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REU Undergraduate Research Projects Astrophysics

May 22-July 29, 2022

X-ray studies of magnetars (Supervisor: Dr. Harsha Blumer)

Magnetars are young neutron stars with the strongest magnetic fields known so far in the universe. Their magnetic fields are ~100-1000 times stronger than the radio pulsars, and are believed to be powered by the decay of their enormous magnetic fields.  As such, they are unique laboratories to test the physics of matter embedded in strong gravitational and magnetic fields. They are also slow rotators completing a rotation once every one to ten seconds and have larger than average spin-down rates, compared to the radio pulsars. Magnetars are mostly discovered as high-energy sources emitting intense bright bursts of X-ray or gamma radiation. The burst episode can last anywhere from a few minutes to hours to days. There are around 30 known, with a handful of them observed in radio wavelengths. One or two REU students will analyze the X-ray data of magnetars to study the spectral and timing evolution of the source during magnetar outbursts. This project is expected to result in a publication.

Examples of magnetar bursts observed with the Neil Gehrels Swift Observatory

Figure: Examples of magnetar bursts observed with the Neil Gehrels Swift Observatory in different energy bands (Black: 15-25 keV; Red: 25-50 keV; Blue: 50-100 keV; Green: 100-150 keV).

Exploring the Birthplaces of Exoplanets via Simulations (Supervisor: Dr. Joseph Glaser)

To fully understand the diverse population of exoplanets, we must study their early lives within open clusters, the birthplace of most stars with masses >0.5M⊙ (including those currently in the field). Indeed, when we observe planets within clustered environments, we notice highly eccentric and odd systems that suggest the importance of dynamical pathways created by interactions with additional bodies (as in the case of HD 285507b). Using an intuitive computational simulation framework wrapped in Python, students REU students engaged in this project will be open to investigating multiple different related subtopics, such as: 1) probing for planetary migration pathways due to stellar encounters; 2) determining the likelihood of a planetary system's configuration; 3) developing a pipeline for coupling mass-inflow around a newly formed star and the post-disk planetary architecture; 4) setting detection limits for brown-dwarf to planetary companions of pulsars within existing datasets. Any project undertaken will involve students getting hands-on knowledge of running sims on computing clusters and how to scale a project to the right piece of tech. In addition, REU students will be encouraged to invest time in creating enjoyable visualizations for their research.

CHIME Outrigger (Supervisor: Dr. Kevin Bandura)

Currently under construction is the CHIME Outrigger Telescope which will sharply localize hundreds of mysterious Fast Radio Bursts (FRBs) by working in concert with CHIME (Canadian Hydrogen Intensity Mapping Experiment).   Once completed it will allow detailed multi-messenger followup observations, precise tests of FRB emission models and improved information on the ionized universe. The Outrigger will use very long baseline interfereometry (VLBI) techniques to achieve milli-arcsecond angular resolution. This, in most cases, will identify a single candidate host galaxy, and localize the burst within that galaxy.  To achieve such precision, the timing between sites must be very exact.  An REU student will use preliminary data gathered at the telescope to evaluate the timing performance of the Green Bank Outrigger telescope.

Population syntheses of pulsars and fast radio bursts (Supervisor: Dr. Duncan Lorimer)

Pulsars and fast radio bursts (FRBs) present many opportunities for statistical studies of their underlying populations. A student is sought to investigate some of these issues which are a current focus of work being carried out by Duncan Lorimer. Using Monte Carlo techniques, synthetic populations of pulsars or FRBs can be generated which are then searched by models of large-scale astronomical surveys to provide mock observed samples which can be compared to the properties of the actual samples that are observed. This work is very accessible and requires only a willingness to develop programming skills in Python and to learn some novel statistical techniques along the way. One of two particular topics are envisaged for summer 2022: (a) the Galactic population of millisecond pulsars as revealed by gamma-ray surveys; (b) the cosmological properties of FRBs, as revealed by the Canadian Hydrogen Intensity Mapping Experiment (CHIME).
Aitoff projection showing the currently known sample of FRBs in Galactic coordinates. The galactic plan is the central horizontal line. The FRBs shown here are predominantly those found by CHIME/FRB, which is known to have significant variations in sensit
Figure: Aitoff projection showing the currently known sample of FRBs in Galactic coordinates. The Galactic plan is the central horizontal line. The FRBs shown here are predominantly those found by CHIME/FRB, which is known to have significant variations in sensitivity over the sky and only views the northern celestial hemisphere. When corrected for non-uniform sky coverage, it has been shown that the underlying distribution is isotropic, as expected for a cosmological population. REU Students would work with this sample as part of the FRB simulation project. Image credit: Emily Petroff

