A5058762546- Astronomy and Astrophysical Research
- Galaxies: Formation, Evolution, Phenomena
- Stellar, planetary, and galactic studies
- Gamma-ray bursts and supernovae
- Astrophysics and Star Formation Studies
- Adaptive optics and wavefront sensing
- Astrophysical Phenomena and Observations
- Astronomical Observations and Instrumentation
- Astrophysics and Cosmic Phenomena
- Calibration and Measurement Techniques
- Nerve injury and regeneration
- Spectroscopy and Laser Applications
- Scientific Measurement and Uncertainty Evaluation
- History and Theory of Mathematics
- High-Energy Particle Collisions Research
- Particle physics theoretical and experimental studies
- Cosmology and Gravitation Theories
- Quantum Chromodynamics and Particle Interactions
- Radio Astronomy Observations and Technology
- CCD and CMOS Imaging Sensors
- Neurogenesis and neuroplasticity mechanisms
- Reservoir Engineering and Simulation Methods
- Impact of Light on Environment and Health
- Spinal Cord Injury Research
Kyoto University
1998-2024
Saint Mary's University
2022-2024
ABSTRACT Early JWST observations that targeted so-called double-break sources (attributed to Lyman and Balmer breaks at z > 7), reported a previously unknown population of very massive, evolved high-redshift galaxies. This surprising discovery led flurry attempts explain these objects’ unexpected existence including invoking alternatives the standard Λ cold dark matter (ΛCDM) cosmological paradigm. To test early results, we adopted same candidate galaxy selection criteria search for...
Abstract We present a new sample of 158 galaxies at redshift z > 7.5 selected from deep James Webb Space Telescope (JWST) NIRCam imaging five widely separated sight lines in the CANUCS survey. Two-thirds pointings and 80% are covered by 12–14 filters, including seven to nine medium bands, providing accurate photometric redshifts robustness against low-redshift interlopers. A 28 with spectroscopic shows low systematic offset scatter difference between redshifts. derive galaxy UV luminosity...
Using data from JWST, we analyze the compact sources ("sparkles") located around a remarkable $z_{\rm spec}=1.378$ galaxy (the "Sparkler") that is strongly gravitationally lensed by $z=0.39$ cluster SMACS J0723.3-7327. Several of these can be cross-identified in multiple images, making it clear they are associated with host galaxy. Combining JWST's {\em Near-Infrared Camera} (NIRCam) archival Hubble Space Telescope} (HST), perform 0.4-4.4$\mu$m photometry on objects, finding several them to...
Abstract We report the discovery of a low-mass z = 5.200 ± 0.002 galaxy that is in process ceasing its star formation. The galaxy, MACS0417-z5BBG, multiply imaged with magnification factors ∼40 by cluster MACS J0417.5-1154, observed as part CAnadian NIRISS Unbiased Cluster Survey (CANUCS). Using observations MACS0417-z5BBG JWST/NIRSpec Prism spectrum and NIRCam imaging, we investigate mechanism responsible for cessation formation speculate about possibilities future. spectrophotometric...
ABSTRACT We present a spectroscopic redshift catalogue of the SMACS J0723.3−7327 field (‘Webb’s First Deep Field’) obtained from JWST/NIRISS grism spectroscopy and supplemented with JWST/NIRSpec VLT/MUSE redshifts. The contains total 190 sources secure redshifts, including 156 NIRISS 123 which are for whose redshifts were previously unknown. These new secured two or more features (64 sources), single spectral feature identity is object’s nine-band photometric (59 sources). complemented 17...
ABSTRACT We use CANUCS JWST/NIRCam imaging of galaxies behind the gravitationally-lensing cluster MACS J0417.5-1154 to investigate star formation burstiness in low-mass (M⋆ ∼ 108 M⊙) at z 4.7–6.5. Our sample 123 is selected using Lyman break selection and photometric emission-line excess methods. Sixty per cent this have Hα-to-UV flux ratios that deviate significantly from range ratio values consistent with smooth steady histories. This large fraction indicates majority experiencing bursty...
