codman

Constraining the neutrino mass using a multi-tracer combination of two galaxy surveys and CMB lensing

13/09/2021 by codman

Measuring the total neutrino mass is one of the most exciting opportunities available with next-generation cosmological data sets. We study the possibility of detecting the total neutrino mass using large-scale clustering in 21cm intensity mapping and photometric galaxy surveys, together with CMB information. We include the scale-dependent halo bias contribution due to the presence of …

UWC’s Best Masters student awarded to Mr Mogamad-Junaid Townsend

27/08/2021 by codman

The award was announced during UWC’s Annual Research Recognition Awards and presented by the DVC Research and Innovation, Prof. Jozé Frantz. Mogamad-Junaid competed his MSc Summa Cum Laude within 2 years of enrolling. His hope is to go on and pursue a career as a cosmologist, studying the history and evolution of the universe, while …

Large fireball illuminates Southern African skies

25/08/202125/08/2021 by codman

On the evening of August 24, a bright object traveling fast in the upper atmosphere had thousands of people mesmerised. It was spotted by many in the Gauteng province of South Africa but was visible further North into Limpopo and Zimbabwe. At first we didn’t know what it was. ☄️BREAKING: SA Astronomical Observatory confirms large #meteor/fireball …

The first nova eruption in a novalike variable: YZ Ret as seen in X-rays and gamma-rays

27/08/202119/08/2021 by codman

Peaking at 3.7 mag on 2020 July 11, YZ Ret was the second-brightest nova of the decade. The nova’s moderate proximity (2.7 kpc from Gaia) provided an opportunity to explore its multi-wavelength properties in great detail. Here we report on YZ Ret as part of a long-term project to identify the physical mechanisms responsible for …

HERA Phase I Limits on the Cosmic 21-cm Signal: Constraints on Astrophysics and Cosmology During the Epoch of Reionization

18/08/2021 by codman

Recently, the Hydrogen Epoch of Reionization Array (HERA) collaboration has produced the experiment’s first upper limits on the power spectrum of 21-cm fluctuations at z~8 and 10. Here, we use several independent theoretical models to infer constraints on the intergalactic medium (IGM) and galaxies during the epoch of reionization (EoR) from these limits. We find …

Multi-wavelength spectroscopic probes: biases from neglecting light-cone effects

13/08/2021 by codman

Next-generation cosmological surveys will observe larger cosmic volumes than ever before, enabling us to access information on the primordial Universe, as well as on relativistic effects. In a companion paper, we applied a Fisher analysis to forecast the expected precision on fNL and the detectability of the lensing magnification and Doppler contributions to the power spectrum. Here …

New analysis of more than 2000 Galaxies with MeerKAT

12/08/2021 by codman

Using early science data for the MIGHTEE project on the MeerKAT radio telescope, a researcher at the University of the Western Cape – with collaborators from eight countries, including four other South African Institutions – has analysed over 2000 galaxies, growing our understanding of the evolution of galaxies over cosmic time. Dr Fangxia An – …

First Results from HERA Phase I: Upper Limits on the Epoch of Reionization 21 cm Power Spectrum

06/08/2021 by codman

We report upper-limits on the Epoch of Reionization (EoR) 21 cm power spectrum at redshifts 7.9 and 10.4 with 18 nights of data (∼36 hours of integration) from Phase I of the Hydrogen Epoch of Reionization Array (HERA). The Phase I data show evidence for systematics that can be largely suppressed with systematic models down to …

Follow-up of 27 radio-quiet gamma-ray pulsars at 110-190 MHz using the international LOFAR station FR606

05/08/2021 by codman

The Fermi Large Area Telescope has detected over 260 gamma-ray pulsars. About one quarter of these are labeled as radio-quiet. In the population of nonrecycled gamma-ray pulsars, the fraction of radio-quiet pulsars is higher, about one half. Most radio observations of gamma-ray pulsars have been performed at frequencies between 300 MHz and 2 GHz. However, …

Optimization of the Observing Cadence for the Rubin Observatory Legacy Survey of Space and Time: a pioneering process of community-focused experimental design

05/08/2021 by codman

Vera C. Rubin Observatory is a ground-based astronomical facility under construction, a joint project of the National Science Foundation and the U.S. Department of Energy, designed to conduct a multi-purpose 10-year optical survey of the southern hemisphere sky: the Legacy Survey of Space and Time. Significant flexibility in survey strategy remains within the constraints imposed …