High Mass X-ray Binaries (HMXBs) are some of the most physically extreme sources in the universe. They comprise of a compact object such as a black hole or a neutron star, and a high mass companion star. The compact object accretes matter from the companion star and forms an accretion disk of material that has temperatures in excess of ten million degrees Kelvin. This accretion disk then radiates out in the X-ray energy band and allows us to ascertain physical properties for the source. However, the very nature of an HMXB constrains the age of the source to a very high degree--this is because the source needs to be old enough for the compact object to form yet it needs to be young enough for the high mass companion star to still have fusion fuel in its core. In this project, we have created star formation histories at the locations of unknown X-ray emitting objects using optical observations from Hubble Space Telescope. These star formation histories determine if there are stars that have an age consistent with HMXBs present. The age of these unknown sources may be associated with these stars, which means they could be HMXBs. We then looked for star formation histories that have constrained ages consistent with an HMXB to try and give more evidence for an unknown object being an HMXB.

Eclipsing binaries (EBs) are systems in which two stars orbit and pass in front of each other as observed from Earth. They are important astrophysical tools utilized in this project to directly measure the fundamental properties of stars, such as their masses and radii. We create a sample of 35 bright, detached EB targets from the Villanova Catalogue, based on high-quality photometry from the Kepler Satellite and spectroscopy from the Apache Point Observatory Galactic Evolution Experiment (APOGEE). Here, we present mass, radius, and orbital solutions for a subset of these EBs. For each system, we extract radial velocities (RVs), the speed at which each star in the system is moving away from the observer, from the APOGEE spectra. Then, we combine the RV with Kepler light curve (LC) information to simultaneously model the system light and line-of-sight speed as a function of time. Because our model has high dimensions with 18 free parameters, we first solve for the LC and RV solutions separately, and then simultaneously solve them. We use a nonlinear least-squares optimization method to determine the best fit solution and quantify the uncertainties in model parameters running Monte Carlo Markov Chain (MCMC) simulations. The model parameters that we find will further our understanding of fundamental stellar properties and binary star orbital parameters.

One of the main science goals of the Large Synoptic Survey Telescope (LSST) is to further understand the relationship between dark energy and the universe's expansion. In order to achieve this scientific goal of the LSST, accurate estimates of photometric redshifts, which are used as a proxy for cosmological distance, for galaxies are required. To improve its estimates of photometric redshifts, the LSST could incorporate near-infrared data from other surveys along with its optical measurements of galaxy brightness. In order to understand how photometric redshifts improve with the addition of near-infrared (NIR) data, we statistically compare the quality of photometric redshifts using simulated galaxy catalogs with optical-only and optical-plus-NIR data. In my poster, I quantify the expected improvements to photometric redshifts when LSST optical data is combined with NIR data from the future ESA Euclid or NASA WFIRST space telescopes. In general, WFIRST has less outlier galaxies because WFIRST’s NIR filters have a redder band and can cover deeper in the IR spectrum.

How is star formation affected by its environment? How big is the effect of having differing metallicities during the star forming process? The goal of this research is to study star formation in low metallicity environments, which are well represented by dwarf galaxies. For this project, we used the Atacama Large Millimeter Array (ALMA) telescope, at an angular resolution of about 0.5 arcseconds (about 66 lys), to observe the 12CO (115 GHZ) distribution in the galaxy Henize 2-10 (He 2-10). He 2-10 is an irregular dwarf galaxy about 30 million lightyears (lys) away, about 1 kilolightyears (kly) across, and has a mass of about 10 billion solar masses. It has a high gas to dust ratio, is star forming, and has a low metallicity of about 12+log(O/H)~8.3. Additionally it contains a supermassive black hole candidate of about 1 billion solar masses, which could have significant dynamical interactions with the molecular gas. We created a zeroth moment map which we used to estimate several properties of the galaxy: including a molecular gas mass of about 38 million solar masses, an observable area of about 1850 square klys, and a molecular gas density of about 3.7x10^(-20) grams per cubic centimeter. We also created multiple channel maps which provide preliminary results that indicate the presence of at least 10 giant molecular clouds within He 2-10.  With what we have done so far, we will be able to compare our results to known giant molecular coulds in the Milky Way Galaxy, and begin to better understand the relationship, if any, between star formation and star forming environments. 

