2024 Research Projects
Unlocking the Early Universe for Weak Lensing with JWST: High-Precision Analysis of z=2 Galaxy Cluster XLSSC122
Advisors: Ranga-Ram Chary & Kyle Finner
LSSC122 is a galaxy cluster at z=2 with a well-established red sequence. The cluster has a distinct XMM-Newton X-ray detection of the intracluster medium and a 7.6 sigma detection of the Sunyaev Zel'dovich decrement. These two measurements result in contrasting mass estimates. The SZ mass (M200~3e14 solar masses) is extreme for a galaxy cluster at redshift 2. Furthermore, the X-ray peak and SZ centroid are significantly offset, which may indicate a recent merger.
We have been granted JWST NIRCam observations to enable a weak-lensing analysis that will map the mass distribution and provide an accurate mass estimate for the galaxy cluster. The successful candidate will work with Dr. Finner on JWST NIRCam data reduction and analysis.
Characterizing High-Redshift Galaxies with ALMA and JWST
Advisor: Andreas Faisst
We seek students to work on combining the extensive multi-wavelength imaging and spectroscopy from ALMA and JWST to conduct a range of studies as part of the ALPINE project (a 70h large ALMA cycle 5 program) on the COSMOS field. The JWST data includes newly taken cycle 1 data from COSMOS-Web as well as data from an approved cycle 2 NIRSpec/IFU program. The sample includes main-sequence galaxies at z = 4 – 6 and provides the currently largest sample with observations from UV to far-IR including JWST optical lines.
A possible project could focus on studying the internal dust attenuation of the galaxies or studying their stellar population distribution via resolved SED fitting and spectroscopy. The findings can then be related to the evolution of galaxies on the z ~ 5 main sequence and their far-IR and [CII] properties and dynamics.
The student would have access to all ALPINE data and ideas for other projects related to the above are very welcome.
Galaxy Survey Enhancements with Deep Learning
Advisor: Shoubaneh Hemmati
The success of many of the upcoming large cosmology missions (e.g., LSST, Roman, Euclid, SPHEREx) relies on the precise measurements of the redshifts, shapes, and other physical properties of galaxies. These measurements often require a joint processing of the observations and the higher the spatial and spectral resolution, wavelength coverage, and depth of these observations, the more information they entail. Given the wealth of the galaxy data today and advancements in image processing with deep learning, huge improvements for future surveys and their combinations can come about using data-driven approaches.
Through this project, we will design and optimize multi-band image enhancement deep learning structures and explore the extent of spatial/spectral resolution boosting, denoising, and in-filling of hyper-spectral images for future large galaxy surveys by training on the deepest existing multi-band observations in the COSMOS and CANDELS fields. We will quantify the gain in the estimation of various physical properties given the enhanced data products.
Looking for Ionizing Photons Escaping from Dwarf Galaxies at High Redshifts
Advisor: Anahita Alavi
The epoch of reionization (EoR) is a crucial benchmark in the history of the universe and a primary science driver for major observing facilities planned for the near future, including JWST and the 30m telescopes. Hundreds of hours of observations have been devoted to understanding when and how EoR occurred. Ionizing radiation (Lyman continuum) from young massive stars in star-forming galaxies is now believed to be the primary source of EoR's total ionizing budget. However, it is not yet known which type of galaxy these stars belong to. These Lyman continuum photons must escape absorption within the interstellar medium and reach the intergalactic medium. Recently, studies of UV luminosity functions at high redshifts have revealed that the faint-end is steep, possibly increasing with redshift, indicating that a large number of faint star-forming galaxies (dwarf galaxies) exist at these redshifts. Dwarf galaxies may play a significant role at EoR depending on 1) the intrinsic luminosity they produce and 2) the fraction of this luminosity that escapes. Studies of local dwarf star-forming galaxies indicate they emit copious amounts of ionizing radiation. Nevertheless, the escape fraction of photons from these objects still needs to be constrained. One powerful way to explore these faint dwarf galaxies is to exploit the magnification of strong gravitational lensing offered by foreground massive clusters.
Our team was granted Hubble Space Telescope time to obtain UV images of six lensing galaxy clusters from the Hubble Frontier Fields survey to search for escaping Lyman Continuum photons from high-redshift dwarf galaxies. A visiting graduate student fellow would be expected to work with these UV HST data and catalogs to identify any possible detection of ionizing radiation from lensed dwarf galaxies. Our team has extensive experience on this topic and can assist the visiting student through a variety of resources including catalogs, ground-based spectroscopic data, as well as analysis tools.
Galaxy Discoveries in the Local Universe
Advisor: David Cook
The Census of the Local Universe (CLU) is a large-area survey that aims to find new galaxies in the local universe out to a distance of 200 Mpc (z~0.05). We utilize four narrow-band filters to search for H-alpha emission-line sources across 3/4 of the sky that is roughly the footprint of Pan-STARRS. The new galaxies found in this survey will be used to search for counterparts to gravitational wave (GW) events and enable the discovery of extreme galaxies (blue compact dwarfs, metal-poor galaxies, green peas, etc.) that are rare in the local universe. An analysis of preliminary data has yielded thousands of new objects, including rare galaxies, and we anticipate finding ~100,000 new objects in the full data set. The CLU source catalog (N~300 million), from which numerous galaxy discoveries can be extracted, will be science-ready in late 2023.
