Authors: M.W. Horbatsch, C.P. Burgess
Date: 18 Jul 2011
Abstract: Observations of pulsar timing provide strong constraints on scalar-tensor theories of gravity, but these constraints are traditionally quoted as limits on the microscopic parameters (like the Brans-Dicke coupling, for example) that govern the strength of scalar-matter couplings at the particle level in particular models. Here we present fits to timing data for several pulsars directly in terms of the phenomenological couplings (masses, scalar charges, moments of inertia and so on) of the stars involved, rather than to the more microscopic parameters of a specific model. For instance, for the double pulsar PSR J0737-3039A/B we find with 95% confidence that m_A = (1.30 +/- 0.04)m_sun, m_B = (1.21 +/- 0.04)m_sun, while the scalar-charge to mass ratios satisfy |a_A| < 0.25, |a_B| < 0.25 and |a_B - a_A| < 0.0022. These constraints are independent of the details of the scalar tensor model involved, and of assumptions about the stellar equations of state. Our fits can be used to constrain a broad class of scalar tensor theories by computing the fit quantities as functions of the microscopic parameters in any particular model, reproducing in particular standard constraints when applied to Brans-Dicke and quasi-Brans-Dicke models.
© M. Vallisneri 2012 — last modified on 2010/01/29
Tantum in modicis, quantum in maximis