The CMB is our key to understanding the Big Bang

The Cosmic Microwave Background (CMB) consists of photons trapped in the early universe. About 375,000 years after the Big Bang, ions cooled and combined with free electrons to form atoms, allowing the CMB to travel freely through space. It acts like a snapshot of the early universe.

Figure uses data from Planck PR3^[2]

The problem is that it's hidden behind the Milky Way

Since the CMB was released 375,000 years after the Big Bang, it lies behind everything that has occurred over the last 13.6 billion years. This includes human-made foregrounds (e.g., emission from radio towers, satellites), solar system objects (e.g., planets, the Sun), extragalactic sources (e.g., the Andromeda Galaxy, Magellanic Clouds), and emission from our own Galaxy.

Figure uses data from Planck PR3^[1]

But importantly - the CMB signal is still there

Since dust is transparent at radio frequencies, we can see beyond the dust that obscures our view in visible light. This means that the CMB signal is still present in our radio maps. To reveal it, we simply need to subtract all other emissions along the line of sight.

Figure uses data from Planck PR3^[1]

Through comparing different maps, we can learn about foreground emission from our Galaxy

By collecting sky maps at various radio frequencies and quantifying how the integrated flux density of different objects changes across the radio spectrum, we can fit models to the Galaxy's emission. These models typically account for synchrotron emission (from cosmic ray electrons and supernova remnants), free-free emission (from ionized gas), spinning dust (from photodissociation regions), and thermal dust (from warm dust).

Figure uses data from Planck PR3^[1]

The more we know, the better our models get, and the better our CMB maps get

Each new map provides an additional data point to further constrain our models of the foreground. This allows us to refine both the spatial distribution and the frequency dependence of foreground components. As our models of the CMB foregrounds become more precise, we gain greater confidence in the final foreground-subtracted CMB maps, leading to higher accuracy in the cosmological parameters derived from them.

Figure uses data from Comoglobe DR1^[3]

My contribution is through processing and analysing survey data

I am currently involved with two experiments:

• CGEM - Polarised foregrounds experiment at DRAO, Canada mapping the north-sky at 8-10 GHz at 30 arcminute resolution. website
• COMAP - CO LIM experiment with a Galctic Plane survey a a secondary science goal. Cited at OVRO, California mapping the Galactic Plane at 26-34 GHz at 5 arcminute resultion. website