Matching Items (4)
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Description

The reionization of the Universe is thought to have completed by redshift z~5.5. To probe this era, galaxy observations in the Subaru Deep Field (SDF) have identified more than 100 galaxies at z~6, many spectroscopically confirmed through follow-up observations. Using available optical/IR data, we model with CIGALE the spectral energy

The reionization of the Universe is thought to have completed by redshift z~5.5. To probe this era, galaxy observations in the Subaru Deep Field (SDF) have identified more than 100 galaxies at z~6, many spectroscopically confirmed through follow-up observations. Using available optical/IR data, we model with CIGALE the spectral energy distributions (SEDs) of 43 SDF galaxies, including newly acquired data from the UKIRT WFCAM K-band for seven previously studied objects. In particular, modeling deep IR photometry is sensitive to the galaxy's Lyman continuum (LyC) escape fraction (fesc). We find the median implied fesc value as ~0.4+/-0.1 (mean error). Significant uncertainties in data and fitting result in a large range of fesc for individual objects, but analysis suggests that fesc is likely high enough for galaxies to finish reionization by z~6. More importantly, we find trends between the CIGALE UV slope b, fesc, and dust extinction E(B-V): for a given E(B-V), b appear steeper by ~0.4 than at z=0. Lower fesc values appear to be associated with bluer b and lower E(B-V), but only weakly. This suggests that LyC could have escaped through holes with sufficiently wide opening angles surrounding the ISM from outflows of supernovae and/or weak AGN to escape, but resulting in a large range of implied fesc values depending on the orientation of each galaxy. The current HST, Spitzer and ground-based photometric and model errors for the 43 galaxies are large, so IR spectroscopic observations with the James Webb Space Telescope are needed to better constrain this possibility.

ContributorsJeon, Junehyoung (Author) / Windhorst, Rogier (Thesis director) / Cohen, Seth (Committee member) / Jansen, Rolf (Committee member) / Department of Physics (Contributor) / School of Earth and Space Exploration (Contributor) / Barrett, The Honors College (Contributor)
Created2021-05
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Description

We present an analysis of the stellar populations of 102 visually selected early-type galaxies (ETGs) with spectroscopic redshifts (0.35 ≲ z ≲ 1.5) from observations in the Early Release Science program with the Wide Field Camera 3 (WFC3) on the Hubble Space Telescope (HST). We fit one- and two-component synthetic

We present an analysis of the stellar populations of 102 visually selected early-type galaxies (ETGs) with spectroscopic redshifts (0.35 ≲ z ≲ 1.5) from observations in the Early Release Science program with the Wide Field Camera 3 (WFC3) on the Hubble Space Telescope (HST). We fit one- and two-component synthetic stellar models to the ETGs UV-optical-near-IR spectral energy distributions and find that a large fraction (∼40%) are likely to have experienced a minor (fYC ≲ 10% of stellar mass) burst of recent (tYC ≲ 1 Gyr) star formation. The measured age and mass fraction of the young stellar populations do not strongly trend with measurements of galaxy morphology. We note that massive (M > 1010.5M☼) recent star-forming ETGs appear to have larger sizes. Furthermore, high-mass, quiescent ETGs identified with likely companions populate a distinct region in the size-mass parameter space, in comparison with the distribution of massive ETGs with evidence of recent star formation (RSF). We conclude that both mechanisms of quenching star formation in disk-like ETGs and (gas-rich, minor) merger activity contribute to the formation of young stars and the size-mass evolution of intermediate redshift ETGs. The number of ETGs for which we have both HST WFC3 panchromatic (especially UV) imaging and spectroscopically confirmed redshifts is relatively small, therefore, a conclusion about the relative roles of both of these mechanisms remains an open question.

ContributorsRutkowski, Michael J. (Author) / Jeong, Hyunjin (Author) / Cohen, Seth (Author) / Kaviraj, Sugata (Author) / Windhorst, Rogier (Author) / Ryan, Russell E. (Author) / Koekemoer, Anton (Author) / Yi, Sukyoung K. (Author) / Hathi, Nimish P. (Author) / Dopita, Michael A. (Author) / College of Liberal Arts and Sciences (Contributor) / School of Earth and Space Exploration (Contributor)
Created2014-12-01
ContributorsBuck, Nancy (Performer) / Ryan, Russell E. (Performer) / Weiss, Stephanie (Performer) / D'Avanzo, Dian (Performer) / ASU Library. Music Library (Publisher)
Created2021-09-26
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Description
Building on the legacies of Planck and the Atacama Cosmology Telescope, among others, future cosmic microwave background (CMB) observatories are poised to revolutionize our understanding of the cosmos by implementing proven detector systems at scales previously incomprehensible. Leading the charge is Simons Observatory (SO), a suite of four telescopes located

Building on the legacies of Planck and the Atacama Cosmology Telescope, among others, future cosmic microwave background (CMB) observatories are poised to revolutionize our understanding of the cosmos by implementing proven detector systems at scales previously incomprehensible. Leading the charge is Simons Observatory (SO), a suite of four telescopes located at 5,200 meters elevation in the Atacama Desert of Chile. With more than 60,000 transition-edge sensor (TES) detectors deployed in six frequency bands across three half-meter telescopes and one 6-meter telescope, SO will observe CMB temperature and polarization at small and large scales with greater sensitivity and control over systematics than has yet been achieved. In deploying more detectors than all other previous CMB experiments combined, SO must also chart new territory in the realm of TES readout. Breakthroughs in microwave multiplexing (μ-mux) readout technology now allow the simultaneous readout of approximately 1,000 detectors on a single set of cables, far surpassing the capabilities of previous systems. For the Large Aperture Telescope’s >30,000 detectors, this translates to a total of just 45 input/output lines. A crucial piece of the SO readout architecture is the Universal Readout Harness (URH), a "plug-and-play" assembly that contains the 300K-4K elements. Configurable to support the readout requirements of each receiver, each URH can support up to 24 readout lines. In addition to the radiofrequency (RF) components, the URH can also support up to 12x50-wire DC cable looms, which provide detector and amplifier power. This dissertation describes the construction and testing of the 6 URHs required for nominal SO operations, as well as the on-site integration of the first Small Aperture Telescope. Separately, an optical stacking analysis of quiescent galaxies at z~1 using images from the Dark Energy Survey is presented. Motivated by a desire to better understand the evolution of massive elliptical galaxies, high signal-to-noise images generated from averaging ~100,000 individual galaxy cutouts are used to calculate surface brightness profiles in the grizY bands. Additionally, the extragalactic background light is derived from these stacks and is found to be in good agreement with previous measurements.
ContributorsMoore, Jenna Elizabeth (Author) / Mauskopf, Philip D (Thesis advisor) / Groppi, Christopher (Committee member) / Scannapieco, Evan (Committee member) / Cohen, Seth (Committee member) / Arnold, Kam (Committee member) / Arizona State University (Publisher)
Created2023