Student Research Projects

I also manage the NANOGrav Student Teams of Astrophysics ResearcherS (NANOStars) program at F&M in which students participate in various research activities with the Arecibo telescope.

Funding sources for these research projects are acknowledged at the bottom of the page.

Melanie Ficarra (F&M '24)

Mel is searching three newly characterized Galactic binary systems which may harbor neutron star companions. Binary pulsars are valuable systems to discover owing to the many physical applications possible from their study. We are proposing deep, sensitive observations with the GBT at a low observing frequency (350 MHz) to try and detect pulsed radio emission from the compact companions. In the cae of non-detecitons, our observations will improve the existing sensitivity limits on these systems to a luminosity level comparable to the lowest luminosities of the known Galactic binary pulsar population. All three target systems are relatively near to us and have small expected dispersion measures. Thus, using a low observing frequency is desirable to take advantage of a likely steep spectrum while not suffering significantly from dispersive and scattering effects. These latter effects can be particularly deleterious for recycled, millisecond pulsars having small spin periods.

Wenky Xia (F&M '24)

Wenky is searching for exotic pulsars and technosignatures in the nearby spiral galaxiy M33. M33 has been observed with long integrations with the Arecibo radio telescope, and an initial search for dispersed bursts and periodicities in the data has been completed. Wenky will revisit these data sets and apply several additional searches.

The first uses the stack search approach (outlined below in Zach Nusbickel's project and in Cadelano et al. 2018) to combine multiple observations that targeted the nucleus of M33. Combining the power spectra from these observations will enhance the sensitivity to any faint periodic signals from pulsars that may be present but would otherwise be undetectale in any single observation.

The second approach is a search for periodic signals that might briefly be made brighter by scintillation in short portions of the (long) total integration and for pulses from highly accelerated and/or partially eclipsed binary systems. This is accomplished by separately searching individual small sections of each integration, where such systems could be more easily detected.

The third analysis is a search or technosignatures from these galaxies using the new software package BLIPSS (see Suresh et al. 2023). From this we can set limits on the presence of technosignatures in the regions we oberved in these galaxies.

Yuta Shiohira (Ph.D. student, Kumamoto University)

Yuta searched for periodic technosignatures in the Parkes 70-cm survey archive (PKS70; see below and here for survey details). In terms of transmission power efficiency, periodic pulse signals are considered one of the promising targets in the radio search for extraterrestrial intelligence. Yuta used the software package BLIPSS (see Suresh et al. 2023) which is based on the Fast Folding Algorithm (FFA), and he searched for pulsed signals with periods between 3 and 56 seconds. No signals were detected, but he set constraints on the number of extraterrestrial transmitters.

He presented his work at the conference Interstellar Frontiers: Bridging Technosignatures, Astrobiology, and the SKA in Perth, Australia.

Liv Young (F&M '23), Dani Zoeller (F&M '23), Andrew Lara (F&M '24), and Gavi Fischer (F&M '25)

These students helped finalize the cooperative robots system we developed and are got things ready for our demonstration of the working system for NATO at a test site at F&M. This involved the following: (1) Making sure the automated navigation of the robot in the test minefield was working, including verifying the GPS localization, running the graphical user interface that controls the robot, and running the robot in test lanes with simulated buried mines; (2) Finishing and testing the camera sensor system on the robot which was used to detect tripwires in minefields. This required that the camera be mountable and controllable from the robot, that the robot had access to frames the camera was taking, and that real-time, automated analysis of the camera frames to detect linear features such as tripwires was tested and could run properly. (3) Collecting LIDAR frames of surface objects under different field conditions (e.g., lighting, angle, distance, scene background). This will be used in an artificial intelligence approach under development to identify mines and other ground objects.

See the description below, the Landmine Detection at F&M web site, or the NATO project websites G5014 and G5731 for more complete details about this project.

Ziyu Mo (F&M '23)

Ziyu was in charge is creating a gallery of heat maps for various objects under investigation with a Fisher M-101 metal detector. These objects are both landmine simulants of various types and different forms of clutter (like a crushed can, knife, and shell casing). The heat maps consist of the signal strength (voltage output form the metal detector) as a function of horizontal position offset between the metal detector coil center and the object center. These maps are also created at different offset heights between the metal detector and object, to measure how the overall sensitivity will change with distance. The heat map gallery will be useful in determining whether such information can be used to help distinguish landmines from buried clutter in real surveys of minefields as part of our multi-sensor approach to landmine detection and identification. His work can be viewed on the Landmine Detection at F&M web site.

Alex worked on developing a matched filtering program that will detect particular kinds of exposed landmines using LIDAR imagery. The landmines in question are the PMA-2 type, which has a small starfish-type plunger extension on top of the mine which acts as the trigger, and the PFM-1 type, which is typically scattered onto the ground and has a distinctive butterfly-like shape. The PMA-2 mine is typically planted in such a way that the starfish is poking up above the ground surface, making it visible. In a real scene with such mines, other shapes that are present on the ground, such as leaves, blades of grass, or ground bumps, make the identification of these mines very difficult since they blend in. Color similarity with the background (camouflage) also inhibits detection through imagery. However, preliminary investigation of LIDAR imagery taken with an iPhone indicates that these mine shapes are in fact distinguishable in high-resolution imagery if one knows where to look. One approach for reliable detection in the absence of a known mine location is to convolve a kernel (consisting of a LIDAR image of the starfish or butterfly on a flat, smooth background) with the scene image to enhance the location of the mine in the convolved (filtered) image, where the starfish or butterfly kernel would match the mine shape. Alex developed test imagery as well as convolution code to test this idea, and he explored exploring whether this can work in real scenes as part of a multi-sensor landmine identification approach.

