Astrophysics and Astronomy Commons^™

A Theoretical Study Of Elementary Processes In Interstellar Plasma, Joshua Forer

Graduate Thesis and Dissertation 2023-2024

Interstellar plasma — interstellar clouds in particular — play an important role in determining the structure and evolution of galaxies. Understanding the time evolution of such plasmas requires knowledge of the chemical processes that drive their dynamics. Two processes are studied in this dissertation: radiative electron attachment (REA) via dipole-bound states (DBSs) and dissociative recombination (DR). Of the several hundred molecules detected in the interstellar medium, only eight anions have been detected: CN-, C3N-, C5N-, C7N-, C4H-, C6H-, C8H-, and C10H-. Their production mechanism is not well known; REA was suggested as a possible formation pathway, but previous theoretical studies …

Astronomy 102 Lab: The Celestial Sphere And Coordinates, Katrina Powers

A with Honors Projects

An astronomy lab that explores introductory topics such as the celestial sphere, celestial coordinates, proper motion, and the impact of time on the location of stars in our sky. This lab is designed to be used on the program Stellarium.

A Literary Analysis Of The Oort Cloud: Summarising Its History And Proposing A Mission To Image Oort Cloud Objects, Avital Keeley

Senior Honors Theses and Projects

The Oort Cloud was hypothesised in 1950 but has lost popularity as a research topic. This literary research summarises the most notable articles and simulations on the Oort Cloud with an analysis on the outdated simulations and assumptions. Finally, this research conflates the hypothesised values of Oort Cloud parameters to calculate the required specifications of instrumentation needed to image an Oort Cloud Object, and a rough budget is proposed of $5 million to launch a 35 km interferometer.

Azimuthal Anisotropy Measurement Of (Multi)Strange Hadrons In Au+Au Collisions At √S Nn = 54.4 Gev, Star Collaboration

Physics and Astronomy Faculty Publications

Azimuthal anisotropy of produced particles is one of the most important observables used to access the collective properties of the expanding medium created in relativistic heavy-ion collisions. In this paper, we present second (v2) and third (v3) order azimuthal anisotropies of KS0, φ, Λ, Ξ, and ω at midrapidity (|y|< 1) in Au+Au collisions at sNN=54.4 GeV measured by the STAR detector. The v2 and v3 are measured as a function of transverse momentum and centrality. Their energy dependence is also studied. v3 is found to be more sensitive to the change in the center-of-mass energy than v2. Scaling by constituent quark number is found to hold for v2 within 10%. This observation could be evidence for the development of partonic collectivity in 54.4 GeV Au+Au collisions. Differences in v2 and v3 between baryons and antibaryons are presented, and ratios of v3/v23/2 are studied and motivated by hydrodynamical calculations. The ratio of v2 of φ mesons to that of antiprotons [v2(φ)/v2(p¯)] shows centrality dependence at low transverse momentum, presumably resulting from the larger effects from hadronic interactions on antiproton v2.

Gauging The Mass Of Metals In The Gas Phase Of Galaxies From The Local Universe To The Epoch Of Reionization, K. E. Heintz, Alice E. Shapley, Ryan L. Sanders, M. Killi, D. Watson, G. Magdis, F. Valentino, M. Ginolfi, D. Narayanan, T. R. Greve, J. P. U. Fynbo, D. Vizgan, S. N. Wilson

Physics and Astronomy Faculty Publications

The chemical enrichment of dust and metals are vital processes in constraining the star formation history of the universe. These are important ingredients in the formation and evolution of galaxies overall. Previously, the dust masses of high-redshift star-forming galaxies have been determined through their far-infrared continuum, however, equivalent, and potentially simpler, approaches to determining the metal masses have yet to be explored at z ≳ 2. Here, we present a new method of inferring the metal mass in the interstellar medium (ISM) of galaxies out to z 8, using the far-infrared [C II]- 158† μm emission line as a proxy. …

Jwst/Nirspec Balmer-Line Measurements Of Star Formation And Dust Attenuation At Z ∼ 3–6, Alice E. Shapley, Ryan L. Sanders, Naveen Reddy, Michael W. Topping, Gabriel B. Brammer