A prospective student will develop and apply sophisticated selection techniques and methodologies to identify high-confidence galaxy candidates and separate them from stars and nebular objects in the Milky Way. The resulting galaxies can then be combined with data from other large surveys to derive physical properties (stellar mass, star formation rate, etc.) and enable studies of galaxy evolution, star formation, or prioritization of galaxy candidates inside GW events.
We seek a student with a background in the following areas: galaxy surveys, star formation, machine learning, or analysis of large data sets. Given the wide range of research topics that can be supported by this data set, there will be flexibility in he science focus of the project.
Preparatory Science for the Roman Coronagraph and Habitable Worlds Observatory
Advisor: Alexandra Greenbaum
The Nancy Grace Roman Space Telescope, scheduled to launch in late 2026, carries a coronagraph instrument to demonstrate, for the first time, key space technologies for future solar-system-analog direct imaging missions like the Habitable Worlds Observatory. While the Coronagraph Instrument will observe celestial targets as a technology demonstration, its predicted performance may enable exciting science in self-luminous exoplanets as well as reflected light observations of exoplanets and disks. Preparatory work to assess the scientific potential of planned observations will enhance not only Roman's scientific legacy but also its utility as a demonstrator for the Habitable Worlds Observatory.
Work for this project may include simulation of circumstellar disks or exoplanet atmospheres, target selection, observation planning, or analysis of instrument test data. The student will connect with both IPAC and JPL experts in pursuit of those activities. Students with experience in high contrast imaging data reduction, orbit determination, spectroscopic characterization, or circumstellar disk modeling are especially encouraged to apply. For more information on the Roman Coronagraph Instrument, see https://roman.gsfc.nasa.gov/coronagraph.html.
Mining a Billion Objects in NED with Machine Learning
Advisors: Joe Mazzarella & David Cook
The NASA/IPAC Extragalactic Database (NED) joins data across the electromagnetic spectrum from space missions, large ground-based sky surveys, and over 130,000 astrophysics journal articles to provide a panchromatic census of objects beyond our Milky Way galaxy. Currently, nearly 14 billion photometric measurements have been fused on an object-by-object basis to construct first-look spectral energy distributions (SEDs) for over 1.1 billion distinct objects, providing a unique resource for a variety of scientific explorations.
We are seeking a visiting graduate student interested in cross-matching additional large survey catalogs (e.g., Pan-STARRS, GAIA, DESI) with current NED holdings (which already joins data from AllWISE, 2MASS, GALEX, SDSS, etc.) and applying statistical data mining or machine-learning algorithms to study the resulting SEDs. The first step is to derive probabilistic classifications (star, galaxy, AGN discrimination) for hundreds of millions of objects that presently lack confident identifications. The scientific goals are to estimate physical quantities and characterize statistically the newly identified extragalactic objects to gain new insights into the demographics, environments, and co-evolution of galaxies and AGN. Applicants are also welcome to focus on a particular subset of the data to conduct a related research project using NED in novel ways.
Students with strong data science skills and interest in studying populations of galaxies and AGN are encouraged to apply.
A Spectroscopic and Imaging Study of Cool White Dwarf and Late-type Dwarf Binaries
Advisor: Sergio Fajardo-Acosta
We have conducted a survey of Cool White Dwarf (CWD) and Late-Type Dwarf Binaries, culled from the literature, in optical spectroscopy with the Double Spectrograph (DSpec) and near-infrared spectroscopy with the Triple Spectrograph (TSpec), both at Palomar Observatory. We are also obtaining follow-up imaging photometry mainly in the J band, for assessment of the proper motions of several of the systems. The purpose of these observations is to compare and contrast the contributions to the metal enrichment in CWD atmospheres from accretion of extant debris disks, and/or from winds from the late-type dwarf companions. This study was motivated by our discovery of a possible such binary system in the enigmatic object WISEA 0615-1247 (Fajardo-Acosta et al. 2016, ApJ, 832, 62).
The successful visiting graduate student at IPAC, who will also collaborate with other IPAC scientists in our group, will assist in the analysis and interpretation of our spectroscopy and imaging measurements of systems possibly analogous to WISEA 0615-1247. We may also request assistance in the reduction of some of our observations, for which training will be provided to the student. We have also obtained spectroscopy of other white dwarfs, as a control sample. Many CWDs are high proper motion objects, for which their space motions are a crucial element to establish their dynamical history in the Galaxy.
The ideal candidate for the IPAC visiting graduate fellowship for this project should demonstrate a strong interest and basic familiarity with low resolution stellar spectroscopy and with studies of stellar proper motions. We expect to publish results of our study during the term of the visiting graduate student. Thus, a strong interest and proficiency in writing for a refereed journal is a big plus.