Stellar mass loss is enormously important for a wide range of astronomical subfields from galactic feedback to stellar evolution, and is particularly vital for understanding time-dependent and transient phenomena like supernovae, gamma-ray bursts, and neutron star and black hole mergers. Despite years of study, it remains poorly understood, and the physical mechanisms driving mass loss remain unclear - especially in the case of stellar binaries. The binary star system V367 Cyg's complex structure offers a unique testing ground for binary mass loss theories. The more evolved star in the system is losing mass that is accreting onto the secondary star, creating a thick disk around it. The thick disk and small separation between the stars prevents us from directly observing the mass transfer, but we can investigate the structure of the V367 Cyg system using polarimetry - the analysis of polarized light - to disentangle its complex spectrum originating from multiple sources. I will discuss the disk-stream geometry of V367 Cyg using new polarization light curves of the system which I extracted from 7 years of spectropolarimetric data taken with the University of Wisconsin’s Half-Wave Spectropolarimeter (HPOL).

As the Kepler Space Telescope's follow-up K2 mission enters its final campaigns of observation, the fuel powering the spacecraft's stabilizing thrusters is expected to begin to run out, causing thruster fires to sputter. Sputtering will cause higher magnitude and less predictable motion of stellar Point Spread Functions (PSFs) relative to the spacecraft detector, generating more noise in transiting exoplanet light curves. To understand this increased noise, I am creating a forward model of the Kepler detector, and simulating stellar targets traversing different regions of quantum sensitivity variation. Using these simulations, I am characterizing the contribution of detector sensitivity variation to the noise of K2 light curves and testing various models for thruster sputtering in preparation for identifying high motion in future K2 data. I am also testing methods to increase the effectiveness of existing noise-removal techniques for space telescope exoplanet targets, focusing my treatment on stars with bright neighbors or high motion relative to the detector. Using techniques tested on simulations, I am studying a population of exoplanet targets that has received less attention due to difficulties arising from contribution by bright nearby stars. In this talk I will demonstrate the potential value in continued observation during thruster sputtering and discuss the results of my follow-up study on crowded exoplanet targets. To ensure a productive legacy for the Kepler mission, it is essential to develop robust tools to analyze existing data after the spacecraft becomes defunct. My noise-removal methods can be applied to current and future K2 data, as well as data from future missions such as the Transiting Exoplanet Survey Satellite (TESS) and the James Webb Space Telescope (JWST).

Werk Student Quasar Absorption Disgnostisions (Werk SQuAD), a group of undergraduate students led by astronomy professor Jessica Werk, aims to assemble a database of identified absorption features present in 230 nearby quasars. The purpose of this database is to provide astronomers studying galaxy evolution more information about the circumgalactic medium (CGM) of galaxies. The CGM is a giant halo of matter gravitationally bound to dark matter surrounding a galaxy, acting as a recycling hub for galactic outflows and accreting material. A major limitation to observing the CGM is that it is so diffuse, it is impossible to observe directly via emission. In order to learn more about the CGM, we must rely on other light sources. As light is emitted from a background quasar, the light passes through the CGM of galaxies in its line of sight as it travels to us in the Milky Way. Every CGM the light passes through leaves a sort of fingerprint, as ions from the CGM absorb some of the original light from the quasar, leaving trenches in the data. By figuring out where those absorptions happened and what ions were present, we can gain insight into what systems of gas were encountered on the quasar’s journey to us. With the use of a specialized GUI, we are able to search for ion absorption features in the spectrum. We look for recognizable signatures such as the Hydrogen Lyman series, while checking for other ion absorbers as well. When there are multiple absorbers at a particular redshift, this is often an indication that we are viewing part of a nearby galaxy’s CGM. By identifying these absorptions and linking them to particular galaxies, we are able to better understand the cycle of galaxy evolution.

Wolf-Rayet stars are massive stars whose high-intensity ultraviolet radiation drives a strong stellar wind, effectively pushing away its outer layers. This process forms an optically thick nebula around the star, making it difficult to obtain high-precision observations of the surface of the star. However, precise observations of the star’s brightness over time could reveal a large amount of information about the behavior of these stars beneath their winds. Our group has obtained high-cadence photometric data from Apache Point Observatory’s ARCTIC camera to construct figures of brightness vs. time (known as a lightcurves) for the Wolf-Rayet star WR124 to search for periodic changes is the star’s brightness. We developed code which reduces and processes images of WR124, extracts the brightness of WR124 in each image, eliminates systematic trends in data, and compiles each data point into a lightcurve. This processing has shown that WR124 exhibits variability, a change in brightness over time. We also search for signals which repeat with a regular period using a hybrid periodogram analysis. Although this periodogram analysis has proven inconclusive, planned future observations of WR124 and more advanced statistical analysis techniques may still yield important results in the study of these interesting objects.

