Hulse Catches the Pulse! PSC Summer Institute 2011

By: Jacob Straley, Jacob Houdyschell, Chandler Smith, Nathan Keithline, Allie Sperry, and student mentor Ethel Perez

Our Goals•Find any known or unknown pulsars in our data•Determine if any pulsars found are known or unknown•If they are known, find exact Right Ascension, Declination, Period, and Dispersion Measure •Confirm all finds with a follow up observation using the GBT

ResultsOnce we had reached the control room, we wasted no time preparing the telescope for our first half hour session. We decided to scan our known pulsars first and figure out what to scan in our second half hour session later that night. When the results came in, we found some interesting things in our plots.

Usually a curve in the Time Domain plot is a very bad thing, but in this case it simply meant that the pulsar was part of a binary system, a solar system with two stars instead of one. In the plot on the right, we had a very high drop average and caught some nasty RFI, which usually covers up a potential discovery. However, the pulsar outshone the RFI and appeared clearly beside the interference.

2nd Half Hour Session

Our Candidates

1219-1608 – Jacob Houdyschell

0824-1609 – Jacob Houdyschell

MethodAfter searching through this data, we found a few good plots to use for a follow up. Our candidates for follow up observations were:

Planning the Scans

We decided to do follow up order based on how likely we felt the plot was of a pulsar. We had to calculate the rise and set times of each pulsar and find the exact RA, Dec, and Period to use the GBT. We decided that the order above was best because the known pulsars were a given and the candidate on the left had a better chance of being a pulsar than the candidate on the right. This was partly due to the strength of the signal in the Time Domain and the Sub-Band had a stronger looking signal than the other. We later, however, found out that the candidate we ranked as least likely had too high of a Dispersion Measure and it wasn’t even in this galaxy! The other candidate also had set by the time we had reached the control room, so we did not scan that signal either. We discontinued these scans immediately and replaced them with a pulsar donated to us by the wonderful scientists in the GBT control room that night. Then, a miracle occurred…

Conclusion

Despite not getting to check a potential pulsar and losing it’s replacement to an overheated antenna, we collected plenty of information and have come to a few conclusions. Of course, the question of whether or not our candidate was a real pulsar or not has not been investigated, but we now know how the pulsars we scanned have changed over time and have even collected a great example of a pulsar leaving an eclipse, along with some more advanced topics. Overall, the results of our data not only met what we expected of it, but it also included some interesting additions. In fact, the only thing we didn’t plan for was the sudden feeling of an emergency crisis when we fried the GBT’s antenna. We have been more than satisfied with our findings and appreciate the chance to observe these things first hand.

Acknowledgements and Special Thanks

We would like to acknowledge and thank the following people for their contributions to this project.

•Sue Ann Heatherly for allowing us to have such an event as this past week.

•Joe Swiggum and Pete Gentile for helping us in the GBT control room and donating us two pulsars to observe.

•The wonderful faculty of the NRAO for teaching us everything we needed to know to search for pulsars with the PSC.

•The entire NRAO for hosting such an event and allowing us time on the GBT.

•Dave for not hurting anyone that broke the GBT the day it went crazy. Thanks Dave!

Our Known Pulsars

J1643-1224 – Allie Sperry

J1610-1322 – Jacob Straley

J1643-1224

J1610-1322

1219-1608 0824-1609

1 2

3 4J1643-1224 J1610-1322

We spent our second visit to the GBT control room searching two signals that the scientists gave us to search. The first of these came back with an extremely lucky result. The pulsar was a part of a binary system that had an orbital period of about 7 hours. This means they orbited each other every 7 hours.

In the Time Domain plot, the vertical black bars are supposed to reach from the top to the bottom of the plot. These bars faded in right after we started the scan. That means the pulsar was in an eclipse when we started, and came out right afterwards. Considering the enormous mass of these objects, we had the chance to observe a real life example of Einstein's Theory of Relativity. This is where the bars start curving near the bottom of the plot. Right after we took this scan though, the antenna of the GBT overheated and we had to abort the scan of our last object.