Precision multi-telescope timing of millisecond pulsars: New limits on the gravitational wave background and other results from the pulsar timing array

This thesis presents new results from the “Pulsar Timing Array” (PTA) which is an array of millisecond pulsars (MSPs) being used to detect a Gravitational Wave Background (GWB). Our goal is to make the PTA as sensitive as possible. To this end, we make a number of advances in precision pulsar timing. We have devised a technique to create idealized analytical templates at arbitrary frequencies. We include the analytical model here for PSRs J1022+1001, J1713+0747, and B1855+09. These templates allow us to connect data at any frequency from any telescope into the same data set, with often less than 5μs of error between the sets. The detailed description of the pulse-profile over a wide range of frequencies also allows new insight into the pulse-emission mechanism.; We have connected pre-upgrade Arecibo telescope data with both Green Bank 140-ft telescope data and with post-upgrade data to make 17-yr data sets on both PSRs B1855+09 and B1937+21, and a 9-yr data set on PSR J1713+0747. These long baselines allow us to refine model parameters, and to suggest that a planet orbits PSR B1937+21. We update the curve of Timing Noise vs. Period Derivative and show that we need not be as pessimistic as previously thought about Timing Noise limiting the PTA. We show that MSP timing will soon have a lower fractional stability than terrestrial time standards. Finally, we place a new limit on the amount of Gravitational Radiation present in the galaxy $rrc$ = 2 × 10−9h−2 . This is more than an order of magnitude lower than the previous result by Kaspi et al. (1994).; The GWB we intend to measure in the near future is expected to be stochastic, but we consider the possibility that we can measure individual coalescence events using the PTA. In particular we consider a binary black hole at the Galactic Center, and go on to consider possible binarity in other known massive black holes in nearby galaxies. We conclude that amplitudes sufficiently large enough for detection would in fact be produced by some of the nearby galaxies, but the timescale for coalescence would be so short that its detection would be highly improbable.; One of the milestones we recommend for the PTA in the next 10 years is the discovery of 6 to 10 more millisecond pulsars that demonstrate sub-microsecond precision in their timing residuals. Here, we report the discovery of pulsars J0030+0451, J0711+0931, and J1313+0931 that were found in a search of 470 square degrees at 430 MHz using the 305m Arecibo telescope. Spin and astrometric parameters for the three pulsars are presented along with polarimetry at 430 MHz. PSR J0030+0451, a nearby pulsar with a period of 4.8 ms, belongs to the less common category of isolated millisecond pulsars. We have measured significant polarization in PSR J0030+0451 over more than 50% of the period, and use these data for a detailed discussion of its magnetospheric geometry.