research on zhi

Sensitivity of He Flames in X-ray Bursts to Nuclear Physics

Sun, 02 Feb 2025 00:00:00 -0500

Introduction

Millisecond burst oscillation phenomenon is often observed during the rise time of the X-ray burst light curve, where the oscillation frequency matches with the X-ray emission pulsation of the neutron star within few Hz. The modulation of asymmetrical burning on the surface of the neutron star due to the spreading of the initial local hotspot is the current contender theory that explains this behavior. Many have attempted to model the laterally flame propagation on the neutron star surface, with successes at studying the flame front and calculating the flame speed. In this project, I conducted a sensitivity test on how choices of nuclear reaction network, plasma screening routines, and integration coupling methods can influence the He flame dynamics. Details of the work is published in ApJ . Here I’ll just summarize the most important finding on the effect of nuclear reaction network on flame dynamics and nucleosynthesis.

Interferometry

Sun, 02 Feb 2025 00:00:00 -0500

This was my research project during my SULI internship in 2021. I was interested in estimating the precision of the two-photon interferometry technique for measuring the relative separation between two light-sources (i.e. stars) using Markov-Chain Monte Carlos (MCMC) simulation.

Two-photon Interferometer Overview

Assume there are two sources which can be observed simultaneously from two stations, L and R , with single spatial mode inputs a, b and e, f. Both sources send out photons in the form of plane wave, the path length difference between the two stations yielding phase delays \(\delta_1\) and \(\delta_2\) between the photons observed at channels a, e from source 1 and b, f from source 2, respectively. If the two detected photons are close enough in frequency and arrival time, then the pattern of coincidences measured at the outputs c, d and g, h will be sensitive to the difference in phase delays after interference at the symmetric beam splitter in each station.