Mia studied the long-term X-ray outburst evolution of the infant magnetar J1818.0-1607 using SWIFT data. The data were modeled using different spectral models, which provided information on the temperature, flux, and luminosity of the source. She found the X-ray flux to show a monotonic decrease over time, a consistent trend observed in other magnetars. The results from this project provide answers regarding the evolution of the spectral properties of magnetars following an outburst.

This project was primarily supervised by Harsha Blumer (West Virginia University).

Maggie and Wenky worked on the analysis of archival Chandra X-ray Observatory data of a supernova remnant (SNR) and its associated nebula. SNRs are among the most fascinating astrophysical objects in the Universe. They are of prime importance for the chemical enrichment and evolution of galaxies, they accelerate cosmic rays to extremely high energies, and SNRs resulting from core-collapse explosions make the most magnetic and compact objects in the Universe: neutron stars. Young neutron stars emit relativistic winds and jets that power beautiful nebulae known as pulsar wind nebulae (PWNe). X-ray observations are an important means to study the many aspects of these objects. The project involved constructing X-ray images of the remnant, searching for a putative central pulsar, and identifying diffuse emission regions within the remnant for spectral analysis.

This project was primarily supervised by Harsha Blumer (West Virginia University).

Gillian and Mel were investigating pulsar candidates generated in a search of unidentified Fermi gamma-ray sources for radio millisecond pulsars. This survey is being conducted with the Green Bank Telescope and is one of the NANOGrav pulsar search projects.

Shin reprocessed the high-resolution survey of the LMC done with Parkes (Ridley et al. 2013) to search for single pulses. This reprocessing was done with the new FETCH software package, which is well-suited to finding and identifying realistic dispersed signals in pulsar survey data. This work was published in Hisano et al. (2022). Shin is also looking through the PALFA survey archive to look for single-pulse events, rotating radio transients (RRATs), and fast radio bursts (FRBs) that may have been missed in the original survey processing. This reprocessing also used the FETCH software package. In addition, Shin also helped with the reprocessing of the Parkes PKS70 survey (see below) and a search for millisecond pulsars in unidentified Fermi gamma-ray sources with the Green Bank Telescope (see above).

Adem Imamovic (F&M '22), Andrew Lara (F&M '24), Ethan Senatore (F&M '24), Yihao Zhang (F&M '23), Erik Lillegard (F&M '23), David Li (F&M '24), and Joey Buck (F&M '24)

These students all continued work on our landmine detection project (see below). Each student focused on a different aspect of the system under development. See the description below, the Landmine Detection at F&M web site, or the NATO project websites G5014 and G5731 for more complete details about this project.

Zach worked on modifying python code that was originally developed for a so-called stack search of pulsars in a globular cluster so that we can use it in a search for pulsars in the neighboring galaxy M33, the Triangulum Galaxy. The stack search is a method in which multiple separate obervations of the same object (or location on the sky) can be combined to improve the sensitivity to periodic signals relative to what can be achieved in any single observation. This is accomplished by adding (stacking) the power spectra computed for each separate observation into a single summed spectrum. This stack search will be applied to about a dozen long integrations that were taken of the core of M33 with the Arecibo radio telescope. Very luminous pulsars residing in the core of M33 may be detectable in this way.

Don worked on analyzing observations of several millisecond pulars (MSPs) taken with the Long Wavelength Array (LWA). The goal of the project is to determine if several regularly observed MSPs in the NANOGrav pulsar timing array can be reliably detected with this instrument at very low frequencies (below 100 MHz). If that were the case, then LWA observations could be used for monitoring changes in the pulsar dispersion measure that occur from changes in the interstellar medium. Such corrections to dispersion measures are more easily estimated at low frequiencies and are necessary to achieve the highest possible timing precision for the detection of gravitational waves through pulsar timing.

Mckenzie Golden (F&M '25), Dani Zoeller (F&M '23), Aubrey Laity (Millersville '21), Jamie Margeson (F&M '21), and Tomonosuke Kikunaga (Ph.D. student, Kumamoto University)

These students have been searching archival data from the Parkes radio telescope to hunt for new pulsars and impulsive signals such as fast radio bursts. The archival data is from a 70 cm survey (called PKS70) conducted at the Parkes telescope in the early 90's which covered much of the southern sky. This data was processed at the time it was taken, and a large number of pulsars were discovered and published. The raw data were recently downloaded and reprocessed at F&M. There are two reasons for doing this reprocessing. The first is that the newer software is better tuned in some ways to find pulsars than the old software from the time of the survey, so there may be pulsars lurking in the data that were missed. The second is that the the newer software searches for radio bursts as well as periodicities, whereas the old software did not. So impulsive signatures such as giant single pulses from neutron stars or fast radio bursts (FRBs) from distant galaxies that were previously undetected may now be discoverable. The signals detected in the reprocessed data (either as periodicities or single-pulse events) need to be checked against the known pulsar catalog to see if it they are in fact new signals. The tasks include viewing and checking all of the plots and other output from the processing, identifying known signals, identifying any promising new candidates, and keeping meticulous bookkeeping records about what has been investigated and checked.

Four new FRBs were found in the analysis The new FRBs have several distinguishing features. All four of the FRBs discovered have significantly larger widths (> 50 ms) than almost all of the FRBs detected and cataloged to date. One of the FRBs has a DM of 3338 pc cm^-3, which is the DM largest measured for any FRB to date. These are the first FRBs detected by any radio telescope (so far), and they predate the Lorimer Burst by almost a decade.