Physics and Astronomy Faculty Publications

We present an analysis of the star formation rates (SFRs) and dust attenuation properties of star-forming galaxies at 2.7 ≤ z < 6.5 drawn from the Cosmic Evolution Early Release Science Survey. Our analysis is based on JWST/NIRSpec Micro-Shutter Assembly R ∼ 1000 spectroscopic observations covering approximately 1-5 μm. Our primary rest-frame optical spectroscopic measurements are Hα/Hβ Balmer decrements, which we use as an indicator of nebular dust attenuation. In turn, we use Balmer decrements to obtain dust-corrected Hα-based SFRs (i.e., SFR(Hα)). We construct the relationship between SFR(Hα) and stellar mass (M _*) in three bins of redshift (2.7 ≤ z < 4.0, 4.0 ≤ z < 5.0, and 5.0 ≤ z < 6.5), which represents the first time the star-forming main sequence has been traced at these redshifts using direct spectroscopic measurements of Balmer emission as a proxy for SFR. In tracing the relationship between SFR(Hα) and M _* back to such early times (z > 3), it is essential to use a conversion factor between Hα and SFR that accounts for the subsolar metallicity prevalent among distant galaxies. We also use measured Balmer decrements to investigate the relationship between dust attenuation and stellar mass out to z ∼ 6. The lack of significant redshift evolution in attenuation at fixed stellar mass, previously confirmed using Balmer decrements out …

Azimuthal Anisotropy Measurement Of (Multi)Strange Hadrons In Au+Au Collisions At √𝑠𝑁⁢𝑁=54.4 Gev, Star Collaboration

Physics and Astronomy Faculty Publications

Azimuthal anisotropy of produced particles is one of the most important observables used to access the collective properties of the expanding medium created in relativistic heavy-ion collisions. In this paper, we present second (v2) and third (v3) order azimuthal anisotropies of KS0, φ, Λ, Ξ, and ω at midrapidity (|y|< 1) in Au+Au collisions at sNN=54.4 GeV measured by the STAR detector. The v2 and v3 are measured as a function of transverse momentum and centrality. Their energy dependence is also studied. v3 is found to be more sensitive to the change in the center-of-mass energy than v2. Scaling by constituent quark number is found to hold for v2 within 10%. This observation could be evidence for the development of partonic collectivity in 54.4 GeV Au+Au collisions. Differences in v2 and v3 between baryons and antibaryons are presented, and ratios of v3/v23/2 are studied and motivated by hydrodynamical calculations. The ratio of v2 of φ mesons to that of antiprotons [v2(φ)/v2(p¯)] shows centrality dependence at low transverse momentum, presumably resulting from the larger effects from hadronic interactions on antiproton v2.

Beam Energy Dependence Of Fifth- And Sixth-Order Net-Proton Number Fluctuations In Au + Au Collisions At Rhic, Star Collaboration

Physics and Astronomy Faculty Publications

We report the beam energy and collision centrality dependence of fifth and sixth order cumulants (C5, C6) and factorial cumulants (κ5, κ6) of net-proton and proton number distributions, from center-of-mass energy (sNN) 3 GeV to 200 GeV Au+Au collisions at RHIC. Cumulant ratios of net-proton (taken as proxy for net-baryon) distributions generally follow the hierarchy expected from QCD thermodynamics, except for the case of collisions at 3 GeV. The measured values of C6/C2 for 0%-40% centrality collisions show progressively negative trend with decreasing energy, while it is positive for the lowest energy studied. These observed negative signs are consistent with …

Measurement Of Sequential ϒ Suppression In Au + Au Collisions At √Snn = 200 Gev With The Star Experiment, Star Collaboration

Physics and Astronomy Faculty Publications

We report on measurements of sequential ϒ suppression in Au+Au collisions at sNN=200 GeV with the STAR detector at the Relativistic Heavy Ion Collider (RHIC) through both the dielectron and dimuon decay channels. In the 0%-60% centrality class, the nuclear modification factors (RAA), which quantify the level of yield suppression in heavy-ion collisions compared to p+p collisions, for ϒ(1S) and ϒ(2S) are 0.40±0.03(stat)±0.03(sys)±0.09(norm) and 0.26±0.08(stat)±0.02(sys)±0.06(norm), respectively, while the upper limit of the ϒ(3S) RAA is 0.17 at a 95% confidence level. This provides experimental evidence that the ϒ(3S) is significantly more suppressed than the ϒ(1S) at RHIC. The level of …

