Episode 43: The search for hidden hydrogen

with Dr Tariq Blecher and Shilpa Ranchod

In this episode we are joined by Dr Tariq Blecher and Shilpa Ranchod who talk to us about the clever ways they are trying to capture the elusive signals of hydrogen gas in the distant Universe.

Hydrogen is one of the most common elements in the Universe and this gas is one of the fundamental building blocks of galaxies. Yet the radio signal released by hydrogen gas is very faint, and so is notoriously difficult to detect.

Tariq and Shilpa, who are colleagues, are both trying to pry open the secrets of hidden hydrogen in the distant Universe by using very clever strategies.

Tariq was recently awarded his PhD from Rhodes University and he joins us to explain some of his thesis research. He tried to make the first detection of hydrogen with “gravitational lensing.” He tells us that giant galaxies and clusters can act as cosmic lenses to magnify the signals from very distant galaxies behind them.

If successful, this technique could help us understand more about galaxy evolution and dark matter.

We are then joined by Shilpa Ranchod who recently completed her MSc at the University of Pretoria. Shilpa is also searching for hydrogen signals using gravitational lensing. She uses South Africa’s powerful MeerKAT telescope, combined with another clever technique called “stacking.”

Shilpa was also recently in the press for her discovery of an entire group of galaxies hiding in plain sight! This galaxy group likely contains more neutral hydrogen gas than most groups ever discovered!

The galaxy group was discovered by the MeerKAT International Gigahertz Tiered Extragalactic Exploration (MIGHTEE) survey. MeerKAT strikes again!

Optical image of the galaxy group with three-colour optical images of each member galaxy. The red outline indicates the extent of the neutral hydrogen gas around each galaxy. The central image, also showing the many thousands of background galaxies, is one degree on each side, large enough to fit four full moons. (Shilpa Ranchod/MIGHTEE/HSC project)
An animation showing the location of neutral hydrogen around a galaxy group (Shilpa Ranchod/MIGHTEE/HSC project)

This week’s guests

Related Links

Shilpa’s contact details:

Instagram @helloshilpa
Email: shiplaranchod_at_gmail.com
Press Release of Shilpa’s paper: https://www.sarao.ac.za/media-releases/meerkat-discovers-large-gas-rich-galaxy-group-hiding-in-plain-sight/

Transcript