More details can be found in Crawford et al. (2022). Several F&M students were co-authors on this paper.

More information about this project can be found here and here.

Jack Sinton (F&M '20), Ileane Ho (F&M '20), and Aaron DiGregorio (F&M '21)

Jack, Ileane, and Aaron continued work on the robotic landmine detection project outlined below. Specific tasks included the following: (1) Development of tripwire detection techniques using cameras to be mounted on the robot. This involves camera testing, developing appropriate image processing algorithms, and field tests to test effectiveness. (2) Investigation, purchase, field testing, and integration of a metal detector for inclusion in the robotic platform (in consultation with partners in Jordan). (3) Design and implementation of a database for real-time storage of position coordinates and auxiliary information from the robot via GPS. This is needed to identify locations of possible explosive ordnace prior to disposal (this work will be conducted in consultation with our robot vendor, ClearPath). (4) Field testing of the robot to identify buried simulated landmines and buried harmless clutter of different varieties.

See the description below, the Landmine Detection at F&M web site, or the NATO project websites G5014 and G5731 for more complete details about this project.

Gaby Sallai (F&M '19), Stasia Kuske (F&M '19), and Jack Sinton (F&M '19)

Gaby, Stasia, and Jack worked as summer and independent study students with Tim Bechtel (Earth and Environment Department) and me on the development of a practical next-generation robotic landmine identification system using a cyber-physical connected systems approach to the problem of mine identification and removal.

The detection and removal of landmines and other unexploded ordnance in current and former conflict zones is a major humanitarian task that can be leveraged by the use of technology to address the complexities and difficulties in correctly identifying mines. Typically more than 99% of a deminer's time is spent identifying and removing inert underground clutter. Sophisticated identification and imaging of underground objects (whether they be landmines or junk; either plastic or metal) can reduce this wasted time and mitigate the physical danger to the deminer. This demining technology comes in multiple forms and needs to work together in a single system to be maximally effective. This technology includes imaging (with LIDAR-enabled cameras for landscapes, and holographic radars for underground objects), ground-penetrating radar for object detection, robotics and field mobility assessments, real-time communication between different parts of the overall system, user databases that are populated in real-time with field data and which are accessible worldwide, wireless data transfer and communication between robots, sensors, users, and databases, and interfaces between users and the instrumentation.

With rapid advances of commercial technology, the costs are reduced while reliability and capability are increased (these are important considerations since cost, ease of use, and reliability are important for the end users of the technology in typically poor and/or underdeveloped conflict zones). Real-world conditions also dictate that the technology be field-ready and simple to use in order to be practical as a tool. These developments and the requirements of the overall problem point to an integrated technology approach, dubbed Industry 4.0 in engineering and industry parlance, which represents a fourth technology revolution. In this paradigm, cyber and physical systems communicate, merge, and integrate into a single, connected, decentralized system that is simple, cheap, and reliable. The name we give to this integrated cyber-physical approach to the landmine problem is Landmine Detection 4.0.

Our research group at F&M is working in tandem with colleagues from Italy and the Ukraine as a NATO-funded team (Projects G5014 and G5731) to enhance existing and proven technology and the techniques that have been developed to address demining in the Ukraine conflict zone of Donbass. The existing work of this team has been successful in testing imaging techniques with holographic radars and with terrain analysis in the Ukraine conflict zone. The integration of these aspects of the system and others are beginning to get underway.

We plan to take the next steps in this project and begin development, testing, and integration of an effective and widely-used demining system. Our work at F&M will initially focus on several aspects of the system development, including LIDAR imaging and digital elevation models (DEMs) for the terrain in the Ukraine conflict zone, and how the robot can use these for navigation and movement decisions. This is necessary because the terrain is generally uneven with lots of obstacles, which can block the robot or get it stuck in the minefield. In addition, accurate cm-scale real-time mapping of the ground in the vicinity of the robot is necessary to correct the holographic radar images for the non-planar ground-air interface through which the radar signal propagates. Additional tasks that our group will tackle are: investigating the possibility of tripwire detection (imaging of wires) using experiments with different infrared and visible cameras and with different wire configurations, wire types, and distances from the camera, determining the feasibility of using publicly available algorithms for automatic wire detection and implementing these; using actual Ukraine terrain data and DEM maps to assess robot maneuverability in the Ukraine mine fields; determining the fraction of area suitable for the selected robot design and ensuring readiness for real-field conditions to maximize usefulness of the robot by local operators; and assisting with the holographic ground-penetrating radar imaging correction work being led by the Italian group by conducting radar and camera detection scans in a soil test bed at F&M under different field assumptions (underground target configuration, shape, size, and depth, background material type, scanning angle, and distance to target.

The project has been described in two news articles published in the F&M News in 2018. These articles can be acccessed here and here

You can learn more about the project at the Landmine Detection at F&M page.

Tori Bonidie (F&M '20)

Tori continued a search for millisecond pulsars and fast radio bursts in the LMC from data taken with the Parkes radio telescope (see the paper by Ridley et al. 2013 which describes this survey). She did this as an independent study project and processed additional data sets on our Beowulf clusters after they were observed and received from Parkes.

Faisal Alam (F&M '19)

Faisal worked with me as a summer student on several projects involving extragalactic pulsars. He examined pulsar search candidates produced from a recent high-resolution Parkes survey of the LMC, he worked on determining timing solutions for a number of LMC pulsars discovered by Ridley et al. (2013), and he compiled a list of the most luminous radio pulsars currently known in the Galaxy and the Magellanic Clouds in order to compare them to our luminosity detection threshold in an Arecibo search for pulsars in the Triangulum Galaxy (M33) (see Kristina Rolph's project below). In addition, Faisal conducted regular Arecibo pulsar search and timing observations for the PALFA survey and the NANOGrav search for gravitational waves. Faisal also classified a number of single pulse candidate plots from the PALFA survey for the purpose of creating a training set for an automatic classification scheme being developed by the pulsar group at McGill University.

