L. Y. Aaron Yung
A5058320974- Astronomy and Astrophysical Research
- Galaxies: Formation, Evolution, Phenomena
- Gamma-ray bursts and supernovae
- Stellar, planetary, and galactic studies
- Astrophysics and Star Formation Studies
- Astrophysical Phenomena and Observations
- Adaptive optics and wavefront sensing
- Astronomical Observations and Instrumentation
- CCD and CMOS Imaging Sensors
- Cosmology and Gravitation Theories
- Superconducting and THz Device Technology
- Astrophysics and Cosmic Phenomena
- Particle physics theoretical and experimental studies
- Remote Sensing in Agriculture
- Scientific Research and Discoveries
- History and Developments in Astronomy
- Plant Water Relations and Carbon Dynamics
- Computational Physics and Python Applications
- Statistical and numerical algorithms
- Advanced Vision and Imaging
- Photocathodes and Microchannel Plates
- Spectroscopy and Laser Applications
- Geophysics and Gravity Measurements
- Calibration and Measurement Techniques
- Advanced Fluorescence Microscopy Techniques
Deleted Institution
2021-2025
Goddard Space Flight Center
2021-2025
Space Telescope Science Institute
2024-2025
Mitchell Institute
2024
Texas A&M University
2024
National Postdoctoral Association
2023
Rutgers, The State University of New Jersey
2018-2021
Flatiron Institute
2019-2021
Flatiron Health (United States)
2019-2021
Abstract We present an investigation into the first 500 Myr of galaxy evolution from Cosmic Evolution Early Release Science (CEERS) survey. CEERS, one 13 JWST ERS programs, targets formation z ∼ 0.5 to >10 using several imaging and spectroscopic modes. make use epoch CEERS NIRCam imaging, spanning 35.5 arcmin 2 , search for candidate galaxies at > 9. Following a detailed data reduction process implementing custom steps produce high-quality reduced images, we perform multiband...
We report the discovery of a candidate galaxy with photo-z z~12 in first epoch JWST Cosmic Evolution Early Release Science (CEERS) Survey. Following conservative selection criteria we identify source robust z_phot = 11.8^+0.3_-0.2 (1-sigma uncertainty) m_F200W=27.3, and >7-sigma detections five filters. The is not detected at lambda < 1.4um deep imaging from both HST JWST, has faint ~3-sigma F150W F160W, which signal Ly-alpha break near red edge filters, implying z~12. This object (Maisie's...
Abstract We report the discovery of an accreting supermassive black hole at z = 8.679. This galaxy, denoted here as CEERS_1019, was previously discovered a Ly α -break galaxy by Hubble with redshift from Keck. As part Cosmic Evolution Early Release Science (CEERS) survey, we have observed this source JWST/NIRSpec, MIRI, NIRCam, and NIRCam/WFSS uncovered plethora emission lines. The H β line is best fit narrow plus broad component, where latter measured 2.5 σ FWHM ∼1200 km s −1 . conclude...
Abstract We report on the discovery of two low-luminosity, broad-line active galactic nuclei (AGNs) at z > 5 identified using JWST NIRSpec spectroscopy from Cosmic Evolution Early Release Science (CEERS) survey. detect broad H α emission in spectra both sources, with FWHM 2060 ± 290 km s −1 and 1800 200 , resulting virial black hole (BH) masses that are 1–2 dex below those existing samples luminous quasars 5. The first source, CEERS 2782 = 5.242, is 2–3 fainter than known similar...
Abstract We present the data release and reduction process for Epoch 1 NIRCam observations Cosmic Evolution Early Release Science Survey (CEERS). These consist of imaging in six broadband filters (F115W, F150W, F200W, F277W, F356W F444W) one medium-band filter (F410M) over four pointings, obtained parallel with primary CEERS MIRI observations. reduced JWST Calibration Pipeline, custom modifications steps designed to address additional features challenges data. Here we provide a detailed...
Abstract We present a detailed stellar population analysis of 11 bright ( H < 26.6) galaxies at z = 9–11 (three spectroscopically confirmed) to constrain the chemical enrichment and growth mass early galaxies. use flexible Bayesian spectral energy distribution (SED) fitting code Prospector with range star formation histories (SFHs), dust attenuation law, self-consistent model emission lines. This approach allows us assess how different priors affect our results well we can break...
