That's it! Thank you for seeing me through to the end of this journey.

This work was done together with a crew of brilliant and talented people, including but not limited to,
@Kerens and @janerigby
plus a number of folks not present in the Fediverse.

Bye for now! 👋

23/23

What can we learn from this?

We can learn that in this galaxy, most of the ionized light is produced in the bright center of the galaxy, but it cannot get out from there.

The smaller amount which is produced in the tidal bridge has a much easier time getting out. 20/

If we look at gas and stars side by side, we can see that there isn't a lot of gas by the "spike" of stars where the ionizing gas escapes.

We can also see a bridge of gas as a vague green strand between the two galaxies. The strand of starlight, from which the ionizing light escapes, is not at the same place as the gas! That is normal for galaxy interactions and is exactly **why** the ionizing light can escape so easily from there. 19/

We used publicly available data from the JWST archives to study how warm ionized is arranged and moves around in these galaxies.

In the picture below, the left panel shows how the gas moves - the difference in redshift means the two galaxies move about 500 km/s relative to each other, which is very typical for galaxies in the early stages of merging.

The right panel shows the brightness of a spectral line shining from warm ionized gas. The circle shows where the ionizing light escapes. 18/

...but if a large clump of young and powerful stars happen to form in such a bridge, they are already removed from most of the neutral gas in the galaxy, and can easily blow or burn the rest away, and their ionizing light get out!

That is exactly what we found!
Here's two Hubble telescope images of the galaxy, the left shows normal starlight, the right shows the ionizing light. Notice how the core of the galaxy is much brighter, but its hydrogen gas completely blocks the ionizing light! 14/

But! What we found in the newly published paper was neither of those, but instead a **third** effect.

When galaxies interact, they can draw out long strands of gas between them, called a "tidal bridge". And sometimes, new stars can form in such a tidal bridge - this is all something that has been observed many times before.

(Here's a nearby galaxy pair with a tidal bridge for illustration) 13/

This effect was first observed a couple of years ago by my collaborator, Alexandra Le Reste, who pulled off what no one had done before and observed the neutral hydrogen in a LyC leaker using the MeerKAT radio telescope array.

The contours on the image below show where the neutral hydrogen is, the red stuff is hydrogen that is already mostly ionized, and the bright star clusters are where the ionizing light escapes from. It should be clear how the gravitational peel helped it along! 12/