GBT19A-411

Timing and Three-Body Integration of the Pulsar Triple System in Messier 4

Abstract

We request eight 45-minute sessions over a 12-month period (beginning in 19A) in order to continue long-term timing observations of the millisecond pulsar PSR B1620-26. This object is believed to be a member of a hierarchical triple system, orbited by a low-mass white dwarf every 191 days and a Jupiter-mass planet every $\sim$ 50-100 years. As described in the proposal text, preliminary progress in our analysis has allowed us, for the first time, to apply predictions of a custom, high-precision numerical three-body integrator to our time-of-arrival (TOA) data. It appears likely that the numerical calculations will largely explain the complex timing variations, and additional TOAs will improve our estimate of the mass and geometric parameters of the entire system, as argued in the proposal. We are currently in the process of refining our integrator-based timing model, as well as improving its runtime performance for more efficient calculations. Our goals are to determine the mass and geometric parameters of both orbits from the observed TOA variations, as well as effects from acceleration in the globular-cluster potential. We will use the VEGAS spectrometer (in "pulsar-fold", coherent-dedispersion mode) and the 1400-MHz receiver at the GBT.

Investigators

Name	Institution
Emmanuel Fonseca *	British Columbia, University of; McGill University; West Virginia University
Ingrid Stairs	British Columbia, University of
Anne Archibald	Netherlands Institute for Radio Astronomy; McGill University; Newcastle University
Nicolas Caballero	Max-Planck-Institut für Radioastronomie
Michael Kramer	Manchester, University of; Max-Planck-Institut für Radioastronomie
Zaven Arzoumanian	Goddard Space Flight Center
Steinn Sigurdsson	Pennsylvania State University
Ben Stappers	Manchester, University of
Andrew Lyne	Manchester, University of
Steve Thorsett	California at Santa Cruz, University of

* indicates the PI