Introduction to Particle Physics and High Energy Astrophysics (HET614)

Big Bang Nucleosynthesis

The origin of the stuff from which the Universe is made has been of interest for many centuries. In recent scientific history several possible scenarios for the origin of the 92 natural elements, consistent with Hubble’s observation
of an expanding Universe, have been proposed. A steady-state theory in which the Universe is eternal, elementary matter is spontaneously created everywhere to maintain a uniform density, and stars convert this to the
elements we see, was championed by Hoyle. An alternate theory, supported by Gamow, postulated that all elementary matter was created in a single primordial explosion, the so-called Big Bang, and that the current state has evolved from there. Observational evidence has since discounted Hoyle’s model by detecting artifacts of the Big Bang.

A key element of both these Universal models is a process called nucleosynthesis. The specifics of this process were of relevance to discounting Hoyle’s model. This essay addresses nucleosynthesis, its role in the Universe, and the constraints placed on the conditions of the Big Bang in order to match observational evidence.
Big Bang Nucleosynthesis Essay PDF

Pulsar Timing

Pulsars are neutron stars, with massive magnetic fields and prodigious spin rates, that emit pulses of energy with extreme regularity. They were discovered in radio wavelengths by Jocelyn Bell in 1967. The physics of pulsars is complex, however, from accurate measurement of the pulse period and its rate of change some estimates may be made of the underlying neutron star’s
age, magnetic field, and energy loss rate.

While many pulsars are visible at radio or optical wavelengths, some are dominated by X-ray emission. The study of astrophysical events in X-ray band requires high altitude or space-borne instruments because of the atmosphere’s opaque nature at these wavelengths. Consequently, it was not until the space age that the discovery and study of pulsars in X-ray wavelengths became possible. Among the notable X-ray capable spacecraft is the Rossi X-ray Timing Explorer (RXTE).

This project takes data from RXTE for two pulsars detected at X-ray wavelengths and attempts to determine the key characteristics of the objects.
Pulsar Timing Project PDF