Measurementus Magnetic Moment To 0.20 Ppm Of The Positive Muon Anomalo, The Muon G − 2 Collaboration

Physics and Astronomy Faculty Publications

We present a new measurement of the positive muon magnetic anomaly, aμ(gμ-2)/2, from the Fermilab Muon g-2 Experiment using data collected in 2019 and 2020. We have analyzed more than 4 times the number of positrons from muon decay than in our previous result from 2018 data. The systematic error is reduced by more than a factor of 2 due to better running conditions, a more stable beam, and improved knowledge of the magnetic field weighted by the muon distribution, p′, and of the anomalous precession frequency corrected for beam dynamics effects, ωa. From the ratio ωa/p′, together with precisely …

Ai-Assisted Optimization Of The Ecce Tracking System At The Electron Ion Collider, C. Fanelli, Z. Papandreou, K. Suresh

Physics and Astronomy Faculty Publications

The Electron-Ion Collider (EIC) is a cutting-edge accelerator facility that will study the nature of the ‘‘glue’’ that binds the building blocks of the visible matter in the universe. The proposed experiment will be realized at Brookhaven National Laboratory in approximately 10 years from now, with detector design and R&D currently ongoing. Notably, EIC is one of the first large-scale facilities to leverage Artificial Intelligence (AI) already starting from the design and R&D phases. The EIC Comprehensive Chromodynamics Experiment (ECCE) is a consortium that proposed a detector design based on a 1.5 T solenoid. The EIC detector proposal review concluded …

Scientific Computing Plan For The Ecce Detector At The Electron Ion Collider, J. C. Bernauer, C. T. Dean, C. Fanelli, J. Huang, K. Kauder, D. Lawrence, J. D. Osborn

Physics and Astronomy Faculty Publications

The Electron Ion Collider (EIC) is the next generation of precision QCD facility to be built at Brookhaven National Laboratory in conjunction with Thomas Jefferson National Laboratory. There are a significant number of software and computing challenges that need to be overcome at the EIC. During the EIC detector proposal development period, the ECCE consortium began identifying and addressing these challenges in the process of producing a complete detector proposal based upon detailed detector and physics simulations. In this document, the software and computing efforts to produce this proposal are discussed; furthermore, the computing and software model and resources required …

Spatially Resolved Imaging Of The Inner Fomalhaut Disk Using Jwst/Miri, András Gáspár, Schuyler Grace Wolff, George H. Rieke, Jarron M. Leisenring, Jane Morrison, Kate Y.L. Su, Kimberly Ward-Duong, Jonathan Aguilar, Marie Ygouf, Charles Beichman, Jorge Llop-Sayson, Geoffrey Bryden

Astronomy: Faculty Publications

Planetary debris disks around other stars are analogous to the asteroid and Kuiper belts in the Solar System. Their structure reveals the configuration of small bodies and provides hints for the presence of planets. The nearby star Fomalhaut hosts one of the most prominent debris disks, resolved by the Hubble Space Telescope, Spitzer, Herschel and the Atacama Large Millimeter Array. Images of this system at mid-infrared wavelengths using JWST/MIRI not only show the narrow Kuiper belt-analogue outer ring, but also that (1) what was thought from indirect evidence to be an asteroid-analogue structure is instead broad, extending outward into the …

Clear: Spatially Resolved Emission Lines And Active Galactic Nuclei At 0.6 < Z < 1.3, Bren E. Backhaus, Joanna S. Bridge, Jonathan R. Trump, Nikko J. Cleri, Casey Papovich, Raymond C. Simons, Ivelina Momcheva, Benne Holwerda, Zhiyuan Ji, Intae Jung, Jasleen Matharu

