A5088208642- Galaxies: Formation, Evolution, Phenomena
- Astronomy and Astrophysical Research
- Stellar, planetary, and galactic studies
- Astrophysics and Star Formation Studies
- Gamma-ray bursts and supernovae
- Adaptive optics and wavefront sensing
- Astrophysical Phenomena and Observations
- Astronomical Observations and Instrumentation
- Astrophysics and Cosmic Phenomena
- Fish Ecology and Management Studies
- Calibration and Measurement Techniques
- Scientific Research and Discoveries
- Particle Accelerators and Free-Electron Lasers
- CCD and CMOS Imaging Sensors
- Pulsars and Gravitational Waves Research
- Spectroscopy and Laser Applications
- Astro and Planetary Science
- Water Quality and Resources Studies
- Radio Astronomy Observations and Technology
- History and Developments in Astronomy
- X-ray Spectroscopy and Fluorescence Analysis
- Optical Systems and Laser Technology
- Cosmology and Gravitation Theories
- Geophysics and Gravity Measurements
- Geomagnetism and Paleomagnetism Studies
University of California, Davis
2017-2025
Emporia State University
2024
Santa Barbara City College
2015-2023
W.M. Keck Observatory
2022
University of Hawaii System
2015-2020
University of California, Santa Barbara
2013-2016
The University of Texas at Austin
2016
California Institute of Technology
2009-2015
University of Hawaiʻi at Mānoa
2015
Oregon Department of Fish and Wildlife
2008-2010
In 1964, Refsdal hypothesized that a supernova whose light traversed multiple paths around strong gravitational lens could be used to measure the rate of cosmic expansion. We report discovery such system. Hubble Space Telescope imaging, we have found four images single forming an Einstein cross configuration redshift z=0.54 elliptical galaxy in MACS J1149.6+2223 cluster. The cluster's potential also creates z=1.49 spiral host galaxy, and future appearance elsewhere cluster field is expected....
The GLASS James Webb Space Telescope Early Release Science (hereafter GLASS-JWST-ERS) Program will obtain and make publicly available the deepest extragalactic data of ERS campaign. It is primarily designed to address two key science questions, namely, "what sources ionized universe when?" "how do baryons cycle through galaxies?", while also enabling a broad variety first look scientific investigations. In primary mode, it NIRISS NIRSpec spectroscopy galaxies lensed by foreground Hubble...
Abstract Detections and non-detections of Lyman alpha (Lyα) emission from z > 6 galaxies (<1 Gyr after the big bang) can be used to measure timeline cosmic reionization. Of key interest measuring reionization’s mid-stages, but also increasing observational challenge, are observations at 7, where Lyα redshifts near infra-red wavelengths. Here we present a search for 7.2 in 53 intrinsically faint Break Galaxy candidates, gravitationally lensed by massive galaxy clusters, KMOS...
Abstract We present the spectroscopic confirmation of a protocluster at z = 7.88 behind galaxy cluster Abell 2744 (hereafter A2744-z7p9OD). Using JWST NIRSpec, we find seven galaxies within projected radius 60 kpc. Although reside in an overdensity around ≳20× greater than random volume, they do not show strong Ly α emission. place 2 σ upper limits on rest-frame equivalent width <16–28 Å. Based tight to emission, constrain volume-averaged neutral fraction hydrogen intergalactic medium be...
We present the first James Webb Space Telescope/NIRCam-led determination of $7<z<9$ galaxy properties based on broadband imaging from 0.8 to 5~$\mathrm{\mu m}$ as part GLASS-JWST Early Release Science program. This is deepest dataset acquired at these wavelengths date, with an angular resolution $\lesssim0.14$ arcsec. robustly identify 13 galaxies $S/N\gtrsim8$ in F444W 8 arcmin$^2$ data $m_{AB}\leq 28$ a combination dropout and photometric redshift selection. From simulated modeling, we...
Abstract We present results on the emission-line properties of z = 1.4–7.5 star-forming galaxies in Assembly Ultradeep Rest-optical Observations Revealing Astrophysics (AURORA) Cycle 1 JWST/NIRSpec program. Based its depth, continuous wavelength coverage from to 5 μ m, and medium spectral resolution ( R ∼ 1000), AURORA includes detections a large suite nebular emission lines spanning broad range rest-frame wavelength. investigate locations multiple different diagrams, including traditional...
