riassunto2

BN1 - Compact Binaries and Strong-Field Tests of Gravity

Speaker

Ridolfi, Alessandro

Coauthors

Freire, Paulo; Kramer, Michael

Talk Title

Early results from M15C, a pulsar in a double neutron star system showing evidence of geodetic precession occurring

Abstract

Pulsars in Double Neutron Star systems (DNSs) are outstanding natural laboratories for studying gravitation. PSR B2127+11C (or M15C) is a pulsar in a double neutron star system in the globular cluster M15, with a very eccentric (e=0.68) orbit and an orbital period of about 8 hours, that makes it very similar to PSR B1913+16, the Hulse-Taylor pulsar. As for the latter, three post-Keplerian parameters have been measured in this system, representing a test of General Relativity (GR). Furthermore, in the last few years, its pulse profile has shown a systematic change that can be ascribed to geodetic precession, an effect predicted by GR. In this talk we report some preliminary results from our continued observing campaign of M15C done at the Arecibo radio telescope and our effort to model the geodetic precession effect, thanks to the new and more sensitive instruments now available. Since the last published timing solution in 2006, the timing precision for M15C has improved by a factor of 50, allowing much better constraints of the parameters. Also, the new polarimetric data will enable us to better map the pulsar beam over time, thus helping us to study the geometry of the system.

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