GALAXY SURVEY
PRESENTATION The Cosmic Dawn Survey is a 50 square degree multi-wavelength survey of the Euclid Deep and Calibration fields. The scientific aim is to understand the co-evolution of galaxies, black holes, and the dark matter haloes that host them from Re-Ionization (z~12, about 500 million years after the big-bang) to the present (z~0). The current dataset comprises ultra-deep griz imaging as part of the H20 Survey and IRAC infrared imaging from the Spitzer Legacy Survey, and will eventually include near-infrared imaging from the Euclid Space Mission from 2022. I am a co-lead of the photometric extraction, redshift computation, and physical parameters team, using The Farmer to produce bleeding-edge measurements of galaxy properties.
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PUBLICATION IN PREPARATION
PhD Student @ The Cosmic Dawn Center, 2018-2020 PRESENTATION The COSMOS survey is one the longest-running galaxy surveys. Over two decades, we have collected observations of x-ray, optical, infrared, and radio light to obtain galaxy distances and understand their evolution over 13.7 billion years of cosmic history. I lead the 2020 edition of the master galaxy catalog, using bleeding-edge galaxy model-fitting techninques from The Farmer to measure galaxy properties. PUBLICATION IN PREPARATION
PhD Student @ The Cosmic Dawn Center, 2018-2020 ADS | PRESENTATION While the increasing depth and area of galaxy surveys promise definitive high-redshift studies, ever more crowded sources challenge current photometric methodology. Recent work by Lang and Hogg (2016) has provided another toolkit: The Tractor. By leveraging our understanding of galaxy morphologies, the Tractor is able to force galaxy models derived from high-resolution images onto less resolved ones, with superior deblending and robust photometric redshifts ─ advantageous for high-redshift studies. We present the Farmer, a comprehensive software interfacing with The Tractor to detect sources, efficiently determine the best model type for each source, and perform forced photometry in a scalable architecture. PRESENTED AT NAM 2016
Research Student @ University of St Andrews, 2015-2018 PAPER | PRESENTATION We present a study of 9258 quasars observed with multi-epoch ugriz photometry with spectroscopic redshifts as part of the SDSS Southern Survey. Using a linear model to fit the spectral variations, we isolate separate spectra for the variable (disc) non-variable(disc + galaxy) components of each quasar. We find evidence for bluer spectral slopes than predicted by cannonical accretion disc theory and excellent agreement with SMC-like dust extinction. This work provides the first direct evidence to support recent groundbreaking theoretical efforts to analytically describe accretion discs in the context of General Relativity and magnetic stress. PUBLISHED IN THE ASTROPHYSICAL JOURNAL
PhD Student @ Cosmic Dawn Center, 2019 ADS | PAPER Large photometric surveys provide a rich source of observations of quiescent galaxies, including a surprisingly large population at z > 1. However, identifying large, but clean, samples of quiescent galaxies has proven difficult because of their near-degeneracy with interlopers such as dusty, star-forming galaxies. We describe a new technique for selecting quiescent galaxies based upon t-distributed stochastic neighbor embedding which provides an improvement both over UVJ. It also may be able to select quiescent galaxies more efficiently at higher redshifts than the training sample. PRESENTED AT AAS 235
Co-supervisor of Albert Sneppen @ Cosmic Dawn Center, 2019 ADS | PRESENTATION In this project a neural network has been designed to classify stars and galaxies, where an optimal use of information and structure of the neural network has been investigated. Thus, the project presents a computationally fast methodology with the freedom to choose between quantity and purity that can accurately predict more than 95 percent of stars and galaxies. PRESENTED AT AAS 235
Supervisor of Julia Tiller @ Cosmic Dawn Center REU, 2019 ADS | POSTER | PRESENTATION Intensive observations required to spectroscopically secure such a faint source necessitates a careful evaluation of the photometry from which the redshift prior is based. Photometric data were re-evaluated by examining individual image cutouts to discount erroneous measurements. Of the 29 galaxies, 3 are found to be outright spurious and 17 are advanced as high-confidence candidates for follow-up observation. MASTERS THESIS
Masters Student @ University of St Andrews, 2018 THESIS | PRESENTATION | THESIS PRIZE AWARD Using the incredible power of spatially-resolved spectroscopy provided by the MaNGA survey, we apply a dimensionality-reduction technique (PCA; PyGappy) to map the stellar ages of quenched post-starburst galaxies. By applying state-of-the art models, we demonstrate that quenching happens nearly simultaneously, and is strongly dependent on the underlying gas reservoir. PUBLISHED IN ASTRONOMY & ASTROPHYSICS
Summer Studentship @ Max Planck Institute of Astronomy, 2017 ADS | PAPER | PRESENTATION | ESO PRESS RELEASE | SKY AT NIGHT NGC 7252 is an exquisite example of a nearby major merger remnant. We use the VIMOS spectrograph on the VLT to map the velocity structure of the stars and the ionised gas, tracing the aftermath of a cosmic collision. We find evidence for a dust-obscured ring of star-formation within the central region of the galaxy, and hints at feedback by the central supermassive black hole. PRESENTED AT AAS 229
Summer Studentship @ Leiden Observatory, 2016 ADS | POSTER | PRESENTATION With ever increasing capability, we are now able to push galaxy evolution studies to extreme high redshift (z>6). At these early times, the first galaxies begin forming stars but some of their light is quickly absorbed by the neutral intergalactic medium. We utilise the unique multiplexing capacity of slitless grism spectroscopy to explore large samples of candidate systems (6<z<13) using Bayesian techniques to quantify line detections. We present preliminary results of 29 spectroscopic candidates selected for the first time as extreme high redshift galaxies. |
Research ProjectsA "completed" project is a matter of perspective. Archives
June 2020
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