Abstract The radial gradient of gas-phase metallicity is a powerful probe the chemical and structural evolution star-forming galaxies, closely tied to disk formation gas kinematics in early Universe. We present spatially resolved dynamical properties for sample 25 galaxies at 0.5 ≲ z 1.7 from MSA-3D survey. These innovative observations provide 3D spectroscopy spatial resolution approaching JWST’s diffraction limit high spectral R ≃ 2700. gradients measured our galaxy range −0.03 0.02 dex...
We present spatially-resolved dynamics for six strongly lensed star-forming galaxies at z=1.7-3.1, each enlarged by a linear magnification factor ~8. Using the Keck laser guide star AO system and OSIRIS integral field unit spectrograph we resolve kinematic morphological detail in our sample with an unprecedented fidelity, some cases achieving spatial resolutions of ~100 pc. With one exception sources have diameters ranging from 1-7 kpc, formation rates 2-40 Msun/yr (uncorrected extinction)...
Nearby dwarf galaxies provide a unique laboratory in which to test stellar population models below $Z_\odot/2$. Such tests are particularly important for interpreting the surprising high-ionization UV line emission detected at $z>6$ recent years. We present HST/COS ultraviolet spectra of ten nearby metal-poor star-forming selected show He II SDSS optical spectra. The targets span nearly dex gas-phase oxygen abundance ($7.8<12+\log\mathrm{O/H}<8.5$) and uniformly large specific star formation...
We present adaptive optics-assisted integral field spectroscopy around the Hα or Hβ lines of 12 gravitationally lensed galaxies obtained with VLT/SINFONI, Keck/OSIRIS and Gemini/NIFS. combine these data previous observations investigate dynamics star formation properties 17 at 1 < z 4. Thanks to gravitational magnification 1.4–90 times by foreground clusters, effective spatial resolutions 40–700 pc are achieved. The also allows us probe lower rates (SFRs) stellar masses than unlensed...
We give an overview of the Grism Lens Amplified Survey from Space (GLASS), a large Hubble Telescope program aimed at obtaining grism spectroscopy fields 10 massive clusters galaxies redshift z = 0.308–0.686, including Frontier Fields (HFF). The Wide Field Camera 3 (WFC3) yields near-infrared spectra cluster cores covering wavelength range 0.81–1.69 μm through grisms G102 and G141, while Advanced for Surveys in parallel mode provides G800L infall regions clusters. WFC3 are taken two almost...
The Grism Lens-Amplified Survey from Space (GLASS) is a Hubble Telescope (HST) Large Program, which will obtain 140 orbits of grism spectroscopy the core and infall regions 10 galaxy clusters, selected to be among very best cosmic telescopes. Extensive HST imaging available many sources including CLASH Frontier Fields programs. We introduce survey by analyzing spectra faint multiply-imaged galaxies $z\gtrsim6$ candidates obtained first seven out fourteen targeting cluster MACS0717.5+3745....
The fraction of ionizing photons that escape from young star-forming galaxies is one the largest uncertainties in determining role cosmic reionization. Yet traditional techniques for measuring this are inapplicable at redshifts interest due to foreground screening by Lyα forest. In an earlier study, we demonstrated a reduction equivalent width low-ionization absorption lines composite spectra Lyman break z ≃ 4 compared similar measures 3. This might imply lower covering neutral gas and hence...
We present and discuss measurements of the gas-phase metallicity gradient in gravitationally lensed galaxies at z=2.0-2.4 based on adaptive optics-assisted imaging spectroscopy with Keck II telescope. Through deep exposures we have secured high signal to noise data for four well-understood kinematic properties. Three well-ordered rotation reveal gradients sense having lower metallicities larger galactocentric radii. Two these display much steeper than found locally, while a third has one...
ABSTRACT We discuss spatially resolved emission line spectroscopy secured for a total sample of 15 gravitationally lensed star-forming galaxies at mean redshift <?CDATA $z\simeq 2$?> <?MML <mml:math> <mml:mi>z</mml:mi> <mml:mo>≃</mml:mo> <mml:mn>2</mml:mn> </mml:math>?> based on Keck laser-assisted adaptive optics observations undertaken with the recently improved OSIRIS integral field unit (IFU) spectrograph. By exploiting sources drawn primarily from CASSOWARY survey, we these sub-L...
