Events in Physics
Andrew Mason: Neutron star masses in High Mass X-ray Binaries
The precise form of the equation of state (EOS) for neutron stars (NS) has long been an outstanding problem within astrophysics. There have been numerous theoretically derived EOS proposed over the previous few decades, each of which define a NS mass-radius relation and predict a maximum NS mass. In order to eliminate some of the contending theories we must however turn to observations.
Within this talk I will describe our ongoing work within the area of High Mass X-ray Binaries (HMXB) in which we have attempted to determine the upper mass limit for neutron stars. The systems in which this can be achieved are rare, and the main part of this talk will comprise our work on 3 HMXB systems containing an eclipsing X-ray pulsar : OAO 1657-415, EXO 1722-363 and IGR J18027-2016.
The companion massive star in each of these systems is extremely obscured and is only observable in the near-infrared (NIR). Observations obtained over the last few years from ESO VLT and the NIR spectrograph ISSAC has allowed the construction of an orbital solution and a corresponding NS mass range determination for each system, the first time this has been achieved in the NIR.