A5068224067- Astronomy and Astrophysical Research
- Galaxies: Formation, Evolution, Phenomena
- Stellar, planetary, and galactic studies
- Gamma-ray bursts and supernovae
- Astrophysics and Star Formation Studies
- Astrophysical Phenomena and Observations
- Adaptive optics and wavefront sensing
- Astronomical Observations and Instrumentation
- Radio Astronomy Observations and Technology
- Cosmology and Gravitation Theories
- Calibration and Measurement Techniques
- Astrophysics and Cosmic Phenomena
- Impact of Light on Environment and Health
- History and Theory of Mathematics
- CCD and CMOS Imaging Sensors
- Particle physics theoretical and experimental studies
- Plant Water Relations and Carbon Dynamics
- Spectroscopy and Laser Applications
- Scientific Measurement and Uncertainty Evaluation
- Pulsars and Gravitational Waves Research
- Spacecraft and Cryogenic Technologies
- High-Energy Particle Collisions Research
- Quantum Chromodynamics and Particle Interactions
- Reservoir Engineering and Simulation Methods
Saint Mary's University
2022-2024
Herzberg Institute of Astrophysics
2021-2024
University of Ljubljana
2024
St. Mary's University
2022-2023
Tufts University
2016-2022
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...
Abstract We present the wide field slitless spectroscopy mode of NIRISS instrument on James Webb Space Telescope. This employs two orthogonal low-resolution (resolving power ≈150) grisms in combination with a set six blocking filters wavelength range 0.8–2.3 μ m to provide spectrum almost every source across field-of-view. When combined low background, high sensitivity and spatial resolution afforded by telescope, this will enable unprecedented studies structure evolution distant galaxies....
We reliably extend the stellar mass-size relation over $0.2\leq z \leq2$ to low mass galaxies by combining depth of Hubble Frontier Fields (HFF) with large volume covered CANDELS. Galaxies are simultaneously modelled in multiple bands using tools developed MegaMorph project, allowing robust size (i.e., half-light radius) estimates even for small, faint, and high redshift galaxies. show that above 10$^7$M$_\odot$, star-forming well represented a single power law on plane our entire range....
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...
We present Hubble multi-wavelength photometric catalogs, including (up to) 17 filters with the Advanced Camera for Surveys and Wide Field 3 from ultra-violet to near-infrared Frontier Fields associated parallels. have constructed homogeneous catalogs all six clusters their To further expand these data we added ultra-deep $K_{S}$-band imaging at 2.2~\micron\ Very Large Telescope HAWK-I Keck-I MOSFIRE instruments. also add post-cryogenic \spitzer\ 3.6~\micron\ 4.5~\micron\ Infrared Array...
We present the census of massive (log(M$_{*}$/M$_{\odot}$)$\geq 11$) galaxies at $3<z<6$ identified over COSMOS/UltraVISTA Ultra-Deep field stripes: consisting $\approx100$ and $\approx20$ high-confidence candidates $3<z<4$ $4<z<6$, respectively. The population is comprised post-starburst, UV star-forming dusty-star forming in roughly equal fractions, while UV-star-forming dominate $4<z<6$ . account for various sources biases SED modelling, finding that treatment emission line contamination...
We present a new rest-frame color-color selection method using "synthetic $u_s-g_s$ and $g_s-i_s$'', $(ugi)_s$ colors to identify star-forming quiescent galaxies. Our is similar the widely-used $U-V$ versus $V-J$ ($UVJ$) diagram. However, $UVJ$ suffers known systematics. Spectroscopic campaigns have shown that $UVJ$-selected samples at $z \gtrsim 3$ include $\sim 10-30\%$ contamination from galaxies with dust-obscured star formation strong emission lines. Moreover, $z>3$, are extrapolated...
We present JWST/Near Infrared Spectrograph (NIRSpec) integral field spectroscopy (IFS) of a lensed Population III candidate stellar complex (dubbed Lensed And Pristine 1, LAP1), with lensing-corrected mass ≲10 4 M ⊙ and an absolute luminosity UV > −11.2 ( m 35.6), confirmed at redshift 6.639 ± 0.004. The system is strongly amplified μ ≳ 100) by straddling critical line the Hubble Frontier Field galaxy cluster MACS J0416. Although continuum currently not detected in Camera (NIRCam) Near...
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...
We present an overview of the "KIFF" project, which provides ultra-deep Ks-band imaging all six Hubble Frontier Fields clusters Abell 2744, MACS-0416, S1063, 370, MACS-0717 and MACS-1149. All these fields have recently been observed with large allocations Directors' Discretionary Time HST Spitzer telescopes covering 0.4 < lambda 1.6 microns 3.6--4.5 microns, respectively. VLT/HAWK-I integrations first four reach 5-sigma limiting depths Ks~26.0 (AB, point sources) excellent image quality...
Abstract We present a study of the incidence active galactic nucleus (AGN) in sample major merging systems at 0.3 < z 2.5. Galaxies this merger have projected separations between 3 and 15 kpc are selected from CANDELS/3D-Hubble Space Telescope catalogs using peak-finding algorithm. AGNs mergers non-mergers identified on basis their X-ray emission, optical lines, mid-infrared colors, radio emission. Among galaxies with adequate measurements to find potential AGNs, we similar fraction (16.4...
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...
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...