Dakota Johnson, Tildon Johnson, Kyle Barker Rowan County Senior High School Mentor: Mrs. Jennifer Carter Abstract Data Analysis Acknowledgements Radio Frequency Interference Pulsars are rapidly rotating neutron stars that have extremely large mass and magnetic fields, and spin precisely in time. Gravitational waves, proposed by Einstein, are thought to be created when large mass objects accelerate. Pulsar astronomers need additional observations of millisecond pulsars for the NANOGrav program that uses precise periods to detect these gravitational waves. A group of pulsar astronomers established a program for high school students called the Pulsar Search Collaboratory (PSC) to use over 30 terabytes of data collected by the Green Bank Telescope (GBT). The data that was collected by the GBT was reduced by using a Fast Fourier Transform algorithm that generated the plots analyzed. During the analysis, pulsar J was rediscovered. The data collected from this pulsar will add to the knowledge of pulsars as a whole despite not being not useful in gravitational wave detection due to the pulsar not being a millisecond pulsar. A special thank you goes out to: Jennifer Carter All PSC Astronomers Pulsar Search Collaboratory staff J Spin Down The spin down rate of pulsar J is calculated using the period and Mean Julian dates from the PSC database and the Australian National Telescope Facility catalogue. Figure 1. The location of the pointings of the data analyzed. This graph displays the Right Ascension and Declination of the plots analyzed: The most common area of Declination was -15:00. There was an almost constant Declination during the time that this pointing took place. The Green Bank Telescope was unable to steer, indicating that it was at immobile declination. As the Earth turned, a range of Right Ascension was observed while not changing the Declination more than a few degrees at a time. Introduction Approximately 17% of RFI analyzed was emitted from power lines at frequencies of 60 Hz and its harmonics. The remaining RFI was emitted from unknown sources. See Figure 3. Figure 3. The amount of RFI that came from power lines. Figure 4. The spin down rate of J The slope of the line is the p-dot. The positive slope indicates the period is increasing with time and is therefore spinning down, as it is expected. As pulsars age, the period usually decreases due to magnetic braking from the emission of magnetic dipole radiation. Binary systems are exceptions as the characteristic age equation only applies to isolated pulsars that have not been spun up by a companion. Image 1. A standard RFI plot. This plot is particularly interesting because of the strong signal that appears sporadic and exceeds the data range of the table. The cause of the phenomenon is a very strong signal from something Pulsar J Pulsar J was discovered by A.J. Turtle and A.E. Vaughan in the southern hemisphere in At the time of its discovery, this pulsar had the longest announced period yet, seconds. The distinct signal in the pulse profile and the vertical broadband emission (due to the pulsar emitting electromagnetic radiation in all spectrums) shown on the sub-band plot indicate that this plot is potentially a pulsar. The dispersion measure (DM) is very peaked and that is a characteristic of this subplot that we want in a pulsar. The fact that it is not peaked at zero indicates it is not located near the surface of the Earth.. Manmade signals that are emitted from near the Earth have dispersion measures at or near zero. Figure 2. The identification of the data analyzed. This chart displays the different categories of identification of data. They were either noise, RFI, or a known pulsar. Only one known pulsar was identified. A pulsar is a highly magnetized neutron star that emits radiation as beams from its magnetic field poles. To observe these types of neutron star, the beam from it must be pointed towards the Earth. Imagine a lighthouse and its rotating beams of light that stem from it. This examples helps demonstrate how you see the light when it is pointing towards you. Pulsars, like all neutron stars, are very dense and they have very precise periods (the time it takes to complete a spin). While the Green Bank Telescope was being repaired in 2007, three astronomers (Dr. Duncan Lorimer, Dr. Maura McLaughlin, and Sue Ann Heatherly) turned on the telescope as it was immobile and recorded data as the Earth rotated. Once completed, they had recorded more than 300 observing hours and over 30 terabytes of data. They realized that they could not analyze all of this data by themselves, so they decided to write a grant to organize the PSC program to train teachers and students to analyze the data sets. J Image 2. The PSC plot of the known pulsar, J Approach The research that was conducted was done by analyzing over 1000 plots of data from the Pulsar Search Collaboratory and identifying them as radio frequency interference, noise, a new pulsar, or a pulsar that had already been discovered. Noise is the discrete signal that the telescope observes. Everything in the universe gives off electromagnetic radiation and it gets collected as the telescope is collecting its data. Radio frequency interference (RFI) is a strong and deceiving signal that may come from space or the Earth. Commonly, RFI is emitted from man-made sources, such as power lines, satellites, etc.