peak. extent these effects increases with area fraction spherulites. procedure suggested determining correction factors that may be applied data obtained during...
We present an objective method to remove the stellar continuum emission from narrow-band images derive emission-line images. The is based on skewness of pixel histogram residual Specifically, we exploit a transition in signal continuum-subtracted image, which appears when image changes being under-subtracted over-subtracted. Tests one-dimensional artificial demonstrate that identifies optimal scaling factor {\mu} be used broad-band IB order produce line-emission IE, i.e., IE =IN - IB, with...
We report the discovery and spectroscopic confirmation of a very large star-forming galaxy, G6025, at . In rest frame ≈2100 Å, G6025 subtends ≈24 kpc in physical extent when measured from 1.5σ isophote, agreement with parametric size measurements that yield half-light radius 4.9 ± 0.5 semimajor axis 12.5 0.1 kpc. It is also UV-luminous () young (≈140 60 Myr). Despite its unusual luminosity, stellar population parameters dust reddening ( E(B − V) ∼ 0.18 0.05) estimated integrated light are...
We investigate the spatial distribution of Lyman alpha emitting galaxies (LAEs) at $z \approx 2.67$, selected from NOAO Deep Wide-Field Survey (NDWFS), using two-point statistics and topological diagnostics adopted network science. measure clustering length, $r_0 4 h^{-1}$ Mpc, bias, $b_{LAE} = 2.2^{+0.2}_{-0.1}$. Fitting with halo occupation (HOD) models results in two disparate possibilities: (1) where fraction central is $<$1% halos mass $>10^{12}$$M_\odot$; (2) $\approx$20%. refer to...