Faculty and Staff Scholarship

We investigate spatially resolved emission-line ratios in a sample of 219 galaxies (0.6 < z < 1.3) detected using the G102 grism on the Hubble Space Telescope Wide Field Camera 3 taken as part of the CANDELS Lyα Emission at Reionization survey to measure ionization profiles and search for low-luminosity active galactic nuclei (AGN). We analyze [O III] and Hβ emission-line maps, enabling us to spatially resolve the [O III]/Hβ emission-line ratio across the galaxies in the sample. We compare the [O III]/Hβ ratio in galaxy centers and outer annular regions to measure ionization differences and investigate the potential of sources with nuclear ionization to host AGN. We investigate some of the individual galaxies that are candidates to host strong nuclear ionization and find that they often have low stellar mass and are undetected in X-rays, as expected for low-luminosity AGN in low-mass galaxies. We do not find evidence for a significant population of off-nuclear AGN or other clumps of off-nuclear ionization. We model the observed distribution of [O III]/Hβ spatial profiles and find that most galaxies are consistent with a small or zero difference between their nuclear and off-nuclear line ratios, but 6%–16% of galaxies in the sample are likely to host nuclear [O III]/Hβ that is ∼0.5 dex higher than in their outer regions. This study is limited by large uncertainties in most of the measured [O III]/Hβ spatial profiles; therefore, deeper data, e.g., from deeper HST/ WFC3 programs or from JWST/NIRISS, are needed to more reliably measure the spatially resolved emission-line conditions of individual high-redshift galaxies.

Evolution Of Density And Velocity Perturbations In A Slowly Contracting Universe, Olivia R. Bitcon

Honors Undergraduate Theses

One focus of research in cosmology regards the growth of structure in the universe: how we end up with stars, galaxies, galaxy clusters, and large scale structure in a universe that appears homogeneous and isotropic on large scales. Using cosmological perturbation theory, we investigate the evolution of density and velocity perturbations corresponding to a universe that is slowly contracting (Ijjas and Steinhardt), testing with and comparing different values for the equation-of-state parameter. This allows for the comparison of the growth of large scale structure in scenarios including a matter-dominated expanding universe, a dark energy-dominated expanding universe, and now, an ekpyrotic …

Impact On Infinite Asteroids: Analysis Of Ejecta Outcomes In Small Body Binary Systems, Jennifer Larson

Electronic Theses and Dissertations, 2020-2023

Binary asteroid systems make up roughly 15% of objects occupying near-Earth space, the Main Belt, and trans-Neptunian space. The impact history of asteroids in binary systems represents an interesting aspect of the general problem pertaining to the nature and evolution of surfaces for such objects. Specifically, the post-impact dynamics of ejecta and its relation to surface modification is a challenging question owing, in part, to the unusual gravitational field in a binary system and the subsequent capture and emplacement of debris on either binary component. Observable differences or similarities between the two bodies in the color, reflectance, thermal properties, and …

Delineating A Stream Network At Gale Crater, Mars, On Arcgis Pro: A Geographic Information Systems Approach, Elpidio Guzman De La Cruz

West Chester University Master’s Theses

The northwestern region of the Gale crater experienced flooding in the past. Delineation of stream networks for the northwestern region of Gale Crater, Mars employing geographic information systems (GIS) techniques is applied. The stream network produced by the algorithm in the study traverses the clay unit in Gediz Vallis, and visual HiRISE imagery analysis correlates with a topologic cross section of an inverted river channel of 750 meters wide and 90 meters deep. HiRISE imagery analysis further confirms a sulfate and clay stratigraphic unit in a stream 125 meters wide and 25 meters deep. Lastly, data smoothing procedures in the …

Paschen-Line Constraints On Dust Attenuation And Star Formation At Z ∼ 1–3 With Jwst/ Nirspec, Naveen Reddy, Michael W. Topping, Ryan L. Sanders, Alice E. Shapley, Gabriel B. Brammer