Journey to the Cosmic Dawn: Exploration of the First Galaxies with JWST
Advisor: Takahiro Morishita
Understanding the properties, formation, and evolution of the first galaxies remains a fundamental pursuit in astrophysics. Key questions such as their formation timeline, acquisition of mass, structural transformations, and star formation suppression continue to intrigue researchers. The James Webb Space Telescope (JWST) has been specifically designed to shed light on these inquiries.
In this program, we invite the participation of a successful candidate to collaborate with a team of scientists on analyzing the extensive dataset acquired through our JWST Cycle 2 GO program (PID 3990, PI: Morishita). Our survey will utilize the NIRCam instruments to construct an unbiased sample of the universe, covering a substantial area of approximately 0.6 square degrees, making it the largest extragalactic dataset among the JWST programs. The primary objective of the candidate's research will be to accurately identify galaxies at redshift z >10, corresponding to a period when the universe was less than 500 million years old. By inferring their physical properties, the candidate will contribute to a deeper understanding of the early universe and its alignment with the currently accepted LambdaCDM model. This research opportunity presents a significant opportunity to explore the properties of the first galaxies and unravel the mysteries surrounding their formation and evolution.
Unveiling the Enigmatic: Exploring the Nature and Impact of Optically Dark Galaxies in the Early Universe
Advisor: Takahiro Morishita
The launch of NASA's James Webb Space Telescope (JWST) has provided us with an unprecedented glimpse into the early universe, unveiling a multitude of previously unseen galaxies and raising intriguing questions. Among these enigmatic entities are optically dark galaxies, also known as "HST"-dark galaxies, which exhibit an intriguing characteristic—they are virtually invisible in optical wavelengths but display an extraordinarily red color spectrum at ~2 microns and beyond. The nature of these galaxies remains largely unknown, prompting a series of compelling inquiries: What causes their extreme color? How does their morphology take shape? And what is their prevalence in the universe?
In this program, we invite a candidate to collaborate with a team of scientists on the study of this unique population of optically dark galaxies, identified through our successful JWST Cycle 2 GO program (PID 3990, PI: Morishita), as well as utilizing other publicly available imaging data. The candidate will leverage the rich data set from JWST's NIRCam imaging instrument and employ our photometric pipeline to identify galaxies and unravel their physical properties, including star formation rate, dust extinction, size, morphology, and more. Ultimately, the candidate will estimate the number density of these enigmatic galaxies and infer their contribution to the cosmic star formation budget across the entire universe.
Understanding the Effects of Stellar Binarity on the Frequency of Small Planets Orbiting Low Mass Stars
Advisor: David Ciardi
One of the most urgent and important questions in exoplanet demographics is that of the frequency of small planets orbiting low-mass stars. These planets are an accessible point of entry for understanding planet formation processes of small planets, and how they might inform us about the frequency of small planets around Sun-like stars, an essential input to the Habitable Worlds Observatory. The presence of detected and undetected stellar companions orbiting exoplanet host stars influences their formation and evolution, and also affects our ability to measure the small planet frequency. Work in recent years shows a decrease in close-in stellar companions for stars known to host planets, and a decrease in the frequency of giant planets for systems where a close-in stellar companion has been detected.
Utilizing data from our high-resolution imaging program, our program is working toward quantifying the physical and observational effects in exoplanetary systems. A student interested in exoplanet demographics, high-resolution imaging, and/or low-mass stars would be well-suited to this project.
Archival Time-domain Light Curve Characterization
Advisors: Andreas Faisst, Shoubaneh Hemmati, Jessica Krick
We seek students to work on broad science related to the study, characterization, or classification of time-variable sources (e.g., stars, AGN, supernovae, etc.) in the optical and infrared. The student will have access to both 1) new tools to extract light curves from archival data at any available wavelength for large samples of sources and 2) NASA’s new science platform designed to help astronomers do data science at scale with ease and reproducibility. Possible projects range from understanding the physical causes of variability of AGN to the development and application of new methods (e.g., using machine learning and AI) to select variable sources. Ideas for other projects along these lines are welcome!
Measuring Star Formation and Black Hole Growth in Luminous Infrared Galaxies with JWST
Advisors: Lee Armus
Luminous Infrared Galaxies (LIRGs) generate their enormous power through intense starbursts and the fueling of Active Galactic Nuclei (AGN). With the Great Observatories All-sky LIRG Survey (GOALS), we are characterizing a sample of over 200 low-redshift LIRGs across the electromagnetic spectrum. A key part of GOALS is the study of how stars form and black holes grow under these extreme conditions, by observing the atomic and molecular gas and star clusters at high resolution. To this end, we have been obtaining imaging and spectroscopic observations of LIRGs with HST, ALMA, Palomar and Keck/AO in the UV through the sub-mm.
We have recently been awarded a large, JWST cycle-2 program to survey a complete sample of the most luminous IR galaxies in the local universe with MIRI, NIRSpec and NIRCam. The successful candidate will work directly with the GOALS team to reduce, analyze and publish JWST observations of the star-forming clusters, dust and warm molecular gas content, and galactic outflows in this sample.