Benjamin Nguyen (F&M '18) and Tanya Saigal (F&M '19)

Ben and Tanya's work was to expand the search of the radio data that we previously collected with the NRAO 140-ft (43-meter) telescope at Green Bank which targeted 91 bright, polarized, but still unidentified point-like radio sources that might be undetected pulsars (see Debbie Schmidt's project below and also Schmidt et al. 2013). Their processing of the survey data went to a much higher dispersion measure (DM) range than the previous processing did (a maximum of 1000 vs. 100 pc cm-3), and it had full sensitivity to a larger range of binary accelerations (up to 1000 m/s^2) for small DMs. This acceleration range makes very tightly orbiting binary pulsars near to Earth more likely to be detected. The high DM range searched ensured that no high-DM pulsars were missed in the search and that highly dispersed (bright) fast radio bursts (FRBs; see Lorimer et al. 2007) originating from outside our Galaxy were also detectable (if present). This work was written up and published by Crawford et al. (2021).

Ben also classified a number of single pulse candidate plots from the PALFA survey for the purpose of creating a training set for an automatic classification scheme being developed by the pulsar group at McGill University.

Rachel Umberger (F&M '17)

Rachel worked with me on two pulsar projects as a summer student. The first project was sifting through timing observations of known pulsars discovered in the Large Magellanic Cloud to search for new, previously undetected pulsars in the data. The timing data in question used the Parkes multibeam receiver, so there are 12 beams in addition to the one timing beam in each observation that have good sky data. We hoped to find a millisecond pulsar in these data and also looked for possible fast radio bursts in the data. The second project was to identify and confirm millisecond pulsar candidates from the PALFA Arecibo survey. These candidates were selected from the PALFA-3 processing pipeline database to have promising visual features in the folded plots. This project used Dominik Rastawicki's IDL code to identify the promising pulsar candidates (see also Jack Madden's PALFA project below). Once harmonics of known pulsars were eliminated and any candidates already identified in a previous analysis of the data have removed from the list, the remaining handful of candidates were selected for confirmation observations at Arecibo.

Lam Tran (F&M '17)

Lam finished the analysis of data from several Parkes pulsar surveys to look for the presence of millisecond-scale radio bursts (fast radio bursts, or FRBs) at very large dispersion measures (see Kristina Rolph's project below). You can read more about F&M's involvement in FRBs here. A large dispersion measure corresponds to a large (cosmological) distance in this case. There have been a number of FRB detections by others at smaller (but still large) DMs in other surveys, but no FRBs have been detected so far at very large DMs. Finding a burst at a very large DM would indicate the presence of millisecond burst progenitors at a much larger distance and at an earlier time in the universe than what has been seen so far. We found no new FRBs in our surveys, but from our non-detections, we have been able to improve upon the upper limit for the all-sky rate of occurrence of FRBs. This results of this work were published by Crawford et al. (2016).

Kristina Rolph (F&M '15)

Kristina worked with me on a search of the Triangulum Galaxy (M33) for dispersed radio pulses from compact objects using the Arecibo telescope. A new wide-bandwidth backend has been installed at Arecibo, making a new search of M33 for pulses feasible with Arecibo. We hope to discover extragalactic radio pulsars from M33, which would be the first confirmed pulses from a compact object in another spiral galaxy. Apart from detecting signals from bright pulsars, our search may be sensitive to bright bursts from other sources, such as rotating radio transients and magnetars. The search is also sensitive to the kind of extremely luminous extragalactic bursts that have been observed in some pulsar surveys (see below). More details can be found here.

Kristina also analyzed data from several Parkes pulsar surveys to look for the presence of millisecond-scale radio bursts (called fast radio bursts, or FRBs) at very large dispersion measures. You can read more about F&M's involvement in FRBs here. A large dispersion measure corresponds to a large (cosmological) distance in this case. There have been several burst detections of this kind by others at smaller (but still large) DMs, but no bursts have been detected so far at very large DMs. Finding a burst at a very large DM would indicate the presence of millisecond burst progenitors at a much larger distance and at an earlier time in the universe than what has been seen so far. No new FRBs were found on these surveys, but the results of this work (including new improved upper limits on the all-sky rate of FRBs) were presented by Crawford et al. (2016).

Chris Morrow (F&M '15)

Chris worked with me as summer student on a project to support modeling of the detection of gravitational waves using pulsar timing. This in turn is part of a larger effort to directly detect gravitational waves by the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) consortium. Gravitational waves are distortions in space-time that are predicted by General Relativity to be generated by the acceleration of masses. Very massive black holes in binary systems that undergo inspiral and coalescence are one source of these waves. These inspiral and merger events early in the evolution of the universe ought to have left a background signal of gravitational waves which may be detectable today with pulsar timing. The idea is that pulses coming from an array of pulsars in space may experience delays (timing residuals) of such a magnitude and with such a correlated relationship that it would indicate the presence of gravitational waves. Currently just a handful of known pulsars with very precisely measured residuals are used in the detection models since these are the most sensitive to slight delays. However, other less precisely measured pulsars may also be useful to include. Nobody had yet compiled a complete census of the characteristics and information relevant for gravitational wave detection for the known pulsar population. Chris tracked down and compiled this information for the known pulsars, and we will determine whether any of these pulsars may be useful to add to the gravitational wave modeling and detection effort.