Physics and Astronomy Faculty Publications

We use medium-resolution JWST/NIRSpec observations from the Cosmic Evolution Early Release Science Survey to place the first constraints on dust attenuation and star formation based on Paschen lines for a sizable sample of 63 galaxies at redshifts z = 1.0-3.1. Our analysis indicates strong correlations between the Balmer decrement, Hα/Hβ, and line ratios that include Paschen lines (i.e., Paα/Hβ, Paβ/Hβ, and the Paschen decrement, Paα/Paβ), suggesting that the former is sensitive to the overall dust obscuration toward H ii regions in high-redshift galaxies. The line ratios are used to derive nebular reddening, E(B − V)_neb, and star formation …

The Gas And Stellar Content Of A Metal-Poor Galaxy At Z = 8.496 As Revealed By Jwst And Alma, K. E. Heintz, C. Giménez-Arteaga, S. Fujimoto, Gabriel B. Brammer, D. Espada, S. Gillman, J. González-López, T. R. Greve, Yuichi Harikane, B. Hatsukade, K. K. Knudsen, Anton M. Koekemoer, K. Kohno, V. Kokorev, M. M. Lee, Georgios E. Magdis, E. J. Nelson, F. Rizzo, Ryan L. Sanders, D. Schaerer, Alice E. Shapley, V. B. Strait, S. Toft, F. Valentino, A. Van Der Wel, A. P. Vijayan, D. Watson, F. E. Bauer, Amber Christiansen, C. R. Christiansen, S. N. Wilson

Physics and Astronomy Faculty Publications

We present a joint analysis of the galaxy S04590 at z = 8.496 based on NIRSpec, NIRCam, and NIRISS observations obtained as part of the Early Release Observations program of the James Webb Space Telescope (JWST) and the far-infrared [C ii] 158 μm emission line detected by dedicated Atacama Large Millimeter/submillimeter Array (ALMA) observations. We determine the physical properties of S04590 from modeling of the spectral energy distribution (SED) and through the redshifted optical nebular emission lines detected with JWST/NIRSpec. The best-fit SED model reveals a low-mass (M _⋆ = 10^7.2-10⁸ M _⊙) galaxy with a …

Development Of Regolith Simulants Of Lunar Permanently Shadowed Regions And Jupiter Trojan Asteroids, Karlis Slumba

Electronic Theses and Dissertations, 2020-2023

Every scientific experiment or innovation goes through a phase of testing equipment. This is not only true for experiments in the laboratory, but also very relevant for experiments on other planetary bodies. In order to test tools and robotic equipment that are destined for another planet, moon, asteroid or comet, it is necessary to simulate the regolith environment on that surface. In this thesis we have provided an overview of two methods for regolith simulant development. In one approach we made simulants in different compositions to find the best spectral fit to Jupiter Trojan asteroids. At visible to near-infrared (VNIR) …

A Jwst/Nirspec Exploration Of The Connection Between Ionization Parameter, Electron Density, And Star-Formation-Rate Surface Density In Z = 2.7–6.3 Galaxies, Naveen Reddy, Michael W. Topping, Ryan L. Sanders, Alice E. Shapley, Gabriel B. Brammer

Physics and Astronomy Faculty Publications

We examine the factors responsible for the variation in the ionization parameter (U) of high-redshift star-forming galaxies based on medium-resolution JWST/NIRSpec observations obtained by the Cosmic Evolution Early Release Science survey. The sample consists of 48 galaxies with redshifts zspec = 2.7−6.3, which are largely representative of typical galaxies at these redshifts. The [S II] λλ6718, 6733 doublet is used to estimate electron densities (n e), and dust-corrected Hα luminosities are used to compute ionizing photon rates (Q). Using composite spectra of galaxies in bins of [O III] λλ4960, 5008/[O II] λλ3727, 3730 (O32) as a proxy for U, we …

An Updated Dust-To-Star Geometry: Dust Attenuation Does Not Depend On Inclination In 1.3 <= Z <= 2.6 Star-Forming Galaxies From Mosdef, Brian Lorenz, Mariska Kriek, Alice E. Shapley, Naveen Reddy, Ryan L. Sanders, Guillermo Barro, Alison L. Coil, Bahram Mobasher, Sedona H. Price, Jordan N. Runco, Irene Shivaei, Brian Siana, Daniel R. Weisz