Abstract We present JWST NIRSpec spectroscopy for 11 galaxy candidates with photometric redshifts of z ≃ 9 − 13 and M UV ∈ [ −21, −18] newly identified in NIRCam images the Cosmic Evolution Early Release Science Survey. confirm emission line 7 galaxies at = 7.762–8.998 using spectra ∼1–5 μ m either prism or its three medium-resolution ( R ∼ 1000) gratings. For candidates, we achieve a high confirmation rate ≃90%, which validates classical dropout selection from photometry. No robust lines...
We present JWST/NIRSpec prism spectroscopy of seven galaxies selected from the Cosmic Evolution Early Release Science Survey (CEERS) NIRCam imaging with photometric redshifts z_phot>8. measure emission line z=7.65 and 8.64 for two galaxies, z=9.77(+0.37,-0.29) 10.01(+0.14,-0.19) others via detection continuum breaks consistent Lyman-alpha opacity a mostly neutral intergalactic medium. The presence (absense) strong (strong lines) give high confidence that these are at z>9.6, but break-derived...
Lyman Break Galaxy (LBG) candidates at z>10 are rapidly being identified in JWST/NIRCam observations. Due to the (redshifted) break produced by neutral hydrogen absorption of rest-frame UV photons, these sources expected drop out bluer filters while well detected redder filters. However, here we show that dust-enshrouded star-forming galaxies lower redshifts (z<7) may also mimic near-infrared (near-IR) colors LBGs, representing potential contaminants LBG candidate samples. First, analyze...
We present the results from a new search for candidate galaxies at z ~ 8.5-11 discovered over 850 arcmin^2 area probed by Cosmic Assembly Near-Infrared Deep Extragalactic Legacy Survey (CANDELS). use photometric redshift selection including both Hubble and Spitzer Space Telescope photometry to robustly identify in this epoch F160W < 26.6. detailed vetting procedure, screening persistence, stellar contamination, inclusion of ground-based imaging, followup space-based imaging build robust...
Abstract We present two bright galaxy candidates at z ∼ 12–13 identified in our H -dropout Lyman break selection with 2.3 deg 2 near-infrared deep imaging data. These candidates, selected after careful screening of foreground interlopers, have spectral energy distributions showing a sharp discontinuity around 1.7 μ m, flat continuum 2–5 and nondetections <1.2 m the available photometric data sets, all which are consistent > 12 galaxy. An ALMA program targeting one shows tentative 4 σ...
We present rest-frame optical emission-line flux ratio measurements for five $z>5$ galaxies observed by the JWST Near-Infared Spectrograph (NIRSpec) in SMACS 0723 Early Release Observations. add several quality-control and post-processing steps to NIRSpec pipeline reduction products order ensure reliable relative calibration of emission lines that are closely separated wavelength, despite uncertain \textit{absolute} spectrophotometry current version reductions. Compared $z\sim3$ literature,...
The new capabilities that JWST offers in the near- and mid-infrared (IR) are used to investigate unprecedented detail nature of optical/near-IR faint, mid-IR bright sources, HST-dark galaxies among them. We gather data from CEERS survey EGS, jointly with HST data, analyze spatially resolved optical-to-mid-IR spectral energy distributions (SEDs) estimate both photometric redshifts 2 dimensions stellar populations properties a pixel-by-pixel basis. select 138 F150W-F356W>1.5 mag, F356W<27.5...
Abstract We present a comprehensive analysis of the evolution morphological and structural properties large sample galaxies at z = 3–9 using early James Webb Space Telescope (JWST) CEERS NIRCam observations. Our consists 850 > 3 detected in both Hubble (HST)/WFC3 JWST/NIRCam images, enabling comparison HST JWST morphologies. conduct set visual classifications, with each galaxy classified three times. also measure quantitative morphologies across all filters. find that have wide diversity...
Abstract We present a sample of 88 candidate z ∼ 8.5–14.5 galaxies selected from the completed NIRCam imaging Cosmic Evolution Early Release Science survey. These data cover ∼90 arcmin 2 (10 pointings) in six broadband filters and one medium-band filter. With this we confirm at higher confidence early JWST conclusions that bright epoch are more abundant than predicted by most theoretical models. construct rest-frame ultraviolet luminosity functions 9, 11, 14 show space density ( M UV = −20)...
