Our man in Cape Town II: What science could MeerKAT do?

Posted by Daniel Pendick
on Friday, February 13, 2009

University of Cape TownIn a recent blog, I introduced you to Benne Holwerde, a young researcher at the University of Cape Town in South Africa. Check out the view from his office in the image at right. He’s on a team of scientists hoping to build a giant new radio telescope called MeerKAT (Karoo Array Telescope), a project Holwerde and his group hope will solidify South Africa as the host site for the Square Kilometre Array. Here’s another report on the project from Holwerde.

We're still busy with the “science case,” a description of what science we think can be done with MeerKAT. The case splits into different sub-fields. Here at the University of Cape Town, we have a group working on research you can do by observing the 21cm emission line of neutral hydrogen.

There are all kinds of different astrophysics you can address with the information in the 21cm line, both how nearby galaxies form and behave and how larger structures of galaxies look. This is what the Cape Town group is working up in its science case.

Nearby galaxies
What does the gas reservoir of spiral galaxies look like? How does the gas move and clump? Where is it lumping together to form stars? Do we see smaller galaxies fall into big ones like our Milky Way, forming new parts of the galaxy? How many dwarf galaxies are there anyway? These are the kind of questions we hope to address with a survey of nearby galaxies using MeerKAT.

Great Attractor
One of the nice things of the 21cm line is that our own Milky Way is transparent for it. In optical or infrared, there is too much absorption by dust in the disk to see much except what is in our own galaxy. But in the 21cm line radio observations, it will be possible to detect the large structures hiding behind the bulge of the Milky Way. There must be something there.

For some time now, we’ve known that the biggest gravitational pull in the local universe is being exerted from somewhere behind the bulge. This Great Attractor is some superstructure made of galaxies, but we scarcely know what it looks like. MeerKAT is situated beautifully for observations of the bulge (best visible in the Southern Hemisphere), so we really hope to work on this.

Hydrogen in the universe
Another issue we hope to make headway on is how much hydrogen there is in the universe, both right now and in earlier times in galaxies much, much farther away. And how that hydrogen is distributed: Is it mostly in small galaxies in the early universe, for instance?

We're now devising observation strategies and describing our plans so we can get teams and collaborations going early, before MeerKAT gets built. In two weeks, there is a big meeting here in Cape Town about the Square Kilometre Array (SKA). [MeerKAT is part of an effort to demonstrate the expertise needed to take on the larger SKA project.] So we plan to show our ideas during that and talk to people about collaborations.

It's not the most spectacular stage of a new project. Basically we're drumming up a policy document, but if we have a good one, and put together good teams, then it pays off in the long run.

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