Jack Madden (F&M '14)

Jack worked with me as an independent study student and summer research student identifying pulsar candidates from both the PALFA survey (see below) and a high-resolution radio pulsar survey of the Large Magellanic Cloud (LMC). The LMC survey data were taken with the Parkes 64-m radio telescope in Australia, and this is the first survey of the LMC that is sensitive to fast-spinning, millisecond pulsars (MSPs) that have been recycled from accretion from a companion star. To date no MSP has been discovered outside of our Galaxy, and we hope that this survey will find the first one. Some initial results from this survey were presented in a conference talk at an American Astronomical Society meeting. Most MSPs reside in binary systems, and in order to detect binaries, the survey is being processed using a search in acceleration parameter space. The acceleration search expands the data processing task by orders of magnitude, so Jack's summer work was to determine a feasible range of parameter space to search with our Beowulf clusters. He then processed the survey data using his chosen search parameters. Jack did not find any pulsars in his search of these data, but he did find a new pulsar in the LMC from reprocessed archival data. His discovery was reported in articles in The Diplomat and in The College Reporter. The pulsar discovery is also presented along with several others in (Ridley et al. 2013).

For a senior project, Jack returned to the PALFA survey and applied the IDL pulsar finder code that was developed by Dominik Rastawicki (see below) to the PALFA "Pipeline 2" database of survey candidates. We wanted to see if we could detect any new pulsars that were missed in the usual candidate inspection (we found only two new weak candidates). In addition, he is applied the filter to select for low dispersion, bright millisecond pulsars that might have been missed in the analysis if they were mistaken for terrestrial radio interference (RFI). Such pulsars could be useful to include in the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) pulsar timing array in the search for gravitational waves. He also evaluated the effectiveness of the code in detecting all known pulsars in these data, and this code is ready to be applied to the latest set of survey candidates being generated by the PALFA survey ("Pipeline 3").

Ryan Anella (F&M '13)

Ryan worked with me on processing pulsar survey data from observations that were coincident with cataloged HMXBs located in the Magellanic Clouds. He looked for faint, pulsed radio emission and radio bursts, which are not generally expected to be detectable from active X-ray binary systems. The data were searched on our Beowulf cluster at a wide range of dispersion trials as well as a large range of acceleration trials to account for any binary orbital motion effects. Detection of radio emission from these systems would have implications for the physics of how accretion from a companion onto a neutron star suppresses the radio emission mechanism. We found no radio pulsars associated with any HMXBs. His work is described in a paper announcing the discovery of several pulsars in the Large Magellanic Cloud (Ridley et al. 2013).

Hannan Li (F&M '14)

Han worked with me as a summer student investigating the modulation characteristics of PSR J0529-6652, a very luminous pulsar in the Large Magellanic Cloud that has shown unusual variability on short time-scales. This is a continuation of work that was first started by Dean Altemose (see below). Han modified and extended some of Dean's code to take a different approach toward characterizing the pulsar variability that was outlined by Jenet & Gil (2003) and Jenet & Gil (2004), and more recently by Weltevrede, Edwards, & Stappers (2006) and Weltevrede, Johnston, & Espinoza (2011). The results from this study were presented in Crawford et al. (2013).

Zach Robinson (F&M '11)

Zach worked as an independent study student continuing our investigation and classification of pulsar candidates produced in the processing at F&M of survey data from the PALFA survey project (see below for more details about candidate analysis work for the PALFA survey). He also was responsible for evaluating the quality of PALFA candidates produced by Dominik Rastawicki's automated pulsar detection algorithm (see below).

Dominik Rastawicki (F&M '11)

For his independent study project, Dominik took a set of algorithms that he had previously developed to detect cavities/voids in maps of the solar corona and applied them to the classification of pulsar candidate plots from the PALFA survey. One goal was to determine whether this artificial detection algorithm can be used to effectively discriminate between real and fake (interference) signals in the PALFA survey candidates at F&M (the answer is yes!). A second goal was to apply this algorithm to identify good pulsar candidates in our existing database of processed data at F&M, which currently has several hundred thousand plots and is growing each month. Investigating the plots one at a time is too big of a task for one or two students without some kind of automation. We also applied Dominik's algorithm to the collection of PALFA candidates produced by the Einstein@Home radio pulsar search project, which processes PALFA survey data in a distributed fashion and is particularly sensitive to finding highly-accelerated binaries with short orbital periods. Dominik's algorithms have proven to be a promising approach to candidate identification, and a modified version of the code was used by the Einstein@Home group to identify roughly half of the 24 new pulsars found in Parkes Multibeam Pulsar Survey data. These results were presented in Knispel et al. (2013).

Claire and Debbie worked as independent study students, and apart from their continuing work on the PALFA survey (see below) and assisting with timing observations for the binary pulsar PSR J1723-2837 (Crawford et al. 2010 and Crawford et al. 2013), they were responsible for regular observations using the NRAO 140-ft (43-meter) telescope in Green Bank, WV. For this project, we collected high-resolution pulsar search data on 92 unidentified radio sources from the FIRST and NVSS VLA surveys that are both bright and highly linearly polarized. This project is a joint collaboration between F&M and NRAO and augments a previous search of these same sources with Jodrell Bank (Crawford et al. 2000). Some of these unidentified sources may be pulsars undiscovered in previous large-scale surveys, perhaps owing to very fast spin periods (i.e., millisecond, or possibly sub-millisecond periods). Discovery of a sub-millisecond pulsar would indeed be very exciting, and the payoff of the search in this case would be huge. Our new search at NRAO used a different frequency than the previous Jodrell Bank search, had a much wider bandwidth, and employed some software tools and observing and computational developments that were not available for the previous search. The 140-ft telescope and data acquisition software were operated remotely from F&M by the students, and the huge amount of data acquired in these sessions has been processed at both NRAO and F&M. Debbie completed the analysis of this survey for her senior thesis project, including a search for single pulse candidates and radio bursts. More details can be found here. Aspects of this work have been presented by Mickaliger et al. (2011), Crawford et al. (2011), Schmidt et al. (2012), and the final project results were presented by Schmidt et al. (2013).