Supermassive Black Holes (Supervisor: Dr. Sarah Burke Spolaor)

One of the main astrophysics research focuses at WVU is to lead gravitational-wave searches for signals from binary supermassive black holes using the North American Nanohertz Observatory for Gravitational Waves (NANOGrav; Figure below). NANOGrav, an NSF Physics Frontiers Center, is an international collaboration that is using pulsar timing to search for gravitational wave signals from supermassive black hole binaries. There is the opportunity for one REU student to build an online database of supermassive black hole binary systems from the literature, extracting the basic parameters from these targets. This is part of an ongoing effort to build a comprehensive database of published binary systems. The student will then run NANOGrav software pipelines to search for (and place limits on) gravitational-wave signals from the systems in the database.

Figure 1: Supermassive Black Hole research project

Figure - Binary supermassive black holes form in galaxy mergers and are expected to be among the brightest gravitational-wave sources in the Universe. A number of candidates currently exist in the literature, and the sensitivity of NANOGrav is now breaching the expected signal level from a number of those objects. At WVU we have developed algorithms to use binary models garnered from electromagnetic emission to raise the sensitivity of our gravitational-wave searches.

Gas in the Interstellar Medium (Supervisor: Dr. Loren Anderson)

Because of the low excitation temperature, the 4.8GHz transition of formaldehyde (H2CO) is frequently seen in absorption, even against the cosmic microwave background. Formaldehyde absorption is expected to be strongest foreground to a bright source of 4.8GHz continuum emission. Many authors have used this fact to determine the distances to the continuum sources. We have a large (400-hour) Green Bank Telescope (GBT) survey of formaldehyde in the Galactic plane (Figure 2), the first such large-scale survey. Early analysis of these data surprisingly shows the formaldehyde absorption has no discernable relationship with radio continuum sources, and therefore its use in distance determinations is suspect. An REU student will create a catalog of formaldehyde clouds, analyze their Galactic distribution, and compare this distribution to that of other tracers.  The student will also investigate whether the old assumption about formaldehyde being seen in absorption toward bright continuum sources is correct, by comparing absorption found in lines of sight toward continuum sources and also nearby regions.

Figure 2: Galactic Plane 

Figure - A portion of the data from Dr. Anderson’s GBT formaldehyde survey integrated over all velocities (background), with radio continuum emission shown as green contours. There are 10s of formaldehyde clouds in this small patch of sky that are clearly detected in absorption (dark regions), but the strength of this absorption does not appear to be correlated with the strength of radio continuum emission.

Pulsar Science with the CHIME Telescope (Supervisor: Dr. Emmanuel Fonseca)

The Canadian Hydrogen Intensity Mapping Experiment (CHIME) telescope is continuously observing hundreds of radio pulsars every day. These growing data sets are becoming increasingly suitable for examining irregular behavior in timing and interstellar-medium properties that were possibly missed in past studies due to the unprecedented high-cadence nature of CHIME observations. One REU student will join the CHIME/Pulsar team for the summer of 2022 in order to learn and apply pulsar-timing techniques to CHIME data, as well as understand and participate and understand in the operation of a large radio telescope.


Pulsar Searches (Supervisor: Dr. Maura McLaughlin)

The group at WVU is involved in multiple large-scale pulsar surveys with the Green Bank and Arecibo telescopes. These searches are critical for discovering high timing precision millisecond pulsars that will increase the sensitivity of the NANOGrav pulsar timing array. Such pulsar searches also reveal exotic binaries that can be used to test general relativity and constrain the neutron star equation of state, young pulsars in supernova remnants that can tell us about supernova kick velocities, pulsars with a range of emission properties and intermittency timescales that inform the physics of pulsar emission, and can discover new FRBs. One REU student will analyze pulsar and transients data, lead follow-up observations of newly discovered pulsars, and learn how to “time” pulsars and thereby determine their periods, period derivatives, and binary parameters (if applicable). This project is expected to result in a publication with timing solutions for a number of newly discovered pulsars.

Figure 4: Green Bank Northern Celestial Cap Survey

Figure  - The sky covered from the start of the Green Bank Northern Celestial Cap (GBNCC) survey from 2009 until 2019. Thus far, 161 pulsars, including 20 MSPs and 11 RRATs, have been discovered in this survey. The REU students funded from this proposal would help process the data accumulated in 2019 and the first half of 2020, which we expect to result in the discovery of ~20 pulsars.