Physics and Astronomy Faculty Publications

We investigate dust attenuation and its dependence on viewing angle for 308 star-forming galaxies at 1.3 < = z < = 2.6 from the MOSFIRE Deep Evolution Field survey. We divide galaxies with a detected Hα emission line and coverage of Hβ into eight groups by stellar mass, star formation rate (SFR), and inclination (i.e., axis ratio), and we then stack their spectra. From each stack, we measure the Balmer decrement and gas-phase metallicity, and then we compute the median AV and UV continuum spectral slope (β). First, we find that none of the dust properties (Balmer decrement, AV , or β) varies with the axis ratio. Second, both stellar and nebular attenuation increase with increasing galaxy mass, showing little residual dependence on SFR or metallicity. Third, nebular emission is more attenuated than stellar emission, and this difference grows even larger at higher galaxy masses and SFRs. Based on these results, we propose a three-component dust model in which attenuation predominantly occurs in star-forming regions and large, dusty star-forming clumps, with minimal attenuation in the diffuse ISM. In this model, nebular attenuation primarily originates in clumps, while stellar attenuation is dominated by star-forming regions. Clumps become larger and more common with increasing galaxy mass, creating the above mass trends. Finally, we argue that a fixed metal yield naturally leads to mass regulating dust attenuation. Infall of low-metallicity gas increases the SFR and lowers the metallicity, but leaves the dust column density mostly unchanged. We quantify this idea using the Kennicutt–Schmidt and fundamental metallicity relations, showing that galaxy mass is indeed the primary driver of dust attenuation.

A Preview Of Jwst Metallicity Studies At Cosmic Noon: The First Detection Of Auroral [O Ii] Emission At High Redshift, Ryan L. Sanders, Alice E. Shapley, Leonardo Clarke, Michael W. Topping, Naveen Reddy, Mariska Kriek, Tucker Jones, Daniel P. Stark, Mengtao Tang

Physics and Astronomy Faculty Publications

We present ultradeep Keck/MOSFIRE rest-optical spectra of two star-forming galaxies at z = 2.18 in the COSMOS field with bright emission lines, representing more than 20 hr of total integration. The fidelity of these spectra enabled the detection of more than 20 unique emission lines for each galaxy, including the first detection of the auroral [O II]λλ7322, 7332 lines at high redshift. We use these measurements to calculate the electron temperature in the low-ionization O+ zone of the ionized interstellar medium and derive abundance ratios of O/H, N/H, and N/O using the direct method. The N/O and α/Fe abundance patterns …

Early Results From Glass–Jwst. Xxi. Rapid Asembly Of A Galaxy At Z = 6.23 Revealed By Its C/O Abundance, Tucker Jones, Ryan L. Sanders, Yuguang Chen, Xin Wang, Takahiro Morishita, Guido Roberts-Borsani, Tommaso Treu, Alan Dressler, Emiliano Merlin, Diego Paris, Paola Santini, Pietro Bergamini, A. Henry, Erin Huntzinger, Themiya Nanayakkara, Kristan Boyett, Marusa Bradac, Gabriel B. Brammer, Antonello Calabró, Karl Glazebrook, Kathryn Grasha, Sara Mascia, Laura Pentericci, Michele Trenti, Benedetta Vulcani

Physics and Astronomy Faculty Publications

The abundance of carbon relative to oxygen (C/O) is a promising probe of star formation history in the early universe, as the ratio changes with time due to production of these elements by different nucleosynthesis pathways. We present a measurement of log ( C / O ) = − 1.01 ± 0.12 (stat) ±0.15 (sys) in a z = 6.23 galaxy observed as part of the GLASS-JWST Early Release Science Program. Notably, we achieve good precision thanks to the detection of the rest-frame ultraviolet O iii], C iii], and C iv emission lines delivered by JWST/NIRSpec. The C/O abundance is …

Co Emission, Molecular Gas, And Metallicity In Main-Sequence Star-Forming Galaxies At Z ∼ 2.3, Ryan L. Sanders, Alice E. Shapley, Tucker Jones, Irene Shivaei, Gergö Popping, Naveen Reddy, Romeel Davé, Sedona H. Price, Bahram Mobasher, Mariska Kriek, Alison L. Coil, Brian Siana

