DRAO Seminar Series 2024

Time & Date Speaker Title
14:00 Tues Feb 13 Carolin Höfer
University of Groningen
Latest results of LOFAR’s Epoch of Reionization Key Science Project
14:00 Tues Mar 19 Denis Leahy
University of Calgary
Properties of Supernova Remnants from 1-D Models

Latest results of LOFAR’s Epoch of Reionization Key Science Project

Carolin Höfer (University of Groningen)

The Low Frequency Observing Array (LOFAR) is European’s largest radio interferometer operating between 30 – 240 MHz and a pathfinder for the SKA. Utilising a phased-array design, the antennae are grouped together into stations, with a dense core located near Exoloo, the northeast of The Netherlands. The Epoch of Reionization Key Science project uses the high-band antenna system, which covers LOFAR’s spectral response between 110-240 MHz corresponding to a redshift range z ~ 6 – 10. Its science goal is to answer how the first stars, galaxies and black holes formed by measuring the spatial fluctuations of the redshifted 21-cm emission of neutral hydrogen.

One of greatest challenges is to calibrate the instrument precisely, considering that astrophysical foregrounds are several orders brighter than the cosmological signal. I will discuss LOFAR’s latest data processing of the NCP and present our current upper limits on the 21-cm power spectrum. I will then discuss in more detail our current calibration strategy and some of the challenges we are still facing. I implemented a simulation pipeline and will show the effects of incomplete sky models on calibration solutions, images and power spectra.

Properties of Supernova Remnants from 1-D Models

Denis Leahy (University of Calgary)

Supernova remnants are the interaction of a supernova explosion with the interstellar medium, and result in spectacular radio and X-ray images. Here is described how 1-dimensional models (from simple to complex) can be used to learn about the physical properties of supernova remnants, such as their ages and explosion energies. Separately is described recent work on the significant effects of a simple (incorrect) assumption of the most common X-ray spectrum fitting software (XSPEC) and how to correct for this assumption to obtain physical values inferred from the X-ray spectrum.