Debbie and J.B. worked as summer students on the ongoing effort at F&M to process data and analyze pulsar candidates from the PALFA survey project. This work was started the previous semester by Claire Gilpin and Matt Jaffee, both of whom also worked on this project during the summer (see the description of their work below). Debbie worked full-time as a research student while J.B. supplemented his internship in another field with some part-time work on this project. In addition to this, J.B. worked on developing an algorithm to determine the spatial location (with uncertainty) of a putative radio signal that had been detected simultaneously in multiple beams of the Parkes multibeam receiver. The signal strengths in the 13 beams vary depending on the location of the source and other factors, including the different beam gains and the signal attenuation as a function of distance from the beam center, both of which must be modeled. The fitted signal position in the model must reproduce the observed ratios of the 13 different signal strengths (within their uncertainties). If no solution to this set of ratios can be found, then this could indicate that the signal might not be celestial in origin. In addition to her PALFA survey work, Debbie re-analyzed some Parkes timing data taken of the binary millisecond pulsar PSR J1723-2837 in order to see if additional timing detections could be made with these data. This work supported a new pulsar timing campaign that collaborators and I began on PSR J1723-2837 (see Crawford et al. 2010 and Crawford et al. 2013). Debbie accompanied me to an AAS meeting as well.

Claire and Matt both worked as independent study students (and subsequently as summer research students) processing and analyzing PALFA survey data at F&M. A good fraction of their their work was identifying promising pulsar candidates from the thousands of output plots that are automatically produced in our batch processing of the survey data with our Beowulf cluster. To help with this, they used a python GUI developed by the pulsar group at McGill University. They also downloaded raw data from Cornell for processing, operated the batch processing of survey data on the computer cluster, and uploaded the resulting candidates to the Cornell PALFA database. In addition, Matt worked on writing scripts which parse the headers of the processed beams in order to extract useful information from them, as well as writing scripts to help automate the review of the single pulse plots produced in the processing. Claire worked on writing up a manual for PALFA data analysis at F&M which can be used by future research students. Claire also assisted with several other ongoing projects. One was a search for very long-period pulsations (8-25 sec) in a radio pulsar survey that had targeted unidentified gamma-ray sources (see Crawford et al. 2006). Slowly-spinning neutron stars, for instance, could be detectable in this way and might have been missed with other search techniques. The other project was an investigation of the orbital phases of observations of PSR J1723-2837 taken with the Parkes Observatory and Green Bank Telescope. PSR J1723-2837 is a binary millisecond pulsar that has proved difficult to detect regularly in previous observations (possibly due to eclipsing from the companion star), and my collaborators and I have begun a timing study of this pulsar system. Claire spent some time in Australia, and Claire and Matt both accompanied me to an AAS meeting.

Dean worked with me as a summer student analyzing the nulling behavior of a very luminous radio pulsar (PSR J0529-6652) in the Large Magellanic Cloud. The pulsar was discovered in a radio pulsar survey of the Magellanic Clouds some years ago (McCulloch et al. 1983), but its nulling behavior has not been studied as far as we can tell. Apart from being very luminous (and having some kind of nulling behavior), this pulsar is not particularly unusual, and it is not yet clear exactly how PSR J0529-6652 is connected to the population of known nulling pulsars, or whether its behavior represents something new. Dean developed code in IDL to turn the raw data we collected at the Parkes telescope into individual phase-resolved pulses, and he applied his software to PSR J0529-6652 as well as several bright test pulsars we also observed. His work was continued by Han Li (F&M '14) (see Han's project above). The results from this study were presented in Crawford et al. (2013).

Jen worked with me on two different summer projects. The first project was finishing up the analysis of candidates in a search for highly-dispersed single radio pulses and bursts in archival survey data taken of mid-latitude EGRET sources with the Parkes telescope (see Crawford et al. 2006, Burke-Spolaor et al. 2011, and also below). Jen also worked on developing a procedure for doing the photometry of variable K-dwarfs in the Pleiades using IRAF. This latter project is part of F&M's long-term collaboration to monitor several variable dwarf stars (see Krishnamurthi et al. 1998). Jen reduced data that F&M students and I had collected at the NURO 31-inch telescope in March 2008, and she created a photometry cookbook that we can use for data reduction in the future. Jen's work on the search for dispersed radio pulses was presented in an AAS conference poster.

Chase's project as a summer research student was searching for a periodic signal from the pulsar candidate J1928+15, which was discovered in the PALFA survey. The discovery observation of J1928+15 showed a single set of three dispersed pulses. Subsequent follow-up observations showed no periodicity in the expected period range. Chase and I searched these follow-up observations for additional single pulses and for a long-period periodicity using the Fast Folding Algorithm. This latter analysis is more sensitive than a Fourier search to very long periods (i.e., more than a couple of seconds). This pulsar may belong to a new observational (and possibly physical) class of serendipitous intermittent objects. This search work was reported in a larger paper on intermittent and transient radio pulsars found in the PALFA survey (Deneva et al. 2009).