 The atoms in the universe are involved in a constant process of enrichment and redistribution. They cycle violently into and out of galaxies over billions of years. This cosmic cycle of baryons creates a diffuse halo of gas, called the circumgalactic medium (CGM), that exists inside the virial radii of galaxies. Characterized by rich dynamics and complex ionization states, the CGM provides galaxies their star-forming fuel by regulating and recycling the gas supply. The CGM is vital to understanding the evolution of galaxies and the universe, but it is difficult to observe directly. Using high-resolution quasar spectra collected by the Cosmic Origins Spectrograph on the Hubble Space Telescope, we identified absorption features found in the spectrum of the quasar. We classified each absorption feature, identifying its species, redshift, velocity dispersion, and density. We discovered several strong hydrogen systems with metal absorption at redshifts where the light from the quasar had passed through a cloud of metal-rich gas. Using the Sloan Digital Sky Survey catalog, we matched our strong hydrogen systems with several galaxies near the line of sight of the quasar. Now we are starting to characterize correlations between the dynamics of gas in the CGM and its influence on the star formation rate of the galaxy it surrounds.

The formation of the universe’s first galaxies is currently not well understood; with the launch of the James Webb Space Telescope (JWST) in the near future, however, it may soon be possible to uncover critical details about how and when the first galaxies formed. In this project, we examine whether it will be possible to discern the clustering of high-mass, high-redshift dark matter halos from background noise when looking at data from the JWST. The ability to detect these halos, which are believed to play a key role in galaxy formation, through their clustering could lead to further breakthroughs in the study of the early universe. An initial test of the effects of projection was run using data from the Illustris simulation at redshifts z=6 and z=10. Halo positions were analyzed in both 3D and 2D at each redshift in order to determine how much projection altered our ability to detect halo clustering. When viewing 2D projections of halo positions, it became evident that projection was significantly reducing our ability to detect clustering. When we made use of the third dimension to eliminate the projection effect, the clustering of high-mass, high-redshift halos become apparent at both redshifts. In reality, it will not be possible to replicate this 3D case; exact measurements for the depths of high-redshift galaxies are not obtainable using the JWST. Going forward, we will work to refine our results by applying real JWST data specifications in order to determine the feasibility of using JWST data to detect early halo clustering. Making use of information such as limits on the detectability of galaxies based on their star formation rates and the uncertainty of JWST spectroscopic measurements will allow us to better determine whether the idea of studying halo clustering at high redshifts using JWST data is worth pursuing.

Radiation emitted from supermassive black holes in the early universe (quasars) is absorbed by hydrogen in the intergalactic medium. Hydrogen absorbs light at certain resonant frequencies in the spectra of quasars. Statistics of Lyman-alpha absorption (the most studied resonant frequency of hydrogen) probes the cosmological parameters governing the universe (e.g. mass of dark matter) and the temperature of intergalactic gas (which constrains how the universe was heated). To further improve these constraints, I will be using another Lyman series transition (Lyman-beta). Due to the smaller absorption cross-section of Lyman-beta, we may probe higher densities than measured with the Lyman-alpha transition therefore increasing the number of data points to analyze. By including the Lyman-beta transition, our analysis allows for a better understanding of intergalactic gas which provides for more robust cosmological constraints.

Core-collapse supernovae (SN/e) are the spectacularly violent deaths of evolved young massive stars, which expel a shock wave into the intergalactic medium that in turn can spark star formation and disperse heavy elements into their host galaxy. While a SN event can be classified by its spectral signature, determining the nature of a supernovae progenitor depends upon chance photometry taken prior to the event. By turning to the study of SN host environments and their surrounding interstellar medium within the unique and rare population of galaxies that have hosted three or more SN events within the last century, we are granted the opportunity to study the locations and environmental properties of stellar populations prone to supernova progenitor production. Using moderate-resolution optical slit spectra taken with the Apache Point Observatory 3.5m DIS spectrograph, we aim to map metallicity, ionization parameter, and star formation rates using emission line diagnostic ratios across each SN-rich galaxy in our sample. Dubbed the “Fireworks Galaxy” at a distance of 5.6 ± 1.5 Mpc, NGC 6946 is of particular interest as it has uniquely produced ten core-collapse supernovae (CCSNe) and several other massive star transients within the last century. We present spatially-resolved metallicity and Hα star formation rate (SFR) maps of NGC 6946, tracing fifty-five slit orientations which span the face of the galaxy and cover all CCSN host sites. Future work will include stellar population synthesis modeling to determine stellar populations, ages, and SFR histories in NGC 6946 and a further expansion of this analysis to the other SN-rich host galaxies in our sample.