Abstract We present measurements of stellar populations properties a z = 9.1 gravitationally lensed galaxy MACS1149-JD1 using deep James Webb Space Telescope NIRISS slitless spectroscopy as well and NIRCam imaging from the CAnadian Unbiased Cluster Survey (CANUCS). The is split into four components. Three magnified ( μ ∼ 11) star-forming components are unresolved, giving intrinsic sizes <25 pc. In addition, underlying extended component contains bulk mass, formed majority its stars ∼50...
Using CANUCS imaging we found an apparent major merger of two $z\sim5$ ultra-low-mass galaxies ($M_\star\sim10^{7}M_\odot$ each) that are doubly imaged and magnified $\sim$12-15$\times$ by the lensing cluster MACS 0417. Both experiencing young ($\sim$100 Myr), synchronised bursts star formation with $\log({\rm sSFR/Gyr^{-1}} )\sim$1.3-1.4, yet SFRs just $\sim 0.2 M_\odot\ {\rm yr}^{-1}$. They have sub-solar ($Z\sim0.2Z_\odot$) gas-phase metallicities connected even more metal-poor...
Abstract We present the first results on spatial distribution of dust attenuation at 1.0 < z 2.4 traced by Balmer decrement, H α /H β , in emission-line galaxies using deep JWST NIRISS slitless spectroscopy from CAnadian Unbiased Cluster Survey (CANUCS). and maps are extracted stacked bins stellar mass for two grism redshift bins, 1.7 2.4. Surface brightness profiles decrement measured radial toward A derived. In both integrated increases with mass. Lower-mass (7.6 ≤ Log( M * / ⊙ ) 10.0)...
Abstract We use JWST/NIRCam medium band photometry in a single pointing of the Canadian NIRISS Unbiased Cluster Survey to identify 118 extreme emission-line galaxies (EELGs) over 1.7 ≲ z 6.7, selected using set color cuts that target with [O iii ] + H β and α emission. show our selections are able select based on EW, which is advantageous more commonly used since it does not require strong continuum emission, can faint or red fluxes. The median EWs sample EW(H ) = 893 Å EW ([O III 1255...
The most distant galaxies detected by JWST are assembling in a Universe that is less than 5\% of its present age. At these times, the progenitors like Milky Way expected to be about 10,000 times massive they now, with masses quite comparable globular clusters seen local Universe. Composed today primarily old stars and correlating properties their parent dark matter halos, first thought have formed during earliest stages galaxy assembly. In this article we explore connection between star...
Abstract Photometrically derived stellar masses are known to suffer from systematic uncertainties, particularly due nebular emission contributions the spectral energy distribution (SED). Using James Webb Space Telescope NIRCam imaging CAnadian NIRISS Unbiased Cluster Survey, we introduce a comparison study of photometrically redshifts and based on two photometric catalogs same field spanning ∼0.4–4.5 μ m: one consisting solely wide band photometry, another employing combination medium...
ABSTRACT The epoch of reionization (EoR) progressed through the emission ionizing photons from galaxies to their local intergalactic medium. In this work, we characterize dwarf star-forming as candidates for source that drove EoR. We investigate properties and star formation histories at last stages EoR $4.8\lt z \lt 7$ using observations CAnadian NIRISS Unbiased Cluster Survey (CANUCS). magnification due gravitational lensing allows us probe large dynamic ranges in stellar mass ($2\times...
The most distant galaxies detected were seen when the Universe was a scant 5% of its current age. At these times, progenitors such as Milky Way about 10,000 times less massive. Using James Webb Space Telescope (JWST) combined with magnification from gravitational lensing, low-mass can not only be but also studied in detail. Here we present JWST observations strongly lensed galaxy at z
We report the discovery of a $z\sim7$ group galaxies that contains two Little Red Dots (LRDs) just 3.3 kpc apart, along with three satellite galaxies, as part Canadian NIRISS Unbiased Cluster Survey (CANUCS). These LRDs are massive ($M_\star\sim10^{10}\,M_\odot$) and dusty (A(V) $>1$ mag) whereas satellites lower-mass objects ($M_\star\sim10^{8-9}\,M_\odot$) subject to low dust attenuations. The spectral energy distributions (SEDs) this LRD pair show strong evidence for Balmer Break,...