Brian worked with me as a summer student searching for highly-dispersed single radio pulses and bursts in archival Parkes survey data taken of mid-latitude EGRET sources (see Crawford et al. 2006, Burke-Spolaor et al. 2011, and also below). Brian modified and ran PERL scripts to process the raw data, and extended the search to a higher dispersion range than what was covered in the prior analysis of these data. The extension in the dispersion range was motivated by the discovery of a highly-dispersed, extragalactic millisecond radio burst in another archival Parkes survey (see Lorimer et al. 2007) which indicated that such bursts might be present in other pulsar data sets. Brian's work on this project was presented in an AAS conference poster. Brian also accompanied me to the Parkes observatory to collect data for several pulsar projects, including a study of a nulling pulsar (see above) and a search for pulsed radio emission from two X-ray sources (including one transient source) in the Magellanic Clouds (see Crawford et al. 2009).

For her senior project, Elisabeth worked on the calibration, editing, and mapping of archival radio interferometry data from the Australia Telescope Compact Array. These data were taken of a young, energetic pulsar (PSR J1301-6305) that was first discovered in the Parkes Multibeam Survey (see also Chelsea Tiffany's project below). The radio observation field happened to include the error circle of a newly discovered TeV gamma-ray source, HESS J1303-631 (Aharonian et al. 2005), so her analysis aimed to determine whether there were any faint extended radio sources within the error circle (such as a pulsar wind nebula) that could be powering the gamma-ray emission. We carefully repeated the prior calibration and editing of the raw data, and we created maps of the region at both 1384 MHz and 2496 MHz. We found a small extended object that had been only hinted at in a previous, low-resolution map taken at 843 MHz. However, further analysis indicated that this source was not a pulsar wind nebula or supernova remnant and is not associated with the TeV source. Some of Elisabeth's calibration work on the PSR J1301-6305 data was used in the polarization analysis of two energetic radio pulsars that was written up in a journal article (Crawford & Tiffany 2007).

Tim's senior project was to search through single pulse plots from a Parkes survey for pulsars in the Magellanic Clouds (see Manchester et al. 2006). The goal was to look for highly dispersed single pulses or bursts from transient neutron stars. Our collaborators were also searching these plots at the same time, and they discovered a very luminous, highly-dispersed millisecond burst in several of the beams. This probably represents a new kind of source, and follow-up search observations revealed no additional signals . The burst discovery and discussion were subsequently written up in a journal article (Lorimer et al. 2007).

Brian's senior project was to model a high-pass filter present in the multibeam receiver system of the Parkes telescope. This filter is modeled as a two-pole filter (see Manchester et al. 2001), and it attenuates variable signals (such as pulses) having characteristic times longer than a few seconds. This receiver has been widely used for pulsar searches and other observations, but the filtering effect is particularly relevant for searches for radio pulses from anomalous X-ray pulsars (see, for example, Crawford et al. 2007) and from other sources having long spin periods. In these cases, the filter can significantly degrade the sensitivity of the search observations. Brian's project was to quantify the effect of the filter on the sensitivity of radio search observations with this system by creating synthetic pulse trains in software having a range of periods and duty cycles. He then passed these signals through a model software filter. Brian developed scripts in Mathematica to do this, and his results were included in a paper in which we reported the results of a sensitive radio search of a long-period transient X-ray source (XTE J0103-728) in the Small Magellanic Cloud (Crawford et al. 2009).

Apart from helping with the maintenance of our distributed Linux cluster (see Cantino et al. 2004 and also below), Peter assisted me with survey observations for the PALFA survey, a survey of the Galactic plane for pulsars being using done with the Arecibo telescope. Peter and I went to Arecibo to conduct some of these observations, and he accompanied me to an AAS conference as well.

All of these students worked with me on troubleshooting and expanding a distributed Linux cluster that we constructed from a collection of decommissioned PCs that were connected to each other through standard ethernet ports throughout the science building (see Cantino et al. 2004 and below). Since the machines were old and no mechanism was in place to automatically synchronize the machine configurations as changes were made, these students spent a lot of time adding and checking software, handling network and system administration tasks, rebooting and resetting machines, dealing with power issues, and adding new machines to the cluster as they became available. During the course of this work, some of the processing of the Parkes survey data taken of mid-latitude EGRET sources was also done (see Crawford et al. 2006).

Gabe worked with me as a summer student on several pulsar projects. He wrote a monitoring script for our distributed Linux cluster in PERL which periodically polled the node machines and recorded the machine loads in a publicly accessible file. This was useful for checking on the status of the cluster during data processing. Gabe also began a modeling study of the Parkes Multibeam Survey sensitivity, comparing model predictions with the sample of observed pulsar detection strengths from both the blind Fourier search and folded-profile detections. Accurately modeling the sensitivity of the survey is important for population modeling work which aims to understand the underlying radio pulsar population in the Galaxy. He also conducted some of the processing of the data from the Parkes survey of mid-latitude EGRET sources (see Crawford et al. 2006).

Steve and Ryan worked over the summer on developing PERL scripts to handle the processing of the data from the Parkes survey of mid-latitude EGRET sources (see Crawford et al. 2006) using the distributed Linux cluster we constructed from decommissioned PCs (see Cantino et al. 2004 and below). These data were loaded from DVD and processed on the cluster, with a range of trial dispersions determined for each individual beam from the NE2001 Galactic electron model (Cordes & Lazio 2002). By separately calculating the dispersion range to be searched for each individual beam, we could more efficiently use the available cluster cycles and more quickly complete the processing.