Obliquity, or axial tilt, is the angle rotational axis and a line perpendicular to the orbital plane. At low obliquity, Earth-like planets will tend to form permanent ice sheets at the poles, if anywhere. However, at high obliquity, the poles receive more sunlight on average than the tropics, and so ice sheets might be expected to form at the equator. We investigate the formation of such “ice-belts” under a range of orbital parameters, obliquities, and host star properties. We find there is a narrow range of semi-major axis and obliquity values that allow for such "ice-belts" to form. First, we experiment with changing the luminosity of the host star to see the effect of changing the stellar flux on ice belt formation, while keeping the relative stellar flux approximate to Earth's, as well as making the appropriate adjustment to the ice-albedo for the host star’s spectrum. Our results suggest that the more luminous the star is, the smaller (and ultimately less stable) the range of ice belt formation becomes. To fully understand the full effect the host star had on ice belt formation, we vary the orbital eccentricity, the spin-axis orientation (precession angle) and the depth of the ocean that can absorb stellar energy (mixing depth). This work suggests that it should not be typical for Earth-like worlds at high obliquity to maintain large ice sheets around main sequence stars.

In our universe, galaxies tend to fall into one of two categories: those that inhabit a clustered environment, and those that lead more solitary lives in the field. Galaxies that reside within a cluster evolve differently from their solitary counterparts; namely, their ability to form stars seems to be stunted over time. However, understanding this phenomenon is hard since it’s difficult to obtain detailed data about the evolution of distant galaxies through strictly observational techniques. Instead, we use a cosmological simulation of a galaxy cluster similar to the real Virgo cluster to discover the mechanisms of star suppression in such environments. Comparing our synthetic observations with existing observations of galaxies in the Virgo cluster will help constrain theories of galaxy evolution. Our preliminary results show signs of all the major forms of star suppression that are believed to exist, as well as a few outlying cases that don’t fit any models we’ve seen so far. Now, we are continuing to look into one specific theory of galaxy evolution, called RAM pressure stripping, that removes the gas required to form stars from a galaxy via an external pressure. We are trying to discern what kinds of galaxies tend to undergo this process, and how exactly it impacts a galaxy over time. Understanding this fascinating phenomenon will result in a more accurate model of galactic evolution.

Enormous outpourings of energy blasted into space by an accreting supermassive black hole (SMBH) are known as quasars. Previously, it was believed that SMBH’s enter a quiet state, thus extinguishing the quasar, over thousand-year-timescales. Changing-look quasars (CLQs) are a recently discovered, rare type of quasar that have been observed to transition far quicker than was thought possible. These short timescales motivated researchers, including ourselves, to reconsider our understanding of accretion phenomena in quasars to better understand what is driving the unexpectedly rapid changes observed in these CLQs. It is essential to establish a larger, more comprehensive, and less biased catalog of CLQs than currently available to answer such questions; and our work emphasizes creating this catalog. Our research involves both visually comparing spectra from the Sloan Digital Sky Survey database to each other and to new Sloan observations in the interest of detecting variations that suggest the quasar has turned on or off between observations. Sierra Dodd has recently identified three extremely probable CLQ candidates, bringing us closer to an improved understanding of which key changes in spectra correspond to CLQs. Further work on our part will aim to discover additional candidates to enlarge the pool of discovered.

In order to yield the maximum number of high quality exoplanet observations, it is crucial to have the right data input based on pre-existing planetary models. Here we use a model of the solar system planets for modeling exoplanet observations that is as accurate as possible. However, the published model did not integrate how the observed spectra of an exoplanet would depend on its phase angle. Thus, we simulated planets with realistic atmospheric and surface features, and calculated high-resolution spectra at different phases. Interpolation further allows users of the Roberge “Haystacks” model to calculate values at exact phase angles. The results reveal how different types of scattering and surface features affect the reflected sunlight. In particular, our results for Venus, Earth, and Mars show that planets appear more reflective at crescent phases due to scattering by clouds and aerosols.

The Astronomy Undergraduate Engineering Group has adapted an amateur solar telescope for use as a research, lecture and public outreach tool. Mounted on the side of the Physics and Astronomy Observing deck telescope, the solar observatory provides a live video feed of the Sun in both H-α and broadband emission, which allows observers to view activity in the solar photosphere and chromosphere. The telescope consists of a Coronado MaxScope40 4 cm H-α telescope mounted on a larger sixteen inch telescope. The right ascension and declination mount of the Physics and Astronomy Observing deck telescope allows for precise software control as well as automatic guiding and tracking. In place of the normal eye piece, an Orion StarShoot G3 camera is used in conjunction with the SharpCap imaging software to digitally capture images and stream them remotely. In addition to applications in teaching and outreach, the rapid image cadence allows for the observation of short duration events like solar flares, which vary on the order of minutes. This is the first solar observing tool at the University of Washington, and opens new avenues for students to conduct research on Earth’s closest star.