Far-ultraviolet (FUV; ~1200-2000 angstroms) spectra are fundamental to our understanding of star-forming galaxies, providing a unique window on massive stellar populations, chemical evolution, feedback processes, and reionization. The launch JWST will soon usher in new era, pushing the UV spectroscopic frontier higher redshifts than ever before, however, its success hinges comprehensive star populations gas conditions that power observed spectral features. This requires level detail is only...
We present the first rest-frame optical size-luminosity relation of galaxies at $z>7$, using NIRCam imaging data obtained by GLASS James Webb Space Telescope Early Release Science (GLASS-JWST-ERS) program, providing deepest extragalactic ERS campaign. Our sample consist 19 photometrically selected bright with $m_\text{F444W}\leq27.8$ $7<z<9$ and $m_\text{F444W}<28.2$ $z\sim9-15$. measure size in 5 bands, from ($\sim4800\,{\rm \AA}$) to ultra-violet (UV; $\sim1600\,{\rm based on S\'ersic...
ABSTRACT The JWST has discovered a surprising abundance of bright galaxy candidates in the very early universe (≤500 Myr after Big Bang), calling into question current formation models. Spectroscopy is needed to confirm primeval nature these candidates, as well understand how first galaxies form stars and grow. Here we present deep spectroscopic continuum ALMA observations towards GHZ2/GLASS-z12, one brightest most robust at z &gt; 10, identified GLASS-JWST Early Release Science Program....
We present the first search for $z\geqslant7$, continuum-confirmed sources with NIRISS/WFS spectroscopy over Abell 2744 Frontier Fields cluster, as part of GLASS-JWST ERS survey. With $\sim15$ hrs pre-imaging and multi-angle grism exposures in F115W, F150W, F200W filters, we describe general data handling (i.e., reduction, cleaning, modeling, extraction processes) analysis showcase power JWST to peer deep into reionization, when most intergalactic hydrogen is neutral, by confirming two...
Star-forming galaxies can exhibit strong morphological differences between the rest-frame far-UV and optical, reflecting inhomogeneities in star-formation dust attenuation. We exploit deep, high resolution NIRCAM 7-band observations to take a first look at morphology of epoch reionization ($z>7$), its variation wavelength range Lyman $\alpha$ 6000-4000\AA, $z=7-12$. find no dramatic variations with -- kind that would have overturned anything we learned from Hubble Space Telescope. No...
We present a rest-frame optical morphological analysis of galaxies observed with the NIRCam imager on James Webb Space Telescope (JWST) as part GLASS-JWST Early Release Science program. select 388 sources at redshifts \(0.8 < z 5.4\) and use seven 0.9--5\micron\ filters to generate $gri$ composite color images, conduct visual classification. Compared HST-based work we find higher incidence disks bulges than expected $z>1.5$, revealed by rest frame imaging. detect 123 clear (58 $z>1.5$) which...
Abstract The abundance of carbon relative to oxygen (C/O) is a promising probe star formation history in the early universe, as ratio changes with time due production these elements by different nucleosynthesis pathways. We present measurement <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>log</mml:mi> <mml:mo stretchy="false">(</mml:mo> <mml:mi mathvariant="normal">C</mml:mi> <mml:mrow> stretchy="true">/</mml:mo> </mml:mrow>...
Abstract Cosmic hydrogen reionization and cosmic production of the first metals are major phase transitions Universe occurring during billion years after Big Bang; however, these still underexplored observationally. Using JWST/NIRSpec prism spectroscopy, we report discovery a sub- L * galaxy at z spec = 8.1623 ± 0.0007, dubbed RX J2129–z8He II , via detection series strong rest-frame UV/optical nebular emission lines clear Lyman break. shows pronounced UV continuum with an extremely steep...
Abstract We present a measurement of the mass–metallicity relation (MZR) at Cosmic Noon, using JWST near-infrared wide-field slitless spectroscopy obtained by GLASS-JWST Early Release Science program. By combining power and lensing magnification foreground cluster A2744, we extend measurements MZR to dwarf mass regime high redshifts. A sample 50 galaxies with several emission lines is identified across two wide redshift ranges z = 1.8–2.3 2.6–3.4 in stellar range <mml:math...