Cole's senior project was to search for radio emission from PSR J0537-6910, an X-ray pulsar with a period of 16 ms in the Large Magellanic Cloud that was first discovered by Marshall et al. (1998). This is the fastest non-recycled rotation-powered pulsar known and is one of the few "Crab-like" pulsars that are known. A previous search for radio emission from this pulsar was unsuccessful (Crawford et al. 1998), so we undertook a more sensitive observation of this pulsar with the Parkes telescope using higher time and frequency resolution. In addition, there is reason to believe that PSR J0537-6910 could be emitting giant single radio pulses. Detection of either giant or regular radio pulses from PSR J0537-6910 would be important for understanding the connection between giant radio pulses, the light-cylinder magnetic field strength, and high-energy and radio emission. Cole searched for periodic emission using both a Fourier search and a folding search at a range of trial dispersions (a computationally demanding problem) while our colleagues searched for single-pulse emission. We made no detections and set upper limits on the radio luminosity of the pulsar. Cole accompanied me to a COSPAR conference meeting in Paris to present these results, which were also written up in a journal article (Crawford et al. 2005).

Andrew's summer project was jointly sponsored by the physics and computer science departments (myself and John Dougherty) to develop a distributed Linux cluster for pulsar data processing and network efficiency analysis. This cluster was to be constructed from decommissioned PCs connected to each other through the standard ethernet ports present throughout the science building. Essentially, this was a simple, low cost solution to the processing problem which used a client-based approach to the data distribution. Andrew also was responsible for writing the majority of the software (in PERL) through which the processing of data from a Parkes pulsar survey of unidentified EGRET sources would be handled. Andrew presented our work at a refereed computer science conference (see Cantino et al. 2004), and the results from the EGRET pulsar survey were later published in a journal article (Crawford et al. 2006). Andrew also presented this work in a KNAC symposium paper.

For his summer project, Reid worked on producing a database archive of the raw data collected in a survey of unidentified mid-latitude EGRET sources for radio pulsars conducted with the Parkes telescope (see Crawford et al. 2006). The data were originally stored on DLT tape when they were acquired at the telescope. Reid read off the survey data files from tape, unpacked them, and archived each set of unpacked beams onto DVD with an additional file that included relevant information about the beams (e.g., sky positions) and instructions for retrieval. Reid created a portable archive of 232 DVDs containing the whole survey (see Cantino et al. 2004), and this archive was used in the processing of the survey data by our group. Reid also created a set of master files containing all of the survey information. This database is publicly accessible here. Reid presented his work in a KNAC symposium paper, and he also went to the Parkes observatory for an extended observing session, which included assistance with pulsar survey observations as well as planetary satellite tracking work.

For Saurav's summer project, he worked on developing code in IDL to cross-check the catalog of known radio pulsars with the positions of the beams from a survey of unidentified mid-latitude EGRET sources for radio pulsars taken with the Parkes telescope. This was important for making sure that we detected the pulsars in the survey that we expected to detect and that our pulsar search code was working properly. Saurav also assisted with the construction of the DVD survey archive (see Reid Sherman's work above). Saurav presented his work in a KNAC symposium presentation and paper.

Chelsea worked me me as a summer student on the analysis of interferometric radio imaging data taken with the Australia Telescope Compact Array. These observations targeted several young, energetic pulsars that were discovered in the Parkes Multibeam Survey. Chelsea worked on the calibration of these data, and she constructed maps of the observed regions at two frequencies (1384 and 2496 MHz) in order to look for extended radio emission associated with the pulsars. These data were taken in pulsar gating mode, which allowed us to separate out the pulsed radio emission of the pulsar itself. The pulsar-gated data was used to construct phase-resolved polarization profiles and determine polarization fractions and rotation measures for two of the pulsars. This work was presented in her KNAC symposium presentation and paper, an AAS conference poster, and a subsequent journal article (Crawford & Tiffany 2007).

Nathan's summer project was to work on the analysis of radio polarization data taken of PSR J1119-6127, a young, high-magnetic field pulsar that was discovered by Camilo et al. (2000) in the Parkes Multibeam Survey. These polarization data were used to constrain the emission geometry of the pulsar and to test a theoretical model of pulsar spin-down proposed by Melatos (1997). Nathan constructed a 1400 MHz polarization profile, measured the polarization fraction and rotation measure for the pulsar, and determined the position angle swing of the pulsar as a function of pulse phase. He also used the measured position angle data to make constraints on the pulsar geometry using the rotating-vector model of Radhakrishnan & Cooke (1969). This work was presented in his KNAC symposium presentation and paper, an AAS conference poster, and a subsequent journal article (Crawford & Keim 2003).

Lindsey's UROP project was looking through plots of pulsar candidates that were produced from the processing of the Parkes Multibeam Survey. Promising candidates were tagged for follow-up confirmation with the Parkes telescope.

Funding

Our work has been supported in part by funds from the following sources:

• American Astronomical Society (AAS)
• Australia Telescope National Facility (ATNF)
• Franklin & Marshall Committee on Grants (COG)
• Franklin & Marshall Hackman Scholars Program
• Fund for Astrophysical Research, Inc.
• Haverford College Zweifler Family and Green Research Funds
• Keck Northeast Astronomy Consortium (KNAC)
• Mount Cuba Astronomical Foundation
• National Aeronautics and Space Administration (NASA)
• National Astronomy and Ionosphere Center (NAIC)
• National Radio Astronomy Observatory (NRAO)
• National Science Foundation (NSF)
• NATO Science for Peace and Security (SPS) Programme
• Pennsylvania Space Grant Consortium
• Research Corporation
• Sigma Xi Grants-in-Aid of Research Program