Physics and Astronomy Faculty Publications

We present observations of CO(3−2) in 13 main-sequence z = 2.0-2.5 star-forming galaxies at log ( M * / M ⊙ ) = 10.2 - 10.6 that span a wide range in metallicity (O/H) based on rest-optical spectroscopy. We find that L CO ( 3 − 2 ) ′ /SFR decreases with decreasing metallicity, implying that the CO luminosity per unit gas mass is lower in low-metallicity galaxies at z ∼ 2. We constrain the CO-to-H₂ conversion factor (α _CO) and find that α _CO inversely correlates with metallicity at z ∼ 2. We derive molecular gas masses …

The Art Of Measuring Physical Parameters In Galaxies: A Critical Assessment Of Spectral Energy Distribution Fitting Techniques, Camilla Pacifici, Kartheik G. Iyer, Bahram Mobasher, Elisabete Da Cunha, Viviana Acquaviva, Denis Burgarella, Gabriela Calistro Rivera, Adam C. Carnall, Yu-Yen Chang, Nima Chartab, Kevin C. Cooke, Ciaran Fairhurst, Jeyhan Kartaltepe, Joel Leja, Katarzyna Małek, Brett Salmon, Marianna Torelli, Alba Vidal-García, Médéric Boquien, Gabriel B. Brammer, Michael J. I. Brown, Peter L. Capak, Jacopo Chevallard, Chiara Circosta, Darren Croton, Iary Davidzon, Mark Dickinson, Kenneth J. Duncan, Sandra M. Faber, Harry C. Ferguson, Adriano Fontana, Yicheng Guo, Boris Haeussler, Shoubaneh Hemmati, Marziye Jafariyazani, Susan A. Kassin, Rebecca L. Larson, Bomee Lee, Kameswara Bharadwaj Mantha, Francesca Marchi, Hooshang Nayyeri, Jeffrey A. Newman, Viraj Pandya, Janine Pforr, Naveen Reddy, Ryan L. Sanders, Ekta Shah, Abtin Shahidi, Matthew L. Stevans, Dian Puspita Triani, Krystal D. Tyler, Brittany N. Vanderhoof, Alexander De La Vega, Weichen Wang, Madalyn E. Weston

Physics and Astronomy Faculty Publications

The study of galaxy evolution hinges on our ability to interpret multiwavelength galaxy observations in terms of their physical properties. To do this, we rely on spectral energy distribution (SED) models, which allow us to infer physical parameters from spectrophotometric data. In recent years, thanks to wide and deep multiwave band galaxy surveys, the volume of high-quality data have significantly increased. Alongside the increased data, algorithms performing SED fitting have improved, including better modeling prescriptions, newer templates, and more extensive sampling in wavelength space. We present a comprehensive analysis of different SED-fitting codes including their methods and output with the …

The Dust-To-Gas Mass Ratio Of Luminous Galaxies As A Function Of Their Metallicity At Cosmic Noon, Gergö Popping, Irene Shivaei, Ryan L. Sanders, Tucker Jones, Alexandra Pope, Naveen Reddy, Alice E. Shapley, Alison L. Coil, Mariska Kriek

Physics and Astronomy Faculty Publications

Aims. We aim to quantify the relation between the dust-to-gas mass ratio (DTG) and gas-phase metallicity of z = 2.1-2.5 luminous galaxies and contrast this high-redshift relation against analogous constraints at z = 0.

Methods. We present a sample of ten star-forming main-sequence galaxies in the redshift range 2.1 < z < 2.5 with rest-optical emission-line information available from the MOSDEF survey and with ALMA 1.2 millimetre and CO J = 3-2 follow-up observations. The galaxies have stellar masses ranging from 1010.3 to 1010.6 M? and cover a range in star-formation rate from 35 to 145 M? yr-1. We calculated the gas-phase oxygen abundance of these galaxies from rest-optical nebular emission lines (8.4 < 12+log (O=H) < 8.8, corresponding to 0.5..1.25 Z?). We estimated the dust and H2 masses of the galaxies (using a metallicity-dependent CO-to-H2 conversion factor) from the 1.2mm and CO J = 3..2 observations, respectively, from which we estimated a DTG.