Stellar bars are key drivers of secular evolution in galaxies and can be effectively studied using rest-frame near-infrared (NIR) images, which trace the underlying stellar mass less impacted by dust star formation than UV or optical images. We leverage power {\it{JWST}} CEERS NIRCam images to present first quantitative identification characterization at $z>1$ based on NIR F444W high resolution (~1.3 kpc z ~ 1-3). identify these criteria ellipse fits. For this pilot study, we six examples...
ABSTRACT A substantial number of ultra-high redshift (8 ≲ z 17) galaxy candidates have been detected with JWST, posing the question: Are these observational results surprising in context current formation models? We address this question using well-established Santa Cruz semi-analytic models, implemented within merger trees from new suite cosmological N-body simulations gureft, which were carefully designed for studies. Using our fiducial models calibrated at = 0, we present predictions...
Abstract Mid-infrared (mid-IR) observations are powerful in identifying heavily obscured active galactic nuclei (AGN) that have weak emission other wavelengths. Data from the Mid-Infrared Instrument (MIRI) on board James Webb Space Telescope provides an excellent opportunity to perform such studies. We take advantage of MIRI imaging data Cosmic Evolution Early Release Science Survey investigate AGN population distant universe. estimate source properties MIRI-selected objects by utilizing...
Abstract We study a new population of extremely red objects (EROs) recently discovered by the James Webb Space Telescope (JWST) based on their NIRCam colors F277W − F444W > 1.5 mag. find 37 EROs in Cosmic Evolution Early Release Science Survey (CEERS) field with < 28 mag and photometric redshifts between 5 z 7, median <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>z</mml:mi> <mml:mo>=</mml:mo> <mml:msubsup> <mml:mrow> <mml:mn>6.9</mml:mn>...
Abstract We present results from the Cosmic Evolution Early Release Survey on stellar population parameters for 28 galaxies with redshifts 4 < z 9 using imaging data James Webb Space Telescope (JWST) Mid-Infrared Instrument (MIRI) combined Hubble and Spitzer Telescope. The JWST/MIRI 5.6 7.7 μ m extend coverage of rest-frame spectral energy distribution to nearly 1 in this redshift range. By modeling galaxies’ SEDs MIRI show that have, average, UV (1600 Å)— I -band colors 0.4 mag bluer...
Abstract We present a robust sample of very high redshift galaxy candidates from the first epoch JWST/NIRCam imaging Next Generation Deep Extragalactic Exploratory Public (NGDEEP) survey. The NGDEEP NIRCam imaging, spanning 9.7 arcmin 2 in Hubble Ultra Field Parallel 2, reaches m = 30.4 (5 σ , point-source, 2″ diameter apertures corrected to total) F277W, making it deepest public JWST GO data set date. describe our detailed reduction process six-filter broadband incorporating custom...
Abstract We combine deep imaging data from the CEERS early release JWST survey and Hubble Space Telescope CANDELS to examine size–mass relation of star-forming galaxies morphology–quenching at stellar masses M ⋆ ≥ 10 9.5 ⊙ over redshift range 0.5 < z 5.5. In this study with a sample 2450 galaxies, we separate quiescent based on their star formation activity confirm that have different morphologies out = 5.5, extending results earlier studies higher redshifts. find typical Sérsic indices n...
Abstract We present the Next Generation Deep Extragalactic Exploratory Public (NGDEEP) Survey, a deep slitless spectroscopic and imaging Cycle 1 JWST treasury survey designed to constrain feedback mechanisms in low-mass galaxies across cosmic time. NGDEEP targets Hubble Ultra Field (HUDF) with NIRISS spectroscopy ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>f</mml:mi> </mml:mrow> <mml:mi>lim</mml:mi> <mml:mo>,</mml:mo>...
The Epoch of Reionization (EoR) began when galaxies grew in abundance and luminosity, so their escaping Lyman continuum (LyC) radiation started ionizing the surrounding neutral intergalactic medium (IGM). Despite significant recent progress, nature role cosmic reionizers are still unclear: order to define them, it would be necessary directly measure LyC escape fraction ( f esc ). However, this is impossible during EoR due opacity IGM. Consequently, many efforts at low intermediate redshift...
Abstract Visual inspections of the first optical rest-frame images from JWST have indicated a surprisingly high fraction disk galaxies at redshifts. Here, we alternatively apply self-supervised machine learning to explore morphological diversity z ≥ 3. Our proposed data-driven representation scheme galaxy morphologies, calibrated on mock TNG50 simulation, is shown be robust noise and correlate well with physical properties simulated galaxies, including their 3D structure. We method...