Field notes

A few plain-language guides to questions behind my research. These short pieces are starting points; the papers contain the detailed methods and results.

How can a galaxy hide its newborn stars?

Imagine a room lit by a lamp but full of smoke. The light is still being made, yet much less reaches your eyes. Cosmic dust does something similar: it absorbs ultraviolet light from young stars and sends the energy back out at longer infrared and millimetre wavelengths. That is why a visible-light census can miss part of the Universe’s star formation. JWST helps us locate distant galaxies in near-infrared light; ALMA and other radio observatories help us measure the cold material and dust. Their combined view tells a fuller story.

Can a neighbour look like the edge of the Universe?

Yes. A very cold brown dwarf in our own Milky Way can have colours that resemble an extremely remote galaxy in deep JWST images. The way to separate them is to let time help: a nearby object can move slightly against the background between observations. That small shift, called proper motion, was central to our work showing that the object nicknamed Capotauro was a cold brown dwarf, rather than a galaxy at redshift about 32. A surprising result can be valuable even when it changes the original story.

Why look at the same patch of sky with many telescopes?

A telescope is sensitive to particular wavelengths, much as a camera might see only one colour. In astronomy, those wavelengths often trace different physical ingredients: starlight, warm dust, cold gas, or energetic activity near a black hole. When the same region has been observed by several facilities, we can compare those clues and test a physical explanation. This is the idea behind multi-wavelength astronomy — assembling a scene from more than one kind of light.