Results. We find that the galaxies in this sample follow the trends already observed between CO line luminosity and dust-continuum luminosity from z = 0 to z = 3, extending such trends to fainter galaxies at 2.1 < z < 2.5 than observed to date. We find no second-order metallicity dependence in the CO - dust-continuum luminosity relation for the galaxies presented in this work. The DTGs of main-sequence galaxies at 2.1 < z < 2.5 are consistent with an increase in the DTG with gas-phase metallicity. The metallicity dependence of the DTG is driven by the metallicity dependence of the CO-to-H2 conversion factor. Galaxies at z = 2.1-2.5 are furthermore consistent with the DTG-metallicity relation found at z = 0 (i.e. with no significant evolution), providing relevant constraints for galaxy formation models. These results furthermore imply that the metallicity of galaxies should be taken into account when estimating cold-gas masses from dust-continuum emission, which is especially relevant when studying metal-poor low-mass or high-redshift galaxies.

Resolved Velocity Profiles Of Galactic Winds At Cosmic Noon, Keerthi Vasan G. C., Tucker Jones, Ryan L. Sanders, Richard S. Ellis, Daniel P. Stark, Glenn G. Kacprzak, Tania M. Barone, Kim-Vy H. Tran, Karl Glazebrook, Colin Jacobs

Physics and Astronomy Faculty Publications

We study the kinematics of the interstellar medium (ISM) viewed “down the barrel” in 20 gravitationally lensed galaxies during cosmic noon (z = 1.5-3.5). We use moderate-resolution spectra (R ∼ 4000) from Keck’s Echellette Spectrograph and Imager and Magellan/MagE to spectrally resolve the ISM absorption in these galaxies into ∼10 independent elements and use double Gaussian fits to quantify the velocity structure of the gas. We find that the bulk motion of gas in this galaxy sample is outflowing, with average velocity centroid v cent = − 141 km s⁻¹ (±111 km s⁻¹ scatter) measured with respect to …

The Mosdef-Lris Survey: Detection Of Inflowing Gas Towards Three Star-Forming Galaxies At Z ∼ 2, Andrew Weldon, Naveen Reddy, Michael W. Topping, Alice E. Shapley, Xinnan Du, Sedona H. Price, Ryan L. Sanders, Alison L. Coil, Bahram Mobasher, Mariska Kriek, Brian Siana, Saeed Rezaee

Physics and Astronomy Faculty Publications

We report on the discovery of cool gas inflows towards three star-forming galaxies at ∼ 2.30. Analysis of Keck Low-Resolution Imaging Spectrometer spectroscopy reveals redshifted low-ionization interstellar (LIS) metal absorption lines with centroid velocities of 60–130 km s⁻¹. These inflows represent some of the most robust detections of inflowing gas into isolated, star-forming galaxies at high redshift. Our analysis suggests that the inflows are due to recycling metal-enriched gas from previous ejections. Comparisons between the galaxies with inflows and a larger parent sample of 131 objects indicate that galaxies with detected inflows may have higher specific star formation …

The Impact Of Star-Formation-Rate Surface Density On The Electron Density And Ionization Parameter Of High-Redshift Galaxies, Naveen Reddy, Ryan L. Sanders, Alice E. Shapley, Michael W. Topping, Mariska Kriek, Alison L. Coil, Bahram Mobasher, Brian Siana, Saeed Rezaee

Physics and Astronomy Faculty Publications

We use the large spectroscopic data set of the MOSFIRE Deep Evolution Field survey to investigate some of the key factors responsible for the elevated ionization parameters (U) inferred for high-redshift galaxies, focusing in particular on the role of star-formation-rate surface density (Σ_SFR). Using a sample of 317 galaxies with spectroscopic redshifts z _spec ≃ 1.9-3.7, we construct composite rest-frame optical spectra in bins of Σ_SFR and infer electron densities, n _e, using the ratio of the [O ii] λ λ3727, 3730 doublet. Our analysis suggests a significant (≃3σ) correlation between n _e and Σ_{SFR …}