We present {\it JWST} observations of a gravitationally-lensed, extremely metal-poor galaxy at redshift $z=8.203\pm 0.001$ from the CANUCS survey. Based on low oxygen to Balmer line ratios we infer gas-phase metallicity $12+{\rm log(O/H)}=6.85$ (1.4\% solar), making CANUCS-A370-z8-LAE most known $z>7$. With high H$\beta$ equivalent width $225\pm50$\,\AA\ and half-light radius only $r_{\rm hl} = 38 ^{+3}_{-19} $\,pc, has star-formation-rate density $50 -...
Strong gravitational lensing in galaxy clusters has become an essential tool astrophysics, as it allows one to directly probe the dark matter distribution and study magnified background sources. The precision reliability of strong models rely heavily on number quality multiple images sources with spectroscopic redshifts. We present updated model cluster MACS J0416.1-2403 largest sample redshifts a field date. Furthermore, we aim demonstrate effectiveness JWST, particularly its NIRISS camera,...
Abstract We present a new analytical model for the attenuation to Epoch of Reionization (EoR) galaxies by proximate neutral hydrogen gas. Many galaxy spectra in EoR taken JWST have shown flux deficit at wavelengths just redward Lyman break, and this has been regarded as resulting from Ly α damping wing absorption increasing amount line sight. However, previous models intergalactic medium (IGM) commonly used photometric redshift template-fitting codes assume that break is rather sharp, which...
We present a methodology for modeling and removing light from cluster galaxies intracluster (ICL) $James\ Webb\ Space\ Telescope$ ($JWST$) images of gravitational lensing clusters. apply our method to Webb's First Deep Field the SMACS 0723 Early Release Observations use ICL subtracted select sample globular clusters (GCs) dwarf within cluster. compare spatial distributions these two samples with models galaxy light, finding significant similarity. Specifically we find that GCs trace diffuse...
We present a new sample of 158 galaxies at redshift $z>7.5$ selected from deep \jwst\ NIRCam imaging five widely-separated sightlines in the CANUCS survey. Two-thirds pointings and 80\% are covered by 12 to 14 filters, including seven nine medium bands, providing accurate photometric redshifts robustness against low interlopers. A 28 with spectroscopic shows systematic offset scatter difference between redshifts. derive galaxy UV luminosity function 8 12, finding slightly higher...
Abstract The most distant galaxies detected by JWST are assembling in a Universe that is less than 5% of its present age. At these times, the progenitors like Milky Way expected to be about 10,000 times massive they now, with masses quite comparable globular clusters seen local Universe. Composed today primarily old stars and correlating properties their parent dark matter halos, first thought have formed during earliest stages galaxy assembly. In this article we explore connection between...
Abstract We present a methodology for modeling and removing light from cluster galaxies intracluster (ICL) James Webb Space Telescope images of gravitational lensing clusters. apply our method to Webb’s First Deep Field the SMACS 0723 Early Release Observations use ICL-subtracted select sample globular clusters (GCs) dwarf within cluster. compare spatial distributions these two samples with models galaxy ICL light, finding significant similarities. In particular, we find that GCs trace...
Abstract CO(2–1) emission is often used as a tracer of giant molecular clouds (GMCs) an alternative to CO(1–0) in recent years. Therefore, understanding the environmental dependence line ratio CO(2–1)/CO(1–0), R 21 , on GMC scale important accurately estimate mass GMCs. We thus measured strongly barred galaxy NGC 1300, where star formation activity depends galactic structure, ∼100 pc scale. CO images were obtained from Atacama Large Millimeter/submillimeter Array and Nobeyama 45 m telescope....
Abstract We search for H α emitters at z ∼ 7.8 in four gravitationally lensed fields observed the Hubble Frontier Fields program. use Lyman break method to select galaxies target redshift and perform photometry Spitzer/IRAC 5.8 μ m band detect emission from candidate galaxies. find no significant detections of counterparts IRAC band, this gives a constraint on luminosity function (LF) 7.8. compare with previous studies based rest-frame UV far-infrared observations using correlation between...
Abstract We present a star formation rate function (SFRF) at z ∼ 4.5 based on photometric data from the rest UV to optical of galaxies in CANDELS GOODS-South field using spectral energy distribution (SED) fitting. evaluate incompleteness our sample and correct for it properly compare SFRF this study with those estimated other probes. The is obtained down ∼10 M ⊙ yr −1 , shows significant excess compared that luminosity dust correction slope. As UV-based SFRF, number density larger by ∼1 dex...