Neutron stars provide precious information about fundamental interactions of particles, the state of dense matter, and physics of high magnetic fields, via a variety of techniques. API faculty use neutron star cooling, thermonuclear bursts on the surface of a neutron star, neutron star accretion outbursts and the oscillations observed during such events, and radio pulsar studies, among others, to probe these extreme physical processes. Radio pulsars also probe fundamentals of spacetime and gravity, e.g., via binary pulsars and pulsar timing arrays.
API's strengths in the study of dense matter and physics of high magnetic fields lie both in observational radio and X-ray studies of neutron stars, as well as their theoretical interpretation. The foreseeable future in this field will likely see the reaping of a few key fruits from the long investments made here. Pulsar searches and pulsar timing will find a nanoHertz gravitational wave background and constrain early cosmology. API scientists are leading efforts to measure the mass and radius simultaneously for millisecond pulsars using the new technique of pulse profile modelling and data from NASA's NICER instrument. Accurate mass and radius determinations of neutron stars, and probing their interiors via puls profile modelling, will finally get us the long-sought strict constraints on the neutron star equation of state and physics of strong magnetic fields. At the same time, they will deepen our understanding of their formation and evolution. In recent years, API researchers have made significant advances in measuring the neutron star equation of state and accretion processes by observations across the electromagnetic spectrum.
Neutron stars, dense matter, radio pulsars, X-ray pulsars, X-ray binaries, accretion, pulsar timing, binaries, magnetic fields
Now: Rossi X-ray Timing Explorer (RXTE) archive, Neil Gehrels Swift Observatory (Swift), Neutron Star Interior Composition Explorer (NICER), Chandra X-ray Observatory, XMM-Newton, NuSTAR, LOFAR, Westerbork Synthesis Radio Telescope (WSRT), Arecibo, Green Bank Telescope (GBT), MeerKAT, large-scale computing
Future: ATHENA, enhanced X-ray Timing and Polarimetry mission (eXTP), X-ray Imaging and Spectroscopy Mission (XRISM), Imaging X-ray Polarimetry (IXPE), LOFAR2.0, Square Kilometre Array (SKA)