Dakota Johnson, Tildon Johnson, Kyle Barker Rowan County Senior High School

1. RFI AND PULSAR ANALYSIS Dakota Johnson, Tildon Johnson, Kyle Barker Rowan County Senior High School Mentor: Mrs. Jennifer Carter Abstract Radio Frequency Interference J2048-1616 Spin Down The spin down rate of pulsar J2048-1616 is calculated using the period and Mean Julian dates from the PSC database and the Australian National Telescope Facility catalogue. 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 J2048-1616 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. 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. Introduction 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. Figure 4. The spin down rate of J2048-1616. 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. Charactersistic Age of J2048-1616 A pulsar’s characteristic age is an estimate of how long it has been since the pulsar was born in a supernova explosion. The characteristic age is calculated by using the pulsar’s period and period derivative. The characteristic age only applies on pulsars that have not re-accelerated from accreting the mass of a companion star. The characteristic age is calculated below: Period – 1.96179738255 s P-dot – The characteristic age is 1334.36 years old. Image 3. The P-Pdot diagram. The P-Pdot diagram displays the pulsar’s estimated age by using the age of other pulsars, the period of your pulsar, and the period derivative of your pulsar. Plotting pulsar J2048-1616 on the P-Pdotdiagram provides an approximation of the magnetic field strength and energy loss. 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. 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 Data Analysis Pulsar J2048-1616 Pulsar J2048-1616 was discovered by A.J. Turtle and A.E. Vaughan in the southern hemisphere in 1968. At the time of its discovery, this pulsar had the longest announced period yet, 1.961 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. J2048-1616 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. Acknowledgements A special thank you goes out to: Jennifer Carter All PSC Astronomers Pulsar Search Collaboratorystaff 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 pulsarwas identified. Image 2. The PSC plot of the known pulsar, J2048-1616.